Line data Source code
1 :
2 : /* pngmem.c - stub functions for memory allocation
3 : *
4 : * Last changed in libpng 1.6.26 [October 20, 2016]
5 : * Copyright (c) 1998-2002,2004,2006-2014,2016 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 31 : png_destroy_png_struct(png_structrp png_ptr)
26 : {
27 31 : 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 31 : png_struct dummy_struct = *png_ptr;
33 31 : memset(png_ptr, 0, (sizeof *png_ptr));
34 31 : png_free(&dummy_struct, png_ptr);
35 :
36 : # ifdef PNG_SETJMP_SUPPORTED
37 : /* We may have a jmp_buf left to deallocate. */
38 31 : png_free_jmpbuf(&dummy_struct);
39 : # endif
40 : }
41 31 : }
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 2 : 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 2 : ret = png_malloc(png_ptr, size);
55 :
56 2 : if (ret != NULL)
57 2 : memset(ret, 0, size);
58 :
59 2 : 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 : */
67 172 : 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 : */
83 172 : 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
95 172 : return malloc((size_t)size); /* checked for truncation above */
96 : }
97 :
98 : else
99 0 : 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 66 : 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 66 : if (png_ptr == NULL)
177 0 : return NULL;
178 :
179 66 : ret = png_malloc_base(png_ptr, size);
180 :
181 66 : if (ret == NULL)
182 0 : png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
183 :
184 66 : 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 75 : PNG_FUNCTION(png_voidp,PNGAPI
212 : png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
213 : PNG_ALLOCATED)
214 : {
215 75 : if (png_ptr != NULL)
216 : {
217 75 : png_voidp ret = png_malloc_base(png_ptr, size);
218 :
219 75 : if (ret != NULL)
220 75 : return ret;
221 :
222 0 : png_warning(png_ptr, "Out of memory");
223 : }
224 :
225 0 : 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
232 327 : png_free(png_const_structrp png_ptr, png_voidp ptr)
233 : {
234 327 : if (png_ptr == NULL || ptr == NULL)
235 155 : 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 :
252 172 : 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 */
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