284 lines
8.1 KiB
C
284 lines
8.1 KiB
C
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/* pngmem.c - stub functions for memory allocation
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*
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* Copyright (c) 2018 Cosmin Truta
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* Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
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* Copyright (c) 1996-1997 Andreas Dilger
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* Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
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*
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* This code is released under the libpng license.
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* For conditions of distribution and use, see the disclaimer
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* and license in png.h
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*
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* This file provides a location for all memory allocation. Users who
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* need special memory handling are expected to supply replacement
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* functions for png_malloc() and png_free(), and to use
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* png_create_read_struct_2() and png_create_write_struct_2() to
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* identify the replacement functions.
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*/
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#include "pngpriv.h"
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#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
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/* Free a png_struct */
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void /* PRIVATE */
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png_destroy_png_struct(png_structrp png_ptr)
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{
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if (png_ptr != NULL)
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{
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/* png_free might call png_error and may certainly call
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* png_get_mem_ptr, so fake a temporary png_struct to support this.
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*/
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png_struct dummy_struct = *png_ptr;
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memset(png_ptr, 0, (sizeof *png_ptr));
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png_free(&dummy_struct, png_ptr);
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# ifdef PNG_SETJMP_SUPPORTED
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/* We may have a jmp_buf left to deallocate. */
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png_free_jmpbuf(&dummy_struct);
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# endif
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}
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}
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/* Allocate memory. For reasonable files, size should never exceed
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* 64K. However, zlib may allocate more than 64K if you don't tell
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* it not to. See zconf.h and png.h for more information. zlib does
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* need to allocate exactly 64K, so whatever you call here must
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* have the ability to do that.
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*/
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PNG_FUNCTION(png_voidp,PNGAPI
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png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
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{
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png_voidp ret;
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ret = png_malloc(png_ptr, size);
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if (ret != NULL)
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memset(ret, 0, size);
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return ret;
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}
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/* png_malloc_base, an internal function added at libpng 1.6.0, does the work of
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* allocating memory, taking into account limits and PNG_USER_MEM_SUPPORTED.
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* Checking and error handling must happen outside this routine; it returns NULL
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* if the allocation cannot be done (for any reason.)
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*/
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PNG_FUNCTION(png_voidp /* PRIVATE */,
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png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
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PNG_ALLOCATED)
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{
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/* Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS
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* allocators have also been removed in 1.6.0, so any 16-bit system now has
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* to implement a user memory handler. This checks to be sure it isn't
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* called with big numbers.
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*/
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#ifndef PNG_USER_MEM_SUPPORTED
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PNG_UNUSED(png_ptr)
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#endif
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/* Some compilers complain that this is always true. However, it
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* can be false when integer overflow happens.
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*/
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if (size > 0 && size <= PNG_SIZE_MAX
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# ifdef PNG_MAX_MALLOC_64K
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&& size <= 65536U
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# endif
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)
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{
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#ifdef PNG_USER_MEM_SUPPORTED
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if (png_ptr != NULL && png_ptr->malloc_fn != NULL)
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return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size);
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else
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#endif
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return malloc((size_t)size); /* checked for truncation above */
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}
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else
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return NULL;
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}
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#if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
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defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
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/* This is really here only to work round a spurious warning in GCC 4.6 and 4.7
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* that arises because of the checks in png_realloc_array that are repeated in
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* png_malloc_array.
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*/
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static png_voidp
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png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
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size_t element_size)
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{
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png_alloc_size_t req = (png_alloc_size_t)nelements; /* known to be > 0 */
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if (req <= PNG_SIZE_MAX/element_size)
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return png_malloc_base(png_ptr, req * element_size);
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/* The failure case when the request is too large */
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return NULL;
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}
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PNG_FUNCTION(png_voidp /* PRIVATE */,
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png_malloc_array,(png_const_structrp png_ptr, int nelements,
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size_t element_size),PNG_ALLOCATED)
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{
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if (nelements <= 0 || element_size == 0)
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png_error(png_ptr, "internal error: array alloc");
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return png_malloc_array_checked(png_ptr, nelements, element_size);
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}
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PNG_FUNCTION(png_voidp /* PRIVATE */,
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png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
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int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
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{
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/* These are internal errors: */
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if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
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(old_array == NULL && old_elements > 0))
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png_error(png_ptr, "internal error: array realloc");
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/* Check for overflow on the elements count (so the caller does not have to
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* check.)
