From 4af921fe882b59d8ad16b2b906e74c28b1b36c20 Mon Sep 17 00:00:00 2001 From: Karolin Seeger Date: Fri, 30 Nov 2012 09:43:33 +0100 Subject: lib/talloc: Move manpage to man/. Trying to be more consistent. Karolin Reviewed-by: Andreas Schneider --- lib/talloc/talloc.3.xml | 813 ------------------------------------------------ 1 file changed, 813 deletions(-) delete mode 100644 lib/talloc/talloc.3.xml (limited to 'lib/talloc/talloc.3.xml') diff --git a/lib/talloc/talloc.3.xml b/lib/talloc/talloc.3.xml deleted file mode 100644 index 85cd6c49d8..0000000000 --- a/lib/talloc/talloc.3.xml +++ /dev/null @@ -1,813 +0,0 @@ - - - - - talloc - 3 - Samba - System Administration tools - 4.0 - - - talloc -hierarchical reference counted memory pool system with destructors - - -#include <talloc.h> - - DESCRIPTION - - If you are used to talloc from Samba3 then please read this - carefully, as talloc has changed a lot. - - - The new talloc is a hierarchical, reference counted memory pool - system with destructors. Quite a mouthful really, but not too bad - once you get used to it. - - - Perhaps the biggest change from Samba3 is that there is no - distinction between a "talloc context" and a "talloc pointer". Any - pointer returned from talloc() is itself a valid talloc context. - This means you can do this: - - - struct foo *X = talloc(mem_ctx, struct foo); - X->name = talloc_strdup(X, "foo"); - - - and the pointer X->name - would be a "child" of the talloc context X which is itself a child of - mem_ctx. So if you do - talloc_free(mem_ctx) then - it is all destroyed, whereas if you do talloc_free(X) then just X and X->name are destroyed, and if - you do talloc_free(X->name) then just - the name element of X is - destroyed. - - - If you think about this, then what this effectively gives you is an - n-ary tree, where you can free any part of the tree with - talloc_free(). - - - If you find this confusing, then I suggest you run the testsuite program to watch talloc - in action. You may also like to add your own tests to testsuite.c to clarify how some - particular situation is handled. - - - TALLOC API - - The following is a complete guide to the talloc API. Read it all at - least twice. - - (type *)talloc(const void *ctx, type); - - The talloc() macro is the core of the talloc library. It takes a - memory ctx and a type, and returns a pointer to a new - area of memory of the given type. - - - The returned pointer is itself a talloc context, so you can use - it as the ctx argument to more - calls to talloc() if you wish. - - - The returned pointer is a "child" of the supplied context. This - means that if you talloc_free() the ctx then the new child disappears as - well. Alternatively you can free just the child. - - - The ctx argument to talloc() - can be NULL, in which case a new top level context is created. - - - void *talloc_size(const void *ctx, size_t size); - - The function talloc_size() should be used when you don't have a - convenient type to pass to talloc(). Unlike talloc(), it is not - type safe (as it returns a void *), so you are on your own for - type checking. - - - (typeof(ptr)) talloc_ptrtype(const void *ctx, ptr); - - The talloc_ptrtype() macro should be used when you have a pointer and - want to allocate memory to point at with this pointer. When compiling - with gcc >= 3 it is typesafe. Note this is a wrapper of talloc_size() - and talloc_get_name() will return the current location in the source file. - and not the type. - - - int talloc_free(void *ptr); - - The talloc_free() function frees a piece of talloc memory, and - all its children. You can call talloc_free() on any pointer - returned by talloc(). - - - The return value of talloc_free() indicates success or failure, - with 0 returned for success and -1 for failure. The only - possible failure condition is if ptr had a destructor attached to it and - the destructor returned -1. See talloc_set_destructor() - for details on destructors. - - - If this pointer has an additional parent when talloc_free() is - called then the memory is not actually released, but instead the - most recently established parent is destroyed. See talloc_reference() - for details on establishing additional parents. - - - For more control on which parent is removed, see talloc_unlink(). - - - talloc_free() operates recursively on its children. - - - From the 2.0 version of talloc, as a special case, - talloc_free() is refused on pointers that have more than one - parent, as talloc would have no way of knowing which parent - should be removed. To free a pointer that has more than one - parent please use talloc_unlink(). - - - To help you find problems in your code caused by this behaviour, if - you do try and free a pointer with more than one parent then the - talloc logging function will be called to give output like this: - - - - ERROR: talloc_free with references at some_dir/source/foo.c:123 - reference at some_dir/source/other.c:325 - reference at some_dir/source/third.c:121 - - - - Please see the documentation for talloc_set_log_fn() and - talloc_set_log_stderr() for more information on talloc logging - functions. - - - void *talloc_reference(const void *ctx, const void *ptr); - - The talloc_reference() function makes ctx an additional parent of ptr. - - - The return value of talloc_reference() is always the original - pointer ptr, unless talloc ran - out of memory in creating the reference in which case it will - return NULL (each additional reference consumes around 48 bytes - of memory on intel x86 platforms). - - - If ptr is NULL, then the - function is a no-op, and simply returns NULL. - - - After creating a reference you can free it in one of the - following ways: - - - - - - you can talloc_free() any parent of the original pointer. - That will reduce the number of parents of this pointer by 1, - and will cause this pointer to be freed if it runs out of - parents. - - - - - you can talloc_free() the pointer itself. That will destroy - the most recently established parent to the pointer and leave - the pointer as a child of its current parent. - - - - - - For more control on which parent to remove, see talloc_unlink(). - - - int talloc_unlink(const void *ctx, const void *ptr); - - The talloc_unlink() function removes a specific parent from - ptr. The ctx passed must either be a context used - in talloc_reference() with this pointer, or must be a direct - parent of ptr. - - - Note that if the parent has already been removed using - talloc_free() then this function will fail and will return -1. - Likewise, if ptr is NULL, then - the function will make no modifications and return -1. - - - Usually you can just use talloc_free() instead of - talloc_unlink(), but sometimes it is useful to have the - additional control on which parent is removed. - - - void talloc_set_destructor(const void *ptr, int (*destructor)(void *)); - - The function talloc_set_destructor() sets the destructor for the pointer ptr. A destructor is a function that is called - when the memory used by a pointer is about to be released. The - destructor receives ptr as an - argument, and should return 0 for success and -1 for failure. - - - The destructor can do anything - it wants to, including freeing other pieces of memory. A common - use for destructors is to clean up operating system resources - (such as open file descriptors) contained in the structure the - destructor is placed on. - - - You can only place one destructor on a pointer. If you need more - than one destructor then you can create a zero-length child of - the pointer and place an additional destructor on that. - - - To remove a destructor call talloc_set_destructor() with NULL for - the destructor. - - - If your destructor attempts to talloc_free() the pointer that it - is the destructor for then talloc_free() will return -1 and the - free will be ignored. This would be a pointless operation - anyway, as the destructor is only called when the memory is just - about to go away. - - - int talloc_increase_ref_count(const void *<emphasis role="italic">ptr</emphasis>); - - The talloc_increase_ref_count(ptr) function is exactly equivalent to: - - talloc_reference(NULL, ptr); - - You can use either syntax, depending on which you think is - clearer in your code. - - - It returns 0 on success and -1 on failure. - - - size_t talloc_reference_count(const void *<emphasis role="italic">ptr</emphasis>); - - Return the number of references to the pointer. - - - void talloc_set_name(const void *ptr, const char *fmt, ...); - - Each talloc pointer has a "name". The name is used principally - for debugging purposes, although it is also possible to set and - get the name on a pointer in as a way of "marking" pointers in - your code. - - - The main use for names on pointer is for "talloc reports". See - talloc_report_depth_cb(), - talloc_report_depth_file(), - talloc_report() - talloc_report() - and talloc_report_full() - for details. Also see talloc_enable_leak_report() - and talloc_enable_leak_report_full(). - - - The talloc_set_name() function allocates memory as a child of the - pointer. It is logically equivalent to: - - talloc_set_name_const(ptr, talloc_asprintf(ptr, fmt, ...)); - - Note that multiple calls to talloc_set_name() will allocate more - memory without releasing the name. All of the memory is released - when the ptr is freed using talloc_free(). - - - void talloc_set_name_const(const void *<emphasis role="italic">ptr</emphasis>, const char *<emphasis role="italic">name</emphasis>); - - The function talloc_set_name_const() is just like - talloc_set_name(), but it takes a string constant, and is much - faster. It is extensively used by the "auto naming" macros, such - as talloc_p(). - - - This function does not allocate any memory. It just copies the - supplied pointer into the internal representation of the talloc - ptr. This means you must not pass a name pointer to memory that will - disappear before ptr is freed - with talloc_free(). - - - void *talloc_named(const void *<emphasis role="italic">ctx</emphasis>, size_t <emphasis role="italic">size</emphasis>, const char *<emphasis role="italic">fmt</emphasis>, ...); - - The talloc_named() function creates a named talloc pointer. It - is equivalent to: - - ptr = talloc_size(ctx, size); -talloc_set_name(ptr, fmt, ....); - - void *talloc_named_const(const void *<emphasis role="italic">ctx</emphasis>, size_t <emphasis role="italic">size</emphasis>, const char *<emphasis role="italic">name</emphasis>); - - This is equivalent to: - - ptr = talloc_size(ctx, size); -talloc_set_name_const(ptr, name); - - const char *talloc_get_name(const void *<emphasis role="italic">ptr</emphasis>); - - This returns the current name for the given talloc pointer, - ptr. See talloc_set_name() - for details. - - - void *talloc_init(const char *<emphasis role="italic">fmt</emphasis>, ...); - - This function creates a zero length named talloc context as a top - level context. It is equivalent to: - - talloc_named(NULL, 0, fmt, ...); - - void *talloc_new(void *<emphasis role="italic">ctx</emphasis>); - - This is a utility macro that creates a new memory context hanging - off an existing context, automatically naming it "talloc_new: - __location__" where __location__ is the source line it is called - from. It is particularly useful for creating a new temporary - working context. - - - (<emphasis role="italic">type</emphasis> *)talloc_realloc(const void *<emphasis role="italic">ctx</emphasis>, void *<emphasis role="italic">ptr</emphasis>, <emphasis role="italic">type</emphasis>, <emphasis role="italic">count</emphasis>); - - The talloc_realloc() macro changes the size of a talloc pointer. - It has the following equivalences: - - talloc_realloc(ctx, NULL, type, 1) ==> talloc(ctx, type); -talloc_realloc(ctx, ptr, type, 0) ==> talloc_free(ptr); - - The ctx argument is only used - if ptr is not NULL, otherwise - it is ignored. - - - talloc_realloc() returns the new pointer, or NULL on failure. - The call will fail either due to a lack of memory, or because the - pointer has more than one parent (see talloc_reference()). - - - void *talloc_realloc_size(const void *ctx, void *ptr, size_t size); - - the talloc_realloc_size() function is useful when the type is not - known so the type-safe talloc_realloc() cannot be used. - - - TYPE *talloc_steal(const void *<emphasis role="italic">new_ctx</emphasis>, const TYPE *<emphasis role="italic">ptr</emphasis>); - - The talloc_steal() function changes the parent context of a - talloc pointer. It is typically used when the context that the - pointer is currently a child of is going to be freed and you wish - to keep the memory for a longer time. - - - The talloc_steal() function returns the pointer that you pass it. - It does not have any failure modes. - - - It is possible to produce loops in the parent/child - relationship if you are not careful with talloc_steal(). No - guarantees are provided as to your sanity or the safety of your - data if you do this. - - - Note that if you try and call talloc_steal() on a pointer that has - more than one parent then the result is ambiguous. Talloc will choose - to remove the parent that is currently indicated by talloc_parent() - and replace it with the chosen parent. You will also get a message - like this via the talloc logging functions: - - - - WARNING: talloc_steal with references at some_dir/source/foo.c:123 - reference at some_dir/source/other.c:325 - reference at some_dir/source/third.c:121 - - - - To unambiguously change the parent of a pointer please see - the - function talloc_reparent(). See - the talloc_set_log_fn() documentation for more information - on talloc logging. - - - TYPE *talloc_reparent(const void *<emphasis role="italic">old_parent</emphasis>, const void *<emphasis role="italic">new_parent</emphasis>, const TYPE *<emphasis role="italic">ptr</emphasis>); - - The talloc_reparent() function changes the parent context of a talloc - pointer. It is typically used when the context that the pointer is - currently a child of is going to be freed and you wish to keep the - memory for a longer time. - - - The talloc_reparent() function returns the pointer that you pass it. It - does not have any failure modes. - - - The difference between talloc_reparent() and talloc_steal() is that - talloc_reparent() can specify which parent you wish to change. This is - useful when a pointer has multiple parents via references. - - - TYPE *talloc_move(const void *<emphasis role="italic">new_ctx</emphasis>, TYPE **<emphasis role="italic">ptr</emphasis>); - - The talloc_move() function is a wrapper around - talloc_steal() which zeros the source pointer after the - move. This avoids a potential source of bugs where a - programmer leaves a pointer in two structures, and uses the - pointer from the old structure after it has been moved to a - new one. - - - size_t talloc_total_size(const void *<emphasis role="italic">ptr</emphasis>); - - The talloc_total_size() function returns the total size in bytes - used by this pointer and all child pointers. Mostly useful for - debugging. - - - Passing NULL is allowed, but it will only give a meaningful - result if talloc_enable_leak_report() or - talloc_enable_leak_report_full() has been called. - - - size_t talloc_total_blocks(const void *<emphasis role="italic">ptr</emphasis>); - - The talloc_total_blocks() function returns the total memory block - count used by this pointer and all child pointers. Mostly useful - for debugging. - - - Passing NULL is allowed, but it will only give a meaningful - result if talloc_enable_leak_report() or - talloc_enable_leak_report_full() has been called. - - - void talloc_report(const void *ptr, FILE *f); - - The talloc_report() function prints a summary report of all - memory used by ptr. One line - of report is printed for each immediate child of ptr, showing the - total memory and number of blocks used by that child. - - - You can pass NULL for the pointer, in which case a report is - printed for the top level memory context, but only if - talloc_enable_leak_report() or talloc_enable_leak_report_full() - has been called. - - - void talloc_report_full(const void *<emphasis role="italic">ptr</emphasis>, FILE *<emphasis role="italic">f</emphasis>); - - This provides a more detailed report than talloc_report(). It - will recursively print the entire tree of memory referenced by - the pointer. References in the tree are shown by giving the name - of the pointer that is referenced. - - - You can pass NULL for the pointer, in which case a report is - printed for the top level memory context, but only if - talloc_enable_leak_report() or talloc_enable_leak_report_full() - has been called. - - - - - void talloc_report_depth_cb - const void *ptr - int depth - int max_depth - void (*callback)(const void *ptr, int depth, int max_depth, int is_ref, void *priv) - void *priv - - - This provides a more flexible reports than talloc_report(). It - will recursively call the callback for the entire tree of memory - referenced by the pointer. References in the tree are passed with - is_ref = 1 and the pointer that is referenced. - - - You can pass NULL for the pointer, in which case a report is - printed for the top level memory context, but only if - talloc_enable_leak_report() or talloc_enable_leak_report_full() - has been called. - - - The recursion is stopped when depth >= max_depth. - max_depth = -1 means only stop at leaf nodes. - - - - - void talloc_report_depth_file - const void *ptr - int depth - int max_depth - FILE *f - - - This provides a more flexible reports than talloc_report(). It - will let you specify the depth and max_depth. - - - void talloc_enable_leak_report(void); - - This enables calling of talloc_report(NULL, stderr) when the - program exits. In Samba4 this is enabled by using the - --leak-report command line option. - - - For it to be useful, this function must be called before any - other talloc function as it establishes a "null context" that - acts as the top of the tree. If you don't call this function - first then passing NULL to talloc_report() or - talloc_report_full() won't give you the full tree printout. - - - Here is a typical talloc report: - - talloc report on 'null_context' (total 267 bytes in 15 blocks) -libcli/auth/spnego_parse.c:55 contains 31 bytes in 2 blocks -libcli/auth/spnego_parse.c:55 contains 31 bytes in 2 blocks -iconv(UTF8,CP850) contains 42 bytes in 2 blocks -libcli/auth/spnego_parse.c:55 contains 31 bytes in 2 blocks -iconv(CP850,UTF8) contains 42 bytes in 2 blocks -iconv(UTF8,UTF-16LE) contains 45 bytes in 2 blocks -iconv(UTF-16LE,UTF8) contains 45 bytes in 2 blocks - - - void talloc_enable_leak_report_full(void); - - This enables calling of talloc_report_full(NULL, stderr) when the - program exits. In Samba4 this is enabled by using the - --leak-report-full command line option. - - - For it to be useful, this function must be called before any - other talloc function as it establishes a "null context" that - acts as the top of the tree. If you don't call this function - first then passing NULL to talloc_report() or - talloc_report_full() won't give you the full tree printout. - - - Here is a typical full report: - - full talloc report on 'root' (total 18 bytes in 8 blocks) -p1 contains 18 bytes in 7 blocks (ref 0) - r1 contains 13 bytes in 2 blocks (ref 0) - reference to: p2 - p2 contains 1 bytes in 1 blocks (ref 1) - x3 contains 1 bytes in 1 blocks (ref 0) - x2 contains 1 bytes in 1 blocks (ref 0) - x1 contains 1 bytes in 1 blocks (ref 0) - - - (<emphasis role="italic">type</emphasis> *)talloc_zero(const void *<emphasis role="italic">ctx</emphasis>, <emphasis role="italic">type</emphasis>); - - The talloc_zero() macro is equivalent to: - - ptr = talloc(ctx, type); -if (ptr) memset(ptr, 0, sizeof(type)); - - void *talloc_zero_size(const void *<emphasis role="italic">ctx</emphasis>, size_t <emphasis role="italic">size</emphasis>) - - The talloc_zero_size() function is useful when you don't have a - known type. - - - void *talloc_memdup(const void *<emphasis role="italic">ctx</emphasis>, const void *<emphasis role="italic">p</emphasis>, size_t size); - - The talloc_memdup() function is equivalent to: - - ptr = talloc_size(ctx, size); -if (ptr) memcpy(ptr, p, size); - - char *talloc_strdup(const void *<emphasis role="italic">ctx</emphasis>, const char *<emphasis role="italic">p</emphasis>); - - The talloc_strdup() function is equivalent to: - - ptr = talloc_size(ctx, strlen(p)+1); -if (ptr) memcpy(ptr, p, strlen(p)+1); - - This function sets the name of the new pointer to the passed - string. This is equivalent to: - - talloc_set_name_const(ptr, ptr) - - char *talloc_strndup(const void *<emphasis role="italic">t</emphasis>, const char *<emphasis role="italic">p</emphasis>, size_t <emphasis role="italic">n</emphasis>); - - The talloc_strndup() function is the talloc equivalent of the C - library function strndup(3). - - - This function sets the name of the new pointer to the passed - string. This is equivalent to: - - talloc_set_name_const(ptr, ptr) - - char *talloc_vasprintf(const void *<emphasis role="italic">t</emphasis>, const char *<emphasis role="italic">fmt</emphasis>, va_list <emphasis role="italic">ap</emphasis>); - - The talloc_vasprintf() function is the talloc equivalent of the C - library function vasprintf(3). - - - This function sets the name of the new pointer to the new - string. This is equivalent to: - - talloc_set_name_const(ptr, ptr) - - char *talloc_asprintf(const void *<emphasis role="italic">t</emphasis>, const char *<emphasis role="italic">fmt</emphasis>, ...); - - The talloc_asprintf() function is the talloc equivalent of the C - library function asprintf(3). - - - This function sets the name of the new pointer to the passed - string. This is equivalent to: - - talloc_set_name_const(ptr, ptr) - - char *talloc_asprintf_append(char *s, const char *fmt, ...); - - The talloc_asprintf_append() function appends the given formatted - string to the given string. - - - This function sets the name of the new pointer to the new - string. This is equivalent to: - - talloc_set_name_const(ptr, ptr) - - (type *)talloc_array(const void *ctx, type, unsigned int count); - - The talloc_array() macro is equivalent to: - - (type *)talloc_size(ctx, sizeof(type) * count); - - except that it provides integer overflow protection for the - multiply, returning NULL if the multiply overflows. - - - void *talloc_array_size(const void *ctx, size_t size, unsigned int count); - - The talloc_array_size() function is useful when the type is not - known. It operates in the same way as talloc_array(), but takes a - size instead of a type. - - - (typeof(ptr)) talloc_array_ptrtype(const void *ctx, ptr, unsigned int count); - - The talloc_ptrtype() macro should be used when you have a pointer to an array - and want to allocate memory of an array to point at with this pointer. When compiling - with gcc >= 3 it is typesafe. Note this is a wrapper of talloc_array_size() - and talloc_get_name() will return the current location in the source file. - and not the type. - - - void *talloc_realloc_fn(const void *ctx, void *ptr, size_t size) - - This is a non-macro version of talloc_realloc(), which is useful - as libraries sometimes want a realloc function pointer. A - realloc(3) implementation encapsulates the functionality of - malloc(3), free(3) and realloc(3) in one call, which is why it is - useful to be able to pass around a single function pointer. - - - void *talloc_autofree_context(void); - - This is a handy utility function that returns a talloc context - which will be automatically freed on program exit. This can be - used to reduce the noise in memory leak reports. - - - void *talloc_check_name(const void *ptr, const char *name); - - This function checks if a pointer has the specified name. If it does then the pointer is - returned. It it doesn't then NULL is returned. - - - (type *)talloc_get_type(const void *ptr, type); - - This macro allows you to do type checking on talloc pointers. It - is particularly useful for void* private pointers. It is - equivalent to this: - - (type *)talloc_check_name(ptr, #type) - - talloc_set_type(const void *ptr, type); - - This macro allows you to force the name of a pointer to be a - particular type. This can be - used in conjunction with talloc_get_type() to do type checking on - void* pointers. - - - It is equivalent to this: - - talloc_set_name_const(ptr, #type) - - talloc_set_log_fn(void (*log_fn)(const char *message)); - - This function sets a logging function that talloc will use for - warnings and errors. By default talloc will not print any warnings or - errors. - - - talloc_set_log_stderr(void); - - This sets the talloc log function to write log messages to stderr - - - - PERFORMANCE - - All the additional features of talloc(3) over malloc(3) do come at a - price. We have a simple performance test in Samba4 that measures - talloc() versus malloc() performance, and it seems that talloc() is - about 10% slower than malloc() on my x86 Debian Linux box. For - Samba, the great reduction in code complexity that we get by using - talloc makes this worthwhile, especially as the total overhead of - talloc/malloc in Samba is already quite small. - - - SEE ALSO - - malloc(3), strndup(3), vasprintf(3), asprintf(3), - - - - - AUTHOR - The original Samba software and related utilities were - created by Andrew Tridgell. Samba is now developed by the - Samba Team as an Open Source project similar to the way the - Linux kernel is developed. - - - - COPYRIGHT/LICENSE - - Copyright (C) Andrew Tridgell 2004 - - - This program is free software; you can redistribute it and/or modify - it under the terms of the GNU Lesser General Public License as - published by the Free Software Foundation; either version 3 of the - License, or (at your option) any later version. - - - This program is distributed in the hope that it will be useful, but - WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - General Public License for more details. - - - You should have received a copy of the GNU General Public License - along with this program; if not, see http://www.gnu.org/licenses/. - - - -- cgit