opencv

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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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