The Tor Browser: comparison media/libpng/pngrutil.c

--1:000000000000
+:60201709ce46
+/* pngrutil.c - utilities to read a PNG file
+*
+* Last changed in libpng 1.6.10 [March 6, 2014]
+* Copyright (c) 1998-2014 Glenn Randers-Pehrson
+* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+*
+* This code is released under the libpng license.
+* For conditions of distribution and use, see the disclaimer
+* and license in png.h
+*
+* This file contains routines that are only called from within
+* libpng itself during the course of reading an image.
+*/
+#include "pngpriv.h"
+#ifdef PNG_READ_SUPPORTED
+png_uint_32 PNGAPI
+png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
+{
+png_uint_32 uval = png_get_uint_32(buf);
+if (uval > PNG_UINT_31_MAX)
+png_error(png_ptr, "PNG unsigned integer out of range");
+return (uval);
+}
+#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
+/* The following is a variation on the above for use with the fixed
+* point values used for gAMA and cHRM.  Instead of png_error it
+* issues a warning and returns (-1) - an invalid value because both
+* gAMA and cHRM use *unsigned* integers for fixed point values.
+*/
+#define PNG_FIXED_ERROR (-1)
+static png_fixed_point /* PRIVATE */
+png_get_fixed_point(png_structrp png_ptr, png_const_bytep buf)
+{
+png_uint_32 uval = png_get_uint_32(buf);
+if (uval <= PNG_UINT_31_MAX)
+return (png_fixed_point)uval; /* known to be in range */
+/* The caller can turn off the warning by passing NULL. */
+if (png_ptr != NULL)
+png_warning(png_ptr, "PNG fixed point integer out of range");
+return PNG_FIXED_ERROR;
+}
+#endif
+#ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
+/* NOTE: the read macros will obscure these definitions, so that if
+* PNG_USE_READ_MACROS is set the library will not use them internally,
+* but the APIs will still be available externally.
+*
+* The parentheses around "PNGAPI function_name" in the following three
+* functions are necessary because they allow the macros to co-exist with
+* these (unused but exported) functions.
+*/
+/* Grab an unsigned 32-bit integer from a buffer in big-endian format. */
+png_uint_32 (PNGAPI
+png_get_uint_32)(png_const_bytep buf)
+{
+png_uint_32 uval =
+((png_uint_32)(*(buf    )) << 24) +
+((png_uint_32)(*(buf + 1)) << 16) +
+((png_uint_32)(*(buf + 2)) <<  8) +
+((png_uint_32)(*(buf + 3))      ) ;
+return uval;
+}
+/* Grab a signed 32-bit integer from a buffer in big-endian format.  The
+* data is stored in the PNG file in two's complement format and there
+* is no guarantee that a 'png_int_32' is exactly 32 bits, therefore
+* the following code does a two's complement to native conversion.
+*/
+png_int_32 (PNGAPI
+png_get_int_32)(png_const_bytep buf)
+{
+png_uint_32 uval = png_get_uint_32(buf);
+if ((uval & 0x80000000) == 0) /* non-negative */
+return uval;
+uval = (uval ^ 0xffffffff) + 1;  /* 2's complement: -x = ~x+1 */
+return -(png_int_32)uval;
+}
+/* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
+png_uint_16 (PNGAPI
+png_get_uint_16)(png_const_bytep buf)
+{
+/* ANSI-C requires an int value to accomodate at least 16 bits so this
+* works and allows the compiler not to worry about possible narrowing
+* on 32 bit systems.  (Pre-ANSI systems did not make integers smaller
+* than 16 bits either.)
+*/
+unsigned int val =
+((unsigned int)(*buf) << 8) +
+((unsigned int)(*(buf + 1)));
+return (png_uint_16)val;
+}
+#endif /* PNG_READ_INT_FUNCTIONS_SUPPORTED */
+/* Read and check the PNG file signature */
+void /* PRIVATE */
+png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
+{
+png_size_t num_checked, num_to_check;
+/* Exit if the user application does not expect a signature. */
+if (png_ptr->sig_bytes >= 8)
+return;
+num_checked = png_ptr->sig_bytes;
+num_to_check = 8 - num_checked;
+#ifdef PNG_IO_STATE_SUPPORTED
+png_ptr->io_state = PNG_IO_READING | PNG_IO_SIGNATURE;
+#endif
+/* The signature must be serialized in a single I/O call. */
+png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
+png_ptr->sig_bytes = 8;
+if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
+{
+if (num_checked < 4 &&
+png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
+png_error(png_ptr, "Not a PNG file");
+else
+png_error(png_ptr, "PNG file corrupted by ASCII conversion");
+}
+if (num_checked < 3)
+png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
+}
+/* Read the chunk header (length + type name).
+* Put the type name into png_ptr->chunk_name, and return the length.
+*/
+png_uint_32 /* PRIVATE */
+png_read_chunk_header(png_structrp png_ptr)
+{
+png_byte buf[8];
+png_uint_32 length;
+#ifdef PNG_IO_STATE_SUPPORTED
+png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
+#endif
+/* Read the length and the chunk name.
+* This must be performed in a single I/O call.
+*/
+png_read_data(png_ptr, buf, 8);
+length = png_get_uint_31(png_ptr, buf);
+/* Put the chunk name into png_ptr->chunk_name. */
+png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(buf+4);
+png_debug2(0, "Reading %lx chunk, length = %lu",
+(unsigned long)png_ptr->chunk_name, (unsigned long)length);
+/* Reset the crc and run it over the chunk name. */
+png_reset_crc(png_ptr);
+png_calculate_crc(png_ptr, buf + 4, 4);
+/* Check to see if chunk name is valid. */
+png_check_chunk_name(png_ptr, png_ptr->chunk_name);
+#ifdef PNG_IO_STATE_SUPPORTED
+png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
+#endif
+return length;
+}
+/* Read data, and (optionally) run it through the CRC. */
+void /* PRIVATE */
+png_crc_read(png_structrp png_ptr, png_bytep buf, png_uint_32 length)
+{
+if (png_ptr == NULL)
+return;
+png_read_data(png_ptr, buf, length);
+png_calculate_crc(png_ptr, buf, length);
+}
+/* Optionally skip data and then check the CRC.  Depending on whether we
+* are reading an ancillary or critical chunk, and how the program has set
+* things up, we may calculate the CRC on the data and print a message.
+* Returns '1' if there was a CRC error, '0' otherwise.
+*/
+int /* PRIVATE */
+png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
+{
+/* The size of the local buffer for inflate is a good guess as to a
+* reasonable size to use for buffering reads from the application.
+*/
+while (skip > 0)
+{
+png_uint_32 len;
+png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
+len = (sizeof tmpbuf);
+if (len > skip)
+len = skip;
+skip -= len;
+png_crc_read(png_ptr, tmpbuf, len);
+}
+if (png_crc_error(png_ptr))
+{
+if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) ?
+!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :
+(png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
+{
+png_chunk_warning(png_ptr, "CRC error");
+}
+else
+png_chunk_error(png_ptr, "CRC error");
+return (1);
+}
+return (0);
+}
+/* Compare the CRC stored in the PNG file with that calculated by libpng from
+* the data it has read thus far.
+*/
+int /* PRIVATE */
+png_crc_error(png_structrp png_ptr)
+{
+png_byte crc_bytes[4];
+png_uint_32 crc;
+int need_crc = 1;
+if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))
+{
+if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
+(PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
+need_crc = 0;
+}
+else /* critical */
+{
+if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
+need_crc = 0;
+}
+#ifdef PNG_IO_STATE_SUPPORTED
+png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
+#endif
+/* The chunk CRC must be serialized in a single I/O call. */
+png_read_data(png_ptr, crc_bytes, 4);
+if (need_crc)
+{
+crc = png_get_uint_32(crc_bytes);
+return ((int)(crc != png_ptr->crc));
+}
+else
+return (0);
+}
+#if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\
+defined(PNG_READ_pCAL_SUPPORTED) || defined(PNG_READ_sCAL_SUPPORTED) ||\
+defined(PNG_READ_sPLT_SUPPORTED) || defined(PNG_READ_tEXt_SUPPORTED) ||\
+defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_SEQUENTIAL_READ_SUPPORTED)
+/* Manage the read buffer; this simply reallocates the buffer if it is not small
+* enough (or if it is not allocated).  The routine returns a pointer to the
+* buffer; if an error occurs and 'warn' is set the routine returns NULL, else
+* it will call png_error (via png_malloc) on failure.  (warn == 2 means
+* 'silent').
+*/
+static png_bytep
+png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
+{
+png_bytep buffer = png_ptr->read_buffer;
+if (buffer != NULL && new_size > png_ptr->read_buffer_size)
+{
+png_ptr->read_buffer = NULL;
+png_ptr->read_buffer = NULL;
+png_ptr->read_buffer_size = 0;
+png_free(png_ptr, buffer);
+buffer = NULL;
+}
+if (buffer == NULL)
+{
+buffer = png_voidcast(png_bytep, png_malloc_base(png_ptr, new_size));
+if (buffer != NULL)
+{
+png_ptr->read_buffer = buffer;
+png_ptr->read_buffer_size = new_size;
+}
+else if (warn < 2) /* else silent */
+{
+if (warn)
+png_chunk_warning(png_ptr, "insufficient memory to read chunk");
+else
+png_chunk_error(png_ptr, "insufficient memory to read chunk");
+}
+}
+return buffer;
+}
+#endif /* PNG_READ_iCCP|iTXt|pCAL|sCAL|sPLT|tEXt|zTXt|SEQUENTIAL_READ */
+/* png_inflate_claim: claim the zstream for some nefarious purpose that involves
+* decompression.  Returns Z_OK on success, else a zlib error code.  It checks
+* the owner but, in final release builds, just issues a warning if some other
+* chunk apparently owns the stream.  Prior to release it does a png_error.
+*/
+static int
+png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
+{
+if (png_ptr->zowner != 0)
+{
+char msg[64];
+PNG_STRING_FROM_CHUNK(msg, png_ptr->zowner);
+/* So the message that results is "<chunk> using zstream"; this is an
+* internal error, but is very useful for debugging.  i18n requirements
+* are minimal.
+*/
+(void)png_safecat(msg, (sizeof msg), 4, " using zstream");
+#     if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
+png_chunk_warning(png_ptr, msg);
+png_ptr->zowner = 0;
+#     else
+png_chunk_error(png_ptr, msg);
+#     endif
+}
+/* Implementation note: unlike 'png_deflate_claim' this internal function
+* does not take the size of the data as an argument.  Some efficiency could
+* be gained by using this when it is known *if* the zlib stream itself does
+* not record the number; however, this is an illusion: the original writer
+* of the PNG may have selected a lower window size, and we really must
+* follow that because, for systems with with limited capabilities, we
+* would otherwise reject the application's attempts to use a smaller window
+* size (zlib doesn't have an interface to say "this or lower"!).
+*
+* inflateReset2 was added to zlib 1.2.4; before this the window could not be
+* reset, therefore it is necessary to always allocate the maximum window
+* size with earlier zlibs just in case later compressed chunks need it.
+*/
+{
+int ret; /* zlib return code */
+#     if PNG_ZLIB_VERNUM >= 0x1240
+#        if defined(PNG_SET_OPTION_SUPPORTED) && \
+defined(PNG_MAXIMUM_INFLATE_WINDOW)
+int window_bits;
+if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
+PNG_OPTION_ON)
+window_bits = 15;
+else
+window_bits = 0;
+#        else
+#           define window_bits 0
+#        endif
+#     endif
+/* Set this for safety, just in case the previous owner left pointers to
+* memory allocations.
+*/
+png_ptr->zstream.next_in = NULL;
+png_ptr->zstream.avail_in = 0;
+png_ptr->zstream.next_out = NULL;
+png_ptr->zstream.avail_out = 0;
+if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
+{
+#        if PNG_ZLIB_VERNUM < 0x1240
+ret = inflateReset(&png_ptr->zstream);
+#        else
+ret = inflateReset2(&png_ptr->zstream, window_bits);
+#        endif
+}
+else
+{
+#        if PNG_ZLIB_VERNUM < 0x1240
+ret = inflateInit(&png_ptr->zstream);
+#        else
+ret = inflateInit2(&png_ptr->zstream, window_bits);
+#        endif
+if (ret == Z_OK)
+png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
+}
+if (ret == Z_OK)
+png_ptr->zowner = owner;
+else
+png_zstream_error(png_ptr, ret);
+return ret;
+}
+#  ifdef window_bits
+#     undef window_bits
+#  endif
+}
+#ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
+/* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
+* allow the caller to do multiple calls if required.  If the 'finish' flag is
+* set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
+* be returned or there has been a problem, otherwise Z_SYNC_FLUSH is used and
+* Z_OK or Z_STREAM_END will be returned on success.
+*
+* The input and output sizes are updated to the actual amounts of data consumed
+* or written, not the amount available (as in a z_stream).  The data pointers
+* are not changed, so the next input is (data+input_size) and the next
+* available output is (output+output_size).
+*/
+static int
+png_inflate(png_structrp png_ptr, png_uint_32 owner, int finish,
+/* INPUT: */ png_const_bytep input, png_uint_32p input_size_ptr,
+/* OUTPUT: */ png_bytep output, png_alloc_size_t *output_size_ptr)
+{
+if (png_ptr->zowner == owner) /* Else not claimed */
+{
+int ret;
+png_alloc_size_t avail_out = *output_size_ptr;
+png_uint_32 avail_in = *input_size_ptr;
+/* zlib can't necessarily handle more than 65535 bytes at once (i.e. it
+* can't even necessarily handle 65536 bytes) because the type uInt is
+* "16 bits or more".  Consequently it is necessary to chunk the input to
+* zlib.  This code uses ZLIB_IO_MAX, from pngpriv.h, as the maximum (the
+* maximum value that can be stored in a uInt.)  It is possible to set
+* ZLIB_IO_MAX to a lower value in pngpriv.h and this may sometimes have
+* a performance advantage, because it reduces the amount of data accessed
+* at each step and that may give the OS more time to page it in.
+*/
+png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input);
+/* avail_in and avail_out are set below from 'size' */
+png_ptr->zstream.avail_in = 0;
+png_ptr->zstream.avail_out = 0;
+/* Read directly into the output if it is available (this is set to
+* a local buffer below if output is NULL).
+*/
+if (output != NULL)
+png_ptr->zstream.next_out = output;
+do
+{
+uInt avail;
+Byte local_buffer[PNG_INFLATE_BUF_SIZE];
+/* zlib INPUT BUFFER */
+/* The setting of 'avail_in' used to be outside the loop; by setting it
+* inside it is possible to chunk the input to zlib and simply rely on
+* zlib to advance the 'next_in' pointer.  This allows arbitrary
+* amounts of data to be passed through zlib at the unavoidable cost of
+* requiring a window save (memcpy of up to 32768 output bytes)
+* every ZLIB_IO_MAX input bytes.
+*/
+avail_in += png_ptr->zstream.avail_in; /* not consumed last time */
+avail = ZLIB_IO_MAX;
+if (avail_in < avail)
+avail = (uInt)avail_in; /* safe: < than ZLIB_IO_MAX */
+avail_in -= avail;
+png_ptr->zstream.avail_in = avail;
+/* zlib OUTPUT BUFFER */
+avail_out += png_ptr->zstream.avail_out; /* not written last time */
+avail = ZLIB_IO_MAX; /* maximum zlib can process */
+if (output == NULL)
+{
+/* Reset the output buffer each time round if output is NULL and
+* make available the full buffer, up to 'remaining_space'
+*/
+png_ptr->zstream.next_out = local_buffer;
+if ((sizeof local_buffer) < avail)
+avail = (sizeof local_buffer);
+}
+if (avail_out < avail)
+avail = (uInt)avail_out; /* safe: < ZLIB_IO_MAX */
+png_ptr->zstream.avail_out = avail;
+avail_out -= avail;
+/* zlib inflate call */
+/* In fact 'avail_out' may be 0 at this point, that happens at the end
+* of the read when the final LZ end code was not passed at the end of
+* the previous chunk of input data.  Tell zlib if we have reached the
+* end of the output buffer.
