pngcrush  1.8.13
About: Pngcrush is an optimizer for PNG (Portable Network Graphics) files.
  Fossies Dox: pngcrush-1.8.13.tar.gz  ("inofficial" and yet experimental doxygen-generated source code documentation)  

pngmem.c
Go to the documentation of this file.
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 */
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  */
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 */,
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
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 */,
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  */
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
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  */
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
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
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
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  */
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 */
png_malloc_array_checked
static png_voidp png_malloc_array_checked(png_const_structrp png_ptr, int nelements, size_t element_size)
Definition: pngmem.c:109
png_error
PNG_IMPEXP void() png_error(png_const_structrp png_ptr, png_const_charp error_message)
Definition: pngerror.c:40
PNG_UNUSED
#define PNG_UNUSED(param)
Definition: pngpriv.h:429
png_voidp
void * png_voidp
Definition: pngconf.h:582
png_free
void png_free(png_const_structrp png_ptr, png_voidp ptr)
Definition: pngmem.c:232
pngpriv.h
free
void free()
png_free_ptr
void(* png_free_ptr)(png_structp, png_voidp)
Definition: png.h:900
png_alloc_size_t
png_size_t png_alloc_size_t
Definition: pngconf.h:562
png_realloc_array
png_voidp png_realloc_array(png_const_structrp png_ptr, png_const_voidp old_array, int old_elements, int add_elements, size_t element_size)
Definition: pngmem.c:133
PNG_SIZE_MAX
#define PNG_SIZE_MAX
Definition: png.h:682
PNG_ALLOCATED
#define PNG_ALLOCATED
Definition: pngconf.h:445
PNGAPI
#define PNGAPI
Definition: pngconf.h:267
png_malloc_default
png_voidp png_malloc_default(png_const_structrp png_ptr, png_alloc_size_t size)
Definition: pngmem.c:190
png_malloc_base
png_voidp png_malloc_base(png_const_structrp png_ptr, png_alloc_size_t size)
Definition: pngmem.c:69
png_free_default
void png_free_default(png_const_structrp png_ptr, png_voidp ptr)
Definition: pngmem.c:246
png_set_mem_fn
void png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn)
Definition: pngmem.c:260
png_free_jmpbuf
void png_free_jmpbuf(png_structrp png_ptr)
Definition: pngerror.c:666
png_malloc
png_voidp png_malloc(png_const_structrp png_ptr, png_alloc_size_t size)
Definition: pngmem.c:172
png_malloc_array
png_voidp png_malloc_array(png_const_structrp png_ptr, int nelements, size_t element_size)
Definition: pngmem.c:123
png_struct_def
Definition: pngstruct.h:143
png_const_voidp
const typedef void * png_const_voidp
Definition: pngconf.h:583
png_malloc_warn
png_voidp png_malloc_warn(png_const_structrp png_ptr, png_alloc_size_t size)
Definition: pngmem.c:213
png_warning
PNG_IMPEXP void() png_warning(png_const_structrp png_ptr, png_const_charp warning_message)
Definition: pngerror.c:216
png_malloc_ptr
png_voidp(* png_malloc_ptr)(png_structp, png_alloc_size_t)
Definition: png.h:899
png_destroy_png_struct
void png_destroy_png_struct(png_structrp png_ptr)
Definition: pngmem.c:25
png_constcast
#define png_constcast(type, value)
Definition: pngpriv.h:495
malloc
voidp malloc()
png_const_structrp
const typedef png_struct * png_const_structrp
Definition: png.h:501
PNG_FUNCTION
#define PNG_FUNCTION(type, name, args, attributes)
Definition: pngconf.h:293
png_calloc
png_voidp png_calloc(png_const_structrp png_ptr, png_alloc_size_t size)
Definition: pngmem.c:50
PNG_DEPRECATED
#define PNG_DEPRECATED
Definition: pngconf.h:436
png_get_mem_ptr
png_voidp png_get_mem_ptr(png_const_structrp png_ptr)
Definition: pngmem.c:276