michael@0: 
michael@0: /* pngmem.c - stub functions for memory allocation
michael@0:  *
michael@0:  * Last changed in libpng 1.6.8 [December 19, 2013]
michael@0:  * Copyright (c) 1998-2013 Glenn Randers-Pehrson
michael@0:  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
michael@0:  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
michael@0:  *
michael@0:  * This code is released under the libpng license.
michael@0:  * For conditions of distribution and use, see the disclaimer
michael@0:  * and license in png.h
michael@0:  *
michael@0:  * This file provides a location for all memory allocation.  Users who
michael@0:  * need special memory handling are expected to supply replacement
michael@0:  * functions for png_malloc() and png_free(), and to use
michael@0:  * png_create_read_struct_2() and png_create_write_struct_2() to
michael@0:  * identify the replacement functions.
michael@0:  */
michael@0: 
michael@0: #include "pngpriv.h"
michael@0: 
michael@0: #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
michael@0: /* Free a png_struct */
michael@0: void /* PRIVATE */
michael@0: png_destroy_png_struct(png_structrp png_ptr)
michael@0: {
michael@0:    if (png_ptr != NULL)
michael@0:    {
michael@0:       /* png_free might call png_error and may certainly call
michael@0:        * png_get_mem_ptr, so fake a temporary png_struct to support this.
michael@0:        */
michael@0:       png_struct dummy_struct = *png_ptr;
michael@0:       memset(png_ptr, 0, (sizeof *png_ptr));
michael@0:       png_free(&dummy_struct, png_ptr);
michael@0: 
michael@0: #     ifdef PNG_SETJMP_SUPPORTED
michael@0:          /* We may have a jmp_buf left to deallocate. */
michael@0:          png_free_jmpbuf(&dummy_struct);
michael@0: #     endif
michael@0:    }
michael@0: }
michael@0: 
michael@0: /* Allocate memory.  For reasonable files, size should never exceed
michael@0:  * 64K.  However, zlib may allocate more then 64K if you don't tell
michael@0:  * it not to.  See zconf.h and png.h for more information.  zlib does
michael@0:  * need to allocate exactly 64K, so whatever you call here must
michael@0:  * have the ability to do that.
michael@0:  */
michael@0: PNG_FUNCTION(png_voidp,PNGAPI
michael@0: png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
michael@0: {
michael@0:    png_voidp ret;
michael@0: 
michael@0:    ret = png_malloc(png_ptr, size);
michael@0: 
michael@0:    if (ret != NULL)
michael@0:       memset(ret, 0, size);
michael@0: 
michael@0:    return ret;
michael@0: }
michael@0: 
michael@0: /* png_malloc_base, an internal function added at libpng 1.6.0, does the work of
michael@0:  * allocating memory, taking into account limits and PNG_USER_MEM_SUPPORTED.
michael@0:  * Checking and error handling must happen outside this routine; it returns NULL
michael@0:  * if the allocation cannot be done (for any reason.)
michael@0:  */
michael@0: PNG_FUNCTION(png_voidp /* PRIVATE */,
michael@0: png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
michael@0:    PNG_ALLOCATED)
michael@0: {
michael@0:    /* Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS
michael@0:     * allocators have also been removed in 1.6.0, so any 16-bit system now has
michael@0:     * to implement a user memory handler.  This checks to be sure it isn't
michael@0:     * called with big numbers.
michael@0:     */
michael@0: #ifndef PNG_USER_MEM_SUPPORTED
michael@0:    PNG_UNUSED(png_ptr)
michael@0: #endif
michael@0: 
michael@0:    if (size > 0 && size <= PNG_SIZE_MAX
michael@0: #     ifdef PNG_MAX_MALLOC_64K
michael@0:          && size <= 65536U
michael@0: #     endif
michael@0:       )
michael@0:    {
michael@0: #ifdef PNG_USER_MEM_SUPPORTED
michael@0:       if (png_ptr != NULL && png_ptr->malloc_fn != NULL)
michael@0:          return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size);
michael@0: 
michael@0:       else
michael@0: #endif
michael@0:          return malloc((size_t)size); /* checked for truncation above */
michael@0:    }
michael@0: 
michael@0:    else
michael@0:       return NULL;
michael@0: }
michael@0: 
michael@0: #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
michael@0:    defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
michael@0: /* This is really here only to work round a spurious warning in GCC 4.6 and 4.7
michael@0:  * that arises because of the checks in png_realloc_array that are repeated in
michael@0:  * png_malloc_array.
michael@0:  */
michael@0: static png_voidp
michael@0: png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
michael@0:    size_t element_size)
michael@0: {
michael@0:    png_alloc_size_t req = nelements; /* known to be > 0 */
michael@0: 
michael@0:    if (req <= PNG_SIZE_MAX/element_size)
michael@0:       return png_malloc_base(png_ptr, req * element_size);
michael@0: 
michael@0:    /* The failure case when the request is too large */
michael@0:    return NULL;
michael@0: }
michael@0: 
michael@0: PNG_FUNCTION(png_voidp /* PRIVATE */,
michael@0: png_malloc_array,(png_const_structrp png_ptr, int nelements,
michael@0:    size_t element_size),PNG_ALLOCATED)
michael@0: {
michael@0:    if (nelements <= 0 || element_size == 0)
michael@0:       png_error(png_ptr, "internal error: array alloc");
michael@0: 
michael@0:    return png_malloc_array_checked(png_ptr, nelements, element_size);
michael@0: }
michael@0: 
michael@0: PNG_FUNCTION(png_voidp /* PRIVATE */,
michael@0: png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
michael@0:    int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
michael@0: {
michael@0:    /* These are internal errors: */
michael@0:    if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
michael@0:       (old_array == NULL && old_elements > 0))
michael@0:       png_error(png_ptr, "internal error: array realloc");
michael@0: 
michael@0:    /* Check for overflow on the elements count (so the caller does not have to
michael@0:     * check.)
michael@0:     */
michael@0:    if (add_elements <= INT_MAX - old_elements)
michael@0:    {
michael@0:       png_voidp new_array = png_malloc_array_checked(png_ptr,
michael@0:          old_elements+add_elements, element_size);
michael@0: 
michael@0:       if (new_array != NULL)
michael@0:       {
michael@0:          /* Because png_malloc_array worked the size calculations below cannot
michael@0:           * overflow.
michael@0:           */
michael@0:          if (old_elements > 0)
michael@0:             memcpy(new_array, old_array, element_size*(unsigned)old_elements);
michael@0: 
michael@0:          memset((char*)new_array + element_size*(unsigned)old_elements, 0,
michael@0:             element_size*(unsigned)add_elements);
michael@0: 
michael@0:          return new_array;
michael@0:       }
michael@0:    }
michael@0: 
michael@0:    return NULL; /* error */
michael@0: }
michael@0: #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
michael@0: 
michael@0: /* Various functions that have different error handling are derived from this.
michael@0:  * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
michael@0:  * function png_malloc_default is also provided.
michael@0:  */
michael@0: PNG_FUNCTION(png_voidp,PNGAPI
michael@0: png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
michael@0: {
michael@0:    png_voidp ret;
michael@0: 
michael@0:    if (png_ptr == NULL)
michael@0:       return NULL;
michael@0: 
michael@0:    ret = png_malloc_base(png_ptr, size);
michael@0: 
michael@0:    if (ret == NULL)
michael@0:        png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
michael@0: 
michael@0:    return ret;
michael@0: }
michael@0: 
michael@0: #ifdef PNG_USER_MEM_SUPPORTED
michael@0: PNG_FUNCTION(png_voidp,PNGAPI
michael@0: png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
michael@0:    PNG_ALLOCATED PNG_DEPRECATED)
michael@0: {
michael@0:    png_voidp ret;
michael@0: 
michael@0:    if (png_ptr == NULL)
michael@0:       return NULL;
michael@0: 
michael@0:    /* Passing 'NULL' here bypasses the application provided memory handler. */
michael@0:    ret = png_malloc_base(NULL/*use malloc*/, size);
michael@0: 
michael@0:    if (ret == NULL)
michael@0:       png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */
michael@0: 
michael@0:    return ret;
michael@0: }
michael@0: #endif /* PNG_USER_MEM_SUPPORTED */
michael@0: 
michael@0: /* This function was added at libpng version 1.2.3.  The png_malloc_warn()
michael@0:  * function will issue a png_warning and return NULL instead of issuing a
michael@0:  * png_error, if it fails to allocate the requested memory.
michael@0:  */
michael@0: PNG_FUNCTION(png_voidp,PNGAPI
michael@0: png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
michael@0:    PNG_ALLOCATED)
michael@0: {
michael@0:    if (png_ptr != NULL)
michael@0:    {
michael@0:       png_voidp ret = png_malloc_base(png_ptr, size);
michael@0: 
michael@0:       if (ret != NULL)
michael@0:          return ret;
michael@0: 
michael@0:       png_warning(png_ptr, "Out of memory");
michael@0:    }
michael@0: 
michael@0:    return NULL;
michael@0: }
michael@0: 
michael@0: /* Free a pointer allocated by png_malloc().  If ptr is NULL, return
michael@0:  * without taking any action.
michael@0:  */
michael@0: void PNGAPI
michael@0: png_free(png_const_structrp png_ptr, png_voidp ptr)
michael@0: {
michael@0:    if (png_ptr == NULL || ptr == NULL)
michael@0:       return;
michael@0: 
michael@0: #ifdef PNG_USER_MEM_SUPPORTED
michael@0:    if (png_ptr->free_fn != NULL)
michael@0:       png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);
michael@0: 
michael@0:    else
michael@0:       png_free_default(png_ptr, ptr);
michael@0: }
michael@0: 
michael@0: PNG_FUNCTION(void,PNGAPI
michael@0: png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED)
michael@0: {
michael@0:    if (png_ptr == NULL || ptr == NULL)
michael@0:       return;
michael@0: #endif /* PNG_USER_MEM_SUPPORTED */
michael@0: 
michael@0:    free(ptr);
michael@0: }
michael@0: 
michael@0: #ifdef PNG_USER_MEM_SUPPORTED
michael@0: /* This function is called when the application wants to use another method
michael@0:  * of allocating and freeing memory.
michael@0:  */
michael@0: void PNGAPI
michael@0: png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr
michael@0:   malloc_fn, png_free_ptr free_fn)
michael@0: {
michael@0:    if (png_ptr != NULL)
michael@0:    {
michael@0:       png_ptr->mem_ptr = mem_ptr;
michael@0:       png_ptr->malloc_fn = malloc_fn;
michael@0:       png_ptr->free_fn = free_fn;
michael@0:    }
michael@0: }
michael@0: 
michael@0: /* This function returns a pointer to the mem_ptr associated with the user
michael@0:  * functions.  The application should free any memory associated with this
michael@0:  * pointer before png_write_destroy and png_read_destroy are called.
michael@0:  */
michael@0: png_voidp PNGAPI
michael@0: png_get_mem_ptr(png_const_structrp png_ptr)
michael@0: {
michael@0:    if (png_ptr == NULL)
michael@0:       return NULL;
michael@0: 
michael@0:    return png_ptr->mem_ptr;
michael@0: }
michael@0: #endif /* PNG_USER_MEM_SUPPORTED */
michael@0: #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */