com32/lib/libpng/pngmem.c

   1
   2 /* pngmem.c - stub functions for memory allocation
   3  *
   4  * Copyright (c) 2018 Cosmin Truta
   5  * Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
   6  * Copyright (c) 1996-1997 Andreas Dilger
   7  * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
   8  *
   9  * This code is released under the libpng license.
  10  * For conditions of distribution and use, see the disclaimer
  11  * and license in png.h
  12  *
  13  * This file provides a location for all memory allocation.  Users who
  14  * need special memory handling are expected to supply replacement
  15  * functions for png_malloc() and png_free(), and to use
  16  * png_create_read_struct_2() and png_create_write_struct_2() to
  17  * identify the replacement functions.
  18  */
  19
  20 #include "pngpriv.h"
  21
  22 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
  23 /* Free a png_struct */
  24 void /* PRIVATE */
  25 png_destroy_png_struct(png_structrp png_ptr)
  26 {
  27    if (png_ptr != NULL)
  28    {
  29       /* png_free might call png_error and may certainly call
  30        * png_get_mem_ptr, so fake a temporary png_struct to support this.
  31        */
  32       png_struct dummy_struct = *png_ptr;
  33       memset(png_ptr, 0, (sizeof *png_ptr));
  34       png_free(&dummy_struct, png_ptr);
  35
  36 #     ifdef PNG_SETJMP_SUPPORTED
  37          /* We may have a jmp_buf left to deallocate. */
  38          png_free_jmpbuf(&dummy_struct);
  39 #     endif
  40    }
  41 }
  42
  43 /* Allocate memory.  For reasonable files, size should never exceed
  44  * 64K.  However, zlib may allocate more than 64K if you don't tell
  45  * it not to.  See zconf.h and png.h for more information.  zlib does
  46  * need to allocate exactly 64K, so whatever you call here must
  47  * have the ability to do that.
  48  */
  49 PNG_FUNCTION(png_voidp,PNGAPI
  50 png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
  51 {
  52    png_voidp ret;
  53
  54    ret = png_malloc(png_ptr, size);
  55
  56    if (ret != NULL)
  57       memset(ret, 0, size);
  58
  59    return ret;
  60 }
  61
  62 /* png_malloc_base, an internal function added at libpng 1.6.0, does the work of
  63  * allocating memory, taking into account limits and PNG_USER_MEM_SUPPORTED.
  64  * Checking and error handling must happen outside this routine; it returns NULL
  65  * if the allocation cannot be done (for any reason.)
  66  */
  67 PNG_FUNCTION(png_voidp /* PRIVATE */,
  68 png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
  69     PNG_ALLOCATED)
  70 {
  71    /* Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS
  72     * allocators have also been removed in 1.6.0, so any 16-bit system now has
  73     * to implement a user memory handler.  This checks to be sure it isn't
  74     * called with big numbers.
  75     */
  76 #ifndef PNG_USER_MEM_SUPPORTED
  77    PNG_UNUSED(png_ptr)
  78 #endif
  79
  80    /* Some compilers complain that this is always true.  However, it
  81     * can be false when integer overflow happens.
  82     */
  83    if (size > 0 && size <= PNG_SIZE_MAX
  84 #     ifdef PNG_MAX_MALLOC_64K
  85          && size <= 65536U
  86 #     endif
  87       )
  88    {
  89 #ifdef PNG_USER_MEM_SUPPORTED
  90       if (png_ptr != NULL && png_ptr->malloc_fn != NULL)
  91          return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size);
  92
  93       else
  94 #endif
  95          return malloc((size_t)size); /* checked for truncation above */
  96    }
  97
  98    else
  99       return NULL;
 100 }
 101
 102 #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
 103    defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
 104 /* This is really here only to work round a spurious warning in GCC 4.6 and 4.7
 105  * that arises because of the checks in png_realloc_array that are repeated in
 106  * png_malloc_array.
 107  */
 108 static png_voidp
 109 png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
 110     size_t element_size)
 111 {
 112    png_alloc_size_t req = (png_alloc_size_t)nelements; /* known to be > 0 */
 113
 114    if (req <= PNG_SIZE_MAX/element_size)
 115       return png_malloc_base(png_ptr, req * element_size);
 116
 117    /* The failure case when the request is too large */
 118    return NULL;
 119 }
 120
 121 PNG_FUNCTION(png_voidp /* PRIVATE */,
 122 png_malloc_array,(png_const_structrp png_ptr, int nelements,
 123     size_t element_size),PNG_ALLOCATED)
 124 {
 125    if (nelements <= 0 || element_size == 0)
 126       png_error(png_ptr, "internal error: array alloc");
 127
 128    return png_malloc_array_checked(png_ptr, nelements, element_size);
 129 }
 130
 131 PNG_FUNCTION(png_voidp /* PRIVATE */,
 132 png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
 133     int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
 134 {
 135    /* These are internal errors: */
 136    if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
 137       (old_array == NULL && old_elements > 0))
 138       png_error(png_ptr, "internal error: array realloc");
 139
 140    /* Check for overflow on the elements count (so the caller does not have to
 141     * check.)
 142     */
 143    if (add_elements <= INT_MAX - old_elements)
 144    {
 145       png_voidp new_array = png_malloc_array_checked(png_ptr,
 146           old_elements+add_elements, element_size);
 147
 148       if (new_array != NULL)
 149       {
 150          /* Because png_malloc_array worked the size calculations below cannot
 151           * overflow.
 152           */
 153          if (old_elements > 0)
 154             memcpy(new_array, old_array, element_size*(unsigned)old_elements);
 155
 156          memset((char*)new_array + element_size*(unsigned)old_elements, 0,
 157              element_size*(unsigned)add_elements);
 158
 159          return new_array;
 160       }
 161    }
 162
 163    return NULL; /* error */
 164 }
 165 #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
 166
 167 /* Various functions that have different error handling are derived from this.
 168  * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
 169  * function png_malloc_default is also provided.
 170  */
 171 PNG_FUNCTION(png_voidp,PNGAPI
 172 png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
 173 {
 174    png_voidp ret;
 175
 176    if (png_ptr == NULL)
 177       return NULL;
 178
 179    ret = png_malloc_base(png_ptr, size);
 180
 181    if (ret == NULL)
 182        png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
 183
 184    return ret;
 185 }
 186
 187 #ifdef PNG_USER_MEM_SUPPORTED
 188 PNG_FUNCTION(png_voidp,PNGAPI
 189 png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
 190     PNG_ALLOCATED PNG_DEPRECATED)
 191 {
 192    png_voidp ret;
 193
 194    if (png_ptr == NULL)
 195       return NULL;
 196
 197    /* Passing 'NULL' here bypasses the application provided memory handler. */
 198    ret = png_malloc_base(NULL/*use malloc*/, size);
 199
 200    if (ret == NULL)
 201       png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */
 202
 203    return ret;
 204 }
 205 #endif /* USER_MEM */
 206
 207 /* This function was added at libpng version 1.2.3.  The png_malloc_warn()
 208  * function will issue a png_warning and return NULL instead of issuing a
 209  * png_error, if it fails to allocate the requested memory.
 210  */
 211 PNG_FUNCTION(png_voidp,PNGAPI
 212 png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
 213     PNG_ALLOCATED)
 214 {
 215    if (png_ptr != NULL)
 216    {
 217       png_voidp ret = png_malloc_base(png_ptr, size);
 218
 219       if (ret != NULL)
 220          return ret;
 221
 222       png_warning(png_ptr, "Out of memory");
 223    }
 224
 225    return NULL;
 226 }
 227
 228 /* Free a pointer allocated by png_malloc().  If ptr is NULL, return
 229  * without taking any action.
 230  */
 231 void PNGAPI
 232 png_free(png_const_structrp png_ptr, png_voidp ptr)
 233 {
 234    if (png_ptr == NULL || ptr == NULL)
 235       return;
 236
 237 #ifdef PNG_USER_MEM_SUPPORTED
 238    if (png_ptr->free_fn != NULL)
 239       png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);
 240
 241    else
 242       png_free_default(png_ptr, ptr);
 243 }
 244
 245 PNG_FUNCTION(void,PNGAPI
 246 png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED)
 247 {
 248    if (png_ptr == NULL || ptr == NULL)
 249       return;
 250 #endif /* USER_MEM */
 251
 252    free(ptr);
 253 }
 254
 255 #ifdef PNG_USER_MEM_SUPPORTED
 256 /* This function is called when the application wants to use another method
 257  * of allocating and freeing memory.
 258  */
 259 void PNGAPI
 260 png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr
 261   malloc_fn, png_free_ptr free_fn)
 262 {
 263    if (png_ptr != NULL)
 264    {
 265       png_ptr->mem_ptr = mem_ptr;
 266       png_ptr->malloc_fn = malloc_fn;
 267       png_ptr->free_fn = free_fn;
 268    }
 269 }
 270
 271 /* This function returns a pointer to the mem_ptr associated with the user
 272  * functions.  The application should free any memory associated with this
 273  * pointer before png_write_destroy and png_read_destroy are called.
 274  */
 275 png_voidp PNGAPI
 276 png_get_mem_ptr(png_const_structrp png_ptr)
 277 {
 278    if (png_ptr == NULL)
 279       return NULL;
 280
 281    return png_ptr->mem_ptr;
 282 }
 283 #endif /* USER_MEM */
 284 #endif /* READ || WRITE */