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 /* pngmem.c - stub functions for memory allocation

  *

  * Last changed in libpng 1.6.8 [December 19, 2013]

  * Copyright (c) 1998-2013 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 provides a location for all memory allocation.  Users who

  * need special memory handling are expected to supply replacement

  * functions for png_malloc() and png_free(), and to use

  * png_create_read_struct_2() and png_create_write_struct_2() to

  * identify the replacement functions.

  */

 #include "pngpriv.h"

 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)

 /* Free a png_struct */

 void /* PRIVATE */

 png_destroy_png_struct(png_structrp png_ptr)

 {

    if (png_ptr != NULL)

    {

       /* png_free might call png_error and may certainly call

        * png_get_mem_ptr, so fake a temporary png_struct to support this.

        */

       png_struct dummy_struct = *png_ptr;

       memset(png_ptr, 0, (sizeof *png_ptr));

       png_free(&dummy_struct, png_ptr);

 #     ifdef PNG_SETJMP_SUPPORTED

          /* We may have a jmp_buf left to deallocate. */

          png_free_jmpbuf(&dummy_struct);

 #     endif

    }

 }

 /* Allocate memory.  For reasonable files, size should never exceed

  * 64K.  However, zlib may allocate more then 64K if you don't tell

  * it not to.  See zconf.h and png.h for more information.  zlib does

  * need to allocate exactly 64K, so whatever you call here must

  * have the ability to do that.

  */

 PNG_FUNCTION(png_voidp,PNGAPI

 png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)

 {

    png_voidp ret;

    ret = png_malloc(png_ptr, size);

    if (ret != NULL)

       memset(ret, 0, size);

    return ret;

 }

 /* png_malloc_base, an internal function added at libpng 1.6.0, does the work of

  * allocating memory, taking into account limits and PNG_USER_MEM_SUPPORTED.

  * Checking and error handling must happen outside this routine; it returns NULL

  * if the allocation cannot be done (for any reason.)

  */

 PNG_FUNCTION(png_voidp /* PRIVATE */,

 png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),

    PNG_ALLOCATED)

 {

    /* Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS

     * allocators have also been removed in 1.6.0, so any 16-bit system now has

     * to implement a user memory handler.  This checks to be sure it isn't

     * called with big numbers.

     */

 #ifndef PNG_USER_MEM_SUPPORTED

    PNG_UNUSED(png_ptr)

 #endif

    if (size > 0 && size <= PNG_SIZE_MAX

 #     ifdef PNG_MAX_MALLOC_64K

          && size <= 65536U

 #     endif

       )

    {

 #ifdef PNG_USER_MEM_SUPPORTED

       if (png_ptr != NULL && png_ptr->malloc_fn != NULL)

          return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size);

       else

 #endif

          return malloc((size_t)size); /* checked for truncation above */

    }

    else

       return NULL;

 }

 #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\

    defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)

 /* This is really here only to work round a spurious warning in GCC 4.6 and 4.7

  * that arises because of the checks in png_realloc_array that are repeated in

  * png_malloc_array.

  */

 static png_voidp

 png_malloc_array_checked(png_const_structrp png_ptr, int nelements,

    size_t element_size)

 {

    png_alloc_size_t req = nelements; /* known to be > 0 */

    if (req <= PNG_SIZE_MAX/element_size)

       return png_malloc_base(png_ptr, req * element_size);

    /* The failure case when the request is too large */

    return NULL;

 }

 PNG_FUNCTION(png_voidp /* PRIVATE */,

 png_malloc_array,(png_const_structrp png_ptr, int nelements,

    size_t element_size),PNG_ALLOCATED)

 {

    if (nelements <= 0 || element_size == 0)

       png_error(png_ptr, "internal error: array alloc");

    return png_malloc_array_checked(png_ptr, nelements, element_size);

 }

 PNG_FUNCTION(png_voidp /* PRIVATE */,

 png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,

    int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)

 {

    /* These are internal errors: */

    if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||

       (old_array == NULL && old_elements > 0))

       png_error(png_ptr, "internal error: array realloc");

    /* Check for overflow on the elements count (so the caller does not have to

     * check.)