+*/
+ret = inflate(&png_ptr->zstream, avail_out > 0 ? Z_NO_FLUSH :
+(finish ? Z_FINISH : Z_SYNC_FLUSH));
+} while (ret == Z_OK);
+/* For safety kill the local buffer pointer now */
+if (output == NULL)
+png_ptr->zstream.next_out = NULL;
+/* Claw back the 'size' and 'remaining_space' byte counts. */
+avail_in += png_ptr->zstream.avail_in;
+avail_out += png_ptr->zstream.avail_out;
+/* Update the input and output sizes; the updated values are the amount
+* consumed or written, effectively the inverse of what zlib uses.
+*/
+if (avail_out > 0)
+*output_size_ptr -= avail_out;
+if (avail_in > 0)
+*input_size_ptr -= avail_in;
+/* Ensure png_ptr->zstream.msg is set (even in the success case!) */
+png_zstream_error(png_ptr, ret);
+return ret;
+}
+else
+{
+/* This is a bad internal error.  The recovery assigns to the zstream msg
+* pointer, which is not owned by the caller, but this is safe; it's only
+* used on errors!
+*/
+png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
+return Z_STREAM_ERROR;
+}
+}
+/*
+* Decompress trailing data in a chunk.  The assumption is that read_buffer
+* points at an allocated area holding the contents of a chunk with a
+* trailing compressed part.  What we get back is an allocated area
+* holding the original prefix part and an uncompressed version of the
+* trailing part (the malloc area passed in is freed).
+*/
+static int
+png_decompress_chunk(png_structrp png_ptr,
+png_uint_32 chunklength, png_uint_32 prefix_size,
+png_alloc_size_t *newlength /* must be initialized to the maximum! */,
+int terminate /*add a '\0' to the end of the uncompressed data*/)
+{
+/* TODO: implement different limits for different types of chunk.
+*
+* The caller supplies *newlength set to the maximum length of the
+* uncompressed data, but this routine allocates space for the prefix and
+* maybe a '\0' terminator too.  We have to assume that 'prefix_size' is
+* limited only by the maximum chunk size.
+*/
+png_alloc_size_t limit = PNG_SIZE_MAX;
+#  ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+if (png_ptr->user_chunk_malloc_max > 0 &&
+png_ptr->user_chunk_malloc_max < limit)
+limit = png_ptr->user_chunk_malloc_max;
+#  elif PNG_USER_CHUNK_MALLOC_MAX > 0
+if (PNG_USER_CHUNK_MALLOC_MAX < limit)
+limit = PNG_USER_CHUNK_MALLOC_MAX;
+#  endif
+if (limit >= prefix_size + (terminate != 0))
+{
+int ret;
+limit -= prefix_size + (terminate != 0);
+if (limit < *newlength)
+*newlength = limit;
+/* Now try to claim the stream. */
+ret = png_inflate_claim(png_ptr, png_ptr->chunk_name);
+if (ret == Z_OK)
+{
+png_uint_32 lzsize = chunklength - prefix_size;
+ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
+/* input: */ png_ptr->read_buffer + prefix_size, &lzsize,
+/* output: */ NULL, newlength);
+if (ret == Z_STREAM_END)
+{
+/* Use 'inflateReset' here, not 'inflateReset2' because this
+* preserves the previously decided window size (otherwise it would
+* be necessary to store the previous window size.)  In practice
+* this doesn't matter anyway, because png_inflate will call inflate
+* with Z_FINISH in almost all cases, so the window will not be
+* maintained.
+*/
+if (inflateReset(&png_ptr->zstream) == Z_OK)
+{
+/* Because of the limit checks above we know that the new,
+* expanded, size will fit in a size_t (let alone an
+* png_alloc_size_t).  Use png_malloc_base here to avoid an
+* extra OOM message.
+*/
+png_alloc_size_t new_size = *newlength;
+png_alloc_size_t buffer_size = prefix_size + new_size +
+(terminate != 0);
+png_bytep text = png_voidcast(png_bytep, png_malloc_base(png_ptr,
+buffer_size));
+if (text != NULL)
+{
+ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
+png_ptr->read_buffer + prefix_size, &lzsize,
+text + prefix_size, newlength);
+if (ret == Z_STREAM_END)
+{
+if (new_size == *newlength)
+{
+if (terminate)
+text[prefix_size + *newlength] = 0;
+if (prefix_size > 0)
+memcpy(text, png_ptr->read_buffer, prefix_size);
+{
+png_bytep old_ptr = png_ptr->read_buffer;
+png_ptr->read_buffer = text;
+png_ptr->read_buffer_size = buffer_size;
+text = old_ptr; /* freed below */
+}
+}
+else
+{
+/* The size changed on the second read, there can be no
+* guarantee that anything is correct at this point.
+* The 'msg' pointer has been set to "unexpected end of
+* LZ stream", which is fine, but return an error code
+* that the caller won't accept.
+*/
+ret = PNG_UNEXPECTED_ZLIB_RETURN;
+}
+}
+else if (ret == Z_OK)
+ret = PNG_UNEXPECTED_ZLIB_RETURN; /* for safety */
+/* Free the text pointer (this is the old read_buffer on
+* success)
+*/
+png_free(png_ptr, text);
+/* This really is very benign, but it's still an error because
+* the extra space may otherwise be used as a Trojan Horse.
+*/
+if (ret == Z_STREAM_END &&
+chunklength - prefix_size != lzsize)
+png_chunk_benign_error(png_ptr, "extra compressed data");
+}
+else
+{
+/* Out of memory allocating the buffer */
+ret = Z_MEM_ERROR;
+png_zstream_error(png_ptr, Z_MEM_ERROR);
+}
+}
+else
+{
+/* inflateReset failed, store the error message */
+png_zstream_error(png_ptr, ret);
+if (ret == Z_STREAM_END)
+ret = PNG_UNEXPECTED_ZLIB_RETURN;
+}
+}
+else if (ret == Z_OK)
+ret = PNG_UNEXPECTED_ZLIB_RETURN;
+/* Release the claimed stream */
+png_ptr->zowner = 0;
+}
+else /* the claim failed */ if (ret == Z_STREAM_END) /* impossible! */
+ret = PNG_UNEXPECTED_ZLIB_RETURN;
+return ret;
+}
+else
+{
+/* Application/configuration limits exceeded */
+png_zstream_error(png_ptr, Z_MEM_ERROR);
+return Z_MEM_ERROR;
+}
+}
+#endif /* PNG_READ_COMPRESSED_TEXT_SUPPORTED */
+#ifdef PNG_READ_iCCP_SUPPORTED
+/* Perform a partial read and decompress, producing 'avail_out' bytes and
+* reading from the current chunk as required.
+*/
+static int
+png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
+png_uint_32p chunk_bytes, png_bytep next_out, png_alloc_size_t *out_size,
+int finish)
+{
+if (png_ptr->zowner == png_ptr->chunk_name)
+{
+int ret;
+/* next_in and avail_in must have been initialized by the caller. */
+png_ptr->zstream.next_out = next_out;
+png_ptr->zstream.avail_out = 0; /* set in the loop */
+do
+{
+if (png_ptr->zstream.avail_in == 0)
+{
+if (read_size > *chunk_bytes)
+read_size = (uInt)*chunk_bytes;
+*chunk_bytes -= read_size;
+if (read_size > 0)
+png_crc_read(png_ptr, read_buffer, read_size);
+png_ptr->zstream.next_in = read_buffer;
+png_ptr->zstream.avail_in = read_size;
+}
+if (png_ptr->zstream.avail_out == 0)
+{
+uInt avail = ZLIB_IO_MAX;
+if (avail > *out_size)
+avail = (uInt)*out_size;
+*out_size -= avail;
+png_ptr->zstream.avail_out = avail;
+}
+/* Use Z_SYNC_FLUSH when there is no more chunk data to ensure that all
+* the available output is produced; this allows reading of truncated
+* streams.
+*/
+ret = inflate(&png_ptr->zstream,
+*chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
+}
+while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
+*out_size += png_ptr->zstream.avail_out;
+png_ptr->zstream.avail_out = 0; /* Should not be required, but is safe */
+/* Ensure the error message pointer is always set: */
+png_zstream_error(png_ptr, ret);
+return ret;
+}
+else
+{
+png_ptr->zstream.msg = PNGZ_MSG_CAST("zstream unclaimed");
+return Z_STREAM_ERROR;
+}
+}
+#endif
+/* Read and check the IDHR chunk */
+void /* PRIVATE */
+png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_byte buf[13];
+png_uint_32 width, height;
+int bit_depth, color_type, compression_type, filter_type;
+int interlace_type;
+png_debug(1, "in png_handle_IHDR");
+if (png_ptr->mode & PNG_HAVE_IHDR)
+png_chunk_error(png_ptr, "out of place");
+/* Check the length */
+if (length != 13)
+png_chunk_error(png_ptr, "invalid");
+png_ptr->mode |= PNG_HAVE_IHDR;
+png_crc_read(png_ptr, buf, 13);
+png_crc_finish(png_ptr, 0);
+width = png_get_uint_31(png_ptr, buf);
+height = png_get_uint_31(png_ptr, buf + 4);
+bit_depth = buf[8];
+color_type = buf[9];
+compression_type = buf[10];
+filter_type = buf[11];
+interlace_type = buf[12];
+#ifdef PNG_READ_APNG_SUPPORTED
+png_ptr->first_frame_width = width;
+png_ptr->first_frame_height = height;
+#endif
+/* Set internal variables */
+png_ptr->width = width;
+png_ptr->height = height;
+png_ptr->bit_depth = (png_byte)bit_depth;
+png_ptr->interlaced = (png_byte)interlace_type;
+png_ptr->color_type = (png_byte)color_type;
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+png_ptr->filter_type = (png_byte)filter_type;
+#endif
+png_ptr->compression_type = (png_byte)compression_type;
+/* Find number of channels */
+switch (png_ptr->color_type)
+{
+default: /* invalid, png_set_IHDR calls png_error */
+case PNG_COLOR_TYPE_GRAY:
+case PNG_COLOR_TYPE_PALETTE:
+png_ptr->channels = 1;
+break;
+case PNG_COLOR_TYPE_RGB:
+png_ptr->channels = 3;
+break;
+case PNG_COLOR_TYPE_GRAY_ALPHA:
+png_ptr->channels = 2;
+break;
+case PNG_COLOR_TYPE_RGB_ALPHA:
+png_ptr->channels = 4;
+break;
+}
+/* Set up other useful info */
+png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth *
+png_ptr->channels);
+png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
+png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
+png_debug1(3, "channels = %d", png_ptr->channels);
+png_debug1(3, "rowbytes = %lu", (unsigned long)png_ptr->rowbytes);
+png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
+color_type, interlace_type, compression_type, filter_type);
+}
+/* Read and check the palette */
+void /* PRIVATE */
+png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_color palette[PNG_MAX_PALETTE_LENGTH];
+int num, i;
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
+png_colorp pal_ptr;
+#endif
+png_debug(1, "in png_handle_PLTE");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+/* Moved to before the 'after IDAT' check below because otherwise duplicate
+* PLTE chunks are potentially ignored (the spec says there shall not be more
+* than one PLTE, the error is not treated as benign, so this check trumps
+* the requirement that PLTE appears before IDAT.)
+*/
+else if (png_ptr->mode & PNG_HAVE_PLTE)
+png_chunk_error(png_ptr, "duplicate");
+else if (png_ptr->mode & PNG_HAVE_IDAT)
+{
+/* This is benign because the non-benign error happened before, when an
+* IDAT was encountered in a color-mapped image with no PLTE.
+*/
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+png_ptr->mode |= PNG_HAVE_PLTE;
+if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
+return;
+}
+#ifndef PNG_READ_OPT_PLTE_SUPPORTED
+if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
+{
+png_crc_finish(png_ptr, length);
+return;
+}
+#endif
+if (length > 3*PNG_MAX_PALETTE_LENGTH || length % 3)
+{
+png_crc_finish(png_ptr, length);
+if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
+png_chunk_benign_error(png_ptr, "invalid");
+else
+png_chunk_error(png_ptr, "invalid");
+return;
+}
+/* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
+num = (int)length / 3;
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
+for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
+{
+png_byte buf[3];
+png_crc_read(png_ptr, buf, 3);
+pal_ptr->red = buf[0];
+pal_ptr->green = buf[1];
+pal_ptr->blue = buf[2];
+}
+#else
+for (i = 0; i < num; i++)
+{
+png_byte buf[3];
+png_crc_read(png_ptr, buf, 3);
+/* Don't depend upon png_color being any order */
+palette[i].red = buf[0];
+palette[i].green = buf[1];
+palette[i].blue = buf[2];
+}
+#endif
+/* If we actually need the PLTE chunk (ie for a paletted image), we do
+* whatever the normal CRC configuration tells us.  However, if we
+* have an RGB image, the PLTE can be considered ancillary, so
+* we will act as though it is.
+*/
+#ifndef PNG_READ_OPT_PLTE_SUPPORTED
+if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+#endif
+{
+png_crc_finish(png_ptr, 0);
+}
+#ifndef PNG_READ_OPT_PLTE_SUPPORTED
+else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
+{
+/* If we don't want to use the data from an ancillary chunk,
+* we have two options: an error abort, or a warning and we
+* ignore the data in this chunk (which should be OK, since
+* it's considered ancillary for a RGB or RGBA image).
+*
+* IMPLEMENTATION NOTE: this is only here because png_crc_finish uses the
+* chunk type to determine whether to check the ancillary or the critical
+* flags.
+*/
+if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
+{
+if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
+return;
+else
+png_chunk_error(png_ptr, "CRC error");
+}
+/* Otherwise, we (optionally) emit a warning and use the chunk. */
+else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
+png_chunk_warning(png_ptr, "CRC error");
+}
+#endif
+/* TODO: png_set_PLTE has the side effect of setting png_ptr->palette to its
+* own copy of the palette.  This has the side effect that when png_start_row
+* is called (this happens after any call to png_read_update_info) the
+* info_ptr palette gets changed.  This is extremely unexpected and
+* confusing.
+*
+* Fix this by not sharing the palette in this way.
+*/
+png_set_PLTE(png_ptr, info_ptr, palette, num);
+/* The three chunks, bKGD, hIST and tRNS *must* appear after PLTE and before
+* IDAT.  Prior to 1.6.0 this was not checked; instead the code merely
+* checked the apparent validity of a tRNS chunk inserted before PLTE on a
+* palette PNG.  1.6.0 attempts to rigorously follow the standard and
+* therefore does a benign error if the erroneous condition is detected *and*
+* cancels the tRNS if the benign error returns.  The alternative is to
+* amend the standard since it would be rather hypocritical of the standards
+* maintainers to ignore it.
+*/
+#ifdef PNG_READ_tRNS_SUPPORTED
+if (png_ptr->num_trans > 0 ||
+(info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0))
+{
+/* Cancel this because otherwise it would be used if the transforms
+* require it.  Don't cancel the 'valid' flag because this would prevent
+* detection of duplicate chunks.
+*/
+png_ptr->num_trans = 0;
+if (info_ptr != NULL)
+info_ptr->num_trans = 0;
+png_chunk_benign_error(png_ptr, "tRNS must be after");
+}
+#endif
+#ifdef PNG_READ_hIST_SUPPORTED
+if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
+png_chunk_benign_error(png_ptr, "hIST must be after");
+#endif
+#ifdef PNG_READ_bKGD_SUPPORTED
+if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
+png_chunk_benign_error(png_ptr, "bKGD must be after");
+#endif
+}
+void /* PRIVATE */
+png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_debug(1, "in png_handle_IEND");
+if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
+png_chunk_error(png_ptr, "out of place");
+png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
+png_crc_finish(png_ptr, length);
+if (length != 0)
+png_chunk_benign_error(png_ptr, "invalid");
+PNG_UNUSED(info_ptr)
+}
+#ifdef PNG_READ_gAMA_SUPPORTED
+void /* PRIVATE */
+png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_fixed_point igamma;
+png_byte buf[4];
+png_debug(1, "in png_handle_gAMA");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+if (length != 4)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_crc_read(png_ptr, buf, 4);
+if (png_crc_finish(png_ptr, 0))
+return;
+igamma = png_get_fixed_point(NULL, buf);
+png_colorspace_set_gamma(png_ptr, &png_ptr->colorspace, igamma);
+png_colorspace_sync(png_ptr, info_ptr);
+}
+#endif
+#ifdef PNG_READ_sBIT_SUPPORTED
+void /* PRIVATE */
+png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+unsigned int truelen, i;
+png_byte sample_depth;
+png_byte buf[4];
+png_debug(1, "in png_handle_sBIT");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "duplicate");
+return;
+}
+if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+{
+truelen = 3;
+sample_depth = 8;
+}
+else
+{
+truelen = png_ptr->channels;
+sample_depth = png_ptr->bit_depth;
+}
+if (length != truelen || length > 4)
+{
+png_chunk_benign_error(png_ptr, "invalid");
+png_crc_finish(png_ptr, length);
+return;
+}
+buf[0] = buf[1] = buf[2] = buf[3] = sample_depth;
+png_crc_read(png_ptr, buf, truelen);
+if (png_crc_finish(png_ptr, 0))
+return;
+for (i=0; i<truelen; ++i)
+if (buf[i] == 0 || buf[i] > sample_depth)
+{
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+{
+png_ptr->sig_bit.red = buf[0];
+png_ptr->sig_bit.green = buf[1];
+png_ptr->sig_bit.blue = buf[2];
+png_ptr->sig_bit.alpha = buf[3];
+}
+else
+{
+png_ptr->sig_bit.gray = buf[0];
+png_ptr->sig_bit.red = buf[0];
+png_ptr->sig_bit.green = buf[0];
+png_ptr->sig_bit.blue = buf[0];
+png_ptr->sig_bit.alpha = buf[1];
+}
+png_set_sBIT(png_ptr, info_ptr, &(png_ptr->sig_bit));
+}
+#endif
+#ifdef PNG_READ_cHRM_SUPPORTED
+void /* PRIVATE */
+png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_byte buf[32];
+png_xy xy;
+png_debug(1, "in png_handle_cHRM");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+if (length != 32)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_crc_read(png_ptr, buf, 32);
+if (png_crc_finish(png_ptr, 0))
+return;
+xy.whitex = png_get_fixed_point(NULL, buf);
+xy.whitey = png_get_fixed_point(NULL, buf + 4);
+xy.redx   = png_get_fixed_point(NULL, buf + 8);
+xy.redy   = png_get_fixed_point(NULL, buf + 12);
+xy.greenx = png_get_fixed_point(NULL, buf + 16);
+xy.greeny = png_get_fixed_point(NULL, buf + 20);
+xy.bluex  = png_get_fixed_point(NULL, buf + 24);
+xy.bluey  = png_get_fixed_point(NULL, buf + 28);
+if (xy.whitex == PNG_FIXED_ERROR ||
+xy.whitey == PNG_FIXED_ERROR ||
+xy.redx   == PNG_FIXED_ERROR ||
+xy.redy   == PNG_FIXED_ERROR ||
+xy.greenx == PNG_FIXED_ERROR ||
+xy.greeny == PNG_FIXED_ERROR ||
+xy.bluex  == PNG_FIXED_ERROR ||
+xy.bluey  == PNG_FIXED_ERROR)
+{
+png_chunk_benign_error(png_ptr, "invalid values");
+return;
+}
+/* If a colorspace error has already been output skip this chunk */
+if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
+return;
+if (png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM)
+{
+png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
+png_colorspace_sync(png_ptr, info_ptr);
+png_chunk_benign_error(png_ptr, "duplicate");
+return;
+}
+png_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;
+(void)png_colorspace_set_chromaticities(png_ptr, &png_ptr->colorspace, &xy,
+1/*prefer cHRM values*/);
+png_colorspace_sync(png_ptr, info_ptr);
+}
+#endif
+#ifdef PNG_READ_sRGB_SUPPORTED
+void /* PRIVATE */
+png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_byte intent;
+png_debug(1, "in png_handle_sRGB");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+if (length != 1)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_crc_read(png_ptr, &intent, 1);
+if (png_crc_finish(png_ptr, 0))
+return;
+/* If a colorspace error has already been output skip this chunk */
+if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
+return;
+/* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
+* this.
+*/
+if (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT)
+{
+png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
+png_colorspace_sync(png_ptr, info_ptr);
+png_chunk_benign_error(png_ptr, "too many profiles");
+return;
+}
+(void)png_colorspace_set_sRGB(png_ptr, &png_ptr->colorspace, intent);
+png_colorspace_sync(png_ptr, info_ptr);
+}
+#endif /* PNG_READ_sRGB_SUPPORTED */
+#ifdef PNG_READ_iCCP_SUPPORTED
+void /* PRIVATE */
+png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+/* Note: this does not properly handle profiles that are > 64K under DOS */
+{
+png_const_charp errmsg = NULL; /* error message output, or no error */
+int finished = 0; /* crc checked */
+png_debug(1, "in png_handle_iCCP");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+/* Consistent with all the above colorspace handling an obviously *invalid*
+* chunk is just ignored, so does not invalidate the color space.  An
+* alternative is to set the 'invalid' flags at the start of this routine
+* and only clear them in they were not set before and all the tests pass.
+* The minimum 'deflate' stream is assumed to be just the 2 byte header and 4
+* byte checksum.  The keyword must be one character and there is a
+* terminator (0) byte and the compression method.
+*/
+if (length < 9)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "too short");
+return;
+}
+/* If a colorspace error has already been output skip this chunk */
+if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
+{
+png_crc_finish(png_ptr, length);
+return;
+}
+/* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
+* this.
+*/
+if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) == 0)
+{
+uInt read_length, keyword_length;
+char keyword[81];
+/* Find the keyword; the keyword plus separator and compression method
+* bytes can be at most 81 characters long.
+*/
+read_length = 81; /* maximum */
+if (read_length > length)
+read_length = (uInt)length;
+png_crc_read(png_ptr, (png_bytep)keyword, read_length);
+length -= read_length;
+keyword_length = 0;
+while (keyword_length < 80 && keyword_length < read_length &&
+keyword[keyword_length] != 0)
+++keyword_length;
+/* TODO: make the keyword checking common */
+if (keyword_length >= 1 && keyword_length <= 79)
+{
+/* We only understand '0' compression - deflate - so if we get a
+* different value we can't safely decode the chunk.
+*/
+if (keyword_length+1 < read_length &&
+keyword[keyword_length+1] == PNG_COMPRESSION_TYPE_BASE)
+{
+read_length -= keyword_length+2;
+if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
+{
+Byte profile_header[132];
+Byte local_buffer[PNG_INFLATE_BUF_SIZE];
+png_alloc_size_t size = (sizeof profile_header);
+png_ptr->zstream.next_in = (Bytef*)keyword + (keyword_length+2);
+png_ptr->zstream.avail_in = read_length;
+(void)png_inflate_read(png_ptr, local_buffer,
+(sizeof local_buffer), &length, profile_header, &size,
+0/*finish: don't, because the output is too small*/);
+if (size == 0)
+{
+/* We have the ICC profile header; do the basic header checks.
+*/
+const png_uint_32 profile_length =
+png_get_uint_32(profile_header);
+if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
+keyword, profile_length))
+{
+/* The length is apparently ok, so we can check the 132
+* byte header.
+*/
+if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
+keyword, profile_length, profile_header,
+png_ptr->color_type))
+{
+/* Now read the tag table; a variable size buffer is
+* needed at this point, allocate one for the whole
+* profile.  The header check has already validated
+* that none of these stuff will overflow.
+*/
+const png_uint_32 tag_count = png_get_uint_32(
+profile_header+128);
+png_bytep profile = png_read_buffer(png_ptr,
+profile_length, 2/*silent*/);
+if (profile != NULL)
+{
+memcpy(profile, profile_header,
+(sizeof profile_header));
+size = 12 * tag_count;
+(void)png_inflate_read(png_ptr, local_buffer,
+(sizeof local_buffer), &length,
+profile + (sizeof profile_header), &size, 0);
+/* Still expect a buffer error because we expect
+* there to be some tag data!
+*/
+if (size == 0)
+{
+if (png_icc_check_tag_table(png_ptr,
+&png_ptr->colorspace, keyword, profile_length,
+profile))
+{
+/* The profile has been validated for basic
+* security issues, so read the whole thing in.
+*/
+size = profile_length - (sizeof profile_header)
+- 12 * tag_count;
+(void)png_inflate_read(png_ptr, local_buffer,
+(sizeof local_buffer), &length,
+profile + (sizeof profile_header) +
+12 * tag_count, &size, 1/*finish*/);
+if (length > 0 && !(png_ptr->flags &
+PNG_FLAG_BENIGN_ERRORS_WARN))
+errmsg = "extra compressed data";
+/* But otherwise allow extra data: */
+else if (size == 0)
+{
+if (length > 0)
+{
+/* This can be handled completely, so
+* keep going.
+*/
+png_chunk_warning(png_ptr,
+"extra compressed data");
+}
+png_crc_finish(png_ptr, length);
+finished = 1;
+#                                   ifdef PNG_sRGB_SUPPORTED
+/* Check for a match against sRGB */
+png_icc_set_sRGB(png_ptr,
+&png_ptr->colorspace, profile,
+png_ptr->zstream.adler);
+#                                   endif
+/* Steal the profile for info_ptr. */
+if (info_ptr != NULL)
+{
+png_free_data(png_ptr, info_ptr,
+PNG_FREE_ICCP, 0);
+info_ptr->iccp_name = png_voidcast(char*,
+png_malloc_base(png_ptr,
+keyword_length+1));
+if (info_ptr->iccp_name != NULL)
+{
+memcpy(info_ptr->iccp_name, keyword,
+keyword_length+1);
+info_ptr->iccp_proflen =
+profile_length;
+info_ptr->iccp_profile = profile;
+png_ptr->read_buffer = NULL; /*steal*/
+info_ptr->free_me |= PNG_FREE_ICCP;
+info_ptr->valid |= PNG_INFO_iCCP;
+}
+else
+{
+png_ptr->colorspace.flags |=
+PNG_COLORSPACE_INVALID;
+errmsg = "out of memory";
+}
+}
+/* else the profile remains in the read
+* buffer which gets reused for subsequent
+* chunks.
+*/
+if (info_ptr != NULL)
+png_colorspace_sync(png_ptr, info_ptr);
+if (errmsg == NULL)
+{
+png_ptr->zowner = 0;
+return;
+}
+}
+else if (size > 0)
+errmsg = "truncated";
+else
+errmsg = png_ptr->zstream.msg;
+}
+/* else png_icc_check_tag_table output an error */
+}
+else /* profile truncated */
+errmsg = png_ptr->zstream.msg;
+}
+else
+errmsg = "out of memory";
+}
+/* else png_icc_check_header output an error */
+}
+/* else png_icc_check_length output an error */
+}
+else /* profile truncated */
+errmsg = png_ptr->zstream.msg;
+/* Release the stream */
+png_ptr->zowner = 0;
+}
+else /* png_inflate_claim failed */
+errmsg = png_ptr->zstream.msg;
+}
+else
+errmsg = "bad compression method"; /* or missing */
+}
+else
+errmsg = "bad keyword";
+}
+else
+errmsg = "too many profiles";
+/* Failure: the reason is in 'errmsg' */
+if (!finished)
+png_crc_finish(png_ptr, length);
+png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
+png_colorspace_sync(png_ptr, info_ptr);
+if (errmsg != NULL) /* else already output */
+png_chunk_benign_error(png_ptr, errmsg);
+}
+#endif /* PNG_READ_iCCP_SUPPORTED */
+#ifdef PNG_READ_sPLT_SUPPORTED
+void /* PRIVATE */
+png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+/* Note: this does not properly handle chunks that are > 64K under DOS */
+{
+png_bytep entry_start, buffer;
+png_sPLT_t new_palette;
+png_sPLT_entryp pp;
+png_uint_32 data_length;
+int entry_size, i;
+png_uint_32 skip = 0;
+png_uint_32 dl;
+png_size_t max_dl;
+png_debug(1, "in png_handle_sPLT");
+#ifdef PNG_USER_LIMITS_SUPPORTED
+if (png_ptr->user_chunk_cache_max != 0)
+{
+if (png_ptr->user_chunk_cache_max == 1)
+{
+png_crc_finish(png_ptr, length);
+return;
+}
+if (--png_ptr->user_chunk_cache_max == 1)
+{
+png_warning(png_ptr, "No space in chunk cache for sPLT");
+png_crc_finish(png_ptr, length);
+return;
+}
+}
+#endif
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & PNG_HAVE_IDAT)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+#ifdef PNG_MAX_MALLOC_64K
+if (length > 65535U)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "too large to fit in memory");
+return;
+}
+#endif
+buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
+if (buffer == NULL)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of memory");
+return;
+}
+/* WARNING: this may break if size_t is less than 32 bits; it is assumed
+* that the PNG_MAX_MALLOC_64K test is enabled in this case, but this is a
+* potential breakage point if the types in pngconf.h aren't exactly right.
+*/
+png_crc_read(png_ptr, buffer, length);
+if (png_crc_finish(png_ptr, skip))
+return;
+buffer[length] = 0;
+for (entry_start = buffer; *entry_start; entry_start++)
+/* Empty loop to find end of name */ ;
+++entry_start;
+/* A sample depth should follow the separator, and we should be on it  */
+if (entry_start > buffer + length - 2)
+{
+png_warning(png_ptr, "malformed sPLT chunk");
+return;
+}
+new_palette.depth = *entry_start++;
+entry_size = (new_palette.depth == 8 ? 6 : 10);
+/* This must fit in a png_uint_32 because it is derived from the original
+* chunk data length.
+*/
+data_length = length - (png_uint_32)(entry_start - buffer);
+/* Integrity-check the data length */
+if (data_length % entry_size)
+{
+png_warning(png_ptr, "sPLT chunk has bad length");
+return;
+}
+dl = (png_int_32)(data_length / entry_size);
+max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
+if (dl > max_dl)
+{
+png_warning(png_ptr, "sPLT chunk too long");
+return;
+}
+new_palette.nentries = (png_int_32)(data_length / entry_size);
+new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
+png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry)));
+if (new_palette.entries == NULL)
+{
+png_warning(png_ptr, "sPLT chunk requires too much memory");
+return;
+}
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
+for (i = 0; i < new_palette.nentries; i++)
+{
+pp = new_palette.entries + i;
+if (new_palette.depth == 8)
+{
+pp->red = *entry_start++;
+pp->green = *entry_start++;
+pp->blue = *entry_start++;
+pp->alpha = *entry_start++;
+}
+else
+{
+pp->red   = png_get_uint_16(entry_start); entry_start += 2;
+pp->green = png_get_uint_16(entry_start); entry_start += 2;
+pp->blue  = png_get_uint_16(entry_start); entry_start += 2;
+pp->alpha = png_get_uint_16(entry_start); entry_start += 2;
+}
+pp->frequency = png_get_uint_16(entry_start); entry_start += 2;
+}
+#else
+pp = new_palette.entries;
+for (i = 0; i < new_palette.nentries; i++)
+{
+if (new_palette.depth == 8)
+{
+pp[i].red   = *entry_start++;
+pp[i].green = *entry_start++;
+pp[i].blue  = *entry_start++;
+pp[i].alpha = *entry_start++;
+}
+else
+{
+pp[i].red   = png_get_uint_16(entry_start); entry_start += 2;
+pp[i].green = png_get_uint_16(entry_start); entry_start += 2;
+pp[i].blue  = png_get_uint_16(entry_start); entry_start += 2;
+pp[i].alpha = png_get_uint_16(entry_start); entry_start += 2;
+}
+pp[i].frequency = png_get_uint_16(entry_start); entry_start += 2;
+}
+#endif
+/* Discard all chunk data except the name and stash that */
+new_palette.name = (png_charp)buffer;
+png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
+png_free(png_ptr, new_palette.entries);
+}
+#endif /* PNG_READ_sPLT_SUPPORTED */
+#ifdef PNG_READ_tRNS_SUPPORTED
+void /* PRIVATE */
+png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_byte readbuf[PNG_MAX_PALETTE_LENGTH];
+png_debug(1, "in png_handle_tRNS");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & PNG_HAVE_IDAT)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "duplicate");
+return;
+}
+if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
+{
+png_byte buf[2];
+if (length != 2)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_crc_read(png_ptr, buf, 2);
+png_ptr->num_trans = 1;
+png_ptr->trans_color.gray = png_get_uint_16(buf);
+}
+else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
+{
+png_byte buf[6];
+if (length != 6)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_crc_read(png_ptr, buf, length);
+png_ptr->num_trans = 1;
+png_ptr->trans_color.red = png_get_uint_16(buf);
+png_ptr->trans_color.green = png_get_uint_16(buf + 2);
+png_ptr->trans_color.blue = png_get_uint_16(buf + 4);
+}
+else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+{
+if (!(png_ptr->mode & PNG_HAVE_PLTE))
+{
+/* TODO: is this actually an error in the ISO spec? */
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+if (length > png_ptr->num_palette || length > PNG_MAX_PALETTE_LENGTH ||
+length == 0)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_crc_read(png_ptr, readbuf, length);
+png_ptr->num_trans = (png_uint_16)length;
+}
+else
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid with alpha channel");
+return;
+}
+if (png_crc_finish(png_ptr, 0))
+{
+png_ptr->num_trans = 0;
+return;
+}
+/* TODO: this is a horrible side effect in the palette case because the
+* png_struct ends up with a pointer to the tRNS buffer owned by the
+* png_info.  Fix this.
+*/
+png_set_tRNS(png_ptr, info_ptr, readbuf, png_ptr->num_trans,
+&(png_ptr->trans_color));
+}
+#endif
+#ifdef PNG_READ_bKGD_SUPPORTED
+void /* PRIVATE */
+png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+unsigned int truelen;
+png_byte buf[6];
+png_color_16 background;
+png_debug(1, "in png_handle_bKGD");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if ((png_ptr->mode & PNG_HAVE_IDAT) ||
+(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
+!(png_ptr->mode & PNG_HAVE_PLTE)))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "duplicate");
+return;
+}
+if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+truelen = 1;
+else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+truelen = 6;
+else
+truelen = 2;
+if (length != truelen)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_crc_read(png_ptr, buf, truelen);
+if (png_crc_finish(png_ptr, 0))
+return;
+/* We convert the index value into RGB components so that we can allow
+* arbitrary RGB values for background when we have transparency, and
+* so it is easy to determine the RGB values of the background color
+* from the info_ptr struct.
+*/
+if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+{
+background.index = buf[0];
+if (info_ptr && info_ptr->num_palette)
+{
+if (buf[0] >= info_ptr->num_palette)
+{
+png_chunk_benign_error(png_ptr, "invalid index");
+return;
+}
+background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
+background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
+background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
+}
+else
+background.red = background.green = background.blue = 0;
+background.gray = 0;
+}
+else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
+{
+background.index = 0;
+background.red =
+background.green =
+background.blue =
+background.gray = png_get_uint_16(buf);
+}
+else
+{
+background.index = 0;
+background.red = png_get_uint_16(buf);
+background.green = png_get_uint_16(buf + 2);
+background.blue = png_get_uint_16(buf + 4);
+background.gray = 0;
+}
+png_set_bKGD(png_ptr, info_ptr, &background);
+}
+#endif
+#ifdef PNG_READ_hIST_SUPPORTED
+void /* PRIVATE */
+png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+unsigned int num, i;
+png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
+png_debug(1, "in png_handle_hIST");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if ((png_ptr->mode & PNG_HAVE_IDAT) || !(png_ptr->mode & PNG_HAVE_PLTE))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "duplicate");
+return;
+}
+num = length / 2 ;
+if (num != png_ptr->num_palette || num > PNG_MAX_PALETTE_LENGTH)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+for (i = 0; i < num; i++)
+{
+png_byte buf[2];
+png_crc_read(png_ptr, buf, 2);
+readbuf[i] = png_get_uint_16(buf);
+}
+if (png_crc_finish(png_ptr, 0))
+return;
+png_set_hIST(png_ptr, info_ptr, readbuf);
+}
+#endif
+#ifdef PNG_READ_pHYs_SUPPORTED
+void /* PRIVATE */
+png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_byte buf[9];
+png_uint_32 res_x, res_y;
+int unit_type;
+png_debug(1, "in png_handle_pHYs");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & PNG_HAVE_IDAT)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "duplicate");
+return;
+}
+if (length != 9)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_crc_read(png_ptr, buf, 9);
+if (png_crc_finish(png_ptr, 0))
+return;
+res_x = png_get_uint_32(buf);
+res_y = png_get_uint_32(buf + 4);
+unit_type = buf[8];
+png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
+}
+#endif
+#ifdef PNG_READ_oFFs_SUPPORTED
+void /* PRIVATE */
+png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_byte buf[9];
+png_int_32 offset_x, offset_y;
+int unit_type;
+png_debug(1, "in png_handle_oFFs");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & PNG_HAVE_IDAT)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "duplicate");
+return;
+}
+if (length != 9)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_crc_read(png_ptr, buf, 9);
+if (png_crc_finish(png_ptr, 0))
+return;
+offset_x = png_get_int_32(buf);
+offset_y = png_get_int_32(buf + 4);
+unit_type = buf[8];
+png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y, unit_type);
+}
+#endif
+#ifdef PNG_READ_pCAL_SUPPORTED
+/* Read the pCAL chunk (described in the PNG Extensions document) */
+void /* PRIVATE */
+png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_int_32 X0, X1;
+png_byte type, nparams;
+png_bytep buffer, buf, units, endptr;
+png_charpp params;
+int i;
+png_debug(1, "in png_handle_pCAL");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & PNG_HAVE_IDAT)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "duplicate");
+return;
+}
+png_debug1(2, "Allocating and reading pCAL chunk data (%u bytes)",
+length + 1);
+buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
+if (buffer == NULL)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of memory");
+return;
+}
+png_crc_read(png_ptr, buffer, length);
+if (png_crc_finish(png_ptr, 0))
+return;
+buffer[length] = 0; /* Null terminate the last string */
+png_debug(3, "Finding end of pCAL purpose string");
+for (buf = buffer; *buf; buf++)
+/* Empty loop */ ;
+endptr = buffer + length;
+/* We need to have at least 12 bytes after the purpose string
+* in order to get the parameter information.
+*/
+if (endptr <= buf + 12)
+{
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_debug(3, "Reading pCAL X0, X1, type, nparams, and units");
+X0 = png_get_int_32((png_bytep)buf+1);
+X1 = png_get_int_32((png_bytep)buf+5);
+type = buf[9];
+nparams = buf[10];
+units = buf + 11;
+png_debug(3, "Checking pCAL equation type and number of parameters");
+/* Check that we have the right number of parameters for known
+* equation types.
+*/
+if ((type == PNG_EQUATION_LINEAR && nparams != 2) ||
+(type == PNG_EQUATION_BASE_E && nparams != 3) ||
+(type == PNG_EQUATION_ARBITRARY && nparams != 3) ||
+(type == PNG_EQUATION_HYPERBOLIC && nparams != 4))
+{
+png_chunk_benign_error(png_ptr, "invalid parameter count");
+return;
+}
+else if (type >= PNG_EQUATION_LAST)
+{
+png_chunk_benign_error(png_ptr, "unrecognized equation type");
+}
+for (buf = units; *buf; buf++)
+/* Empty loop to move past the units string. */ ;
+png_debug(3, "Allocating pCAL parameters array");
+params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
+nparams * (sizeof (png_charp))));
+if (params == NULL)
+{
+png_chunk_benign_error(png_ptr, "out of memory");
+return;
+}
+/* Get pointers to the start of each parameter string. */
+for (i = 0; i < nparams; i++)
+{
+buf++; /* Skip the null string terminator from previous parameter. */
+png_debug1(3, "Reading pCAL parameter %d", i);
+for (params[i] = (png_charp)buf; buf <= endptr && *buf != 0; buf++)
+/* Empty loop to move past each parameter string */ ;
+/* Make sure we haven't run out of data yet */
+if (buf > endptr)
+{
+png_free(png_ptr, params);
+png_chunk_benign_error(png_ptr, "invalid data");
+return;
+}
+}
+png_set_pCAL(png_ptr, info_ptr, (png_charp)buffer, X0, X1, type, nparams,
+(png_charp)units, params);
+png_free(png_ptr, params);
+}
+#endif
+#ifdef PNG_READ_sCAL_SUPPORTED
+/* Read the sCAL chunk */
+void /* PRIVATE */
+png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_bytep buffer;
+png_size_t i;
+int state;
+png_debug(1, "in png_handle_sCAL");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (png_ptr->mode & PNG_HAVE_IDAT)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of place");
+return;
+}
+else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "duplicate");
+return;
+}
+/* Need unit type, width, \0, height: minimum 4 bytes */
+else if (length < 4)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_debug1(2, "Allocating and reading sCAL chunk data (%u bytes)",
+length + 1);
+buffer = png_read_buffer(png_ptr, length+1, 2/*silent*/);
+if (buffer == NULL)
+{
+png_chunk_benign_error(png_ptr, "out of memory");
+png_crc_finish(png_ptr, length);
+return;
+}
+png_crc_read(png_ptr, buffer, length);
+buffer[length] = 0; /* Null terminate the last string */
+if (png_crc_finish(png_ptr, 0))
+return;
+/* Validate the unit. */
+if (buffer[0] != 1 && buffer[0] != 2)
+{
+png_chunk_benign_error(png_ptr, "invalid unit");
+return;
+}
+/* Validate the ASCII numbers, need two ASCII numbers separated by
+* a '\0' and they need to fit exactly in the chunk data.
+*/
+i = 1;
+state = 0;
+if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
+i >= length || buffer[i++] != 0)
+png_chunk_benign_error(png_ptr, "bad width format");
+else if (!PNG_FP_IS_POSITIVE(state))
+png_chunk_benign_error(png_ptr, "non-positive width");
+else
+{
+png_size_t heighti = i;
+state = 0;
+if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
+i != length)
+png_chunk_benign_error(png_ptr, "bad height format");
+else if (!PNG_FP_IS_POSITIVE(state))
+png_chunk_benign_error(png_ptr, "non-positive height");
+else
+/* This is the (only) success case. */
+png_set_sCAL_s(png_ptr, info_ptr, buffer[0],
+(png_charp)buffer+1, (png_charp)buffer+heighti);
+}
+}
+#endif
+#ifdef PNG_READ_tIME_SUPPORTED
+void /* PRIVATE */
+png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_byte buf[7];
+png_time mod_time;
+png_debug(1, "in png_handle_tIME");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "duplicate");
+return;
+}
+if (png_ptr->mode & PNG_HAVE_IDAT)
+png_ptr->mode |= PNG_AFTER_IDAT;
+if (length != 7)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "invalid");
+return;
+}
+png_crc_read(png_ptr, buf, 7);
+if (png_crc_finish(png_ptr, 0))
+return;
+mod_time.second = buf[6];
+mod_time.minute = buf[5];
+mod_time.hour = buf[4];
+mod_time.day = buf[3];
+mod_time.month = buf[2];
+mod_time.year = png_get_uint_16(buf);
+png_set_tIME(png_ptr, info_ptr, &mod_time);
+}
+#endif
+#ifdef PNG_READ_tEXt_SUPPORTED
+/* Note: this does not properly handle chunks that are > 64K under DOS */
+void /* PRIVATE */
+png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_text  text_info;
+png_bytep buffer;
+png_charp key;
+png_charp text;
+png_uint_32 skip = 0;
+png_debug(1, "in png_handle_tEXt");
+#ifdef PNG_USER_LIMITS_SUPPORTED
+if (png_ptr->user_chunk_cache_max != 0)
+{
+if (png_ptr->user_chunk_cache_max == 1)
+{
+png_crc_finish(png_ptr, length);
+return;
+}
+if (--png_ptr->user_chunk_cache_max == 1)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "no space in chunk cache");
+return;
+}
+}
+#endif
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+if (png_ptr->mode & PNG_HAVE_IDAT)
+png_ptr->mode |= PNG_AFTER_IDAT;
+#ifdef PNG_MAX_MALLOC_64K
+if (length > 65535U)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "too large to fit in memory");
+return;
+}
+#endif
+buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
+if (buffer == NULL)
+{
+png_chunk_benign_error(png_ptr, "out of memory");
+return;
+}
+png_crc_read(png_ptr, buffer, length);
+if (png_crc_finish(png_ptr, skip))
+return;
+key = (png_charp)buffer;
+key[length] = 0;
+for (text = key; *text; text++)
+/* Empty loop to find end of key */ ;
+if (text != key + length)
+text++;
+text_info.compression = PNG_TEXT_COMPRESSION_NONE;
+text_info.key = key;
+text_info.lang = NULL;
+text_info.lang_key = NULL;
+text_info.itxt_length = 0;
+text_info.text = text;
+text_info.text_length = strlen(text);
+if (png_set_text_2(png_ptr, info_ptr, &text_info, 1))
+png_warning(png_ptr, "Insufficient memory to process text chunk");
+}
+#endif
+#ifdef PNG_READ_zTXt_SUPPORTED
+/* Note: this does not correctly handle chunks that are > 64K under DOS */
+void /* PRIVATE */
+png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_const_charp errmsg = NULL;
+png_bytep       buffer;
+png_uint_32     keyword_length;
+png_debug(1, "in png_handle_zTXt");
+#ifdef PNG_USER_LIMITS_SUPPORTED
+if (png_ptr->user_chunk_cache_max != 0)
+{
+if (png_ptr->user_chunk_cache_max == 1)
+{
+png_crc_finish(png_ptr, length);
+return;
+}
+if (--png_ptr->user_chunk_cache_max == 1)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "no space in chunk cache");
+return;
+}
+}
+#endif
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+if (png_ptr->mode & PNG_HAVE_IDAT)
+png_ptr->mode |= PNG_AFTER_IDAT;
+buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
+if (buffer == NULL)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of memory");
+return;
+}
+png_crc_read(png_ptr, buffer, length);
+if (png_crc_finish(png_ptr, 0))
+return;
+/* TODO: also check that the keyword contents match the spec! */
+for (keyword_length = 0;
+keyword_length < length && buffer[keyword_length] != 0;
+++keyword_length)
+/* Empty loop to find end of name */ ;
+if (keyword_length > 79 || keyword_length < 1)
+errmsg = "bad keyword";
+/* zTXt must have some LZ data after the keyword, although it may expand to
+* zero bytes; we need a '\0' at the end of the keyword, the compression type
+* then the LZ data:
+*/
+else if (keyword_length + 3 > length)
+errmsg = "truncated";
+else if (buffer[keyword_length+1] != PNG_COMPRESSION_TYPE_BASE)
+errmsg = "unknown compression type";
+else
+{
+png_alloc_size_t uncompressed_length = PNG_SIZE_MAX;
+/* TODO: at present png_decompress_chunk imposes a single application
+* level memory limit, this should be split to different values for iCCP
+* and text chunks.
+*/
+if (png_decompress_chunk(png_ptr, length, keyword_length+2,
+&uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
+{
+png_text text;
+/* It worked; png_ptr->read_buffer now looks like a tEXt chunk except
+* for the extra compression type byte and the fact that it isn't
+* necessarily '\0' terminated.
+*/
+buffer = png_ptr->read_buffer;
+buffer[uncompressed_length+(keyword_length+2)] = 0;
+text.compression = PNG_TEXT_COMPRESSION_zTXt;
+text.key = (png_charp)buffer;
+text.text = (png_charp)(buffer + keyword_length+2);
+text.text_length = uncompressed_length;
+text.itxt_length = 0;
+text.lang = NULL;
+text.lang_key = NULL;
+if (png_set_text_2(png_ptr, info_ptr, &text, 1))
+errmsg = "insufficient memory";
+}
+else
+errmsg = png_ptr->zstream.msg;
+}
+if (errmsg != NULL)
+png_chunk_benign_error(png_ptr, errmsg);
+}
+#endif
+#ifdef PNG_READ_iTXt_SUPPORTED
+/* Note: this does not correctly handle chunks that are > 64K under DOS */
+void /* PRIVATE */
+png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
+{
+png_const_charp errmsg = NULL;
+png_bytep buffer;
+png_uint_32 prefix_length;
+png_debug(1, "in png_handle_iTXt");
+#ifdef PNG_USER_LIMITS_SUPPORTED
+if (png_ptr->user_chunk_cache_max != 0)
+{
+if (png_ptr->user_chunk_cache_max == 1)
+{
+png_crc_finish(png_ptr, length);
+return;
+}
+if (--png_ptr->user_chunk_cache_max == 1)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "no space in chunk cache");
+return;
+}
+}
+#endif
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+png_chunk_error(png_ptr, "missing IHDR");
+if (png_ptr->mode & PNG_HAVE_IDAT)
+png_ptr->mode |= PNG_AFTER_IDAT;
+buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
+if (buffer == NULL)
+{
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "out of memory");
+return;
+}
+png_crc_read(png_ptr, buffer, length);
+if (png_crc_finish(png_ptr, 0))
+return;
+/* First the keyword. */
+for (prefix_length=0;
+prefix_length < length && buffer[prefix_length] != 0;
+++prefix_length)
+/* Empty loop */ ;
+/* Perform a basic check on the keyword length here. */
+if (prefix_length > 79 || prefix_length < 1)
+errmsg = "bad keyword";
+/* Expect keyword, compression flag, compression type, language, translated
+* keyword (both may be empty but are 0 terminated) then the text, which may
+* be empty.
+*/
+else if (prefix_length + 5 > length)
+errmsg = "truncated";
+else if (buffer[prefix_length+1] == 0 ||
+(buffer[prefix_length+1] == 1 &&
+buffer[prefix_length+2] == PNG_COMPRESSION_TYPE_BASE))
+{
+int compressed = buffer[prefix_length+1] != 0;
+png_uint_32 language_offset, translated_keyword_offset;
+png_alloc_size_t uncompressed_length = 0;
+/* Now the language tag */
+prefix_length += 3;
+language_offset = prefix_length;
+for (; prefix_length < length && buffer[prefix_length] != 0;
+++prefix_length)
+/* Empty loop */ ;
+/* WARNING: the length may be invalid here, this is checked below. */
+translated_keyword_offset = ++prefix_length;
+for (; prefix_length < length && buffer[prefix_length] != 0;
+++prefix_length)
+/* Empty loop */ ;
+/* prefix_length should now be at the trailing '\0' of the translated
+* keyword, but it may already be over the end.  None of this arithmetic
+* can overflow because chunks are at most 2^31 bytes long, but on 16-bit
+* systems the available allocaton may overflow.
+*/
+++prefix_length;
+if (!compressed && prefix_length <= length)
+uncompressed_length = length - prefix_length;
+else if (compressed && prefix_length < length)
+{
+uncompressed_length = PNG_SIZE_MAX;
+/* TODO: at present png_decompress_chunk imposes a single application
+* level memory limit, this should be split to different values for
+* iCCP and text chunks.
+*/
+if (png_decompress_chunk(png_ptr, length, prefix_length,
+&uncompressed_length, 1/*terminate*/) == Z_STREAM_END)
+buffer = png_ptr->read_buffer;
+else
+errmsg = png_ptr->zstream.msg;
+}
+else
+errmsg = "truncated";
+if (errmsg == NULL)
+{
+png_text text;
+buffer[uncompressed_length+prefix_length] = 0;
+if (compressed)
+text.compression = PNG_ITXT_COMPRESSION_NONE;
+else
+text.compression = PNG_ITXT_COMPRESSION_zTXt;
+text.key = (png_charp)buffer;
+text.lang = (png_charp)buffer + language_offset;
+text.lang_key = (png_charp)buffer + translated_keyword_offset;
+text.text = (png_charp)buffer + prefix_length;
+text.text_length = 0;
+text.itxt_length = uncompressed_length;
+if (png_set_text_2(png_ptr, info_ptr, &text, 1))
+errmsg = "insufficient memory";
+}
+}
+else
+errmsg = "bad compression info";
+if (errmsg != NULL)
+png_chunk_benign_error(png_ptr, errmsg);
+}
+#endif
+#ifdef PNG_READ_APNG_SUPPORTED
+void /* PRIVATE */
+png_handle_acTL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+png_byte data[8];
+png_uint_32 num_frames;
+png_uint_32 num_plays;
+png_uint_32 didSet;
+png_debug(1, "in png_handle_acTL");
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+{
+png_error(png_ptr, "Missing IHDR before acTL");
+}
+else if (png_ptr->mode & PNG_HAVE_IDAT)
+{
+png_warning(png_ptr, "Invalid acTL after IDAT skipped");
+png_crc_finish(png_ptr, length);
+return;
+}
+else if (png_ptr->mode & PNG_HAVE_acTL)
+{
+png_warning(png_ptr, "Duplicate acTL skipped");
+png_crc_finish(png_ptr, length);
+return;
+}
+else if (length != 8)
+{
+png_warning(png_ptr, "acTL with invalid length skipped");
+png_crc_finish(png_ptr, length);
+return;
+}
+png_crc_read(png_ptr, data, 8);
+png_crc_finish(png_ptr, 0);
+num_frames = png_get_uint_31(png_ptr, data);
+num_plays = png_get_uint_31(png_ptr, data + 4);
+/* the set function will do error checking on num_frames */
+didSet = png_set_acTL(png_ptr, info_ptr, num_frames, num_plays);
+if(didSet)
+png_ptr->mode |= PNG_HAVE_acTL;
+}
+void /* PRIVATE */
+png_handle_fcTL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+png_byte data[22];
+png_uint_32 width;
+png_uint_32 height;
+png_uint_32 x_offset;
+png_uint_32 y_offset;
+png_uint_16 delay_num;
+png_uint_16 delay_den;
+png_byte dispose_op;
+png_byte blend_op;
+png_debug(1, "in png_handle_fcTL");
+png_ensure_sequence_number(png_ptr, length);
+if (!(png_ptr->mode & PNG_HAVE_IHDR))
+{
+png_error(png_ptr, "Missing IHDR before fcTL");
+}
+else if (png_ptr->mode & PNG_HAVE_IDAT)
+{
+/* for any frames other then the first this message may be misleading,
+* but correct. PNG_HAVE_IDAT is unset before the frame head is read
+* i can't think of a better message */
+png_warning(png_ptr, "Invalid fcTL after IDAT skipped");
+png_crc_finish(png_ptr, length-4);
+return;
+}
+else if (png_ptr->mode & PNG_HAVE_fcTL)
+{
+png_warning(png_ptr, "Duplicate fcTL within one frame skipped");
+png_crc_finish(png_ptr, length-4);
+return;
+}
+else if (length != 26)
+{
+png_warning(png_ptr, "fcTL with invalid length skipped");
+png_crc_finish(png_ptr, length-4);
+return;
+}
+png_crc_read(png_ptr, data, 22);
+png_crc_finish(png_ptr, 0);
+width = png_get_uint_31(png_ptr, data);
+height = png_get_uint_31(png_ptr, data + 4);
+x_offset = png_get_uint_31(png_ptr, data + 8);
+y_offset = png_get_uint_31(png_ptr, data + 12);
+delay_num = png_get_uint_16(data + 16);
+delay_den = png_get_uint_16(data + 18);
+dispose_op = data[20];
+blend_op = data[21];
+if (png_ptr->num_frames_read == 0 && (x_offset != 0 || y_offset != 0))
+{
+png_warning(png_ptr, "fcTL for the first frame must have zero offset");
+return;
+}
+if (info_ptr != NULL)
+{
+if (png_ptr->num_frames_read == 0 &&
+(width != info_ptr->width || height != info_ptr->height))
+{
+png_warning(png_ptr, "size in first frame's fcTL must match "
+"the size in IHDR");
+return;
+}
+/* The set function will do more error checking */
+png_set_next_frame_fcTL(png_ptr, info_ptr, width, height,
+x_offset, y_offset, delay_num, delay_den,
+dispose_op, blend_op);
+png_read_reinit(png_ptr, info_ptr);
+png_ptr->mode |= PNG_HAVE_fcTL;
+}
+}
+void /* PRIVATE */
+png_have_info(png_structp png_ptr, png_infop info_ptr)
+{
+if((info_ptr->valid & PNG_INFO_acTL) && !(info_ptr->valid & PNG_INFO_fcTL))
+{
+png_ptr->apng_flags |= PNG_FIRST_FRAME_HIDDEN;
+info_ptr->num_frames++;
+}
+}
+void /* PRIVATE */
+png_handle_fdAT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+png_ensure_sequence_number(png_ptr, length);
+/* This function is only called from png_read_end(), png_read_info(),
+* and png_push_read_chunk() which means that:
+* - the user doesn't want to read this frame
+* - or this is an out-of-place fdAT
+* in either case it is safe to ignore the chunk with a warning */
+png_warning(png_ptr, "ignoring fdAT chunk");
+png_crc_finish(png_ptr, length - 4);
+PNG_UNUSED(info_ptr)
+}
+void /* PRIVATE */
+png_ensure_sequence_number(png_structp png_ptr, png_uint_32 length)
+{
+png_byte data[4];
+png_uint_32 sequence_number;
+if (length < 4)
+png_error(png_ptr, "invalid fcTL or fdAT chunk found");
+png_crc_read(png_ptr, data, 4);
+sequence_number = png_get_uint_31(png_ptr, data);
+if (sequence_number != png_ptr->next_seq_num)
+png_error(png_ptr, "fcTL or fdAT chunk with out-of-order sequence "
+"number found");
+png_ptr->next_seq_num++;
+}
+#endif /* PNG_READ_APNG_SUPPORTED */
+#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+/* Utility function for png_handle_unknown; set up png_ptr::unknown_chunk */
+static int
+png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
+{
+png_alloc_size_t limit = PNG_SIZE_MAX;
+if (png_ptr->unknown_chunk.data != NULL)
+{
+png_free(png_ptr, png_ptr->unknown_chunk.data);
+png_ptr->unknown_chunk.data = NULL;
+}
+#  ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+if (png_ptr->user_chunk_malloc_max > 0 &&
+png_ptr->user_chunk_malloc_max < limit)
+limit = png_ptr->user_chunk_malloc_max;
+#  elif PNG_USER_CHUNK_MALLOC_MAX > 0
+if (PNG_USER_CHUNK_MALLOC_MAX < limit)
+limit = PNG_USER_CHUNK_MALLOC_MAX;
+#  endif
+if (length <= limit)
+{
+PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
+/* The following is safe because of the PNG_SIZE_MAX init above */
+png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/;
+/* 'mode' is a flag array, only the bottom four bits matter here */
+png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
+if (length == 0)
+png_ptr->unknown_chunk.data = NULL;
+else
+{
+/* Do a 'warn' here - it is handled below. */
+png_ptr->unknown_chunk.data = png_voidcast(png_bytep,
+png_malloc_warn(png_ptr, length));
+}
+}
+if (png_ptr->unknown_chunk.data == NULL && length > 0)
+{
+/* This is benign because we clean up correctly */
+png_crc_finish(png_ptr, length);
+png_chunk_benign_error(png_ptr, "unknown chunk exceeds memory limits");
+return 0;
+}
+else
+{
+if (length > 0)
+png_crc_read(png_ptr, png_ptr->unknown_chunk.data, length);
+png_crc_finish(png_ptr, 0);
+return 1;
+}
+}
+#endif /* PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
+/* Handle an unknown, or known but disabled, chunk */
+void /* PRIVATE */
+png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
+png_uint_32 length, int keep)
+{
+int handled = 0; /* the chunk was handled */
+png_debug(1, "in png_handle_unknown");
+#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+/* NOTE: this code is based on the code in libpng-1.4.12 except for fixing
+* the bug which meant that setting a non-default behavior for a specific
+* chunk would be ignored (the default was always used unless a user
+* callback was installed).
+*
+* 'keep' is the value from the png_chunk_unknown_handling, the setting for
+* this specific chunk_name, if PNG_HANDLE_AS_UNKNOWN_SUPPORTED, if not it
+* will always be PNG_HANDLE_CHUNK_AS_DEFAULT and it needs to be set here.
+* This is just an optimization to avoid multiple calls to the lookup
+* function.
+*/
+#  ifndef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+#     ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+keep = png_chunk_unknown_handling(png_ptr, png_ptr->chunk_name);
+#     endif
+#  endif
+/* One of the following methods will read the chunk or skip it (at least one
+* of these is always defined because this is the only way to switch on
+* PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
+*/
+#  ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+/* The user callback takes precedence over the chunk keep value, but the
+* keep value is still required to validate a save of a critical chunk.
+*/
+if (png_ptr->read_user_chunk_fn != NULL)
+{
+if (png_cache_unknown_chunk(png_ptr, length))
+{
+/* Callback to user unknown chunk handler */
+int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
+&png_ptr->unknown_chunk);
+/* ret is:
+* negative: An error occured, png_chunk_error will be called.
+*     zero: The chunk was not handled, the chunk will be discarded
+*           unless png_set_keep_unknown_chunks has been used to set
+*           a 'keep' behavior for this particular chunk, in which
+*           case that will be used.  A critical chunk will cause an
+*           error at this point unless it is to be saved.
+* positive: The chunk was handled, libpng will ignore/discard it.
+*/
+if (ret < 0)
+png_chunk_error(png_ptr, "error in user chunk");
+else if (ret == 0)
+{
+/* If the keep value is 'default' or 'never' override it, but
+* still error out on critical chunks unless the keep value is
+* 'always'  While this is weird it is the behavior in 1.4.12.
+* A possible improvement would be to obey the value set for the
+* chunk, but this would be an API change that would probably
+* damage some applications.
+*
+* The png_app_warning below catches the case that matters, where
+* the application has not set specific save or ignore for this
+* chunk or global save or ignore.
+*/
+if (keep < PNG_HANDLE_CHUNK_IF_SAFE)
+{
+#                 ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+if (png_ptr->unknown_default < PNG_HANDLE_CHUNK_IF_SAFE)
+{
+png_chunk_warning(png_ptr, "Saving unknown chunk:");
+png_app_warning(png_ptr,
+"forcing save of an unhandled chunk;"
+" please call png_set_keep_unknown_chunks");
+/* with keep = PNG_HANDLE_CHUNK_IF_SAFE */
+}
+#                 endif
+keep = PNG_HANDLE_CHUNK_IF_SAFE;
+}
+}
+else /* chunk was handled */
+{
+handled = 1;
+/* Critical chunks can be safely discarded at this point. */
+keep = PNG_HANDLE_CHUNK_NEVER;
+}
+}
+else
+keep = PNG_HANDLE_CHUNK_NEVER; /* insufficient memory */
+}
+else
+/* Use the SAVE_UNKNOWN_CHUNKS code or skip the chunk */
+#  endif /* PNG_READ_USER_CHUNKS_SUPPORTED */
+#  ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
+{
+/* keep is currently just the per-chunk setting, if there was no
+* setting change it to the global default now (not that this may
+* still be AS_DEFAULT) then obtain the cache of the chunk if required,
+* if not simply skip the chunk.
+*/
+if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
+keep = png_ptr->unknown_default;
+if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
+(keep == PNG_HANDLE_CHUNK_IF_SAFE &&
+PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
+{
+if (!png_cache_unknown_chunk(png_ptr, length))
+keep = PNG_HANDLE_CHUNK_NEVER;
+}
+else
+png_crc_finish(png_ptr, length);
+}
+#  else
+#     ifndef PNG_READ_USER_CHUNKS_SUPPORTED
+#        error no method to support READ_UNKNOWN_CHUNKS
+#     endif
+{
+/* If here there is no read callback pointer set and no support is
+* compiled in to just save the unknown chunks, so simply skip this
+* chunk.  If 'keep' is something other than AS_DEFAULT or NEVER then
+* the app has erroneously asked for unknown chunk saving when there
+* is no support.
+*/
+if (keep > PNG_HANDLE_CHUNK_NEVER)
+png_app_error(png_ptr, "no unknown chunk support available");
+png_crc_finish(png_ptr, length);
+}
+#  endif
+#  ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+/* Now store the chunk in the chunk list if appropriate, and if the limits
+* permit it.
+*/
+if (keep == PNG_HANDLE_CHUNK_ALWAYS ||
+(keep == PNG_HANDLE_CHUNK_IF_SAFE &&
+PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
+{
+#     ifdef PNG_USER_LIMITS_SUPPORTED
+switch (png_ptr->user_chunk_cache_max)
+{
+case 2:
+png_ptr->user_chunk_cache_max = 1;
+png_chunk_benign_error(png_ptr, "no space in chunk cache");
+/* FALL THROUGH */
+case 1:
+/* NOTE: prior to 1.6.0 this case resulted in an unknown critical
+* chunk being skipped, now there will be a hard error below.
+*/
+break;
+default: /* not at limit */
+--(png_ptr->user_chunk_cache_max);
+/* FALL THROUGH */
+case 0: /* no limit */
+#     endif /* PNG_USER_LIMITS_SUPPORTED */
+/* Here when the limit isn't reached or when limits are compiled
+* out; store the chunk.
+*/
+png_set_unknown_chunks(png_ptr, info_ptr,
+&png_ptr->unknown_chunk, 1);
+handled = 1;
+#     ifdef PNG_USER_LIMITS_SUPPORTED
+break;
+}
+#     endif
+}
+#  else /* no store support: the chunk must be handled by the user callback */
+PNG_UNUSED(info_ptr)
+#  endif
+/* Regardless of the error handling below the cached data (if any) can be
+* freed now.  Notice that the data is not freed if there is a png_error, but
+* it will be freed by destroy_read_struct.
+*/
+if (png_ptr->unknown_chunk.data != NULL)
+png_free(png_ptr, png_ptr->unknown_chunk.data);
+png_ptr->unknown_chunk.data = NULL;
+#else /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
+/* There is no support to read an unknown chunk, so just skip it. */
+png_crc_finish(png_ptr, length);
+PNG_UNUSED(info_ptr)
+PNG_UNUSED(keep)
+#endif /* !PNG_READ_UNKNOWN_CHUNKS_SUPPORTED */
+/* Check for unhandled critical chunks */
+if (!handled && PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
+png_chunk_error(png_ptr, "unhandled critical chunk");
+}
+/* This function is called to verify that a chunk name is valid.
+* This function can't have the "critical chunk check" incorporated
+* into it, since in the future we will need to be able to call user
+* functions to handle unknown critical chunks after we check that
+* the chunk name itself is valid.
+*/
+/* Bit hacking: the test for an invalid byte in the 4 byte chunk name is:
+*
+* ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
+*/
+void /* PRIVATE */
+png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
+{
+int i;
+png_debug(1, "in png_check_chunk_name");
+for (i=1; i<=4; ++i)
+{
+int c = chunk_name & 0xff;
+if (c < 65 || c > 122 || (c > 90 && c < 97))
+png_chunk_error(png_ptr, "invalid chunk type");
+chunk_name >>= 8;
+}
+}
+/* Combines the row recently read in with the existing pixels in the row.  This
+* routine takes care of alpha and transparency if requested.  This routine also
+* handles the two methods of progressive display of interlaced images,
+* depending on the 'display' value; if 'display' is true then the whole row
+* (dp) is filled from the start by replicating the available pixels.  If
+* 'display' is false only those pixels present in the pass are filled in.
+*/
+void /* PRIVATE */
+png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
+{
+unsigned int pixel_depth = png_ptr->transformed_pixel_depth;
+png_const_bytep sp = png_ptr->row_buf + 1;
+png_uint_32 row_width = png_ptr->width;
+unsigned int pass = png_ptr->pass;
+png_bytep end_ptr = 0;
+png_byte end_byte = 0;
+unsigned int end_mask;
+png_debug(1, "in png_combine_row");
+/* Added in 1.5.6: it should not be possible to enter this routine until at
+* least one row has been read from the PNG data and transformed.
+*/
+if (pixel_depth == 0)
+png_error(png_ptr, "internal row logic error");
+/* Added in 1.5.4: the pixel depth should match the information returned by
+* any call to png_read_update_info at this point.  Do not continue if we got
+* this wrong.
+*/
+if (png_ptr->info_rowbytes != 0 && png_ptr->info_rowbytes !=
+PNG_ROWBYTES(pixel_depth, row_width))
+png_error(png_ptr, "internal row size calculation error");
+/* Don't expect this to ever happen: */
+if (row_width == 0)
+png_error(png_ptr, "internal row width error");
+/* Preserve the last byte in cases where only part of it will be overwritten,
+* the multiply below may overflow, we don't care because ANSI-C guarantees
+* we get the low bits.
+*/
+end_mask = (pixel_depth * row_width) & 7;
+if (end_mask != 0)
+{
+/* end_ptr == NULL is a flag to say do nothing */
+end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
+end_byte = *end_ptr;
+#     ifdef PNG_READ_PACKSWAP_SUPPORTED
+if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */
+end_mask = 0xff << end_mask;
+else /* big-endian byte */
+#     endif
+end_mask = 0xff >> end_mask;
+/* end_mask is now the bits to *keep* from the destination row */
+}
+/* For non-interlaced images this reduces to a memcpy(). A memcpy()
+* will also happen if interlacing isn't supported or if the application
+* does not call png_set_interlace_handling().  In the latter cases the
+* caller just gets a sequence of the unexpanded rows from each interlace
+* pass.
+*/
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) &&
+pass < 6 && (display == 0 ||
+/* The following copies everything for 'display' on passes 0, 2 and 4. */
+(display == 1 && (pass & 1) != 0)))
+{
+/* Narrow images may have no bits in a pass; the caller should handle
+* this, but this test is cheap:
+*/
+if (row_width <= PNG_PASS_START_COL(pass))
+return;
+if (pixel_depth < 8)
+{
+/* For pixel depths up to 4 bpp the 8-pixel mask can be expanded to fit
+* into 32 bits, then a single loop over the bytes using the four byte
+* values in the 32-bit mask can be used.  For the 'display' option the
+* expanded mask may also not require any masking within a byte.  To
+* make this work the PACKSWAP option must be taken into account - it
+* simply requires the pixels to be reversed in each byte.
+*
+* The 'regular' case requires a mask for each of the first 6 passes,
+* the 'display' case does a copy for the even passes in the range
+* 0..6.  This has already been handled in the test above.
+*
+* The masks are arranged as four bytes with the first byte to use in
+* the lowest bits (little-endian) regardless of the order (PACKSWAP or
+* not) of the pixels in each byte.
+*
+* NOTE: the whole of this logic depends on the caller of this function
+* only calling it on rows appropriate to the pass.  This function only
+* understands the 'x' logic; the 'y' logic is handled by the caller.
+*
+* The following defines allow generation of compile time constant bit
+* masks for each pixel depth and each possibility of swapped or not
+* swapped bytes.  Pass 'p' is in the range 0..6; 'x', a pixel index,
+* is in the range 0..7; and the result is 1 if the pixel is to be
+* copied in the pass, 0 if not.  'S' is for the sparkle method, 'B'
+* for the block method.
+*
+* With some compilers a compile time expression of the general form:
+*
+*    (shift >= 32) ? (a >> (shift-32)) : (b >> shift)
+*
+* Produces warnings with values of 'shift' in the range 33 to 63
+* because the right hand side of the ?: expression is evaluated by
+* the compiler even though it isn't used.  Microsoft Visual C (various
+* versions) and the Intel C compiler are known to do this.  To avoid
+* this the following macros are used in 1.5.6.  This is a temporary
+* solution to avoid destabilizing the code during the release process.
+*/
+#        if PNG_USE_COMPILE_TIME_MASKS
+#           define PNG_LSR(x,s) ((x)>>((s) & 0x1f))
+#           define PNG_LSL(x,s) ((x)<<((s) & 0x1f))
+#        else
+#           define PNG_LSR(x,s) ((x)>>(s))
+#           define PNG_LSL(x,s) ((x)<<(s))
+#        endif
+#        define S_COPY(p,x) (((p)<4 ? PNG_LSR(0x80088822,(3-(p))*8+(7-(x))) :\
+PNG_LSR(0xaa55ff00,(7-(p))*8+(7-(x)))) & 1)
+#        define B_COPY(p,x) (((p)<4 ? PNG_LSR(0xff0fff33,(3-(p))*8+(7-(x))) :\
+PNG_LSR(0xff55ff00,(7-(p))*8+(7-(x)))) & 1)
+/* Return a mask for pass 'p' pixel 'x' at depth 'd'.  The mask is
+* little endian - the first pixel is at bit 0 - however the extra
+* parameter 's' can be set to cause the mask position to be swapped
+* within each byte, to match the PNG format.  This is done by XOR of
+* the shift with 7, 6 or 4 for bit depths 1, 2 and 4.
+*/
+#        define PIXEL_MASK(p,x,d,s) \
+(PNG_LSL(((PNG_LSL(1U,(d)))-1),(((x)*(d))^((s)?8-(d):0))))
+/* Hence generate the appropriate 'block' or 'sparkle' pixel copy mask.
+*/
+#        define S_MASKx(p,x,d,s) (S_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
+#        define B_MASKx(p,x,d,s) (B_COPY(p,x)?PIXEL_MASK(p,x,d,s):0)
+/* Combine 8 of these to get the full mask.  For the 1-bpp and 2-bpp
+* cases the result needs replicating, for the 4-bpp case the above
+* generates a full 32 bits.
+*/
+#        define MASK_EXPAND(m,d) ((m)*((d)==1?0x01010101:((d)==2?0x00010001:1)))
+#        define S_MASK(p,d,s) MASK_EXPAND(S_MASKx(p,0,d,s) + S_MASKx(p,1,d,s) +\
+S_MASKx(p,2,d,s) + S_MASKx(p,3,d,s) + S_MASKx(p,4,d,s) +\
+S_MASKx(p,5,d,s) + S_MASKx(p,6,d,s) + S_MASKx(p,7,d,s), d)
+#        define B_MASK(p,d,s) MASK_EXPAND(B_MASKx(p,0,d,s) + B_MASKx(p,1,d,s) +\
+B_MASKx(p,2,d,s) + B_MASKx(p,3,d,s) + B_MASKx(p,4,d,s) +\
+B_MASKx(p,5,d,s) + B_MASKx(p,6,d,s) + B_MASKx(p,7,d,s), d)
+#if PNG_USE_COMPILE_TIME_MASKS
+/* Utility macros to construct all the masks for a depth/swap
+* combination.  The 's' parameter says whether the format is PNG
+* (big endian bytes) or not.  Only the three odd-numbered passes are
+* required for the display/block algorithm.
+*/
+#        define S_MASKS(d,s) { S_MASK(0,d,s), S_MASK(1,d,s), S_MASK(2,d,s),\
+S_MASK(3,d,s), S_MASK(4,d,s), S_MASK(5,d,s) }
+#        define B_MASKS(d,s) { B_MASK(1,d,s), S_MASK(3,d,s), S_MASK(5,d,s) }
+#        define DEPTH_INDEX(d) ((d)==1?0:((d)==2?1:2))
+/* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
+* then pass:
+*/
+static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
+{
+/* Little-endian byte masks for PACKSWAP */
+{ S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
+/* Normal (big-endian byte) masks - PNG format */
+{ S_MASKS(1,1), S_MASKS(2,1), S_MASKS(4,1) }
+};
+/* display_mask has only three entries for the odd passes, so index by
+* pass>>1.
+*/
+static PNG_CONST png_uint_32 display_mask[2][3][3] =
+{
+/* Little-endian byte masks for PACKSWAP */
+{ B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
+/* Normal (big-endian byte) masks - PNG format */
+{ B_MASKS(1,1), B_MASKS(2,1), B_MASKS(4,1) }
+};
+#        define MASK(pass,depth,display,png)\
+((display)?display_mask[png][DEPTH_INDEX(depth)][pass>>1]:\
+row_mask[png][DEPTH_INDEX(depth)][pass])
+#else /* !PNG_USE_COMPILE_TIME_MASKS */
+/* This is the runtime alternative: it seems unlikely that this will
+* ever be either smaller or faster than the compile time approach.
+*/
+#        define MASK(pass,depth,display,png)\
+((display)?B_MASK(pass,depth,png):S_MASK(pass,depth,png))
+#endif /* !PNG_USE_COMPILE_TIME_MASKS */
+/* Use the appropriate mask to copy the required bits.  In some cases
+* the byte mask will be 0 or 0xff, optimize these cases.  row_width is
+* the number of pixels, but the code copies bytes, so it is necessary
+* to special case the end.
+*/
+png_uint_32 pixels_per_byte = 8 / pixel_depth;
+png_uint_32 mask;
+#        ifdef PNG_READ_PACKSWAP_SUPPORTED
+if (png_ptr->transformations & PNG_PACKSWAP)
+mask = MASK(pass, pixel_depth, display, 0);
+else
+#        endif
+mask = MASK(pass, pixel_depth, display, 1);
+for (;;)
+{
+png_uint_32 m;
+/* It doesn't matter in the following if png_uint_32 has more than
+* 32 bits because the high bits always match those in m<<24; it is,
+* however, essential to use OR here, not +, because of this.
+*/
+m = mask;
+mask = (m >> 8) | (m << 24); /* rotate right to good compilers */
+m &= 0xff;
+if (m != 0) /* something to copy */
+{
+if (m != 0xff)
+*dp = (png_byte)((*dp & ~m) | (*sp & m));
+else
+*dp = *sp;
+}
+/* NOTE: this may overwrite the last byte with garbage if the image
+* is not an exact number of bytes wide; libpng has always done
+* this.
+*/
+if (row_width <= pixels_per_byte)
+break; /* May need to restore part of the last byte */
+row_width -= pixels_per_byte;
+++dp;
+++sp;
+}
+}
+else /* pixel_depth >= 8 */
+{
+unsigned int bytes_to_copy, bytes_to_jump;
+/* Validate the depth - it must be a multiple of 8 */
+if (pixel_depth & 7)
+png_error(png_ptr, "invalid user transform pixel depth");
+pixel_depth >>= 3; /* now in bytes */
+row_width *= pixel_depth;
+/* Regardless of pass number the Adam 7 interlace always results in a
+* fixed number of pixels to copy then to skip.  There may be a
+* different number of pixels to skip at the start though.
+*/
+{
+unsigned int offset = PNG_PASS_START_COL(pass) * pixel_depth;
+row_width -= offset;
+dp += offset;
+sp += offset;
+}
+/* Work out the bytes to copy. */
+if (display)
+{
+/* When doing the 'block' algorithm the pixel in the pass gets
+* replicated to adjacent pixels.  This is why the even (0,2,4,6)
+* passes are skipped above - the entire expanded row is copied.
+*/
+bytes_to_copy = (1<<((6-pass)>>1)) * pixel_depth;
+/* But don't allow this number to exceed the actual row width. */
+if (bytes_to_copy > row_width)
+bytes_to_copy = row_width;
+}
+else /* normal row; Adam7 only ever gives us one pixel to copy. */
+bytes_to_copy = pixel_depth;
+/* In Adam7 there is a constant offset between where the pixels go. */
+bytes_to_jump = PNG_PASS_COL_OFFSET(pass) * pixel_depth;
+/* And simply copy these bytes.  Some optimization is possible here,
+* depending on the value of 'bytes_to_copy'.  Special case the low
+* byte counts, which we know to be frequent.
+*
+* Notice that these cases all 'return' rather than 'break' - this
+* avoids an unnecessary test on whether to restore the last byte
+* below.
+*/
+switch (bytes_to_copy)
+{
+case 1:
+for (;;)
+{
+*dp = *sp;
+if (row_width <= bytes_to_jump)
+return;
+dp += bytes_to_jump;
+sp += bytes_to_jump;
+row_width -= bytes_to_jump;
+}
+case 2:
+/* There is a possibility of a partial copy at the end here; this
+* slows the code down somewhat.
+*/
+do
+{
+dp[0] = sp[0], dp[1] = sp[1];
+if (row_width <= bytes_to_jump)
+return;
+sp += bytes_to_jump;
+dp += bytes_to_jump;
+row_width -= bytes_to_jump;
+}
+while (row_width > 1);
+/* And there can only be one byte left at this point: */
+*dp = *sp;
+return;
+case 3:
+/* This can only be the RGB case, so each copy is exactly one
+* pixel and it is not necessary to check for a partial copy.
