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-<?xml version="1.0"?>
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
-<refentry>
- <refmeta>
- <refentrytitle>talloc</refentrytitle>
- <manvolnum>3</manvolnum>
- </refmeta>
- <refnamediv>
- <refname>talloc</refname>
-<refpurpose>hierarchical reference counted memory pool system with destructors</refpurpose>
- </refnamediv>
- <refsynopsisdiv>
-<synopsis>#include &lt;talloc/talloc.h&gt;</synopsis>
- </refsynopsisdiv>
- <refsect1><title>DESCRIPTION</title>
- <para>
- If you are used to talloc from Samba3 then please read this
- carefully, as talloc has changed a lot.
- </para>
- <para>
- 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.
- </para>
- <para>
- 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:
- </para>
- <programlisting>
- struct foo *X = talloc(mem_ctx, struct foo);
- X->name = talloc_strdup(X, "foo");
- </programlisting>
- <para>
- and the pointer <literal role="code">X-&gt;name</literal>
- would be a "child" of the talloc context <literal
- role="code">X</literal> which is itself a child of
- <literal role="code">mem_ctx</literal>. So if you do
- <literal role="code">talloc_free(mem_ctx)</literal> then
- it is all destroyed, whereas if you do <literal
- role="code">talloc_free(X)</literal> then just <literal
- role="code">X</literal> and <literal
- role="code">X-&gt;name</literal> are destroyed, and if
- you do <literal
- role="code">talloc_free(X-&gt;name)</literal> then just
- the name element of <literal role="code">X</literal> is
- destroyed.
- </para>
- <para>
- 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().
- </para>
- <para>
- If you find this confusing, then I suggest you run the <literal
- role="code">testsuite</literal> program to watch talloc
- in action. You may also like to add your own tests to <literal
- role="code">testsuite.c</literal> to clarify how some
- particular situation is handled.
- </para>
- </refsect1>
- <refsect1><title>TALLOC API</title>
- <para>
- The following is a complete guide to the talloc API. Read it all at
- least twice.
- </para>
- <refsect2><title>(type *)talloc(const void *ctx, type);</title>
- <para>
- The talloc() macro is the core of the talloc library. It takes a
- memory <emphasis role="italic">ctx</emphasis> and a <emphasis
- role="italic">type</emphasis>, and returns a pointer to a new
- area of memory of the given <emphasis
- role="italic">type</emphasis>.
- </para>
- <para>
- The returned pointer is itself a talloc context, so you can use
- it as the <emphasis role="italic">ctx</emphasis> argument to more
- calls to talloc() if you wish.
- </para>
- <para>
- The returned pointer is a "child" of the supplied context. This
- means that if you talloc_free() the <emphasis
- role="italic">ctx</emphasis> then the new child disappears as
- well. Alternatively you can free just the child.
- </para>
- <para>
- The <emphasis role="italic">ctx</emphasis> argument to talloc()
- can be NULL, in which case a new top level context is created.
- </para>
- </refsect2>
- <refsect2><title>void *talloc_size(const void *ctx, size_t size);</title>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2><title>(typeof(ptr)) talloc_ptrtype(const void *ctx, ptr);</title>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2><title>int talloc_free(void *ptr);</title>
- <para>
- 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().
- </para>
- <para>
- 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 <emphasis
- role="italic">ptr</emphasis> had a destructor attached to it and
- the destructor returned -1. See <link
- linkend="talloc_set_destructor"><quote>talloc_set_destructor()</quote></link>
- for details on destructors.
- </para>
- <para>
- 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 <link
- linkend="talloc_reference"><quote>talloc_reference()</quote></link>
- for details on establishing additional parents.
- </para>
- <para>
- For more control on which parent is removed, see <link
- linkend="talloc_unlink"><quote>talloc_unlink()</quote></link>.
- </para>
- <para>
- talloc_free() operates recursively on its children.
- </para>
- </refsect2>
- <refsect2 id="talloc_reference"><title>void *talloc_reference(const void *ctx, const void *ptr);</title>
- <para>
- The talloc_reference() function makes <emphasis
- role="italic">ctx</emphasis> an additional parent of <emphasis
- role="italic">ptr</emphasis>.
- </para>
- <para>
- The return value of talloc_reference() is always the original
- pointer <emphasis role="italic">ptr</emphasis>, 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).
- </para>
- <para>
- If <emphasis role="italic">ptr</emphasis> is NULL, then the
- function is a no-op, and simply returns NULL.