     */

    if (add_elements <= INT_MAX - old_elements)

    {

       png_voidp new_array = png_malloc_array_checked(png_ptr,

          old_elements+add_elements, element_size);

       if (new_array != NULL)

       {

          /* Because png_malloc_array worked the size calculations below cannot

           * overflow.

           */

          if (old_elements > 0)

             memcpy(new_array, old_array, element_size*(unsigned)old_elements);

          memset((char*)new_array + element_size*(unsigned)old_elements, 0,

             element_size*(unsigned)add_elements);

          return new_array;

       }

    }

    return NULL; /* error */

 }

 #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */

 /* Various functions that have different error handling are derived from this.

  * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate

  * function png_malloc_default is also provided.

  */

 PNG_FUNCTION(png_voidp,PNGAPI

 png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)

 {

    png_voidp ret;

    if (png_ptr == NULL)

       return NULL;

    ret = png_malloc_base(png_ptr, size);

    if (ret == NULL)

        png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */

    return ret;

 }

 #ifdef PNG_USER_MEM_SUPPORTED

 PNG_FUNCTION(png_voidp,PNGAPI

 png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),

    PNG_ALLOCATED PNG_DEPRECATED)

 {

    png_voidp ret;

    if (png_ptr == NULL)

       return NULL;

    /* Passing 'NULL' here bypasses the application provided memory handler. */

    ret = png_malloc_base(NULL/*use malloc*/, size);

    if (ret == NULL)

       png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */

    return ret;

 }

 #endif /* PNG_USER_MEM_SUPPORTED */

 /* This function was added at libpng version 1.2.3.  The png_malloc_warn()

  * function will issue a png_warning and return NULL instead of issuing a

  * png_error, if it fails to allocate the requested memory.

  */

 PNG_FUNCTION(png_voidp,PNGAPI

 png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),

    PNG_ALLOCATED)

 {

    if (png_ptr != NULL)

    {

       png_voidp ret = png_malloc_base(png_ptr, size);

       if (ret != NULL)

          return ret;

       png_warning(png_ptr, "Out of memory");

    }

    return NULL;

 }

 /* Free a pointer allocated by png_malloc().  If ptr is NULL, return

  * without taking any action.

  */

 void PNGAPI

 png_free(png_const_structrp png_ptr, png_voidp ptr)

 {

    if (png_ptr == NULL || ptr == NULL)

       return;

 #ifdef PNG_USER_MEM_SUPPORTED

    if (png_ptr->free_fn != NULL)

       png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);

    else

       png_free_default(png_ptr, ptr);

 }

 PNG_FUNCTION(void,PNGAPI

 png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED)

 {

    if (png_ptr == NULL || ptr == NULL)

       return;

 #endif /* PNG_USER_MEM_SUPPORTED */

    free(ptr);

 }

 #ifdef PNG_USER_MEM_SUPPORTED

 /* This function is called when the application wants to use another method

  * of allocating and freeing memory.

  */

 void PNGAPI

 png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr

   malloc_fn, png_free_ptr free_fn)

 {

    if (png_ptr != NULL)

    {

       png_ptr->mem_ptr = mem_ptr;

       png_ptr->malloc_fn = malloc_fn;

       png_ptr->free_fn = free_fn;

    }

 }

 /* This function returns a pointer to the mem_ptr associated with the user

  * functions.  The application should free any memory associated with this

  * pointer before png_write_destroy and png_read_destroy are called.

  */

 png_voidp PNGAPI

 png_get_mem_ptr(png_const_structrp png_ptr)

 {

    if (png_ptr == NULL)

       return NULL;

    return png_ptr->mem_ptr;

 }

 #endif /* PNG_USER_MEM_SUPPORTED */

 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */