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apr_pools.h
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16 
17 #ifndef APR_POOLS_H
18 #define APR_POOLS_H
19 
20 /**
21  * @file apr_pools.h
22  * @brief APR memory allocation
23  *
24  * Resource allocation routines...
25  *
26  * designed so that we don't have to keep track of EVERYTHING so that
27  * it can be explicitly freed later (a fundamentally unsound strategy ---
28  * particularly in the presence of die()).
29  *
30  * Instead, we maintain pools, and allocate items (both memory and I/O
31  * handlers) from the pools --- currently there are two, one for
32  * per-transaction info, and one for config info. When a transaction is
33  * over, we can delete everything in the per-transaction apr_pool_t without
34  * fear, and without thinking too hard about it either.
35  *
36  * Note that most operations on pools are not thread-safe: a single pool
37  * should only be accessed by a single thread at any given time. The one
38  * exception to this rule is creating a subpool of a given pool: one or more
39  * threads can safely create subpools at the same time that another thread
40  * accesses the parent pool.
41  */
42 
43 #include "apr.h"
44 #include "apr_errno.h"
45 #include "apr_general.h" /* for APR_STRINGIFY */
46 #define APR_WANT_MEMFUNC /**< for no good reason? */
47 #include "apr_want.h"
48 
49 #ifdef __cplusplus
50 extern "C" {
51 #endif
52 
53 /**
54  * @defgroup apr_pools Memory Pool Functions
55  * @ingroup APR
56  * @{
57  */
58 
59 /** The fundamental pool type */
60 typedef struct apr_pool_t apr_pool_t;
61 
62 
63 /**
64  * Declaration helper macro to construct apr_foo_pool_get()s.
65  *
66  * This standardized macro is used by opaque (APR) data types to return
67  * the apr_pool_t that is associated with the data type.
68  *
69  * APR_POOL_DECLARE_ACCESSOR() is used in a header file to declare the
70  * accessor function. A typical usage and result would be:
71  * <pre>
72  * APR_POOL_DECLARE_ACCESSOR(file);
73  * becomes:
74  * APR_DECLARE(apr_pool_t *) apr_file_pool_get(const apr_file_t *thefile);
75  * </pre>
76  * @remark Doxygen unwraps this macro (via doxygen.conf) to provide
77  * actual help for each specific occurrence of apr_foo_pool_get.
78  * @remark the linkage is specified for APR. It would be possible to expand
79  * the macros to support other linkages.
80  */
81 #define APR_POOL_DECLARE_ACCESSOR(type) \
82  APR_DECLARE(apr_pool_t *) apr_##type##_pool_get \
83  (const apr_##type##_t *the##type)
84 
85 /**
86  * Implementation helper macro to provide apr_foo_pool_get()s.
87  *
88  * In the implementation, the APR_POOL_IMPLEMENT_ACCESSOR() is used to
89  * actually define the function. It assumes the field is named "pool".
90  */
91 #define APR_POOL_IMPLEMENT_ACCESSOR(type) \
92  APR_DECLARE(apr_pool_t *) apr_##type##_pool_get \
93  (const apr_##type##_t *the##type) \
94  { return the##type->pool; }
95 
96 
97 /**
98  * Pool debug levels
99  *
100  * <pre>
101  * | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
102  * ---------------------------------
103  * | | | | | | | | x | General debug code enabled (useful in
104  * combination with --with-efence).
105  *
106  * | | | | | | | x | | Verbose output on stderr (report
107  * CREATE, CLEAR, DESTROY).
108  *
109  * | | | | x | | | | | Verbose output on stderr (report
110  * PALLOC, PCALLOC).
111  *
112  * | | | | | | x | | | Lifetime checking. On each use of a
113  * pool, check its lifetime. If the pool
114  * is out of scope, abort().
115  * In combination with the verbose flag
116  * above, it will output LIFE in such an
117  * event prior to aborting.
118  *
119  * | | | | | x | | | | Pool owner checking. On each use of a
120  * pool, check if the current thread is the
121  * pool's owner. If not, abort(). In
122  * combination with the verbose flag above,
123  * it will output OWNER in such an event
124  * prior to aborting. Use the debug
125  * function apr_pool_owner_set() to switch
126  * a pool's ownership.
127  *
128  * When no debug level was specified, assume general debug mode.
129  * If level 0 was specified, debugging is switched off.
130  * </pre>
131  */
132 #if defined(APR_POOL_DEBUG)
133 /* If APR_POOL_DEBUG is blank, we get 1; if it is a number, we get -1. */
134 #if (APR_POOL_DEBUG - APR_POOL_DEBUG -1 == 1)
135 #undef APR_POOL_DEBUG
136 #define APR_POOL_DEBUG 1
137 #endif
138 #else
139 #define APR_POOL_DEBUG 0
140 #endif
141 
142 /** the place in the code where the particular function was called */
143 #define APR_POOL__FILE_LINE__ __FILE__ ":" APR_STRINGIFY(__LINE__)
144 
145 
146 
147 /** A function that is called when allocation fails. */
148 typedef int (*apr_abortfunc_t)(int retcode);
149 
150 /*
151  * APR memory structure manipulators (pools, tables, and arrays).
152  */
153 
154 /*
155  * Initialization
156  */
157 
158 /**
159  * Setup all of the internal structures required to use pools
160  * @remark Programs do NOT need to call this directly. APR will call this
161  * automatically from apr_initialize.
162  * @internal
163  */
165 
166 /**
167  * Tear down all of the internal structures required to use pools
168  * @remark Programs do NOT need to call this directly. APR will call this
169  * automatically from apr_terminate.
170  * @internal
171  */
172 APR_DECLARE(void) apr_pool_terminate(void);
173 
174 
175 /*
176  * Pool creation/destruction
177  */
178 
179 #include "apr_allocator.h"
180 
181 /**
182  * Create a new pool.
183  * @param newpool The pool we have just created.
184  * @param parent The parent pool. If this is NULL, the new pool is a root
185  * pool. If it is non-NULL, the new pool will inherit all
186  * of its parent pool's attributes, except the apr_pool_t will
187  * be a sub-pool.
188  * @param abort_fn A function to use if the pool cannot allocate more memory.
189  * @param allocator The allocator to use with the new pool. If NULL the
190  * allocator of the parent pool will be used.
191  * @remark This function is thread-safe, in the sense that multiple threads
192  * can safely create subpools of the same parent pool concurrently.
193  * Similarly, a subpool can be created by one thread at the same
194  * time that another thread accesses the parent pool.
195  */
197  apr_pool_t *parent,
198  apr_abortfunc_t abort_fn,
199  apr_allocator_t *allocator)
200  __attribute__((nonnull(1)));
201 
202 /**
203  * Create a new pool.
204  * @deprecated @see apr_pool_create_unmanaged_ex.
205  */
207  apr_abortfunc_t abort_fn,
208  apr_allocator_t *allocator);
209 
210 /**
211  * Create a new unmanaged pool.
212  * @param newpool The pool we have just created.
213  * @param abort_fn A function to use if the pool cannot allocate more memory.
214  * @param allocator The allocator to use with the new pool. If NULL a
215  * new allocator will be created with the new pool as owner.
216  * @remark An unmanaged pool is a special pool without a parent; it will
217  * NOT be destroyed upon apr_terminate. It must be explicitly
218  * destroyed by calling apr_pool_destroy, to prevent memory leaks.
219  * Use of this function is discouraged, think twice about whether
220  * you really really need it.
221  * @warning Any child cleanups registered against the new pool, or
222  * against sub-pools thereof, will not be executed during an
223  * invocation of apr_proc_create(), so resources created in an
224  * "unmanaged" pool hierarchy will leak to child processes.
225  */
227  apr_abortfunc_t abort_fn,
228  apr_allocator_t *allocator)
229  __attribute__((nonnull(1)));
230 
231 /**
232  * Debug version of apr_pool_create_ex.
233  * @param newpool @see apr_pool_create.
234  * @param parent @see apr_pool_create.
235  * @param abort_fn @see apr_pool_create.
236  * @param allocator @see apr_pool_create.
237  * @param file_line Where the function is called from.
238  * This is usually APR_POOL__FILE_LINE__.
239  * @remark Only available when APR_POOL_DEBUG is defined.
240  * Call this directly if you have your apr_pool_create_ex
241  * calls in a wrapper function and wish to override
242  * the file_line argument to reflect the caller of
243  * your wrapper function. If you do not have
244  * apr_pool_create_ex in a wrapper, trust the macro
245  * and don't call apr_pool_create_ex_debug directly.
246  */
248  apr_pool_t *parent,
249  apr_abortfunc_t abort_fn,
250  apr_allocator_t *allocator,
251  const char *file_line)
252  __attribute__((nonnull(1)));
253 
254 #if APR_POOL_DEBUG
255 #define apr_pool_create_ex(newpool, parent, abort_fn, allocator) \
256  apr_pool_create_ex_debug(newpool, parent, abort_fn, allocator, \
257  APR_POOL__FILE_LINE__)
258 #endif
259 
260 /**
261  * Debug version of apr_pool_create_core_ex.
262  * @deprecated @see apr_pool_create_unmanaged_ex_debug.
263  */
265  apr_abortfunc_t abort_fn,
266  apr_allocator_t *allocator,
267  const char *file_line);
268 
269 /**
270  * Debug version of apr_pool_create_unmanaged_ex.
271  * @param newpool @see apr_pool_create_unmanaged.
272  * @param abort_fn @see apr_pool_create_unmanaged.
273  * @param allocator @see apr_pool_create_unmanaged.
274  * @param file_line Where the function is called from.
275  * This is usually APR_POOL__FILE_LINE__.
276  * @remark Only available when APR_POOL_DEBUG is defined.
277  * Call this directly if you have your apr_pool_create_unmanaged_ex
278  * calls in a wrapper function and wish to override
279  * the file_line argument to reflect the caller of
280  * your wrapper function. If you do not have
281  * apr_pool_create_core_ex in a wrapper, trust the macro
282  * and don't call apr_pool_create_core_ex_debug directly.
283  */
285  apr_abortfunc_t abort_fn,
286  apr_allocator_t *allocator,
287  const char *file_line)
288  __attribute__((nonnull(1)));
289 
290 #if APR_POOL_DEBUG
291 #define apr_pool_create_core_ex(newpool, abort_fn, allocator) \
292  apr_pool_create_unmanaged_ex_debug(newpool, abort_fn, allocator, \
293  APR_POOL__FILE_LINE__)
294 
295 #define apr_pool_create_unmanaged_ex(newpool, abort_fn, allocator) \
296  apr_pool_create_unmanaged_ex_debug(newpool, abort_fn, allocator, \
297  APR_POOL__FILE_LINE__)
298 
299 #endif
300 
301 /**
302  * Create a new pool.
303  * @param newpool The pool we have just created.
304  * @param parent The parent pool. If this is NULL, the new pool is a root
305  * pool. If it is non-NULL, the new pool will inherit all
306  * of its parent pool's attributes, except the apr_pool_t will
307  * be a sub-pool.
308  * @remark This function is thread-safe, in the sense that multiple threads
309  * can safely create subpools of the same parent pool concurrently.
310  * Similarly, a subpool can be created by one thread at the same
311  * time that another thread accesses the parent pool.
312  */
313 #if defined(DOXYGEN)
315  apr_pool_t *parent);
316 #else
317 #if APR_POOL_DEBUG
318 #define apr_pool_create(newpool, parent) \
319  apr_pool_create_ex_debug(newpool, parent, NULL, NULL, \
320  APR_POOL__FILE_LINE__)
321 #else
322 #define apr_pool_create(newpool, parent) \
323  apr_pool_create_ex(newpool, parent, NULL, NULL)
324 #endif
325 #endif
326 
327 /**
328  * Create a new unmanaged pool.
329  * @param newpool The pool we have just created.
330  */
331 #if defined(DOXYGEN)
333 APR_DECLARE(apr_status_t) apr_pool_create_unmanaged(apr_pool_t **newpool);
334 #else
335 #if APR_POOL_DEBUG
336 #define apr_pool_create_core(newpool) \
337  apr_pool_create_unmanaged_ex_debug(newpool, NULL, NULL, \
338  APR_POOL__FILE_LINE__)
339 #define apr_pool_create_unmanaged(newpool) \
340  apr_pool_create_unmanaged_ex_debug(newpool, NULL, NULL, \
341  APR_POOL__FILE_LINE__)
342 #else
343 #define apr_pool_create_core(newpool) \
344  apr_pool_create_unmanaged_ex(newpool, NULL, NULL)
345 #define apr_pool_create_unmanaged(newpool) \
346  apr_pool_create_unmanaged_ex(newpool, NULL, NULL)
347 #endif
348 #endif
349 
350 /**
351  * Find the pool's allocator
352  * @param pool The pool to get the allocator from.
353  */
355  __attribute__((nonnull(1)));
356 
357 /**
358  * Clear all memory in the pool and run all the cleanups. This also destroys all
359  * subpools.
360  * @param p The pool to clear
361  * @remark This does not actually free the memory, it just allows the pool
362  * to re-use this memory for the next allocation.
363  * @see apr_pool_destroy()
364  */
365 APR_DECLARE(void) apr_pool_clear(apr_pool_t *p) __attribute__((nonnull(1)));
366 
367 /**
368  * Debug version of apr_pool_clear.
369  * @param p See: apr_pool_clear.
370  * @param file_line Where the function is called from.
371  * This is usually APR_POOL__FILE_LINE__.
372  * @remark Only available when APR_POOL_DEBUG is defined.
373  * Call this directly if you have your apr_pool_clear
374  * calls in a wrapper function and wish to override
375  * the file_line argument to reflect the caller of
376  * your wrapper function. If you do not have
377  * apr_pool_clear in a wrapper, trust the macro
378  * and don't call apr_pool_destroy_clear directly.
379  */
381  const char *file_line)
382  __attribute__((nonnull(1)));
383 
384 #if APR_POOL_DEBUG
385 #define apr_pool_clear(p) \
386  apr_pool_clear_debug(p, APR_POOL__FILE_LINE__)
387 #endif
388 
389 /**
390  * Destroy the pool. This takes similar action as apr_pool_clear() and then
391  * frees all the memory.
392  * @param p The pool to destroy
393  * @remark This will actually free the memory
394  */
395 APR_DECLARE(void) apr_pool_destroy(apr_pool_t *p) __attribute__((nonnull(1)));
396 
397 /**
398  * Debug version of apr_pool_destroy.
399  * @param p See: apr_pool_destroy.
400  * @param file_line Where the function is called from.
401  * This is usually APR_POOL__FILE_LINE__.
402  * @remark Only available when APR_POOL_DEBUG is defined.
403  * Call this directly if you have your apr_pool_destroy
404  * calls in a wrapper function and wish to override
405  * the file_line argument to reflect the caller of
406  * your wrapper function. If you do not have
407  * apr_pool_destroy in a wrapper, trust the macro
408  * and don't call apr_pool_destroy_debug directly.
409  */
411  const char *file_line)
412  __attribute__((nonnull(1)));
413 
414 #if APR_POOL_DEBUG
415 #define apr_pool_destroy(p) \
416  apr_pool_destroy_debug(p, APR_POOL__FILE_LINE__)
417 #endif
418 
419 
420 /*
421  * Memory allocation
422  */
423 
424 /**
425  * Allocate a block of memory from a pool
426  * @param p The pool to allocate from
427  * @param size The amount of memory to allocate
428  * @return The allocated memory
429  */
430 APR_DECLARE(void *) apr_palloc(apr_pool_t *p, apr_size_t size)
431 #if defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4))
432  __attribute__((alloc_size(2)))
433 #endif
434  __attribute__((nonnull(1)));
435 
436 /**
437  * Debug version of apr_palloc
438  * @param p See: apr_palloc
439  * @param size See: apr_palloc
440  * @param file_line Where the function is called from.
441  * This is usually APR_POOL__FILE_LINE__.
442  * @return See: apr_palloc
443  */
444 APR_DECLARE(void *) apr_palloc_debug(apr_pool_t *p, apr_size_t size,
445  const char *file_line)
446 #if defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4))
447  __attribute__((alloc_size(2)))
448 #endif
449  __attribute__((nonnull(1)));
450 
451 #if APR_POOL_DEBUG
452 #define apr_palloc(p, size) \
453  apr_palloc_debug(p, size, APR_POOL__FILE_LINE__)
454 #endif
455 
456 /**
457  * Allocate a block of memory from a pool and set all of the memory to 0
458  * @param p The pool to allocate from
459  * @param size The amount of memory to allocate
460  * @return The allocated memory
461  */
462 #if defined(DOXYGEN)
463 APR_DECLARE(void *) apr_pcalloc(apr_pool_t *p, apr_size_t size);
464 #elif !APR_POOL_DEBUG
465 #define apr_pcalloc(p, size) memset(apr_palloc(p, size), 0, size)
466 #endif
467 
468 /**
469  * Debug version of apr_pcalloc
470  * @param p See: apr_pcalloc
471  * @param size See: apr_pcalloc
472  * @param file_line Where the function is called from.
473  * This is usually APR_POOL__FILE_LINE__.
474  * @return See: apr_pcalloc
475  */
476 APR_DECLARE(void *) apr_pcalloc_debug(apr_pool_t *p, apr_size_t size,
477  const char *file_line)
478  __attribute__((nonnull(1)));
479 
480 #if APR_POOL_DEBUG
481 #define apr_pcalloc(p, size) \
482  apr_pcalloc_debug(p, size, APR_POOL__FILE_LINE__)
483 #endif
484 
485 
486 /*
487  * Pool Properties
488  */
489 
490 /**
491  * Set the function to be called when an allocation failure occurs.
492  * @remark If the program wants APR to exit on a memory allocation error,
493  * then this function can be called to set the callback to use (for
494  * performing cleanup and then exiting). If this function is not called,
495  * then APR will return an error and expect the calling program to
496  * deal with the error accordingly.
497  */
499  apr_pool_t *pool)
500  __attribute__((nonnull(2)));
501 
502 /**
503  * Get the abort function associated with the specified pool.
504  * @param pool The pool for retrieving the abort function.
505  * @return The abort function for the given pool.
506  */
508  __attribute__((nonnull(1)));
509 
510 /**
511  * Get the parent pool of the specified pool.
512  * @param pool The pool for retrieving the parent pool.
513  * @return The parent of the given pool.
514  */
516  __attribute__((nonnull(1)));
517 
518 /**
519  * Determine if pool a is an ancestor of pool b.
520  * @param a The pool to search
521  * @param b The pool to search for
522  * @return True if a is an ancestor of b, NULL is considered an ancestor
523  * of all pools.
524  * @remark if compiled with APR_POOL_DEBUG, this function will also
525  * return true if A is a pool which has been guaranteed by the caller
526  * (using apr_pool_join) to have a lifetime at least as long as some
527  * ancestor of pool B.
528  */
530 
531 /**
532  * Tag a pool (give it a name)
533  * @param pool The pool to tag
534  * @param tag The tag
535  */
536 APR_DECLARE(void) apr_pool_tag(apr_pool_t *pool, const char *tag)
537  __attribute__((nonnull(1)));
538 
539 
540 /*
541  * User data management
542  */
543 
544 /**
545  * Set the data associated with the current pool
546  * @param data The user data associated with the pool.
547  * @param key The key to use for association
548  * @param cleanup The cleanup program to use to cleanup the data (NULL if none)
549  * @param pool The current pool
550  * @warning The data to be attached to the pool should have a life span
551  * at least as long as the pool it is being attached to.
552  *
553  * Users of APR must take EXTREME care when choosing a key to
554  * use for their data. It is possible to accidentally overwrite
555  * data by choosing a key that another part of the program is using.
556  * Therefore it is advised that steps are taken to ensure that unique
557  * keys are used for all of the userdata objects in a particular pool
558  * (the same key in two different pools or a pool and one of its
559  * subpools is okay) at all times. Careful namespace prefixing of
560  * key names is a typical way to help ensure this uniqueness.
561  *
562  */
564  const char *key,
565  apr_status_t (*cleanup)(void *),
566  apr_pool_t *pool)
567  __attribute__((nonnull(2,4)));
568 
569 /**
570  * Set the data associated with the current pool
571  * @param data The user data associated with the pool.
572  * @param key The key to use for association
573  * @param cleanup The cleanup program to use to cleanup the data (NULL if none)
574  * @param pool The current pool
575  * @note same as apr_pool_userdata_set(), except that this version doesn't
576  * make a copy of the key (this function is useful, for example, when
577  * the key is a string literal)
578  * @warning This should NOT be used if the key could change addresses by
579  * any means between the apr_pool_userdata_setn() call and a
580  * subsequent apr_pool_userdata_get() on that key, such as if a
581  * static string is used as a userdata key in a DSO and the DSO could
582  * be unloaded and reloaded between the _setn() and the _get(). You
583  * MUST use apr_pool_userdata_set() in such cases.
584  * @warning More generally, the key and the data to be attached to the
585  * pool should have a life span at least as long as the pool itself.
586  *
587  */
589  const void *data, const char *key,
590  apr_status_t (*cleanup)(void *),
591  apr_pool_t *pool)
592  __attribute__((nonnull(2,4)));
593 
594 /**
595  * Return the data associated with the current pool.
596  * @param data The user data associated with the pool.
597  * @param key The key for the data to retrieve
598  * @param pool The current pool.
599  */
600 APR_DECLARE(apr_status_t) apr_pool_userdata_get(void **data, const char *key,
601  apr_pool_t *pool)
602  __attribute__((nonnull(1,2,3)));
603 
604 
605 /**
606  * @defgroup PoolCleanup Pool Cleanup Functions
607  *
608  * Cleanups are performed in the reverse order they were registered. That is:
609  * Last In, First Out. A cleanup function can safely allocate memory from
610  * the pool that is being cleaned up. It can also safely register additional
611  * cleanups which will be run LIFO, directly after the current cleanup
612  * terminates. Cleanups have to take caution in calling functions that
613  * create subpools. Subpools, created during cleanup will NOT automatically
614  * be cleaned up. In other words, cleanups are to clean up after themselves.
615  *
616  * @{
617  */
618 
619 /**
620  * Register a function to be called when a pool is cleared or destroyed
621  * @param p The pool to register the cleanup with
622  * @param data The data to pass to the cleanup function.
623  * @param plain_cleanup The function to call when the pool is cleared
624  * or destroyed
625  * @param child_cleanup The function to call when a child process is about
626  * to exec - this function is called in the child, obviously!
627  */
629  apr_pool_t *p, const void *data,
630  apr_status_t (*plain_cleanup)(void *),
631  apr_status_t (*child_cleanup)(void *))
632  __attribute__((nonnull(3,4)));
633 
634 /**
635  * Register a function to be called when a pool is cleared or destroyed.
636  *
637  * Unlike apr_pool_cleanup_register which registers a cleanup
638  * that is called AFTER all subpools are destroyed, this function registers
639  * a function that will be called before any of the subpools are destroyed.
640  *
641  * @param p The pool to register the cleanup with
642  * @param data The data to pass to the cleanup function.
643  * @param plain_cleanup The function to call when the pool is cleared
644  * or destroyed
645  */
647  apr_pool_t *p, const void *data,
648  apr_status_t (*plain_cleanup)(void *))
649  __attribute__((nonnull(3)));
650 
651 /**
652  * Remove a previously registered cleanup function.
653  *
654  * The cleanup most recently registered with @a p having the same values of
655  * @a data and @a cleanup will be removed.
656  *
657  * @param p The pool to remove the cleanup from
658  * @param data The data of the registered cleanup
659  * @param cleanup The function to remove from cleanup
660  * @remarks For some strange reason only the plain_cleanup is handled by this
661  * function
662  */
663 APR_DECLARE(void) apr_pool_cleanup_kill(apr_pool_t *p, const void *data,
664  apr_status_t (*cleanup)(void *))
665  __attribute__((nonnull(3)));
666 
667 /**
668  * Replace the child cleanup function of a previously registered cleanup.
669  *
670  * The cleanup most recently registered with @a p having the same values of
671  * @a data and @a plain_cleanup will have the registered child cleanup
672  * function replaced with @a child_cleanup.
673  *
674  * @param p The pool of the registered cleanup
675  * @param data The data of the registered cleanup
676  * @param plain_cleanup The plain cleanup function of the registered cleanup
677  * @param child_cleanup The function to register as the child cleanup
678  */
680  apr_pool_t *p, const void *data,
681  apr_status_t (*plain_cleanup)(void *),
682  apr_status_t (*child_cleanup)(void *))
683  __attribute__((nonnull(3,4)));
684 
685 /**
686  * Run the specified cleanup function immediately and unregister it.
687  *
688  * The cleanup most recently registered with @a p having the same values of
689  * @a data and @a cleanup will be removed and @a cleanup will be called
690  * with @a data as the argument.
691  *
692  * @param p The pool to remove the cleanup from
693  * @param data The data to remove from cleanup
694  * @param cleanup The function to remove from cleanup
695  */
697  apr_status_t (*cleanup)(void *))
698  __attribute__((nonnull(3)));
699 
700 /**
701  * An empty cleanup function.
702  *
703  * Passed to apr_pool_cleanup_register() when no cleanup is required.
704  *
705  * @param data The data to cleanup, will not be used by this function.
706  */
708 
709 /**
710  * Run all registered child cleanups, in preparation for an exec()
711  * call in a forked child -- close files, etc., but *don't* flush I/O
712  * buffers, *don't* wait for subprocesses, and *don't* free any
713  * memory.
714  */
716 
717 /** @} */
718 
719 /**
720  * @defgroup PoolDebug Pool Debugging functions.
721  *
722  * pools have nested lifetimes -- sub_pools are destroyed when the
723  * parent pool is cleared. We allow certain liberties with operations
724  * on things such as tables (and on other structures in a more general
725  * sense) where we allow the caller to insert values into a table which
726  * were not allocated from the table's pool. The table's data will
727  * remain valid as long as all the pools from which its values are
728  * allocated remain valid.
729  *
730  * For example, if B is a sub pool of A, and you build a table T in
731  * pool B, then it's safe to insert data allocated in A or B into T
732  * (because B lives at most as long as A does, and T is destroyed when
733  * B is cleared/destroyed). On the other hand, if S is a table in
734  * pool A, it is safe to insert data allocated in A into S, but it
735  * is *not safe* to insert data allocated from B into S... because
736  * B can be cleared/destroyed before A is (which would leave dangling
737  * pointers in T's data structures).
738  *
739  * In general we say that it is safe to insert data into a table T
740  * if the data is allocated in any ancestor of T's pool. This is the
741  * basis on which the APR_POOL_DEBUG code works -- it tests these ancestor
742  * relationships for all data inserted into tables. APR_POOL_DEBUG also
743  * provides tools (apr_pool_find, and apr_pool_is_ancestor) for other
744  * folks to implement similar restrictions for their own data
745  * structures.
746  *
747  * However, sometimes this ancestor requirement is inconvenient --
748  * sometimes it's necessary to create a sub pool where the sub pool is
749  * guaranteed to have the same lifetime as the parent pool. This is a
750  * guarantee implemented by the *caller*, not by the pool code. That
751  * is, the caller guarantees they won't destroy the sub pool
752  * individually prior to destroying the parent pool.
753  *
754  * In this case the caller must call apr_pool_join() to indicate this
755  * guarantee to the APR_POOL_DEBUG code.
756  *
757  * These functions are only implemented when #APR_POOL_DEBUG is set.
758  *
759  * @{
760  */
761 #if APR_POOL_DEBUG || defined(DOXYGEN)
762 /**
763  * Guarantee that a subpool has the same lifetime as the parent.
764  * @param p The parent pool
765  * @param sub The subpool
766  */
768  __attribute__((nonnull(2)));
769 
770 /**
771  * Find a pool from something allocated in it.
772  * @param mem The thing allocated in the pool
773  * @return The pool it is allocated in
774  */
775 APR_DECLARE(apr_pool_t *) apr_pool_find(const void *mem);
776 
777 /**
778  * Report the number of bytes currently in the pool
779  * @param p The pool to inspect
780  * @param recurse Recurse/include the subpools' sizes
781  * @return The number of bytes
782  */
783 APR_DECLARE(apr_size_t) apr_pool_num_bytes(apr_pool_t *p, int recurse)
784  __attribute__((nonnull(1)));
785 
786 /**
787  * Lock a pool
788  * @param pool The pool to lock
789  * @param flag The flag
790  */
791 APR_DECLARE(void) apr_pool_lock(apr_pool_t *pool, int flag);
792 
793 /* @} */
794 
795 #else /* APR_POOL_DEBUG or DOXYGEN */
796 
797 #ifdef apr_pool_join
798 #undef apr_pool_join
799 #endif
800 #define apr_pool_join(a,b)
801 
802 #ifdef apr_pool_lock
803 #undef apr_pool_lock
804 #endif
805 #define apr_pool_lock(pool, lock)
806 
807 #endif /* APR_POOL_DEBUG or DOXYGEN */
808 
809 /** @} */
810 
811 #ifdef __cplusplus
812 }
813 #endif
814 
815 #endif /* !APR_POOLS_H */