2 /* pngmem.c - stub functions for memory allocation
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.)
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
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.
22 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
23 /* Free a png_struct */
25 png_destroy_png_struct(png_structrp png_ptr
)
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.
32 png_struct dummy_struct
= *png_ptr
;
33 memset(png_ptr
, 0, (sizeof *png_ptr
));
34 png_free(&dummy_struct
, png_ptr
);
36 # ifdef PNG_SETJMP_SUPPORTED
37 /* We may have a jmp_buf left to deallocate. */
38 png_free_jmpbuf(&dummy_struct
);
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.
49 PNG_FUNCTION(png_voidp
,PNGAPI
50 png_calloc
,(png_const_structrp png_ptr
, png_alloc_size_t size
),PNG_ALLOCATED
)
54 ret
= png_malloc(png_ptr
, size
);
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.)
67 PNG_FUNCTION(png_voidp
/* PRIVATE */,
68 png_malloc_base
,(png_const_structrp png_ptr
, png_alloc_size_t size
),
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.
76 #ifndef PNG_USER_MEM_SUPPORTED
80 if (size
> 0 && size
<= PNG_SIZE_MAX
81 # ifdef PNG_MAX_MALLOC_64K
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
);
92 return malloc((size_t)size
); /* checked for truncation above */
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
106 png_malloc_array_checked(png_const_structrp png_ptr
, int nelements
,
109 png_alloc_size_t req
= nelements
; /* known to be > 0 */
111 if (req
<= PNG_SIZE_MAX
/element_size
)
112 return png_malloc_base(png_ptr
, req
* element_size
);
114 /* The failure case when the request is too large */
118 PNG_FUNCTION(png_voidp
/* PRIVATE */,
119 png_malloc_array
,(png_const_structrp png_ptr
, int nelements
,
120 size_t element_size
),PNG_ALLOCATED
)
122 if (nelements
<= 0 || element_size
== 0)
123 png_error(png_ptr
, "internal error: array alloc");
125 return png_malloc_array_checked(png_ptr
, nelements
, element_size
);
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
)
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");
137 /* Check for overflow on the elements count (so the caller does not have to
140 if (add_elements
<= INT_MAX
- old_elements
)
142 png_voidp new_array
= png_malloc_array_checked(png_ptr
,
143 old_elements
+add_elements
, element_size
);
145 if (new_array
!= NULL
)
147 /* Because png_malloc_array worked the size calculations below cannot
150 if (old_elements
> 0)
151 memcpy(new_array
, old_array
, element_size
*(unsigned)old_elements
);
153 memset((char*)new_array
+ element_size
*(unsigned)old_elements
, 0,
154 element_size
*(unsigned)add_elements
);
160 return NULL
; /* error */
162 #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
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.
168 PNG_FUNCTION(png_voidp
,PNGAPI
169 png_malloc
,(png_const_structrp png_ptr
, png_alloc_size_t size
),PNG_ALLOCATED
)
176 ret
= png_malloc_base(png_ptr
, size
);
179 png_error(png_ptr
, "Out of memory"); /* 'm' means png_malloc */
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
)
194 /* Passing 'NULL' here bypasses the application provided memory handler. */
195 ret
= png_malloc_base(NULL
/*use malloc*/, size
);
198 png_error(png_ptr
, "Out of Memory"); /* 'M' means png_malloc_default */
202 #endif /* PNG_USER_MEM_SUPPORTED */
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.
208 PNG_FUNCTION(png_voidp
,PNGAPI
209 png_malloc_warn
,(png_const_structrp png_ptr
, png_alloc_size_t size
),
214 png_voidp ret
= png_malloc_base(png_ptr
, size
);
219 png_warning(png_ptr
, "Out of memory");
225 /* Free a pointer allocated by png_malloc(). If ptr is NULL, return
226 * without taking any action.
229 png_free(png_const_structrp png_ptr
, png_voidp ptr
)
231 if (png_ptr
== NULL
|| ptr
== NULL
)
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
);
239 png_free_default(png_ptr
, ptr
);
242 PNG_FUNCTION(void,PNGAPI
243 png_free_default
,(png_const_structrp png_ptr
, png_voidp ptr
),PNG_DEPRECATED
)
245 if (png_ptr
== NULL
|| ptr
== NULL
)
247 #endif /* PNG_USER_MEM_SUPPORTED */
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.
257 png_set_mem_fn(png_structrp png_ptr
, png_voidp mem_ptr
, png_malloc_ptr
258 malloc_fn
, png_free_ptr free_fn
)
262 png_ptr
->mem_ptr
= mem_ptr
;
263 png_ptr
->malloc_fn
= malloc_fn
;
264 png_ptr
->free_fn
= free_fn
;
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.
273 png_get_mem_ptr(png_const_structrp png_ptr
)
278 return png_ptr
->mem_ptr
;
280 #endif /* PNG_USER_MEM_SUPPORTED */
281 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */