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27 * ralloc: a recursive memory allocator
29 * The ralloc memory allocator creates a hierarchy of allocated
30 * objects. Every allocation is in reference to some parent, and
31 * every allocated object can in turn be used as the parent of a
32 * subsequent allocation. This allows for extremely convenient
33 * discarding of an entire tree/sub-tree of allocations by calling
34 * ralloc_free on any particular object to free it and all of its
37 * The conceptual working of ralloc was directly inspired by Andrew
38 * Tridgell's talloc, but ralloc is an independent implementation
39 * released under the MIT license and tuned for Mesa.
41 * The talloc implementation is available under the GNU Lesser
42 * General Public License (GNU LGPL), version 3 or later. It is
43 * more sophisticated than ralloc in that it includes reference
44 * counting and debugging features. See: http://talloc.samba.org/
57 #include "main/compiler.h"
60 * \def ralloc(ctx, type)
61 * Allocate a new object chained off of the given context.
63 * This is equivalent to:
65 * ((type *) ralloc_size(ctx, sizeof(type))
68 #define ralloc(ctx, type) ((type *) ralloc_size(ctx, sizeof(type)))
71 * \def rzalloc(ctx, type)
72 * Allocate a new object out of the given context and initialize it to zero.
74 * This is equivalent to:
76 * ((type *) rzalloc_size(ctx, sizeof(type))
79 #define rzalloc(ctx, type) ((type *) rzalloc_size(ctx, sizeof(type)))
82 * Allocate a new ralloc context.
84 * While any ralloc'd pointer can be used as a context, sometimes it is useful
85 * to simply allocate a context with no associated memory.
87 * It is equivalent to:
89 * ((type *) ralloc_size(ctx, 0)
92 void *ralloc_context(const void *ctx
);
95 * Allocate memory chained off of the given context.
97 * This is the core allocation routine which is used by all others. It
98 * simply allocates storage for \p size bytes and returns the pointer,
99 * similar to \c malloc.
101 void *ralloc_size(const void *ctx
, size_t size
);
104 * Allocate zero-initialized memory chained off of the given context.
106 * This is similar to \c calloc with a size of 1.
108 void *rzalloc_size(const void *ctx
, size_t size
);
111 * Resize a piece of ralloc-managed memory, preserving data.
113 * Similar to \c realloc. Unlike C89, passing 0 for \p size does not free the
114 * memory. Instead, it resizes it to a 0-byte ralloc context, just like
115 * calling ralloc_size(ctx, 0). This is different from talloc.
117 * \param ctx The context to use for new allocation. If \p ptr != NULL,
118 * it must be the same as ralloc_parent(\p ptr).
119 * \param ptr Pointer to the memory to be resized. May be NULL.
120 * \param size The amount of memory to allocate, in bytes.
122 void *reralloc_size(const void *ctx
, void *ptr
, size_t size
);
124 /// \defgroup array Array Allocators @{
127 * \def ralloc_array(ctx, type, count)
128 * Allocate an array of objects chained off the given context.
130 * Similar to \c calloc, but does not initialize the memory to zero.
132 * More than a convenience function, this also checks for integer overflow when
133 * multiplying \c sizeof(type) and \p count. This is necessary for security.
135 * This is equivalent to:
137 * ((type *) ralloc_array_size(ctx, sizeof(type), count)
140 #define ralloc_array(ctx, type, count) \
141 ((type *) ralloc_array_size(ctx, sizeof(type), count))
144 * \def rzalloc_array(ctx, type, count)
145 * Allocate a zero-initialized array chained off the given context.
147 * Similar to \c calloc.
149 * More than a convenience function, this also checks for integer overflow when
150 * multiplying \c sizeof(type) and \p count. This is necessary for security.
152 * This is equivalent to:
154 * ((type *) rzalloc_array_size(ctx, sizeof(type), count)
157 #define rzalloc_array(ctx, type, count) \
158 ((type *) rzalloc_array_size(ctx, sizeof(type), count))
161 * \def reralloc(ctx, ptr, type, count)
162 * Resize a ralloc-managed array, preserving data.
164 * Similar to \c realloc. Unlike C89, passing 0 for \p size does not free the
165 * memory. Instead, it resizes it to a 0-byte ralloc context, just like
166 * calling ralloc_size(ctx, 0). This is different from talloc.
168 * More than a convenience function, this also checks for integer overflow when
169 * multiplying \c sizeof(type) and \p count. This is necessary for security.
171 * \param ctx The context to use for new allocation. If \p ptr != NULL,
172 * it must be the same as ralloc_parent(\p ptr).
173 * \param ptr Pointer to the array to be resized. May be NULL.
174 * \param type The element type.
175 * \param count The number of elements to allocate.
177 #define reralloc(ctx, ptr, type, count) \
178 ((type *) reralloc_array_size(ctx, ptr, sizeof(type), count))
181 * Allocate memory for an array chained off the given context.
183 * Similar to \c calloc, but does not initialize the memory to zero.
185 * More than a convenience function, this also checks for integer overflow when
186 * multiplying \p size and \p count. This is necessary for security.
188 void *ralloc_array_size(const void *ctx
, size_t size
, unsigned count
);
191 * Allocate a zero-initialized array chained off the given context.
193 * Similar to \c calloc.
195 * More than a convenience function, this also checks for integer overflow when
196 * multiplying \p size and \p count. This is necessary for security.
198 void *rzalloc_array_size(const void *ctx
, size_t size
, unsigned count
);
201 * Resize a ralloc-managed array, preserving data.
203 * Similar to \c realloc. Unlike C89, passing 0 for \p size does not free the
204 * memory. Instead, it resizes it to a 0-byte ralloc context, just like
205 * calling ralloc_size(ctx, 0). This is different from talloc.
207 * More than a convenience function, this also checks for integer overflow when
208 * multiplying \c sizeof(type) and \p count. This is necessary for security.
210 * \param ctx The context to use for new allocation. If \p ptr != NULL,
211 * it must be the same as ralloc_parent(\p ptr).
212 * \param ptr Pointer to the array to be resized. May be NULL.
213 * \param size The size of an individual element.
214 * \param count The number of elements to allocate.
216 * \return True unless allocation failed.
218 void *reralloc_array_size(const void *ctx
, void *ptr
, size_t size
,
223 * Free a piece of ralloc-managed memory.
225 * This will also free the memory of any children allocated this context.
227 void ralloc_free(void *ptr
);
230 * "Steal" memory from one context, changing it to another.
232 * This changes \p ptr's context to \p new_ctx. This is quite useful if
233 * memory is allocated out of a temporary context.
235 void ralloc_steal(const void *new_ctx
, void *ptr
);
238 * Return the given pointer's ralloc context.
240 void *ralloc_parent(const void *ptr
);
243 * Return a context whose memory will be automatically freed at program exit.
245 * The first call to this function creates a context and registers a handler
246 * to free it using \c atexit. This may cause trouble if used in a library
247 * loaded with \c dlopen.
249 void *ralloc_autofree_context(void);
252 * Set a callback to occur just before an object is freed.
254 void ralloc_set_destructor(const void *ptr
, void(*destructor
)(void *));
256 /// \defgroup array String Functions @{
258 * Duplicate a string, allocating the memory from the given context.
260 char *ralloc_strdup(const void *ctx
, const char *str
);
263 * Duplicate a string, allocating the memory from the given context.
265 * Like \c strndup, at most \p n characters are copied. If \p str is longer
266 * than \p n characters, \p n are copied, and a termining \c '\0' byte is added.
268 char *ralloc_strndup(const void *ctx
, const char *str
, size_t n
);
271 * Concatenate two strings, allocating the necessary space.
273 * This appends \p str to \p *dest, similar to \c strcat, using ralloc_resize
274 * to expand \p *dest to the appropriate size. \p dest will be updated to the
275 * new pointer unless allocation fails.
277 * The result will always be null-terminated.
279 * \return True unless allocation failed.
281 bool ralloc_strcat(char **dest
, const char *str
);
284 * Concatenate two strings, allocating the necessary space.
286 * This appends at most \p n bytes of \p str to \p *dest, using ralloc_resize
287 * to expand \p *dest to the appropriate size. \p dest will be updated to the
288 * new pointer unless allocation fails.
290 * The result will always be null-terminated; \p str does not need to be null
291 * terminated if it is longer than \p n.
293 * \return True unless allocation failed.
295 bool ralloc_strncat(char **dest
, const char *str
, size_t n
);
300 * This is analogous to \c sprintf, but allocates enough space (using \p ctx
301 * as the context) for the resulting string.
303 * \return The newly allocated string.
305 char *ralloc_asprintf (const void *ctx
, const char *fmt
, ...) PRINTFLIKE(2, 3);
308 * Print to a string, given a va_list.
310 * This is analogous to \c vsprintf, but allocates enough space (using \p ctx
311 * as the context) for the resulting string.
313 * \return The newly allocated string.
315 char *ralloc_vasprintf(const void *ctx
, const char *fmt
, va_list args
);
318 * Rewrite the tail of an existing string, starting at a given index.
320 * Overwrites the contents of *str starting at \p start with newly formatted
321 * text, including a new null-terminator. Allocates more memory as necessary.
323 * This can be used to append formatted text when the length of the existing
324 * string is already known, saving a strlen() call.
326 * \sa ralloc_asprintf_append
328 * \param str The string to be updated.
329 * \param start The index to start appending new data at.
330 * \param fmt A printf-style formatting string
332 * \p str will be updated to the new pointer unless allocation fails.
333 * \p start will be increased by the length of the newly formatted text.
335 * \return True unless allocation failed.
337 bool ralloc_asprintf_rewrite_tail(char **str
, size_t *start
,
338 const char *fmt
, ...)
342 * Rewrite the tail of an existing string, starting at a given index.
344 * Overwrites the contents of *str starting at \p start with newly formatted
345 * text, including a new null-terminator. Allocates more memory as necessary.
347 * This can be used to append formatted text when the length of the existing
348 * string is already known, saving a strlen() call.
350 * \sa ralloc_vasprintf_append
352 * \param str The string to be updated.
353 * \param start The index to start appending new data at.
354 * \param fmt A printf-style formatting string
355 * \param args A va_list containing the data to be formatted
357 * \p str will be updated to the new pointer unless allocation fails.
358 * \p start will be increased by the length of the newly formatted text.
360 * \return True unless allocation failed.
362 bool ralloc_vasprintf_rewrite_tail(char **str
, size_t *start
, const char *fmt
,
366 * Append formatted text to the supplied string.
368 * This is equivalent to
370 * ralloc_asprintf_rewrite_tail(str, strlen(*str), fmt, ...)
373 * \sa ralloc_asprintf
374 * \sa ralloc_asprintf_rewrite_tail
377 * \p str will be updated to the new pointer unless allocation fails.
379 * \return True unless allocation failed.
381 bool ralloc_asprintf_append (char **str
, const char *fmt
, ...)
385 * Append formatted text to the supplied string, given a va_list.
387 * This is equivalent to
389 * ralloc_vasprintf_rewrite_tail(str, strlen(*str), fmt, args)
392 * \sa ralloc_vasprintf
393 * \sa ralloc_vasprintf_rewrite_tail
396 * \p str will be updated to the new pointer unless allocation fails.
398 * \return True unless allocation failed.
400 bool ralloc_vasprintf_append(char **str
, const char *fmt
, va_list args
);
404 } /* end of extern "C" */