X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=talloc%2Ftalloc_guide.txt;fp=talloc%2Ftalloc_guide.txt;h=c4634ae19a9192533d85d54c342d00668f4b6a8f;hp=0000000000000000000000000000000000000000;hb=29149d39d59c6b46535f237563732092397331f0;hpb=f7315b84a70f81579971d3450a2865fde3b71a7a

diff --git a/talloc/talloc_guide.txt b/talloc/talloc_guide.txt
new file mode 100644
index 00000000..c4634ae1
--- /dev/null
+++ b/talloc/talloc_guide.txt
@@ -0,0 +1,670 @@
+Using talloc in Samba4
+----------------------
+
+Andrew Tridgell
+September 2004
+
+The most current version of this document is available at
+   http://samba.org/ftp/unpacked/samba4/source/lib/talloc/talloc_guide.txt
+
+If you are used to the "old" talloc from Samba3 before 3.0.20 then please read
+this carefully, as talloc has changed a lot. With 3.0.20 (or 3.0.14?) the
+Samba4 talloc has been ported back to Samba3, so this guide applies to both.
+
+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 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.
+
+
+Performance
+-----------
+
+All the additional features of talloc() over malloc() 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 4% 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.
+
+
+talloc API
+----------
+
+The following is a complete guide to the talloc API. Read it all at
+least twice.
+
+Multi-threading
+---------------
+
+talloc itself does not deal with threads. It is thread-safe (assuming  
+the underlying "malloc" is), as long as each thread uses different  
+memory contexts.
+If two threads uses the same context then they need to synchronize in  
+order to be safe. In particular:
+- when using talloc_enable_leak_report(), giving directly NULL as a  
+parent context implicitly refers to a hidden "null context" global  
+variable, so this should not be used in a multi-threaded environment  
+without proper synchronization ;
+- the context returned by talloc_autofree_context() is also global so  
+shouldn't be used by several threads simultaneously without  
+synchronization.
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+(type *)talloc(const void *context, type);
+
+The talloc() macro is the core of the talloc library. It takes a
+memory context 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 context 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 context then the new child disappears as
+well. Alternatively you can free just the child.
+
+The context argument to talloc() can be NULL, in which case a new top
+level context is created. 
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void *talloc_size(const void *context, 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 the pointer 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.
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+int talloc_free_children(void *ptr);
+
+The talloc_free_children() walks along the list of all children of a
+talloc context and talloc_free()s only the children, not the context
+itself.
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void *talloc_reference(const void *context, const void *ptr);
+
+The talloc_reference() function makes "context" 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 *context, const void *ptr);
+
+The talloc_unlink() function removes a specific parent from ptr. The
+context 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 the pointer 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 *ptr);
+
+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 *ptr);
+
+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() 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 *ptr, const char *name);
+
+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 the ptr is freed with talloc_free().
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void *talloc_named(const void *context, size_t size, const char *fmt, ...);
+
+The talloc_named() function creates a named talloc pointer. It is
+equivalent to:
+
+   ptr = talloc_size(context, size);
+   talloc_set_name(ptr, fmt, ....);
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void *talloc_named_const(const void *context, size_t size, const char *name);
+
+This is equivalent to:
+
+   ptr = talloc_size(context, size);
+   talloc_set_name_const(ptr, name);
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+const char *talloc_get_name(const void *ptr);
+
+This returns the current name for the given talloc pointer. See
+talloc_set_name() for details.
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void *talloc_init(const char *fmt, ...);
+
+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 *ctx);
+
+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.
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+(type *)talloc_realloc(const void *context, void *ptr, type, count);
+
+The talloc_realloc() macro changes the size of a talloc
+pointer. The "count" argument is the number of elements of type "type"
+that you want the resulting pointer to hold. 
+
+talloc_realloc() has the following equivalences:
+
+  talloc_realloc(context, NULL, type, 1) ==> talloc(context, type);
+  talloc_realloc(context, NULL, type, N) ==> talloc_array(context, type, N);
+  talloc_realloc(context, ptr, type, 0)  ==> talloc_free(ptr);
+
+The "context" argument is only used if "ptr" is 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 *context, void *ptr, size_t size);
+
+the talloc_realloc_size() function is useful when the type is not 
+known so the typesafe talloc_realloc() cannot be used.
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void *talloc_steal(const void *new_ctx, const void *ptr);
+
+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.
+
+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.
+
+talloc_steal (new_ctx, NULL) will return NULL with no sideeffects.
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+size_t talloc_total_size(const void *ptr);
+
+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 *ptr);
+
+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_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_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 *ptr, FILE *f);
+
+This provides a more detailed report than talloc_report(). It will
+recursively print the ensire 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_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)
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void talloc_enable_null_tracking(void);
+
+This enables tracking of the NULL memory context without enabling leak
+reporting on exit. Useful for when you want to do your own leak
+reporting call via talloc_report_null_full();
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void talloc_disable_null_tracking(void);
+
+This disables tracking of the NULL memory context.
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+(type *)talloc_zero(const void *ctx, type);
+
+The talloc_zero() macro is equivalent to:
+
+  ptr = talloc(ctx, type);
+  if (ptr) memset(ptr, 0, sizeof(type));
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void *talloc_zero_size(const void *ctx, size_t size)
+
+The talloc_zero_size() function is useful when you don't have a known type
+
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void *talloc_memdup(const void *ctx, const void *p, 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 *ctx, const char *p);
+
+The talloc_strdup() function is equivalent to:
+
+  ptr = talloc_size(ctx, strlen(p)+1);
+  if (ptr) memcpy(ptr, p, strlen(p)+1);
+
+This functions 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 *t, const char *p, size_t n);
+
+The talloc_strndup() function is the talloc equivalent of the C
+library function strndup()
+
+This functions sets the name of the new pointer to the passed
+string. This is equivalent to:
+   talloc_set_name_const(ptr, ptr)
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+char *talloc_append_string(const void *t, char *orig, const char *append);
+
+The talloc_append_string() 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)
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+char *talloc_vasprintf(const void *t, const char *fmt, va_list ap);
+
+The talloc_vasprintf() function is the talloc equivalent of the C
+library function vasprintf()
+
+This functions 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 *t, const char *fmt, ...);
+
+The talloc_asprintf() function is the talloc equivalent of the C
+library function asprintf()
+
+This functions sets the name of the new pointer to the new
+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 functions 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, uint_t 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, uint_t 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, uint_t 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 ralloc function pointer. A realloc()
+implementation encapsulates the functionality of malloc(), free() and
+realloc() 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_get_size(const void *ctx);
+
+This function lets you know the amount of memory alloced so far by
+this context. It does NOT account for subcontext memory.
+This can be used to calculate the size of an array.
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+void *talloc_find_parent_byname(const void *ctx, const char *name);
+
+Find a parent memory context of the current context that has the given
+name. This can be very useful in complex programs where it may be
+difficult to pass all information down to the level you need, but you
+know the structure you want is a parent of another context.
+
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+(type *)talloc_find_parent_bytype(ctx, type);
+
+Like talloc_find_parent_byname() but takes a type, making it typesafe.
+