[apple/libc.git] / gen / ftw.3

.\"	$OpenBSD: ftw.3,v 1.4 2003/10/30 18:52:58 jmc Exp $
.\"
.\" Copyright (c) 2003 Todd C. Miller <Todd.Miller@courtesan.com>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.\" Sponsored in part by the Defense Advanced Research Projects
.\" Agency (DARPA) and Air Force Research Laboratory, Air Force
.\" Materiel Command, USAF, under agreement number F39502-99-1-0512.
.\"
.Dd May 20, 2003
.Dt FTW 3
.Os
.Sh NAME
.Nm ftw, nftw
.Nd traverse (walk) a file tree
.Sh SYNOPSIS
.Fd #include <ftw.h>
.Ft int
.Fo ftw
.Fa "const char *path"
.Fa "int (*fn)(const\ char\ *, const\ struct\ stat\ *ptr, int\ flag)"
.Fa "int depth"
.Fc
.Ft int
.Fo nftw
.Fa "const char *path"
.Fa "int (*fn)(const\ char\ *, const\ struct\ stat\ *ptr, \
     int\ flag, struct\ FTW\ *)"
.Fa "int depth"
.Fa "int flags"
.Fc
.Sh DESCRIPTION
.Bf -symbolic
These functions are provided for compatibility with legacy code.
New code should use the
.Xr fts 3
functions.
.Ef
.Pp
The
.Fn ftw
and
.Fn nftw
functions traverse (walk) the directory hierarchy rooted in
.Fa path .
For each object in the hierarchy, these functions call the function
pointed to by
.Fa fn .
The
.Fn ftw
function passes this function a pointer to a NUL-terminated string containing
the name of the object, a pointer to a stat structure corresponding to the
object, and an integer flag.
The
.Fn nftw
function passes the aforementioned arguments plus a pointer to a
.Dv FTW
structure as defined by
.Aq Pa ftw.h
(shown below):
.Bd -literal
struct FTW {
    int base;	/* offset of basename into pathname */
    int level;	/* directory depth relative to starting point */
};
.Ed
.Pp
Possible values for the flag passed to
.Fa fn
are:
.Bl -tag -width FTW_DNR
.It Dv FTW_F
A regular file.
.It Dv FTW_D
A directory being visited in pre-order.
.It Dv FTW_DNR
A directory which cannot be read.
The directory will not be descended into.
.It Dv FTW_DP
A directory being visited in post-order
.No ( Ns Fn nftw
only).
.It Dv FTW_NS
A file for which no
.Xr stat 2
information was available.
The contents of the stat structure are undefined.
.It Dv FTW_SL
A symbolic link.
.It Dv FTW_SLN
A symbolic link with a non-existent target
.No ( Ns Fn nftw
only).
.El
.Pp
The
.Fn ftw
function traverses the tree in pre-order.
That is, it processes the directory before the directory's contents.
.Pp
The
.Fa depth
argument specifies the maximum number of file descriptors
to keep open while traversing the tree.
It has no effect in this implementation.
.Pp
The
.Fn nftw
function has an additional
.Fa flags
argument with the following possible values:
.Bl -tag -width FTW_MOUNT
.It Dv FTW_PHYS
Physical walk, don't follow symbolic links.
.It Dv FTW_MOUNT
The walk will not cross a mount point.
.It FTW_DEPTH
Process directories in post-order.
Contents of a directory are visited before the directory itself.
By default,
.Fn nftw
traverses the tree in pre-order.
.It FTW_CHDIR
Change to a directory before reading it.
By default,
.Fn nftw
will change its starting directory.
The current working directory will be restored to its original value before
.Fn nftw
returns.
.El
.Sh RETURN VALUES
If the tree was traversed successfully, the
.Fn ftw
and
.Fn nftw
functions return 0.
If the function pointed to by
.Fa fn
returns a non-zero value,
.Fn ftw
and
.Fn nftw
will stop processing the tree and return the value from
.Fa fn .
Both functions return \-1 if an error is detected.
.Sh ERRORS
The
.Fn ftw
and
.Fn nftw
functions may fail and set
.Va errno
for any of the errors specified for the library functions
.Xr close 2 ,
.Xr open 2 ,
.Xr stat 2 ,
.Xr malloc 3 ,
.Xr opendir 3
and
.Xr readdir 3 .
If the
.Dv FTW_CHDIR
flag is set, the
.Fn nftw
function may fail and set
.Va errno
for any of the errors specified for
.Xr chdir 2 .
In addition, either function may fail and set
.Va errno
as follows:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa depth
argument is less than 1 or greater than
.Dv OPEN_MAX .
.El
.Sh LEGACY ERRORS
The
.Fn ftw
and
.Fn nftw
functions are far more tolerant of symlink cycles and are lax in reporting
errors while accessing the initial path.  When
.Fn nftw
is passed
.Dv FTW_MOUNT ,
it will pass the mount point to the callback function.
.Sh SEE ALSO
.Xr chdir 2 ,
.Xr close 2 ,
.Xr open 2 ,
.Xr stat 2 ,
.Xr fts 3 ,
.Xr malloc 3 ,
.Xr opendir 3 ,
.Xr readdir 3 ,
.Xr compat 5
.Sh STANDARDS
The
.Fn ftw
and
.Fn nftw
functions conform to
.St -p1003.1-2001 and
.St -susv3 .
.Sh HISTORY
Prior to MacOS X 10.4 
.Nm ftw
did not follow symlinks.
.Sh BUGS
The
.Fa depth
argument is currently ignored.
Commit	Line	Data
59e0d9fe A	1	.\" $OpenBSD: ftw.3,v 1.4 2003/10/30 18:52:58 jmc Exp $
	2	.\"
	3	.\" Copyright (c) 2003 Todd C. Miller <Todd.Miller@courtesan.com>
	4	.\"
	5	.\" Permission to use, copy, modify, and distribute this software for any
	6	.\" purpose with or without fee is hereby granted, provided that the above
	7	.\" copyright notice and this permission notice appear in all copies.
	8	.\"
	9	.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	10	.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	11	.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	12	.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	13	.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	14	.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	15	.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	16	.\"
	17	.\" Sponsored in part by the Defense Advanced Research Projects
	18	.\" Agency (DARPA) and Air Force Research Laboratory, Air Force
	19	.\" Materiel Command, USAF, under agreement number F39502-99-1-0512.
	20	.\"
	21	.Dd May 20, 2003
	22	.Dt FTW 3
	23	.Os
	24	.Sh NAME
	25	.Nm ftw, nftw
	26	.Nd traverse (walk) a file tree
	27	.Sh SYNOPSIS
	28	.Fd #include <ftw.h>
	29	.Ft int
	30	.Fo ftw
	31	.Fa "const char *path"
224c7076 A	32	.Fa "int (fn)(const\ char\ , const\ struct\ stat\ *ptr, int\ flag)"
224c7076 A	33	.Fa "int depth"
59e0d9fe A	34	.Fc
	35	.Ft int
	36	.Fo nftw
	37	.Fa "const char *path"
224c7076 A	38	.Fa "int (fn)(const\ char\ , const\ struct\ stat\ *ptr, \
	39	int\ flag, struct\ FTW\ *)"
	40	.Fa "int depth"
59e0d9fe A	41	.Fa "int flags"
	42	.Fc
	43	.Sh DESCRIPTION
	44	.Bf -symbolic
	45	These functions are provided for compatibility with legacy code.
	46	New code should use the
	47	.Xr fts 3
	48	functions.
	49	.Ef
	50	.Pp
	51	The
	52	.Fn ftw
	53	and
	54	.Fn nftw
	55	functions traverse (walk) the directory hierarchy rooted in
	56	.Fa path .
	57	For each object in the hierarchy, these functions call the function
	58	pointed to by
	59	.Fa fn .
	60	The
	61	.Fn ftw
	62	function passes this function a pointer to a NUL-terminated string containing
	63	the name of the object, a pointer to a stat structure corresponding to the
	64	object, and an integer flag.
	65	The
	66	.Fn nftw
	67	function passes the aforementioned arguments plus a pointer to a
	68	.Dv FTW
	69	structure as defined by
	70	.Aq Pa ftw.h
	71	(shown below):
	72	.Bd -literal
	73	struct FTW {
	74	int base; /* offset of basename into pathname */
	75	int level; /* directory depth relative to starting point */
	76	};
	77	.Ed
	78	.Pp
	79	Possible values for the flag passed to
	80	.Fa fn
	81	are:
	82	.Bl -tag -width FTW_DNR
	83	.It Dv FTW_F
	84	A regular file.
	85	.It Dv FTW_D
	86	A directory being visited in pre-order.
	87	.It Dv FTW_DNR
	88	A directory which cannot be read.
	89	The directory will not be descended into.
	90	.It Dv FTW_DP
	91	A directory being visited in post-order
	92	.No ( Ns Fn nftw
	93	only).
	94	.It Dv FTW_NS
	95	A file for which no
	96	.Xr stat 2
	97	information was available.
	98	The contents of the stat structure are undefined.
	99	.It Dv FTW_SL
	100	A symbolic link.
	101	.It Dv FTW_SLN
	102	A symbolic link with a non-existent target
	103	.No ( Ns Fn nftw
	104	only).
105	.El
106	.Pp
107	The
108	.Fn ftw
109	function traverses the tree in pre-order.
110	That is, it processes the directory before the directory's contents.
111	.Pp
112	The
224c7076	113	.Fa depth
59e0d9fe A	114	argument specifies the maximum number of file descriptors
	115	to keep open while traversing the tree.
	116	It has no effect in this implementation.
	117	.Pp
	118	The
	119	.Fn nftw
	120	function has an additional
	121	.Fa flags
	122	argument with the following possible values:
	123	.Bl -tag -width FTW_MOUNT
	124	.It Dv FTW_PHYS
	125	Physical walk, don't follow symbolic links.
	126	.It Dv FTW_MOUNT
	127	The walk will not cross a mount point.
	128	.It FTW_DEPTH
	129	Process directories in post-order.
	130	Contents of a directory are visited before the directory itself.
	131	By default,
	132	.Fn nftw
	133	traverses the tree in pre-order.
	134	.It FTW_CHDIR
	135	Change to a directory before reading it.
	136	By default,
	137	.Fn nftw
	138	will change its starting directory.
	139	The current working directory will be restored to its original value before
	140	.Fn nftw
	141	returns.
	142	.El
	143	.Sh RETURN VALUES
	144	If the tree was traversed successfully, the
	145	.Fn ftw
	146	and
	147	.Fn nftw
	148	functions return 0.
	149	If the function pointed to by
	150	.Fa fn
	151	returns a non-zero value,
	152	.Fn ftw
	153	and
	154	.Fn nftw
	155	will stop processing the tree and return the value from
	156	.Fa fn .
	157	Both functions return \-1 if an error is detected.
	158	.Sh ERRORS
	159	The
	160	.Fn ftw
	161	and
	162	.Fn nftw
	163	functions may fail and set
	164	.Va errno
	165	for any of the errors specified for the library functions
	166	.Xr close 2 ,
	167	.Xr open 2 ,
	168	.Xr stat 2 ,
	169	.Xr malloc 3 ,
	170	.Xr opendir 3
	171	and
	172	.Xr readdir 3 .
	173	If the
3d9156a7	174	.Dv FTW_CHDIR
59e0d9fe A	175	flag is set, the
	176	.Fn nftw
	177	function may fail and set
	178	.Va errno
	179	for any of the errors specified for
	180	.Xr chdir 2 .
	181	In addition, either function may fail and set
	182	.Va errno
	183	as follows:
	184	.Bl -tag -width Er
	185	.It Bq Er EINVAL
	186	The
224c7076	187	.Fa depth
59e0d9fe A	188	argument is less than 1 or greater than
	189	.Dv OPEN_MAX .
	190	.El
3d9156a7 A	191	.Sh LEGACY ERRORS
	192	The
	193	.Fn ftw
	194	and
	195	.Fn nftw
	196	functions are far more tolerant of symlink cycles and are lax in reporting
	197	errors while accessing the initial path. When
	198	.Fn nftw
	199	is passed
224c7076 A	200	.Dv FTW_MOUNT ,
224c7076 A	201	it will pass the mount point to the callback function.
59e0d9fe A	202	.Sh SEE ALSO
	203	.Xr chdir 2 ,
	204	.Xr close 2 ,
	205	.Xr open 2 ,
	206	.Xr stat 2 ,
	207	.Xr fts 3 ,
	208	.Xr malloc 3 ,
	209	.Xr opendir 3 ,
224c7076 A	210	.Xr readdir 3 ,
224c7076 A	211	.Xr compat 5
59e0d9fe A	212	.Sh STANDARDS
	213	The
	214	.Fn ftw
	215	and
	216	.Fn nftw
	217	functions conform to
3d9156a7 A	218	.St -p1003.1-2001 and
	219	.St -susv3 .
	220	.Sh HISTORY
	221	Prior to MacOS X 10.4
	222	.Nm ftw
	223	did not follow symlinks.
59e0d9fe A	224	.Sh BUGS
59e0d9fe A	225	The
224c7076	226	.Fa depth
59e0d9fe	227	argument is currently ignored.