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 */