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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 <talloc/talloc.h></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->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->name</literal> are destroyed, and if
+ you do <literal
+ role="code">talloc_free(X->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>
projects / ccan / blobdiff