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*/
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if (add_elements <= INT_MAX - old_elements)
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{
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png_voidp new_array = png_malloc_array_checked(png_ptr,
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old_elements+add_elements, element_size);
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if (new_array != NULL)
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{
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/* Because png_malloc_array worked the size calculations below cannot
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* overflow.
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*/
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if (old_elements > 0)
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memcpy(new_array, old_array, element_size*(unsigned)old_elements);
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memset((char*)new_array + element_size*(unsigned)old_elements, 0,
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element_size*(unsigned)add_elements);
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return new_array;
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}
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}
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return NULL; /* error */
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}
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#endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
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/* Various functions that have different error handling are derived from this.
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* png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
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* function png_malloc_default is also provided.
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*/
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PNG_FUNCTION(png_voidp,PNGAPI
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png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
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{
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png_voidp ret;
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if (png_ptr == NULL)
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return NULL;
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ret = png_malloc_base(png_ptr, size);
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if (ret == NULL)
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png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
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return ret;
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}
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#ifdef PNG_USER_MEM_SUPPORTED
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PNG_FUNCTION(png_voidp,PNGAPI
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png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
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PNG_ALLOCATED PNG_DEPRECATED)
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{
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png_voidp ret;
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if (png_ptr == NULL)
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return NULL;
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/* Passing 'NULL' here bypasses the application provided memory handler. */
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ret = png_malloc_base(NULL/*use malloc*/, size);
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if (ret == NULL)
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png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */
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return ret;
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}
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#endif /* USER_MEM */
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/* This function was added at libpng version 1.2.3. The png_malloc_warn()
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* function will issue a png_warning and return NULL instead of issuing a
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* png_error, if it fails to allocate the requested memory.
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*/
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PNG_FUNCTION(png_voidp,PNGAPI
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png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
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PNG_ALLOCATED)
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{
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if (png_ptr != NULL)
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{
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png_voidp ret = png_malloc_base(png_ptr, size);
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if (ret != NULL)
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return ret;
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png_warning(png_ptr, "Out of memory");
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}
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return NULL;
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}
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/* Free a pointer allocated by png_malloc(). If ptr is NULL, return
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* without taking any action.
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*/
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void PNGAPI
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png_free(png_const_structrp png_ptr, png_voidp ptr)
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{
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if (png_ptr == NULL || ptr == NULL)
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return;
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#ifdef PNG_USER_MEM_SUPPORTED
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if (png_ptr->free_fn != NULL)
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png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);
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else
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png_free_default(png_ptr, ptr);
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}
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PNG_FUNCTION(void,PNGAPI
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png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED)
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{
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if (png_ptr == NULL || ptr == NULL)
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return;
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#endif /* USER_MEM */
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free(ptr);
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}
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#ifdef PNG_USER_MEM_SUPPORTED
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/* This function is called when the application wants to use another method
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* of allocating and freeing memory.
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*/
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void PNGAPI
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png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr
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malloc_fn, png_free_ptr free_fn)
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{
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if (png_ptr != NULL)
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{
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png_ptr->mem_ptr = mem_ptr;
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png_ptr->malloc_fn = malloc_fn;
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png_ptr->free_fn = free_fn;
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}
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}
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/* This function returns a pointer to the mem_ptr associated with the user
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* functions. The application should free any memory associated with this
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* pointer before png_write_destroy and png_read_destroy are called.
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*/
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png_voidp PNGAPI
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png_get_mem_ptr(png_const_structrp png_ptr)
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{
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if (png_ptr == NULL)
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return NULL;
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return png_ptr->mem_ptr;
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}
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#endif /* USER_MEM */
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#endif /* READ || WRITE */
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