share/png/pngmem.c

   1
   2 /* pngmem.c - stub functions for memory allocation
   3  *
   4  * Last changed in libpng 1.6.8 [December 19, 2013]
   5  * Copyright (c) 1998-2013 Glenn Randers-Pehrson
   6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   7  * (Version 0.88 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 then 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    if (size > 0 && size <= PNG_SIZE_MAX
  81 #     ifdef PNG_MAX_MALLOC_64K
  82          && size <= 65536U
  83 #     endif
  84       )
  85    {
  86 #ifdef PNG_USER_MEM_SUPPORTED
  87       if (png_ptr != NULL && png_ptr->malloc_fn != NULL)
  88          return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size);
  89
  90       else
  91 #endif
  92          return malloc((size_t)size); /* checked for truncation above */
  93    }
  94
  95    else
  96       return NULL;
  97 }
  98
  99 #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
 100    defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
 101 /* This is really here only to work round a spurious warning in GCC 4.6 and 4.7
 102  * that arises because of the checks in png_realloc_array that are repeated in
 103  * png_malloc_array.
 104  */
 105 static png_voidp
 106 png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
 107    size_t element_size)
 108 {
 109    png_alloc_size_t req = nelements; /* known to be > 0 */
 110
 111    if (req <= PNG_SIZE_MAX/element_size)
 112       return png_malloc_base(png_ptr, req * element_size);
 113
 114    /* The failure case when the request is too large */
 115    return NULL;
 116 }
 117
 118 PNG_FUNCTION(png_voidp /* PRIVATE */,
 119 png_malloc_array,(png_const_structrp png_ptr, int nelements,
 120    size_t element_size),PNG_ALLOCATED)
 121 {
 122    if (nelements <= 0 || element_size == 0)
 123       png_error(png_ptr, "internal error: array alloc");
 124
 125    return png_malloc_array_checked(png_ptr, nelements, element_size);
 126 }
 127
 128 PNG_FUNCTION(png_voidp /* PRIVATE */,
 129 png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
 130    int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
 131 {
 132    /* These are internal errors: */
 133    if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
 134       (old_array == NULL && old_elements > 0))
 135       png_error(png_ptr, "internal error: array realloc");
 136
 137    /* Check for overflow on the elements count (so the caller does not have to
 138     * check.)
 139     */
 140    if (add_elements <= INT_MAX - old_elements)
 141    {
 142       png_voidp new_array = png_malloc_array_checked(png_ptr,
 143          old_elements+add_elements, element_size);
 144
 145       if (new_array != NULL)
 146       {
 147          /* Because png_malloc_array worked the size calculations below cannot
 148           * overflow.
 149           */
 150          if (old_elements > 0)
 151             memcpy(new_array, old_array, element_size*(unsigned)old_elements);
 152
 153          memset((char*)new_array + element_size*(unsigned)old_elements, 0,
 154             element_size*(unsigned)add_elements);
 155
 156          return new_array;
 157       }
 158    }
 159
 160    return NULL; /* error */
 161 }
 162 #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
 163
 164 /* Various functions that have different error handling are derived from this.
 165  * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
 166  * function png_malloc_default is also provided.
 167  */
 168 PNG_FUNCTION(png_voidp,PNGAPI
 169 png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
 170 {
 171    png_voidp ret;
 172
 173    if (png_ptr == NULL)
 174       return NULL;
 175
 176    ret = png_malloc_base(png_ptr, size);
 177
 178    if (ret == NULL)
 179        png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
 180
 181    return ret;
 182 }
 183
 184 #ifdef PNG_USER_MEM_SUPPORTED
 185 PNG_FUNCTION(png_voidp,PNGAPI
 186 png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
 187    PNG_ALLOCATED PNG_DEPRECATED)
 188 {
 189    png_voidp ret;
 190
 191    if (png_ptr == NULL)
 192       return NULL;
 193
 194    /* Passing 'NULL' here bypasses the application provided memory handler. */
 195    ret = png_malloc_base(NULL/*use malloc*/, size);
 196
 197    if (ret == NULL)
 198       png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */
 199
 200    return ret;
 201 }
 202 #endif /* PNG_USER_MEM_SUPPORTED */
 203
 204 /* This function was added at libpng version 1.2.3.  The png_malloc_warn()
 205  * function will issue a png_warning and return NULL instead of issuing a
 206  * png_error, if it fails to allocate the requested memory.
 207  */
 208 PNG_FUNCTION(png_voidp,PNGAPI
 209 png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
 210    PNG_ALLOCATED)
 211 {
 212    if (png_ptr != NULL)
 213    {
 214       png_voidp ret = png_malloc_base(png_ptr, size);
 215
 216       if (ret != NULL)
 217          return ret;
 218
 219       png_warning(png_ptr, "Out of memory");
 220    }
 221
 222    return NULL;
 223 }
 224
 225 /* Free a pointer allocated by png_malloc().  If ptr is NULL, return
 226  * without taking any action.
 227  */
 228 void PNGAPI
 229 png_free(png_const_structrp png_ptr, png_voidp ptr)
 230 {
 231    if (png_ptr == NULL || ptr == NULL)
 232       return;
 233
 234 #ifdef PNG_USER_MEM_SUPPORTED
 235    if (png_ptr->free_fn != NULL)
 236       png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);
 237
 238    else
 239       png_free_default(png_ptr, ptr);
 240 }
 241
 242 PNG_FUNCTION(void,PNGAPI
 243 png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED)
 244 {
 245    if (png_ptr == NULL || ptr == NULL)
 246       return;
 247 #endif /* PNG_USER_MEM_SUPPORTED */
 248
 249    free(ptr);
 250 }
 251
 252 #ifdef PNG_USER_MEM_SUPPORTED
 253 /* This function is called when the application wants to use another method
 254  * of allocating and freeing memory.
 255  */
 256 void PNGAPI
 257 png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr
 258   malloc_fn, png_free_ptr free_fn)
 259 {
 260    if (png_ptr != NULL)
 261    {
 262       png_ptr->mem_ptr = mem_ptr;
 263       png_ptr->malloc_fn = malloc_fn;
 264       png_ptr->free_fn = free_fn;
 265    }
 266 }
 267
 268 /* This function returns a pointer to the mem_ptr associated with the user
 269  * functions.  The application should free any memory associated with this
 270  * pointer before png_write_destroy and png_read_destroy are called.
 271  */
 272 png_voidp PNGAPI
 273 png_get_mem_ptr(png_const_structrp png_ptr)
 274 {
 275    if (png_ptr == NULL)
 276       return NULL;
 277
 278    return png_ptr->mem_ptr;
 279 }
 280 #endif /* PNG_USER_MEM_SUPPORTED */
 281 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */