7 The most current version of this document is available at
8 http://samba.org/ftp/unpacked/samba4/source/lib/talloc/talloc_guide.txt
10 If you are used to the "old" talloc from Samba3 before 3.0.20 then please read
11 this carefully, as talloc has changed a lot. With 3.0.20 (or 3.0.14?) the
12 Samba4 talloc has been ported back to Samba3, so this guide applies to both.
14 The new talloc is a hierarchical, reference counted memory pool system
15 with destructors. Quite a mounthful really, but not too bad once you
18 Perhaps the biggest change from Samba3 is that there is no distinction
19 between a "talloc context" and a "talloc pointer". Any pointer
20 returned from talloc() is itself a valid talloc context. This means
23 struct foo *X = talloc(mem_ctx, struct foo);
24 X->name = talloc_strdup(X, "foo");
26 and the pointer X->name would be a "child" of the talloc context "X"
27 which is itself a child of mem_ctx. So if you do talloc_free(mem_ctx)
28 then it is all destroyed, whereas if you do talloc_free(X) then just X
29 and X->name are destroyed, and if you do talloc_free(X->name) then
30 just the name element of X is destroyed.
32 If you think about this, then what this effectively gives you is an
33 n-ary tree, where you can free any part of the tree with
36 If you find this confusing, then I suggest you run the testsuite to
37 watch talloc in action. You may also like to add your own tests to
38 testsuite.c to clarify how some particular situation is handled.
44 All the additional features of talloc() over malloc() do come at a
45 price. We have a simple performance test in Samba4 that measures
46 talloc() versus malloc() performance, and it seems that talloc() is
47 about 4% slower than malloc() on my x86 Debian Linux box. For Samba,
48 the great reduction in code complexity that we get by using talloc
49 makes this worthwhile, especially as the total overhead of
50 talloc/malloc in Samba is already quite small.
56 The following is a complete guide to the talloc API. Read it all at
60 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
61 (type *)talloc(const void *context, type);
63 The talloc() macro is the core of the talloc library. It takes a
64 memory context and a type, and returns a pointer to a new area of
65 memory of the given type.
67 The returned pointer is itself a talloc context, so you can use it as
68 the context argument to more calls to talloc if you wish.
70 The returned pointer is a "child" of the supplied context. This means
71 that if you talloc_free() the context then the new child disappears as
72 well. Alternatively you can free just the child.
74 The context argument to talloc() can be NULL, in which case a new top
75 level context is created.
78 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
79 void *talloc_size(const void *context, size_t size);
81 The function talloc_size() should be used when you don't have a
82 convenient type to pass to talloc(). Unlike talloc(), it is not type
83 safe (as it returns a void *), so you are on your own for type checking.
85 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
86 (typeof(ptr)) talloc_ptrtype(const void *ctx, ptr);
88 The talloc_ptrtype() macro should be used when you have a pointer and
89 want to allocate memory to point at with this pointer. When compiling
90 with gcc >= 3 it is typesafe. Note this is a wrapper of talloc_size()
91 and talloc_get_name() will return the current location in the source file.
94 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
95 int talloc_free(void *ptr);
97 The talloc_free() function frees a piece of talloc memory, and all its
98 children. You can call talloc_free() on any pointer returned by
101 The return value of talloc_free() indicates success or failure, with 0
102 returned for success and -1 for failure. The only possible failure
103 condition is if the pointer had a destructor attached to it and the
104 destructor returned -1. See talloc_set_destructor() for details on
107 If this pointer has an additional parent when talloc_free() is called
108 then the memory is not actually released, but instead the most
109 recently established parent is destroyed. See talloc_reference() for
110 details on establishing additional parents.
112 For more control on which parent is removed, see talloc_unlink()
114 talloc_free() operates recursively on its children.
117 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
118 int talloc_free_children(void *ptr);
120 The talloc_free_children() walks along the list of all children of a
121 talloc context and talloc_free()s only the children, not the context
125 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
126 void *talloc_reference(const void *context, const void *ptr);
128 The talloc_reference() function makes "context" an additional parent
131 The return value of talloc_reference() is always the original pointer
132 "ptr", unless talloc ran out of memory in creating the reference in
133 which case it will return NULL (each additional reference consumes
134 around 48 bytes of memory on intel x86 platforms).
136 If "ptr" is NULL, then the function is a no-op, and simply returns NULL.
138 After creating a reference you can free it in one of the following
141 - you can talloc_free() any parent of the original pointer. That
142 will reduce the number of parents of this pointer by 1, and will
143 cause this pointer to be freed if it runs out of parents.
145 - you can talloc_free() the pointer itself. That will destroy the
146 most recently established parent to the pointer and leave the
147 pointer as a child of its current parent.
149 For more control on which parent to remove, see talloc_unlink()
152 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
153 int talloc_unlink(const void *context, const void *ptr);
155 The talloc_unlink() function removes a specific parent from ptr. The
156 context passed must either be a context used in talloc_reference()
157 with this pointer, or must be a direct parent of ptr.
159 Note that if the parent has already been removed using talloc_free()
160 then this function will fail and will return -1. Likewise, if "ptr"
161 is NULL, then the function will make no modifications and return -1.
163 Usually you can just use talloc_free() instead of talloc_unlink(), but
164 sometimes it is useful to have the additional control on which parent
168 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
169 void talloc_set_destructor(const void *ptr, int (*destructor)(void *));
171 The function talloc_set_destructor() sets the "destructor" for the
172 pointer "ptr". A destructor is a function that is called when the
173 memory used by a pointer is about to be released. The destructor
174 receives the pointer as an argument, and should return 0 for success
177 The destructor can do anything it wants to, including freeing other
178 pieces of memory. A common use for destructors is to clean up
179 operating system resources (such as open file descriptors) contained
180 in the structure the destructor is placed on.
182 You can only place one destructor on a pointer. If you need more than
183 one destructor then you can create a zero-length child of the pointer
184 and place an additional destructor on that.
186 To remove a destructor call talloc_set_destructor() with NULL for the
189 If your destructor attempts to talloc_free() the pointer that it is
190 the destructor for then talloc_free() will return -1 and the free will
191 be ignored. This would be a pointless operation anyway, as the
192 destructor is only called when the memory is just about to go away.
195 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
196 int talloc_increase_ref_count(const void *ptr);
198 The talloc_increase_ref_count(ptr) function is exactly equivalent to:
200 talloc_reference(NULL, ptr);
202 You can use either syntax, depending on which you think is clearer in
205 It returns 0 on success and -1 on failure.
207 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
208 size_t talloc_reference_count(const void *ptr);
210 Return the number of references to the pointer.
212 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
213 void talloc_set_name(const void *ptr, const char *fmt, ...);
215 Each talloc pointer has a "name". The name is used principally for
216 debugging purposes, although it is also possible to set and get the
217 name on a pointer in as a way of "marking" pointers in your code.
219 The main use for names on pointer is for "talloc reports". See
220 talloc_report() and talloc_report_full() for details. Also see
221 talloc_enable_leak_report() and talloc_enable_leak_report_full().
223 The talloc_set_name() function allocates memory as a child of the
224 pointer. It is logically equivalent to:
225 talloc_set_name_const(ptr, talloc_asprintf(ptr, fmt, ...));
227 Note that multiple calls to talloc_set_name() will allocate more
228 memory without releasing the name. All of the memory is released when
229 the ptr is freed using talloc_free().
232 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
233 void talloc_set_name_const(const void *ptr, const char *name);
235 The function talloc_set_name_const() is just like talloc_set_name(),
236 but it takes a string constant, and is much faster. It is extensively
237 used by the "auto naming" macros, such as talloc_p().
239 This function does not allocate any memory. It just copies the
240 supplied pointer into the internal representation of the talloc
241 ptr. This means you must not pass a name pointer to memory that will
242 disappear before the ptr is freed with talloc_free().
245 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
246 void *talloc_named(const void *context, size_t size, const char *fmt, ...);
248 The talloc_named() function creates a named talloc pointer. It is
251 ptr = talloc_size(context, size);
252 talloc_set_name(ptr, fmt, ....);
255 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
256 void *talloc_named_const(const void *context, size_t size, const char *name);
258 This is equivalent to:
260 ptr = talloc_size(context, size);
261 talloc_set_name_const(ptr, name);
264 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
265 const char *talloc_get_name(const void *ptr);
267 This returns the current name for the given talloc pointer. See
268 talloc_set_name() for details.
271 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
272 void *talloc_init(const char *fmt, ...);
274 This function creates a zero length named talloc context as a top
275 level context. It is equivalent to:
277 talloc_named(NULL, 0, fmt, ...);
280 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
281 void *talloc_new(void *ctx);
283 This is a utility macro that creates a new memory context hanging
284 off an exiting context, automatically naming it "talloc_new: __location__"
285 where __location__ is the source line it is called from. It is
286 particularly useful for creating a new temporary working context.
289 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
290 (type *)talloc_realloc(const void *context, void *ptr, type, count);
292 The talloc_realloc() macro changes the size of a talloc
293 pointer. The "count" argument is the number of elements of type "type"
294 that you want the resulting pointer to hold.
296 talloc_realloc() has the following equivalences:
298 talloc_realloc(context, NULL, type, 1) ==> talloc(context, type);
299 talloc_realloc(context, NULL, type, N) ==> talloc_array(context, type, N);
300 talloc_realloc(context, ptr, type, 0) ==> talloc_free(ptr);
302 The "context" argument is only used if "ptr" is NULL, otherwise it is
305 talloc_realloc() returns the new pointer, or NULL on failure. The call
306 will fail either due to a lack of memory, or because the pointer has
307 more than one parent (see talloc_reference()).
310 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
311 void *talloc_realloc_size(const void *context, void *ptr, size_t size);
313 the talloc_realloc_size() function is useful when the type is not
314 known so the typesafe talloc_realloc() cannot be used.
317 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
318 void *talloc_steal(const void *new_ctx, const void *ptr);
320 The talloc_steal() function changes the parent context of a talloc
321 pointer. It is typically used when the context that the pointer is
322 currently a child of is going to be freed and you wish to keep the
323 memory for a longer time.
325 The talloc_steal() function returns the pointer that you pass it. It
326 does not have any failure modes.
328 NOTE: It is possible to produce loops in the parent/child relationship
329 if you are not careful with talloc_steal(). No guarantees are provided
330 as to your sanity or the safety of your data if you do this.
332 talloc_steal (new_ctx, NULL) will return NULL with no sideeffects.
334 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
335 size_t talloc_total_size(const void *ptr);
337 The talloc_total_size() function returns the total size in bytes used
338 by this pointer and all child pointers. Mostly useful for debugging.
340 Passing NULL is allowed, but it will only give a meaningful result if
341 talloc_enable_leak_report() or talloc_enable_leak_report_full() has
345 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
346 size_t talloc_total_blocks(const void *ptr);
348 The talloc_total_blocks() function returns the total memory block
349 count used by this pointer and all child pointers. Mostly useful for
352 Passing NULL is allowed, but it will only give a meaningful result if
353 talloc_enable_leak_report() or talloc_enable_leak_report_full() has
356 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
357 void talloc_report_depth_cb(const void *ptr, int depth, int max_depth,
358 void (*callback)(const void *ptr,
359 int depth, int max_depth,
364 This provides a more flexible reports than talloc_report(). It
365 will recursively call the callback for the entire tree of memory
366 referenced by the pointer. References in the tree are passed with
367 is_ref = 1 and the pointer that is referenced.
369 You can pass NULL for the pointer, in which case a report is
370 printed for the top level memory context, but only if
371 talloc_enable_leak_report() or talloc_enable_leak_report_full()
374 The recursion is stopped when depth >= max_depth.
375 max_depth = -1 means only stop at leaf nodes.
378 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
379 void talloc_report_depth_file(const void *ptr, int depth, int max_depth, FILE *f);
381 This provides a more flexible reports than talloc_report(). It
382 will let you specify the depth and max_depth.
385 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
386 void talloc_report(const void *ptr, FILE *f);
388 The talloc_report() function prints a summary report of all memory
389 used by ptr. One line of report is printed for each immediate child of
390 ptr, showing the total memory and number of blocks used by that child.
392 You can pass NULL for the pointer, in which case a report is printed
393 for the top level memory context, but only if
394 talloc_enable_leak_report() or talloc_enable_leak_report_full() has
398 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
399 void talloc_report_full(const void *ptr, FILE *f);
401 This provides a more detailed report than talloc_report(). It will
402 recursively print the ensire tree of memory referenced by the
403 pointer. References in the tree are shown by giving the name of the
404 pointer that is referenced.
406 You can pass NULL for the pointer, in which case a report is printed
407 for the top level memory context, but only if
408 talloc_enable_leak_report() or talloc_enable_leak_report_full() has
412 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
413 void talloc_enable_leak_report(void);
415 This enables calling of talloc_report(NULL, stderr) when the program
416 exits. In Samba4 this is enabled by using the --leak-report command
419 For it to be useful, this function must be called before any other
420 talloc function as it establishes a "null context" that acts as the
421 top of the tree. If you don't call this function first then passing
422 NULL to talloc_report() or talloc_report_full() won't give you the
425 Here is a typical talloc report:
427 talloc report on 'null_context' (total 267 bytes in 15 blocks)
428 libcli/auth/spnego_parse.c:55 contains 31 bytes in 2 blocks
429 libcli/auth/spnego_parse.c:55 contains 31 bytes in 2 blocks
430 iconv(UTF8,CP850) contains 42 bytes in 2 blocks
431 libcli/auth/spnego_parse.c:55 contains 31 bytes in 2 blocks
432 iconv(CP850,UTF8) contains 42 bytes in 2 blocks
433 iconv(UTF8,UTF-16LE) contains 45 bytes in 2 blocks
434 iconv(UTF-16LE,UTF8) contains 45 bytes in 2 blocks
437 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
438 void talloc_enable_leak_report_full(void);
440 This enables calling of talloc_report_full(NULL, stderr) when the
441 program exits. In Samba4 this is enabled by using the
442 --leak-report-full command line option.
444 For it to be useful, this function must be called before any other
445 talloc function as it establishes a "null context" that acts as the
446 top of the tree. If you don't call this function first then passing
447 NULL to talloc_report() or talloc_report_full() won't give you the
450 Here is a typical full report:
452 full talloc report on 'root' (total 18 bytes in 8 blocks)
453 p1 contains 18 bytes in 7 blocks (ref 0)
454 r1 contains 13 bytes in 2 blocks (ref 0)
456 p2 contains 1 bytes in 1 blocks (ref 1)
457 x3 contains 1 bytes in 1 blocks (ref 0)
458 x2 contains 1 bytes in 1 blocks (ref 0)
459 x1 contains 1 bytes in 1 blocks (ref 0)
462 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
463 void talloc_enable_null_tracking(void);
465 This enables tracking of the NULL memory context without enabling leak
466 reporting on exit. Useful for when you want to do your own leak
467 reporting call via talloc_report_null_full();
469 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
470 void talloc_disable_null_tracking(void);
472 This disables tracking of the NULL memory context.
474 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
475 (type *)talloc_zero(const void *ctx, type);
477 The talloc_zero() macro is equivalent to:
479 ptr = talloc(ctx, type);
480 if (ptr) memset(ptr, 0, sizeof(type));
483 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
484 void *talloc_zero_size(const void *ctx, size_t size)
486 The talloc_zero_size() function is useful when you don't have a known type
489 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
490 void *talloc_memdup(const void *ctx, const void *p, size_t size);
492 The talloc_memdup() function is equivalent to:
494 ptr = talloc_size(ctx, size);
495 if (ptr) memcpy(ptr, p, size);
498 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
499 char *talloc_strdup(const void *ctx, const char *p);
501 The talloc_strdup() function is equivalent to:
503 ptr = talloc_size(ctx, strlen(p)+1);
504 if (ptr) memcpy(ptr, p, strlen(p)+1);
506 This functions sets the name of the new pointer to the passed
507 string. This is equivalent to:
508 talloc_set_name_const(ptr, ptr)
510 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
511 char *talloc_strndup(const void *t, const char *p, size_t n);
513 The talloc_strndup() function is the talloc equivalent of the C
514 library function strndup()
516 This functions sets the name of the new pointer to the passed
517 string. This is equivalent to:
518 talloc_set_name_const(ptr, ptr)
521 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
522 char *talloc_vasprintf(const void *t, const char *fmt, va_list ap);
524 The talloc_vasprintf() function is the talloc equivalent of the C
525 library function vasprintf()
528 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
529 char *talloc_asprintf(const void *t, const char *fmt, ...);
531 The talloc_asprintf() function is the talloc equivalent of the C
532 library function asprintf()
534 This functions sets the name of the new pointer to the passed
535 string. This is equivalent to:
536 talloc_set_name_const(ptr, ptr)
539 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
540 char *talloc_asprintf_append(char *s, const char *fmt, ...);
542 The talloc_asprintf_append() function appends the given formatted
543 string to the given string.
546 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
547 (type *)talloc_array(const void *ctx, type, uint_t count);
549 The talloc_array() macro is equivalent to:
551 (type *)talloc_size(ctx, sizeof(type) * count);
553 except that it provides integer overflow protection for the multiply,
554 returning NULL if the multiply overflows.
557 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
558 void *talloc_array_size(const void *ctx, size_t size, uint_t count);
560 The talloc_array_size() function is useful when the type is not
561 known. It operates in the same way as talloc_array(), but takes a size
564 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
565 (typeof(ptr)) talloc_array_ptrtype(const void *ctx, ptr, uint_t count);
567 The talloc_ptrtype() macro should be used when you have a pointer to an array
568 and want to allocate memory of an array to point at with this pointer. When compiling
569 with gcc >= 3 it is typesafe. Note this is a wrapper of talloc_array_size()
570 and talloc_get_name() will return the current location in the source file.
573 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
574 void *talloc_realloc_fn(const void *ctx, void *ptr, size_t size);
576 This is a non-macro version of talloc_realloc(), which is useful
577 as libraries sometimes want a ralloc function pointer. A realloc()
578 implementation encapsulates the functionality of malloc(), free() and
579 realloc() in one call, which is why it is useful to be able to pass
580 around a single function pointer.
583 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
584 void *talloc_autofree_context(void);
586 This is a handy utility function that returns a talloc context
587 which will be automatically freed on program exit. This can be used
588 to reduce the noise in memory leak reports.
591 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
592 void *talloc_check_name(const void *ptr, const char *name);
594 This function checks if a pointer has the specified name. If it does
595 then the pointer is returned. It it doesn't then NULL is returned.
598 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
599 (type *)talloc_get_type(const void *ptr, type);
601 This macro allows you to do type checking on talloc pointers. It is
602 particularly useful for void* private pointers. It is equivalent to
605 (type *)talloc_check_name(ptr, #type)
608 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
609 talloc_set_type(const void *ptr, type);
611 This macro allows you to force the name of a pointer to be a
612 particular type. This can be used in conjunction with
613 talloc_get_type() to do type checking on void* pointers.
615 It is equivalent to this:
616 talloc_set_name_const(ptr, #type)
618 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
619 talloc_get_size(const void *ctx);
621 This function lets you know the amount of memory alloced so far by
622 this context. It does NOT account for subcontext memory.
623 This can be used to calculate the size of an array.
625 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
626 void *talloc_find_parent_byname(const void *ctx, const char *name);
628 Find a parent memory context of the current context that has the given
629 name. This can be very useful in complex programs where it may be
630 difficult to pass all information down to the level you need, but you
631 know the structure you want is a parent of another context.
633 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
634 (type *)talloc_find_parent_bytype(ctx, type);
636 Like talloc_find_parent_byname() but takes a type, making it typesafe.