1
2 /* pngmem.c - stub functions for memory allocation
3 *
4 * Last changed in libpng 1.6.15 [November 20, 2014]
5 * Copyright (c) 1998-2002,2004,2006-2014 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 void* FXMEM_DefaultAlloc(int byte_size, int);
23 void FXMEM_DefaultFree(void* pointer, int);
24
25 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
26 /* Free a png_struct */
27 void /* PRIVATE */
png_destroy_png_struct(png_structrp png_ptr)28 png_destroy_png_struct(png_structrp png_ptr)
29 {
30 if (png_ptr != NULL)
31 {
32 /* png_free might call png_error and may certainly call
33 * png_get_mem_ptr, so fake a temporary png_struct to support this.
34 */
35 png_struct dummy_struct = *png_ptr;
36 memset(png_ptr, 0, (sizeof *png_ptr));
37 png_free(&dummy_struct, png_ptr);
38
39 # ifdef PNG_SETJMP_SUPPORTED
40 /* We may have a jmp_buf left to deallocate. */
41 png_free_jmpbuf(&dummy_struct);
42 # endif
43 }
44 }
45
46 /* Allocate memory. For reasonable files, size should never exceed
47 * 64K. However, zlib may allocate more than 64K if you don't tell
48 * it not to. See zconf.h and png.h for more information. zlib does
49 * need to allocate exactly 64K, so whatever you call here must
50 * have the ability to do that.
51 */
52 PNG_FUNCTION(png_voidp,PNGAPI
53 png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
54 {
55 png_voidp ret;
56
57 ret = png_malloc(png_ptr, size);
58
59 if (ret != NULL)
60 memset(ret, 0, size);
61
62 return ret;
63 }
64
65 /* png_malloc_base, an internal function added at libpng 1.6.0, does the work of
66 * allocating memory, taking into account limits and PNG_USER_MEM_SUPPORTED.
67 * Checking and error handling must happen outside this routine; it returns NULL
68 * if the allocation cannot be done (for any reason.)
69 */
70 PNG_FUNCTION(png_voidp /* PRIVATE */,
71 png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
72 PNG_ALLOCATED)
73 {
74 /* Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS
75 * allocators have also been removed in 1.6.0, so any 16-bit system now has
76 * to implement a user memory handler. This checks to be sure it isn't
77 * called with big numbers.
78 */
79 #ifndef PNG_USER_MEM_SUPPORTED
80 PNG_UNUSED(png_ptr)
81 #endif
82
83 /* Some compilers complain that this is always true. However, it
84 * can be false when integer overflow happens.
85 */
86 if (size > 0 && size <= PNG_SIZE_MAX
87 # ifdef PNG_MAX_MALLOC_64K
88 && size <= 65536U
89 # endif
90 )
91 {
92 #ifdef PNG_USER_MEM_SUPPORTED
93 if (png_ptr != NULL && png_ptr->malloc_fn != NULL)
94 return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size);
95
96 else
97 #endif
98 return FXMEM_DefaultAlloc((int)size, 0);
99 }
100
101 else
102 return NULL;
103 }
104
105 #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
106 defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
107 /* This is really here only to work round a spurious warning in GCC 4.6 and 4.7
108 * that arises because of the checks in png_realloc_array that are repeated in
109 * png_malloc_array.
110 */
111 static png_voidp
png_malloc_array_checked(png_const_structrp png_ptr,int nelements,size_t element_size)112 png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
113 size_t element_size)
114 {
115 png_alloc_size_t req = nelements; /* known to be > 0 */
116
117 if (req <= PNG_SIZE_MAX/element_size)
118 return png_malloc_base(png_ptr, req * element_size);
119
120 /* The failure case when the request is too large */
121 return NULL;
122 }
123
124 PNG_FUNCTION(png_voidp /* PRIVATE */,
125 png_malloc_array,(png_const_structrp png_ptr, int nelements,
126 size_t element_size),PNG_ALLOCATED)
127 {
128 if (nelements <= 0 || element_size == 0)
129 png_error(png_ptr, "internal error: array alloc");
130
131 return png_malloc_array_checked(png_ptr, nelements, element_size);
132 }
133
134 PNG_FUNCTION(png_voidp /* PRIVATE */,
135 png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
136 int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
137 {
138 /* These are internal errors: */
139 if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
140 (old_array == NULL && old_elements > 0))
141 png_error(png_ptr, "internal error: array realloc");
142
143 /* Check for overflow on the elements count (so the caller does not have to
144 * check.)
