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/man/talloc.3.xml | 813 ++++++++++++++++++++++++++++++++++++++++++++ lib/talloc/talloc.3.xml | 813 -------------------------------------------- lib/talloc/wscript | 2 +- 3 files changed, 814 insertions(+), 814 deletions(-) create mode 100644 lib/talloc/man/talloc.3.xml delete mode 100644 lib/talloc/talloc.3.xml (limited to 'lib/talloc') diff --git a/lib/talloc/man/talloc.3.xml b/lib/talloc/man/talloc.3.xml new file mode 100644 index 0000000000..553eaec7ea --- /dev/null +++ b/lib/talloc/man/talloc.3.xml @@ -0,0 +1,813 @@ + + + + + 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/. + + + 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/. - - - diff --git a/lib/talloc/wscript b/lib/talloc/wscript index 8d3246b26b..bd7708e47d 100644 --- a/lib/talloc/wscript +++ b/lib/talloc/wscript @@ -108,7 +108,7 @@ def build(bld): pc_files='talloc.pc', public_headers_install=not private_library, private_library=private_library, - manpages='talloc.3') + manpages='man/talloc.3') if not bld.CONFIG_SET('USING_SYSTEM_PYTALLOC_UTIL') and not bld.env.disable_python: bld.SAMBA_LIBRARY('pytalloc-util', -- cgit