/* pngmem.c - stub functions for memory allocation
*
* Copyright (c) 2018 Cosmin Truta
* Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
* Copyright (c) 1996-1997 Andreas Dilger
* 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 than 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.
*/
# ifdef PNG_MAX_MALLOC_64K
/* This is support for legacy systems which had segmented addressing
* limiting the maximum allocation size to 65536. It takes precedence
* over PNG_SIZE_MAX which is set to 65535 on true 16-bit systems.
*
* TODO: libpng-1.8: finally remove both cases.
*/
if (size > 65536U) return NULL;
# endif
/* This is checked too because the system malloc call below takes a (size_t).
*/
if (size > PNG_SIZE_MAX) return NULL;
# 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
PNG_UNUSED(png_ptr)
# endif
/* Use the system malloc */
return malloc((size_t)/*SAFE*/size); /* checked for truncation above */
}
#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 = (png_alloc_size_t)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 /* USER_MEM */
/* 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 /* USER_MEM */
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 /* USER_MEM */
#endif /* READ || WRITE */