- </para>
- <para>
- After creating a reference you can free it in one of the
- following ways:
- </para>
- <para>
- <itemizedlist>
- <listitem>
- <para>
- 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.
- </para>
- </listitem>
- <listitem>
- <para>
- 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.
- </para>
- </listitem>
- </itemizedlist>
- </para>
- <para>
- For more control on which parent to remove, see <link
- linkend="talloc_unlink"><quote>talloc_unlink()</quote></link>.
- </para>
- </refsect2>
- <refsect2 id="talloc_unlink"><title>int talloc_unlink(const void *ctx, const void *ptr);</title>
- <para>
- The talloc_unlink() function removes a specific parent from
- <emphasis role="italic">ptr</emphasis>. The <emphasis
- role="italic">ctx</emphasis> passed must either be a context used
- in talloc_reference() with this pointer, or must be a direct
- parent of ptr.
- </para>
- <para>
- Note that if the parent has already been removed using
- talloc_free() then this function will fail and will return -1.
- Likewise, if <emphasis role="italic">ptr</emphasis> is NULL, then
- the function will make no modifications and return -1.
- </para>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2 id="talloc_set_destructor"><title>void talloc_set_destructor(const void *ptr, int (*destructor)(void *));</title>
- <para>
- The function talloc_set_destructor() sets the <emphasis
- role="italic">destructor</emphasis> for the pointer <emphasis
- role="italic">ptr</emphasis>. A <emphasis
- role="italic">destructor</emphasis> is a function that is called
- when the memory used by a pointer is about to be released. The
- destructor receives <emphasis role="italic">ptr</emphasis> as an
- argument, and should return 0 for success and -1 for failure.
- </para>
- <para>
- The <emphasis role="italic">destructor</emphasis> 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.
- </para>
- <para>
- 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.
- </para>
- <para>
- To remove a destructor call talloc_set_destructor() with NULL for
- the destructor.
- </para>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2><title>int talloc_increase_ref_count(const void *<emphasis role="italic">ptr</emphasis>);</title>
- <para>
- The talloc_increase_ref_count(<emphasis
- role="italic">ptr</emphasis>) function is exactly equivalent to:
- </para>
- <programlisting>talloc_reference(NULL, ptr);</programlisting>
- <para>
- You can use either syntax, depending on which you think is
- clearer in your code.
- </para>
- <para>
- It returns 0 on success and -1 on failure.
- </para>
- </refsect2>
- <refsect2><title>size_t talloc_reference_count(const void *<emphasis role="italic">ptr</emphasis>);</title>
- <para>
- Return the number of references to the pointer.
- </para>
- </refsect2>
- <refsect2 id="talloc_set_name"><title>void talloc_set_name(const void *ptr, const char *fmt, ...);</title>
- <para>
- 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.
- </para>
- <para>
- The main use for names on pointer is for "talloc reports". See
- <link
- linkend="talloc_report"><quote>talloc_report_depth_cb()</quote></link>,
- <link
- linkend="talloc_report"><quote>talloc_report_depth_file()</quote></link>,
- <link
- linkend="talloc_report"><quote>talloc_report()</quote></link>
- <link
- linkend="talloc_report"><quote>talloc_report()</quote></link>
- and <link
- linkend="talloc_report_full"><quote>talloc_report_full()</quote></link>
- for details. Also see <link
- linkend="talloc_enable_leak_report"><quote>talloc_enable_leak_report()</quote></link>
- and <link
- linkend="talloc_enable_leak_report_full"><quote>talloc_enable_leak_report_full()</quote></link>.
- </para>
- <para>
- The talloc_set_name() function allocates memory as a child of the
- pointer. It is logically equivalent to:
- </para>
- <programlisting>talloc_set_name_const(ptr, talloc_asprintf(ptr, fmt, ...));</programlisting>
- <para>
- 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().
- </para>
- </refsect2>
- <refsect2><title>void talloc_set_name_const(const void *<emphasis role="italic">ptr</emphasis>, const char *<emphasis role="italic">name</emphasis>);</title>
- <para>
- 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().
- </para>
- <para>
- 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 <emphasis
- role="italic">name</emphasis> pointer to memory that will
- disappear before <emphasis role="italic">ptr</emphasis> is freed
- with talloc_free().
- </para>
- </refsect2>
- <refsect2><title>void *talloc_named(const void *<emphasis role="italic">ctx</emphasis>, size_t <emphasis role="italic">size</emphasis>, const char *<emphasis role="italic">fmt</emphasis>, ...);</title>
- <para>
- The talloc_named() function creates a named talloc pointer. It
- is equivalent to:
- </para>
- <programlisting>ptr = talloc_size(ctx, size);
-talloc_set_name(ptr, fmt, ....);</programlisting>
- </refsect2>
- <refsect2><title>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>);</title>
- <para>
- This is equivalent to:
- </para>
- <programlisting>ptr = talloc_size(ctx, size);
-talloc_set_name_const(ptr, name);</programlisting>
- </refsect2>
- <refsect2><title>const char *talloc_get_name(const void *<emphasis role="italic">ptr</emphasis>);</title>
- <para>
- This returns the current name for the given talloc pointer,
- <emphasis role="italic">ptr</emphasis>. See <link
- linkend="talloc_set_name"><quote>talloc_set_name()</quote></link>
- for details.
- </para>
- </refsect2>
- <refsect2><title>void *talloc_init(const char *<emphasis role="italic">fmt</emphasis>, ...);</title>
- <para>
- This function creates a zero length named talloc context as a top
- level context. It is equivalent to:
- </para>
- <programlisting>talloc_named(NULL, 0, fmt, ...);</programlisting>
- </refsect2>
- <refsect2><title>void *talloc_new(void *<emphasis role="italic">ctx</emphasis>);</title>
- <para>
- This is a utility macro that creates a new memory context hanging
- off an exiting 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.
- </para>
- </refsect2>
- <refsect2><title>(<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>);</title>
- <para>
- The talloc_realloc() macro changes the size of a talloc pointer.
- It has the following equivalences:
- </para>
- <programlisting>talloc_realloc(ctx, NULL, type, 1) ==> talloc(ctx, type);
-talloc_realloc(ctx, ptr, type, 0) ==> talloc_free(ptr);</programlisting>
- <para>
- The <emphasis role="italic">ctx</emphasis> argument is only used
- if <emphasis role="italic">ptr</emphasis> is not NULL, otherwise
- it is ignored.
- </para>
- <para>
- 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 <link
- linkend="talloc_reference"><quote>talloc_reference()</quote></link>).
- </para>
- </refsect2>
- <refsect2><title>void *talloc_realloc_size(const void *ctx, void *ptr, size_t size);</title>
- <para>
- the talloc_realloc_size() function is useful when the type is not
- known so the type-safe talloc_realloc() cannot be used.
- </para>
- </refsect2>
- <refsect2><title>TYPE *talloc_steal(const void *<emphasis role="italic">new_ctx</emphasis>, const TYPE *<emphasis role="italic">ptr</emphasis>);</title>
- <para>
- 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.
- </para>
- <para>
- The talloc_steal() function returns the pointer that you pass it.
- It does not have any failure modes.
- </para>
- <para>
- NOTE: 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.
- </para>
- </refsect2>
- <refsect2><title>TYPE *talloc_move(const void *<emphasis role="italic">new_ctx</emphasis>, TYPE **<emphasis role="italic">ptr</emphasis>);</title>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2><title>size_t talloc_total_size(const void *<emphasis role="italic">ptr</emphasis>);</title>
- <para>
- The talloc_total_size() function returns the total size in bytes
- used by this pointer and all child pointers. Mostly useful for
- debugging.
- </para>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2><title>size_t talloc_total_blocks(const void *<emphasis role="italic">ptr</emphasis>);</title>
- <para>
- The talloc_total_blocks() function returns the total memory block
- count used by this pointer and all child pointers. Mostly useful
- for debugging.
- </para>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2 id="talloc_report"><title>void talloc_report(const void *ptr, FILE *f);</title>
- <para>
- The talloc_report() function prints a summary report of all
- memory used by <emphasis role="italic">ptr</emphasis>. One line
- of report is printed for each immediate child of ptr, showing the
- total memory and number of blocks used by that child.
- </para>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2 id="talloc_report_full"><title>void talloc_report_full(const void *<emphasis role="italic">ptr</emphasis>, FILE *<emphasis role="italic">f</emphasis>);</title>
- <para>
- 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.
- </para>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2 id="talloc_report_depth_cb">
- <funcsynopsis><funcprototype>
- <funcdef>void <function>talloc_report_depth_cb</function></funcdef>
- <paramdef><parameter>const void *ptr</parameter></paramdef>
- <paramdef><parameter>int depth</parameter></paramdef>
- <paramdef><parameter>int max_depth</parameter></paramdef>
- <paramdef><parameter>void (*callback)(const void *ptr, int depth, int max_depth, int is_ref, void *priv)</parameter></paramdef>
- <paramdef><parameter>void *priv</parameter></paramdef>
- </funcprototype></funcsynopsis>
- <para>
- 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
- <emphasis role="italic">is_ref = 1</emphasis> and the pointer that is referenced.
- </para>
- <para>
- 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.
- </para>
- <para>
- The recursion is stopped when depth >= max_depth.
- max_depth = -1 means only stop at leaf nodes.
- </para>
- </refsect2>
- <refsect2 id="talloc_report_depth_file">
- <funcsynopsis><funcprototype>
- <funcdef>void <function>talloc_report_depth_file</function></funcdef>
- <paramdef><parameter>const void *ptr</parameter></paramdef>
- <paramdef><parameter>int depth</parameter></paramdef>
- <paramdef><parameter>int max_depth</parameter></paramdef>
- <paramdef><parameter>FILE *f</parameter></paramdef>
- </funcprototype></funcsynopsis>
- <para>
- This provides a more flexible reports than talloc_report(). It
- will let you specify the depth and max_depth.
- </para>
- </refsect2>
- <refsect2 id="talloc_enable_leak_report"><title>void talloc_enable_leak_report(void);</title>
- <para>
- 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.
- </para>
- <para>
- 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.
- </para>
- <para>
- Here is a typical talloc report:
- </para>
- <screen format="linespecific">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
- </screen>
- </refsect2>
- <refsect2 id="talloc_enable_leak_report_full"><title>void talloc_enable_leak_report_full(void);</title>
- <para>
- 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.
- </para>
- <para>
- 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.
- </para>
- <para>
- Here is a typical full report:
- </para>
- <screen format="linespecific">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)
- </screen>
- </refsect2>
- <refsect2><title>(<emphasis role="italic">type</emphasis> *)talloc_zero(const void *<emphasis role="italic">ctx</emphasis>, <emphasis role="italic">type</emphasis>);</title>
- <para>
- The talloc_zero() macro is equivalent to:
- </para>
- <programlisting>ptr = talloc(ctx, type);
-if (ptr) memset(ptr, 0, sizeof(type));</programlisting>
- </refsect2>
- <refsect2><title>void *talloc_zero_size(const void *<emphasis role="italic">ctx</emphasis>, size_t <emphasis role="italic">size</emphasis>)</title>
- <para>
- The talloc_zero_size() function is useful when you don't have a
- known type.
- </para>
- </refsect2>
- <refsect2><title>void *talloc_memdup(const void *<emphasis role="italic">ctx</emphasis>, const void *<emphasis role="italic">p</emphasis>, size_t size);</title>
- <para>
- The talloc_memdup() function is equivalent to:
- </para>
- <programlisting>ptr = talloc_size(ctx, size);
-if (ptr) memcpy(ptr, p, size);</programlisting>
- </refsect2>
- <refsect2><title>char *talloc_strdup(const void *<emphasis role="italic">ctx</emphasis>, const char *<emphasis role="italic">p</emphasis>);</title>
- <para>
- The talloc_strdup() function is equivalent to:
- </para>
- <programlisting>ptr = talloc_size(ctx, strlen(p)+1);
-if (ptr) memcpy(ptr, p, strlen(p)+1);</programlisting>
- <para>
- This function sets the name of the new pointer to the passed
- string. This is equivalent to:
- </para>
- <programlisting>talloc_set_name_const(ptr, ptr)</programlisting>
- </refsect2>
- <refsect2><title>char *talloc_strndup(const void *<emphasis role="italic">t</emphasis>, const char *<emphasis role="italic">p</emphasis>, size_t <emphasis role="italic">n</emphasis>);</title>
- <para>
- The talloc_strndup() function is the talloc equivalent of the C
- library function strndup(3).
- </para>
- <para>
- This function sets the name of the new pointer to the passed
- string. This is equivalent to:
- </para>
- <programlisting>talloc_set_name_const(ptr, ptr)</programlisting>
- </refsect2>
- <refsect2><title>char *talloc_append_string(const void *<emphasis role="italic">t</emphasis>, char *<emphasis role="italic">orig</emphasis>, const char *<emphasis role="italic">append</emphasis>);</title>
- <para>
- The talloc_append_string() function appends the given formatted
- string to the given string.
- </para>
- <para>
- This function sets the name of the new pointer to the new
- string. This is equivalent to:
- </para>
- <programlisting>talloc_set_name_const(ptr, ptr)</programlisting>
- </refsect2>
- <refsect2><title>char *talloc_vasprintf(const void *<emphasis role="italic">t</emphasis>, const char *<emphasis role="italic">fmt</emphasis>, va_list <emphasis role="italic">ap</emphasis>);</title>
- <para>
- The talloc_vasprintf() function is the talloc equivalent of the C
- library function vasprintf(3).
- </para>
- <para>
- This function sets the name of the new pointer to the new
- string. This is equivalent to:
- </para>
- <programlisting>talloc_set_name_const(ptr, ptr)</programlisting>
- </refsect2>
- <refsect2><title>char *talloc_asprintf(const void *<emphasis role="italic">t</emphasis>, const char *<emphasis role="italic">fmt</emphasis>, ...);</title>
- <para>
- The talloc_asprintf() function is the talloc equivalent of the C
- library function asprintf(3).
- </para>
- <para>
- This function sets the name of the new pointer to the passed
- string. This is equivalent to:
- </para>
- <programlisting>talloc_set_name_const(ptr, ptr)</programlisting>
- </refsect2>
- <refsect2><title>char *talloc_asprintf_append(char *s, const char *fmt, ...);</title>
- <para>
- The talloc_asprintf_append() function appends the given formatted
- string to the given string.
- </para>
- <para>
- This function sets the name of the new pointer to the new
- string. This is equivalent to:
- </para>
- <programlisting>talloc_set_name_const(ptr, ptr)</programlisting>
- </refsect2>
- <refsect2><title>(type *)talloc_array(const void *ctx, type, uint_t count);</title>
- <para>
- The talloc_array() macro is equivalent to:
- </para>
- <programlisting>(type *)talloc_size(ctx, sizeof(type) * count);</programlisting>
- <para>
- except that it provides integer overflow protection for the
- multiply, returning NULL if the multiply overflows.
- </para>
- </refsect2>
- <refsect2><title>void *talloc_array_size(const void *ctx, size_t size, uint_t count);</title>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2><title>(typeof(ptr)) talloc_array_ptrtype(const void *ctx, ptr, uint_t count);</title>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2><title>void *talloc_realloc_fn(const void *ctx, void *ptr, size_t size)</title>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2><title>void *talloc_autofree_context(void);</title>
- <para>
- 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.
- </para>
- </refsect2>
- <refsect2><title>void *talloc_check_name(const void *ptr, const char *name);</title>
- <para>
- This function checks if a pointer has the specified <emphasis
- role="italic">name</emphasis>. If it does then the pointer is
- returned. It it doesn't then NULL is returned.
- </para>
- </refsect2>
- <refsect2><title>(type *)talloc_get_type(const void *ptr, type);</title>
- <para>
- This macro allows you to do type checking on talloc pointers. It
- is particularly useful for void* private pointers. It is
- equivalent to this:
- </para>
- <programlisting>(type *)talloc_check_name(ptr, #type)</programlisting>
- </refsect2>
- <refsect2><title>talloc_set_type(const void *ptr, type);</title>
- <para>
- This macro allows you to force the name of a pointer to be a
- particular <emphasis>type</emphasis>. This can be
- used in conjunction with talloc_get_type() to do type checking on
- void* pointers.
- </para>
- <para>
- It is equivalent to this:
- </para>
- <programlisting>talloc_set_name_const(ptr, #type)</programlisting>
- </refsect2>
- </refsect1>
- <refsect1><title>PERFORMANCE</title>
- <para>
- 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.
- </para>
- </refsect1>
- <refsect1><title>SEE ALSO</title>
- <para>
- malloc(3), strndup(3), vasprintf(3), asprintf(3),
- <ulink url="http://talloc.samba.org/"/>
- </para>
- </refsect1>
- <refsect1><title>COPYRIGHT/LICENSE</title>
- <para>
- Copyright (C) Andrew Tridgell 2004
- </para>
- <para>
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or (at
- your option) any later version.
- </para>
- <para>
- 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.
- </para>
- <para>
- You should have received a copy of the GNU General Public License
- along with this program; if not, see http://www.gnu.org/licenses/.
- </para>
- </refsect1>
-</refentry>