+*/
+for(;;)
+{
+dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];
+if (row_width <= bytes_to_jump)
+return;
+sp += bytes_to_jump;
+dp += bytes_to_jump;
+row_width -= bytes_to_jump;
+}
+default:
+#if PNG_ALIGN_TYPE != PNG_ALIGN_NONE
+/* Check for double byte alignment and, if possible, use a
+* 16-bit copy.  Don't attempt this for narrow images - ones that
+* are less than an interlace panel wide.  Don't attempt it for
+* wide bytes_to_copy either - use the memcpy there.
+*/
+if (bytes_to_copy < 16 /*else use memcpy*/ &&
+png_isaligned(dp, png_uint_16) &&
+png_isaligned(sp, png_uint_16) &&
+bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
+bytes_to_jump % (sizeof (png_uint_16)) == 0)
+{
+/* Everything is aligned for png_uint_16 copies, but try for
+* png_uint_32 first.
+*/
+if (png_isaligned(dp, png_uint_32) &&
+png_isaligned(sp, png_uint_32) &&
+bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
+bytes_to_jump % (sizeof (png_uint_32)) == 0)
+{
+png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
+png_const_uint_32p sp32 = png_aligncastconst(
+png_const_uint_32p, sp);
+size_t skip = (bytes_to_jump-bytes_to_copy) /
+(sizeof (png_uint_32));
+do
+{
+size_t c = bytes_to_copy;
+do
+{
+*dp32++ = *sp32++;
+c -= (sizeof (png_uint_32));
+}
+while (c > 0);
+if (row_width <= bytes_to_jump)
+return;
+dp32 += skip;
+sp32 += skip;
+row_width -= bytes_to_jump;
+}
+while (bytes_to_copy <= row_width);
+/* Get to here when the row_width truncates the final copy.
+* There will be 1-3 bytes left to copy, so don't try the
+* 16-bit loop below.
+*/
+dp = (png_bytep)dp32;
+sp = (png_const_bytep)sp32;
+do
+*dp++ = *sp++;
+while (--row_width > 0);
+return;
+}
+/* Else do it in 16-bit quantities, but only if the size is
+* not too large.
+*/
+else
+{
+png_uint_16p dp16 = png_aligncast(png_uint_16p, dp);
+png_const_uint_16p sp16 = png_aligncastconst(
+png_const_uint_16p, sp);
+size_t skip = (bytes_to_jump-bytes_to_copy) /
+(sizeof (png_uint_16));
+do
+{
+size_t c = bytes_to_copy;
+do
+{
+*dp16++ = *sp16++;
+c -= (sizeof (png_uint_16));
+}
+while (c > 0);
+if (row_width <= bytes_to_jump)
+return;
+dp16 += skip;
+sp16 += skip;
+row_width -= bytes_to_jump;
+}
+while (bytes_to_copy <= row_width);
+/* End of row - 1 byte left, bytes_to_copy > row_width: */
+dp = (png_bytep)dp16;
+sp = (png_const_bytep)sp16;
+do
+*dp++ = *sp++;
+while (--row_width > 0);
+return;
+}
+}
+#endif /* PNG_ALIGN_ code */
+/* The true default - use a memcpy: */
+for (;;)
+{
+memcpy(dp, sp, bytes_to_copy);
+if (row_width <= bytes_to_jump)
+return;
+sp += bytes_to_jump;
+dp += bytes_to_jump;
+row_width -= bytes_to_jump;
+if (bytes_to_copy > row_width)
+bytes_to_copy = row_width;
+}
+}
+/* NOT REACHED*/
+} /* pixel_depth >= 8 */
+/* Here if pixel_depth < 8 to check 'end_ptr' below. */
+}
+else
+#endif
+/* If here then the switch above wasn't used so just memcpy the whole row
+* from the temporary row buffer (notice that this overwrites the end of the
+* destination row if it is a partial byte.)
+*/
+memcpy(dp, sp, PNG_ROWBYTES(pixel_depth, row_width));
+/* Restore the overwritten bits from the last byte if necessary. */
+if (end_ptr != NULL)
+*end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
+}
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+void /* PRIVATE */
+png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
+png_uint_32 transformations /* Because these may affect the byte layout */)
+{
+/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+/* Offset to next interlace block */
+static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+png_debug(1, "in png_do_read_interlace");
+if (row != NULL && row_info != NULL)
+{
+png_uint_32 final_width;
+final_width = row_info->width * png_pass_inc[pass];
+switch (row_info->pixel_depth)
+{
+case 1:
+{
+png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);
+png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);
+int sshift, dshift;
+int s_start, s_end, s_inc;
+int jstop = png_pass_inc[pass];
+png_byte v;
+png_uint_32 i;
+int j;
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+if (transformations & PNG_PACKSWAP)
+{
+sshift = (int)((row_info->width + 7) & 0x07);
+dshift = (int)((final_width + 7) & 0x07);
+s_start = 7;
+s_end = 0;
+s_inc = -1;
+}
+else
+#endif
+{
+sshift = 7 - (int)((row_info->width + 7) & 0x07);
+dshift = 7 - (int)((final_width + 7) & 0x07);
+s_start = 0;
+s_end = 7;
+s_inc = 1;
+}
+for (i = 0; i < row_info->width; i++)
+{
+v = (png_byte)((*sp >> sshift) & 0x01);
+for (j = 0; j < jstop; j++)
+{
+unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
+tmp |= v << dshift;
+*dp = (png_byte)(tmp & 0xff);
+if (dshift == s_end)
+{
+dshift = s_start;
+dp--;
+}
+else
+dshift += s_inc;
+}
+if (sshift == s_end)
+{
+sshift = s_start;
+sp--;
+}
+else
+sshift += s_inc;
+}
+break;
+}
+case 2:
+{
+png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
+png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
+int sshift, dshift;
+int s_start, s_end, s_inc;
+int jstop = png_pass_inc[pass];
+png_uint_32 i;
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+if (transformations & PNG_PACKSWAP)
+{
+sshift = (int)(((row_info->width + 3) & 0x03) << 1);
+dshift = (int)(((final_width + 3) & 0x03) << 1);
+s_start = 6;
+s_end = 0;
+s_inc = -2;
+}
+else
+#endif
+{
+sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1);
+dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1);
+s_start = 0;
+s_end = 6;
+s_inc = 2;
+}
+for (i = 0; i < row_info->width; i++)
+{
+png_byte v;
+int j;
+v = (png_byte)((*sp >> sshift) & 0x03);
+for (j = 0; j < jstop; j++)
+{
+unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
+tmp |= v << dshift;
+*dp = (png_byte)(tmp & 0xff);
+if (dshift == s_end)
+{
+dshift = s_start;
+dp--;
+}
+else
+dshift += s_inc;
+}
+if (sshift == s_end)
+{
+sshift = s_start;
+sp--;
+}
+else
+sshift += s_inc;
+}
+break;
+}
+case 4:
+{
+png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
+png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);
+int sshift, dshift;
+int s_start, s_end, s_inc;
+png_uint_32 i;
+int jstop = png_pass_inc[pass];
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+if (transformations & PNG_PACKSWAP)
+{
+sshift = (int)(((row_info->width + 1) & 0x01) << 2);
+dshift = (int)(((final_width + 1) & 0x01) << 2);
+s_start = 4;
+s_end = 0;
+s_inc = -4;
+}
+else
+#endif
+{
+sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2);
+dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2);
+s_start = 0;
+s_end = 4;
+s_inc = 4;
+}
+for (i = 0; i < row_info->width; i++)
+{
+png_byte v = (png_byte)((*sp >> sshift) & 0x0f);
+int j;
+for (j = 0; j < jstop; j++)
+{
+unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
+tmp |= v << dshift;
+*dp = (png_byte)(tmp & 0xff);
+if (dshift == s_end)
+{
+dshift = s_start;
+dp--;
+}
+else
+dshift += s_inc;
+}
+if (sshift == s_end)
+{
+sshift = s_start;
+sp--;
+}
+else
+sshift += s_inc;
+}
+break;
+}
+default:
+{
+png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
+png_bytep sp = row + (png_size_t)(row_info->width - 1)
+* pixel_bytes;
+png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
+int jstop = png_pass_inc[pass];
+png_uint_32 i;
+for (i = 0; i < row_info->width; i++)
+{
+png_byte v[8]; /* SAFE; pixel_depth does not exceed 64 */
+int j;
+memcpy(v, sp, pixel_bytes);
+for (j = 0; j < jstop; j++)
+{
+memcpy(dp, v, pixel_bytes);
+dp -= pixel_bytes;
+}
+sp -= pixel_bytes;
+}
+break;
+}
+}
+row_info->width = final_width;
+row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
+}
+#ifndef PNG_READ_PACKSWAP_SUPPORTED
+PNG_UNUSED(transformations)  /* Silence compiler warning */
+#endif
+}
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+static void
+png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
+png_const_bytep prev_row)
+{
+png_size_t i;
+png_size_t istop = row_info->rowbytes;
+unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+png_bytep rp = row + bpp;
+PNG_UNUSED(prev_row)
+for (i = bpp; i < istop; i++)
+{
+*rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
+rp++;
+}
+}
+static void
+png_read_filter_row_up(png_row_infop row_info, png_bytep row,
+png_const_bytep prev_row)
+{
+png_size_t i;
+png_size_t istop = row_info->rowbytes;
+png_bytep rp = row;
+png_const_bytep pp = prev_row;
+for (i = 0; i < istop; i++)
+{
+*rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
+rp++;
+}
+}
+static void
+png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
+png_const_bytep prev_row)
+{
+png_size_t i;
+png_bytep rp = row;
+png_const_bytep pp = prev_row;
+unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+png_size_t istop = row_info->rowbytes - bpp;
+for (i = 0; i < bpp; i++)
+{
+*rp = (png_byte)(((int)(*rp) +
+((int)(*pp++) / 2 )) & 0xff);
+rp++;
+}
+for (i = 0; i < istop; i++)
+{
+*rp = (png_byte)(((int)(*rp) +
+(int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+rp++;
+}
+}
+static void
+png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
+png_const_bytep prev_row)
+{
+png_bytep rp_end = row + row_info->rowbytes;
+int a, c;
+/* First pixel/byte */
+c = *prev_row++;
+a = *row + c;
+*row++ = (png_byte)a;
+/* Remainder */
+while (row < rp_end)
+{
+int b, pa, pb, pc, p;
+a &= 0xff; /* From previous iteration or start */
+b = *prev_row++;
+p = b - c;
+pc = a - c;
+#     ifdef PNG_USE_ABS
+pa = abs(p);
+pb = abs(pc);
+pc = abs(p + pc);
+#     else
+pa = p < 0 ? -p : p;
+pb = pc < 0 ? -pc : pc;
+pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+#     endif
+/* Find the best predictor, the least of pa, pb, pc favoring the earlier
+* ones in the case of a tie.
+*/
+if (pb < pa) pa = pb, a = b;
+if (pc < pa) a = c;
+/* Calculate the current pixel in a, and move the previous row pixel to c
+* for the next time round the loop
+*/
+c = b;
+a += *row;
+*row++ = (png_byte)a;
+}
+}
+static void
+png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
+png_const_bytep prev_row)
+{
+int bpp = (row_info->pixel_depth + 7) >> 3;
+png_bytep rp_end = row + bpp;
+/* Process the first pixel in the row completely (this is the same as 'up'
+* because there is only one candidate predictor for the first row).
+*/
+while (row < rp_end)
+{
+int a = *row + *prev_row++;
+*row++ = (png_byte)a;
+}
+/* Remainder */
+rp_end += row_info->rowbytes - bpp;
+while (row < rp_end)
+{
+int a, b, c, pa, pb, pc, p;
+c = *(prev_row - bpp);
+a = *(row - bpp);
+b = *prev_row++;
+p = b - c;
+pc = a - c;
+#     ifdef PNG_USE_ABS
+pa = abs(p);
+pb = abs(pc);
+pc = abs(p + pc);
+#     else
+pa = p < 0 ? -p : p;
+pb = pc < 0 ? -pc : pc;
+pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+#     endif
+if (pb < pa) pa = pb, a = b;
+if (pc < pa) a = c;
+a += *row;
+*row++ = (png_byte)a;
+}
+}
+static void
+png_init_filter_functions(png_structrp pp)
+/* This function is called once for every PNG image (except for PNG images
+* that only use PNG_FILTER_VALUE_NONE for all rows) to set the
+* implementations required to reverse the filtering of PNG rows.  Reversing
+* the filter is the first transformation performed on the row data.  It is
+* performed in place, therefore an implementation can be selected based on
+* the image pixel format.  If the implementation depends on image width then
+* take care to ensure that it works correctly if the image is interlaced -
+* interlacing causes the actual row width to vary.
+*/
+{
+unsigned int bpp = (pp->pixel_depth + 7) >> 3;
+pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub;
+pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up;
+pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg;
+if (bpp == 1)
+pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+png_read_filter_row_paeth_1byte_pixel;
+else
+pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+png_read_filter_row_paeth_multibyte_pixel;
+#ifdef PNG_FILTER_OPTIMIZATIONS
+/* To use this define PNG_FILTER_OPTIMIZATIONS as the name of a function to
+* call to install hardware optimizations for the above functions; simply
+* replace whatever elements of the pp->read_filter[] array with a hardware
+* specific (or, for that matter, generic) optimization.
+*
+* To see an example of this examine what configure.ac does when
+* --enable-arm-neon is specified on the command line.
+*/
+PNG_FILTER_OPTIMIZATIONS(pp, bpp);
+#endif
+}
+void /* PRIVATE */
+png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
+png_const_bytep prev_row, int filter)
+{
+/* OPTIMIZATION: DO NOT MODIFY THIS FUNCTION, instead #define
+* PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
+* implementations.  See png_init_filter_functions above.
+*/
+if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
+{
+if (pp->read_filter[0] == NULL)
+png_init_filter_functions(pp);
+pp->read_filter[filter-1](row_info, row, prev_row);
+}
+}
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+void /* PRIVATE */
+png_read_IDAT_data(png_structrp png_ptr, png_bytep output,
+png_alloc_size_t avail_out)
+{
+/* Loop reading IDATs and decompressing the result into output[avail_out] */
+png_ptr->zstream.next_out = output;
+png_ptr->zstream.avail_out = 0; /* safety: set below */
+if (output == NULL)
+avail_out = 0;
+do
+{
+int ret;
+png_byte tmpbuf[PNG_INFLATE_BUF_SIZE];
+if (png_ptr->zstream.avail_in == 0)
+{
+uInt avail_in;
+png_bytep buffer;
+#ifdef PNG_READ_APNG_SUPPORTED
+png_uint_32 bytes_to_skip = 0;
+while (png_ptr->idat_size == 0 || bytes_to_skip != 0)
+{
+png_crc_finish(png_ptr, bytes_to_skip);
+bytes_to_skip = 0;
+png_ptr->idat_size = png_read_chunk_header(png_ptr);
+if (png_ptr->num_frames_read == 0)
+{
+if (png_ptr->chunk_name != png_IDAT)
+png_error(png_ptr, "Not enough image data");
+}
+else
+{
+if (png_ptr->chunk_name == png_IEND)
+png_error(png_ptr, "Not enough image data");
+if (png_ptr->chunk_name != png_fdAT)
+{
+png_warning(png_ptr, "Skipped (ignored) a chunk "
+"between APNG chunks");
+bytes_to_skip = png_ptr->idat_size;
+continue;
+}
+png_ensure_sequence_number(png_ptr, png_ptr->idat_size);
+png_ptr->idat_size -= 4;
+}
+}
+#else
+while (png_ptr->idat_size == 0)
+{
+png_crc_finish(png_ptr, 0);
+png_ptr->idat_size = png_read_chunk_header(png_ptr);
+/* This is an error even in the 'check' case because the code just
+* consumed a non-IDAT header.
+*/
+if (png_ptr->chunk_name != png_IDAT)
+png_error(png_ptr, "Not enough image data");
+}
+#endif /* PNG_READ_APNG_SUPPORTED */
+avail_in = png_ptr->IDAT_read_size;
+if (avail_in > png_ptr->idat_size)
+avail_in = (uInt)png_ptr->idat_size;
+/* A PNG with a gradually increasing IDAT size will defeat this attempt
+* to minimize memory usage by causing lots of re-allocs, but
+* realistically doing IDAT_read_size re-allocs is not likely to be a
+* big problem.
+*/
+buffer = png_read_buffer(png_ptr, avail_in, 0/*error*/);
+png_crc_read(png_ptr, buffer, avail_in);
+png_ptr->idat_size -= avail_in;
+png_ptr->zstream.next_in = buffer;
+png_ptr->zstream.avail_in = avail_in;
+}
+/* And set up the output side. */
+if (output != NULL) /* standard read */
+{
+uInt out = ZLIB_IO_MAX;
+if (out > avail_out)
+out = (uInt)avail_out;
+avail_out -= out;
+png_ptr->zstream.avail_out = out;
+}
+else /* after last row, checking for end */
+{
+png_ptr->zstream.next_out = tmpbuf;
+png_ptr->zstream.avail_out = (sizeof tmpbuf);
+}
+/* Use NO_FLUSH; this gives zlib the maximum opportunity to optimize the
+* process.  If the LZ stream is truncated the sequential reader will
+* terminally damage the stream, above, by reading the chunk header of the
+* following chunk (it then exits with png_error).
+*
+* TODO: deal more elegantly with truncated IDAT lists.
+*/
+ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
+/* Take the unconsumed output back. */
+if (output != NULL)
+avail_out += png_ptr->zstream.avail_out;
+else /* avail_out counts the extra bytes */
+avail_out += (sizeof tmpbuf) - png_ptr->zstream.avail_out;
+png_ptr->zstream.avail_out = 0;
+if (ret == Z_STREAM_END)
+{
+/* Do this for safety; we won't read any more into this row. */
+png_ptr->zstream.next_out = NULL;
+png_ptr->mode |= PNG_AFTER_IDAT;
+png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
+#ifdef PNG_READ_APNG_SUPPORTED
+png_ptr->num_frames_read++;
+#endif
+if (png_ptr->zstream.avail_in > 0 || png_ptr->idat_size > 0)
+png_chunk_benign_error(png_ptr, "Extra compressed data");
+break;
+}
+if (ret != Z_OK)
+{
+png_zstream_error(png_ptr, ret);
+if (output != NULL)
+png_chunk_error(png_ptr, png_ptr->zstream.msg);
+else /* checking */
+{
+png_chunk_benign_error(png_ptr, png_ptr->zstream.msg);
+return;
+}
+}
+} while (avail_out > 0);
+if (avail_out > 0)
+{
+/* The stream ended before the image; this is the same as too few IDATs so
+* should be handled the same way.
+*/
+if (output != NULL)
+png_error(png_ptr, "Not enough image data");
+else /* the deflate stream contained extra data */
+png_chunk_benign_error(png_ptr, "Too much image data");
+}
+}
+void /* PRIVATE */
+png_read_finish_IDAT(png_structrp png_ptr)
+{
+/* We don't need any more data and the stream should have ended, however the
+* LZ end code may actually not have been processed.  In this case we must
+* read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
+* may still remain to be consumed.
+*/
+if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
+{
+/* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
+* the compressed stream, but the stream may be damaged too, so even after
+* this call we may need to terminate the zstream ownership.
+*/
+png_read_IDAT_data(png_ptr, NULL, 0);
+png_ptr->zstream.next_out = NULL; /* safety */
+/* Now clear everything out for safety; the following may not have been
+* done.
+*/
+if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
+{
+png_ptr->mode |= PNG_AFTER_IDAT;
+png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
+}
+}
+/* If the zstream has not been released do it now *and* terminate the reading
+* of the final IDAT chunk.
+*/
+if (png_ptr->zowner == png_IDAT)
+{
+/* Always do this; the pointers otherwise point into the read buffer. */
+png_ptr->zstream.next_in = NULL;
+png_ptr->zstream.avail_in = 0;
+/* Now we no longer own the zstream. */
+png_ptr->zowner = 0;
+/* The slightly weird semantics of the sequential IDAT reading is that we
+* are always in or at the end of an IDAT chunk, so we always need to do a
+* crc_finish here.  If idat_size is non-zero we also need to read the
+* spurious bytes at the end of the chunk now.
+*/
+(void)png_crc_finish(png_ptr, png_ptr->idat_size);
+}
+}
+void /* PRIVATE */
+png_read_finish_row(png_structrp png_ptr)
+{
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+/* Start of interlace block */
+static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+/* Offset to next interlace block */
+static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+/* Start of interlace block in the y direction */
+static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+/* Offset to next interlace block in the y direction */
+static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+png_debug(1, "in png_read_finish_row");
+png_ptr->row_number++;
+if (png_ptr->row_number < png_ptr->num_rows)
+return;
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+if (png_ptr->interlaced)
+{
+png_ptr->row_number = 0;
+/* TO DO: don't do this if prev_row isn't needed (requires
+* read-ahead of the next row's filter byte.
+*/
+memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+do
+{
+png_ptr->pass++;
+if (png_ptr->pass >= 7)
+break;
+png_ptr->iwidth = (png_ptr->width +
+png_pass_inc[png_ptr->pass] - 1 -
+png_pass_start[png_ptr->pass]) /
+png_pass_inc[png_ptr->pass];
+if (!(png_ptr->transformations & PNG_INTERLACE))
+{
+png_ptr->num_rows = (png_ptr->height +
+png_pass_yinc[png_ptr->pass] - 1 -
+png_pass_ystart[png_ptr->pass]) /
+png_pass_yinc[png_ptr->pass];
+}
+else  /* if (png_ptr->transformations & PNG_INTERLACE) */
+break; /* libpng deinterlacing sees every row */
+} while (png_ptr->num_rows == 0 || png_ptr->iwidth == 0);
+if (png_ptr->pass < 7)
+return;
+}
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+/* Here after at the end of the last row of the last pass. */
+png_read_finish_IDAT(png_ptr);
+}
+#endif /* PNG_SEQUENTIAL_READ_SUPPORTED */
+void /* PRIVATE */
+png_read_start_row(png_structrp png_ptr)
+{
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+/* Start of interlace block */
+static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+/* Offset to next interlace block */
+static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+/* Start of interlace block in the y direction */
+static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+/* Offset to next interlace block in the y direction */
+static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+#endif
+int max_pixel_depth;
+png_size_t row_bytes;
+png_debug(1, "in png_read_start_row");
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+png_init_read_transformations(png_ptr);
+#endif
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+if (png_ptr->interlaced)
+{
+if (!(png_ptr->transformations & PNG_INTERLACE))
+png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
+png_pass_ystart[0]) / png_pass_yinc[0];
+else
+png_ptr->num_rows = png_ptr->height;
+png_ptr->iwidth = (png_ptr->width +
+png_pass_inc[png_ptr->pass] - 1 -
+png_pass_start[png_ptr->pass]) /
+png_pass_inc[png_ptr->pass];
+}
+else
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+{
+png_ptr->num_rows = png_ptr->height;
+png_ptr->iwidth = png_ptr->width;
+}
+max_pixel_depth = png_ptr->pixel_depth;
+/* WARNING: * png_read_transform_info (pngrtran.c) performs a simpliar set of
+* calculations to calculate the final pixel depth, then
+* png_do_read_transforms actually does the transforms.  This means that the
+* code which effectively calculates this value is actually repeated in three
+* separate places.  They must all match.  Innocent changes to the order of
+* transformations can and will break libpng in a way that causes memory
+* overwrites.
+*
+* TODO: fix this.
+*/
+#ifdef PNG_READ_PACK_SUPPORTED
+if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
+max_pixel_depth = 8;
+#endif
+#ifdef PNG_READ_EXPAND_SUPPORTED
+if (png_ptr->transformations & PNG_EXPAND)
+{
+if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+{
+if (png_ptr->num_trans)
+max_pixel_depth = 32;
+else
+max_pixel_depth = 24;
+}
+else if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
+{
+if (max_pixel_depth < 8)
+max_pixel_depth = 8;
+if (png_ptr->num_trans)
+max_pixel_depth *= 2;
+}
+else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
+{
+if (png_ptr->num_trans)
+{
+max_pixel_depth *= 4;
+max_pixel_depth /= 3;
+}
+}
+}
+#endif
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+if (png_ptr->transformations & PNG_EXPAND_16)
+{
+#     ifdef PNG_READ_EXPAND_SUPPORTED
+/* In fact it is an error if it isn't supported, but checking is
+* the safe way.
+*/
+if (png_ptr->transformations & PNG_EXPAND)
+{
+if (png_ptr->bit_depth < 16)
+max_pixel_depth *= 2;
+}
+else
+#     endif
+png_ptr->transformations &= ~PNG_EXPAND_16;
+}
+#endif
+#ifdef PNG_READ_FILLER_SUPPORTED
+if (png_ptr->transformations & (PNG_FILLER))
+{
+if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
+{
+if (max_pixel_depth <= 8)
+max_pixel_depth = 16;
+else
+max_pixel_depth = 32;
+}
+else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB ||
+png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+{
+if (max_pixel_depth <= 32)
+max_pixel_depth = 32;
+else
+max_pixel_depth = 64;
+}
+}
+#endif
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+if (png_ptr->transformations & PNG_GRAY_TO_RGB)
+{
+if (
+#ifdef PNG_READ_EXPAND_SUPPORTED
+(png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
+#endif
+#ifdef PNG_READ_FILLER_SUPPORTED
+(png_ptr->transformations & (PNG_FILLER)) ||
+#endif
+png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+{
+if (max_pixel_depth <= 16)
+max_pixel_depth = 32;
+else
+max_pixel_depth = 64;
+}
+else
+{
+if (max_pixel_depth <= 8)
+{
+if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+max_pixel_depth = 32;
+else
+max_pixel_depth = 24;
+}
+else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+max_pixel_depth = 64;
+else
+max_pixel_depth = 48;
+}
+}
+#endif
+#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
+defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
+if (png_ptr->transformations & PNG_USER_TRANSFORM)
+{
+int user_pixel_depth = png_ptr->user_transform_depth *
+png_ptr->user_transform_channels;
+if (user_pixel_depth > max_pixel_depth)
+max_pixel_depth = user_pixel_depth;
+}
+#endif
+/* This value is stored in png_struct and double checked in the row read
+* code.
+*/
+png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
+png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
+/* Align the width on the next larger 8 pixels.  Mainly used
+* for interlacing
+*/
+row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
+/* Calculate the maximum bytes needed, adding a byte and a pixel
+* for safety's sake
+*/
+row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
+1 + ((max_pixel_depth + 7) >> 3);
+#ifdef PNG_MAX_MALLOC_64K
+if (row_bytes > (png_uint_32)65536L)
+png_error(png_ptr, "This image requires a row greater than 64KB");
+#endif
+if (row_bytes + 48 > png_ptr->old_big_row_buf_size)
+{
+png_free(png_ptr, png_ptr->big_row_buf);
+png_free(png_ptr, png_ptr->big_prev_row);
+if (png_ptr->interlaced)
+png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
+row_bytes + 48);
+else
+png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
+png_ptr->big_prev_row = (png_bytep)png_malloc(png_ptr, row_bytes + 48);
+#ifdef PNG_ALIGNED_MEMORY_SUPPORTED
+/* Use 16-byte aligned memory for row_buf with at least 16 bytes
+* of padding before and after row_buf; treat prev_row similarly.
+* NOTE: the alignment is to the start of the pixels, one beyond the start
+* of the buffer, because of the filter byte.  Prior to libpng 1.5.6 this
+* was incorrect; the filter byte was aligned, which had the exact
+* opposite effect of that intended.
+*/
+{
+png_bytep temp = png_ptr->big_row_buf + 32;
+int extra = (int)((temp - (png_bytep)0) & 0x0f);
+png_ptr->row_buf = temp - extra - 1/*filter byte*/;
+temp = png_ptr->big_prev_row + 32;
+extra = (int)((temp - (png_bytep)0) & 0x0f);
+png_ptr->prev_row = temp - extra - 1/*filter byte*/;
+}
+#else
+/* Use 31 bytes of padding before and 17 bytes after row_buf. */
+png_ptr->row_buf = png_ptr->big_row_buf + 31;
+png_ptr->prev_row = png_ptr->big_prev_row + 31;
+#endif
+png_ptr->old_big_row_buf_size = row_bytes + 48;
+}
+#ifdef PNG_MAX_MALLOC_64K
+if (png_ptr->rowbytes > 65535)
+png_error(png_ptr, "This image requires a row greater than 64KB");
+#endif
+if (png_ptr->rowbytes > (PNG_SIZE_MAX - 1))
+png_error(png_ptr, "Row has too many bytes to allocate in memory");
+memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+png_debug1(3, "width = %u,", png_ptr->width);
+png_debug1(3, "height = %u,", png_ptr->height);
+png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
+png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
+png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
+png_debug1(3, "irowbytes = %lu",
+(unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
+/* The sequential reader needs a buffer for IDAT, but the progressive reader
+* does not, so free the read buffer now regardless; the sequential reader
+* reallocates it on demand.
+*/
+if (png_ptr->read_buffer)
+{
+png_bytep buffer = png_ptr->read_buffer;
+png_ptr->read_buffer_size = 0;
+png_ptr->read_buffer = NULL;
+png_free(png_ptr, buffer);
+}
+/* Finally claim the zstream for the inflate of the IDAT data, use the bits
+* value from the stream (note that this will result in a fatal error if the
+* IDAT stream has a bogus deflate header window_bits value, but this should
+* not be happening any longer!)
+*/
+if (png_inflate_claim(png_ptr, png_IDAT) != Z_OK)
+png_error(png_ptr, png_ptr->zstream.msg);
+png_ptr->flags |= PNG_FLAG_ROW_INIT;
+}
+#ifdef PNG_READ_APNG_SUPPORTED
+/* This function is to be called after the main IDAT set has been read and
+* before a new IDAT is read. It resets some parts of png_ptr
+* to make them usable by the read functions again */
+void /* PRIVATE */
+png_read_reset(png_structp png_ptr)
+{
+png_ptr->mode &= ~PNG_HAVE_IDAT;
+png_ptr->mode &= ~PNG_AFTER_IDAT;
+png_ptr->row_number = 0;
+png_ptr->pass = 0;
+}
+void /* PRIVATE */
+png_read_reinit(png_structp png_ptr, png_infop info_ptr)
+{
+png_ptr->width = info_ptr->next_frame_width;
+png_ptr->height = info_ptr->next_frame_height;
+png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth,png_ptr->width);
+png_ptr->info_rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth,
+png_ptr->width);
+if (png_ptr->prev_row)
+memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+}
+#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+/* same as png_read_reset() but for the progressive reader */
+void /* PRIVATE */
+png_progressive_read_reset(png_structp png_ptr)
+{
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+/* Start of interlace block */
+static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
+/* Offset to next interlace block */
+static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
+/* Start of interlace block in the y direction */
+static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
+/* Offset to next interlace block in the y direction */
+static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
+if (png_ptr->interlaced)
+{
+if (!(png_ptr->transformations & PNG_INTERLACE))
+png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
+png_pass_ystart[0]) / png_pass_yinc[0];
+else
+png_ptr->num_rows = png_ptr->height;
+png_ptr->iwidth = (png_ptr->width +
+png_pass_inc[png_ptr->pass] - 1 -
+png_pass_start[png_ptr->pass]) /
+png_pass_inc[png_ptr->pass];
+}
+else
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+{
+png_ptr->num_rows = png_ptr->height;
+png_ptr->iwidth = png_ptr->width;
+}
+png_ptr->flags &= ~PNG_FLAG_ZSTREAM_ENDED;
+if (inflateReset(&(png_ptr->zstream)) != Z_OK)
+png_error(png_ptr, "inflateReset failed");
+png_ptr->zstream.avail_in = 0;
+png_ptr->zstream.next_in = 0;
+png_ptr->zstream.next_out = png_ptr->row_buf;
+png_ptr->zstream.avail_out = (uInt)PNG_ROWBYTES(png_ptr->pixel_depth,
+png_ptr->iwidth) + 1;
+}
+#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
+#endif /* PNG_READ_APNG_SUPPORTED */
+#endif /* PNG_READ_SUPPORTED */

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media/libpng/pngrutil.c