145 */
146 if (add_elements <= INT_MAX - old_elements)
147 {
148 png_voidp new_array = png_malloc_array_checked(png_ptr,
149 old_elements+add_elements, element_size);
150
151 if (new_array != NULL)
152 {
153 /* Because png_malloc_array worked the size calculations below cannot
154 * overflow.
155 */
156 if (old_elements > 0)
157 memcpy(new_array, old_array, element_size*(unsigned)old_elements);
158
159 memset((char*)new_array + element_size*(unsigned)old_elements, 0,
160 element_size*(unsigned)add_elements);
161
162 return new_array;
163 }
164 }
165
166 return NULL; /* error */
167 }
168 #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
169
170 /* Various functions that have different error handling are derived from this.
171 * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
172 * function png_malloc_default is also provided.
173 */
174 PNG_FUNCTION(png_voidp,PNGAPI
175 png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
176 {
177 png_voidp ret;
178
179 if (png_ptr == NULL)
180 return NULL;
181
182 ret = png_malloc_base(png_ptr, size);
183
184 if (ret == NULL)
185 png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
186
187 return ret;
188 }
189
190 #ifdef PNG_USER_MEM_SUPPORTED
191 PNG_FUNCTION(png_voidp,PNGAPI
192 png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
193 PNG_ALLOCATED PNG_DEPRECATED)
194 {
195 png_voidp ret;
196
197 if (png_ptr == NULL)
198 return NULL;
199
200 /* Passing 'NULL' here bypasses the application provided memory handler. */
201 ret = png_malloc_base(NULL/*use malloc*/, size);
202
203 if (ret == NULL)
204 png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */
205
206 return ret;
207 }
208 #endif /* USER_MEM */
209
210 /* This function was added at libpng version 1.2.3. The png_malloc_warn()
211 * function will issue a png_warning and return NULL instead of issuing a
212 * png_error, if it fails to allocate the requested memory.
213 */
214 PNG_FUNCTION(png_voidp,PNGAPI
215 png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
216 PNG_ALLOCATED)
217 {
218 if (png_ptr != NULL)
219 {
220 png_voidp ret = png_malloc_base(png_ptr, size);
221
222 if (ret != NULL)
223 return ret;
224
225 png_warning(png_ptr, "Out of memory");
226 }
227
228 return NULL;
229 }
230
231 /* Free a pointer allocated by png_malloc(). If ptr is NULL, return
232 * without taking any action.
233 */
234 void PNGAPI
png_free(png_const_structrp png_ptr,png_voidp ptr)235 png_free(png_const_structrp png_ptr, png_voidp ptr)
236 {
237 if (png_ptr == NULL || ptr == NULL)
238 return;
239
240 #ifdef PNG_USER_MEM_SUPPORTED
241 if (png_ptr->free_fn != NULL)
242 png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);
243
244 else
245 png_free_default(png_ptr, ptr);
246 }
247
248 PNG_FUNCTION(void,PNGAPI
249 png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED)
250 {
251 if (png_ptr == NULL || ptr == NULL)
252 return;
253 #endif /* USER_MEM */
254
255 FXMEM_DefaultFree(ptr, 0);
256 }
257
258 #ifdef PNG_USER_MEM_SUPPORTED
259 /* This function is called when the application wants to use another method
260 * of allocating and freeing memory.
261 */
262 void PNGAPI
png_set_mem_fn(png_structrp png_ptr,png_voidp mem_ptr,png_malloc_ptr malloc_fn,png_free_ptr free_fn)263 png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr
264 malloc_fn, png_free_ptr free_fn)
265 {
266 if (png_ptr != NULL)
267 {
268 png_ptr->mem_ptr = mem_ptr;
269 png_ptr->malloc_fn = malloc_fn;
270 png_ptr->free_fn = free_fn;
271 }
272 }
273
274 /* This function returns a pointer to the mem_ptr associated with the user
275 * functions. The application should free any memory associated with this
276 * pointer before png_write_destroy and png_read_destroy are called.
277 */
278 png_voidp PNGAPI
png_get_mem_ptr(png_const_structrp png_ptr)279 png_get_mem_ptr(png_const_structrp png_ptr)
280 {
281 if (png_ptr == NULL)
282 return NULL;
283
284 return png_ptr->mem_ptr;
285 }
286 #endif /* USER_MEM */
287 #endif /* READ || WRITE */
288