[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 *, int)"
.Fa "int maxfds"
.Fc
.Ft int
.Fo nftw
.Fa "const char *path"
.Fa "int (*fn)(const\ char\ *, const\ struct\ stat\ *, int, struct\ FTW\ *)"
.Fa "int maxfds"
.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 maxfds
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 maxfds
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 callback the mount point.
.Sh SEE ALSO
.Xr chdir 2 ,
.Xr close 2 ,
.Xr open 2 ,
.Xr stat 2 ,
.Xr compat 5 ,
.Xr fts 3 ,
.Xr malloc 3 ,
.Xr opendir 3 ,
.Xr readdir 3
.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 maxfds
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"
	32	.Fa "int (fn)(const char , const struct stat *, int)"
	33	.Fa "int maxfds"
	34	.Fc
	35	.Ft int
	36	.Fo nftw
	37	.Fa "const char *path"
	38	.Fa "int (fn)(const\ char\ , const\ struct\ stat\ , int, struct\ FTW\ )"
	39	.Fa "int maxfds"
	40	.Fa "int flags"
	41	.Fc
	42	.Sh DESCRIPTION
	43	.Bf -symbolic
	44	These functions are provided for compatibility with legacy code.
	45	New code should use the
	46	.Xr fts 3
	47	functions.
	48	.Ef
	49	.Pp
	50	The
	51	.Fn ftw
	52	and
	53	.Fn nftw
	54	functions traverse (walk) the directory hierarchy rooted in
	55	.Fa path .
	56	For each object in the hierarchy, these functions call the function
	57	pointed to by
	58	.Fa fn .
	59	The
	60	.Fn ftw
	61	function passes this function a pointer to a NUL-terminated string containing
	62	the name of the object, a pointer to a stat structure corresponding to the
	63	object, and an integer flag.
	64	The
65	.Fn nftw
66	function passes the aforementioned arguments plus a pointer to a
67	.Dv FTW
68	structure as defined by
69	.Aq Pa ftw.h
70	(shown below):
71	.Bd -literal
72	struct FTW {
73	int base; /* offset of basename into pathname */
74	int level; /* directory depth relative to starting point */
75	};
76	.Ed
77	.Pp
78	Possible values for the flag passed to
79	.Fa fn
80	are:
81	.Bl -tag -width FTW_DNR
82	.It Dv FTW_F
83	A regular file.
84	.It Dv FTW_D
85	A directory being visited in pre-order.
86	.It Dv FTW_DNR
87	A directory which cannot be read.
88	The directory will not be descended into.
89	.It Dv FTW_DP
90	A directory being visited in post-order
91	.No ( Ns Fn nftw
92	only).
93	.It Dv FTW_NS
94	A file for which no
95	.Xr stat 2
96	information was available.
97	The contents of the stat structure are undefined.
98	.It Dv FTW_SL
99	A symbolic link.
100	.It Dv FTW_SLN
101	A symbolic link with a non-existent target
102	.No ( Ns Fn nftw
103	only).
104	.El
105	.Pp
106	The
107	.Fn ftw
108	function traverses the tree in pre-order.
109	That is, it processes the directory before the directory's contents.
110	.Pp
111	The
112	.Fa maxfds
113	argument specifies the maximum number of file descriptors
114	to keep open while traversing the tree.
115	It has no effect in this implementation.
116	.Pp
117	The
118	.Fn nftw
119	function has an additional
120	.Fa flags
121	argument with the following possible values:
122	.Bl -tag -width FTW_MOUNT
123	.It Dv FTW_PHYS
124	Physical walk, don't follow symbolic links.
125	.It Dv FTW_MOUNT
126	The walk will not cross a mount point.
127	.It FTW_DEPTH
128	Process directories in post-order.
129	Contents of a directory are visited before the directory itself.
130	By default,
131	.Fn nftw
132	traverses the tree in pre-order.
133	.It FTW_CHDIR
134	Change to a directory before reading it.
135	By default,
136	.Fn nftw
137	will change its starting directory.
138	The current working directory will be restored to its original value before
139	.Fn nftw
140	returns.
141	.El
142	.Sh RETURN VALUES
143	If the tree was traversed successfully, the
144	.Fn ftw
145	and
146	.Fn nftw
147	functions return 0.
148	If the function pointed to by
149	.Fa fn
150	returns a non-zero value,
151	.Fn ftw
152	and
153	.Fn nftw
154	will stop processing the tree and return the value from
155	.Fa fn .
156	Both functions return \-1 if an error is detected.
157	.Sh ERRORS
158	The
159	.Fn ftw
160	and
161	.Fn nftw
162	functions may fail and set
163	.Va errno
164	for any of the errors specified for the library functions
165	.Xr close 2 ,
166	.Xr open 2 ,
167	.Xr stat 2 ,
168	.Xr malloc 3 ,
169	.Xr opendir 3
170	and
171	.Xr readdir 3 .
172	If the
3d9156a7	173	.Dv FTW_CHDIR
59e0d9fe A	174	flag is set, the
	175	.Fn nftw
	176	function may fail and set
	177	.Va errno
	178	for any of the errors specified for
	179	.Xr chdir 2 .
	180	In addition, either function may fail and set
	181	.Va errno
	182	as follows:
	183	.Bl -tag -width Er
	184	.It Bq Er EINVAL
	185	The
	186	.Fa maxfds
	187	argument is less than 1 or greater than
	188	.Dv OPEN_MAX .
	189	.El
3d9156a7 A	190	.Sh LEGACY ERRORS
	191	The
	192	.Fn ftw
	193	and
	194	.Fn nftw
	195	functions are far more tolerant of symlink cycles and are lax in reporting
	196	errors while accessing the initial path. When
	197	.Fn nftw
	198	is passed
	199	.Dv FTW_MOUNT
	200	it will pass the callback the mount point.
59e0d9fe A	201	.Sh SEE ALSO
	202	.Xr chdir 2 ,
	203	.Xr close 2 ,
	204	.Xr open 2 ,
	205	.Xr stat 2 ,
3d9156a7	206	.Xr compat 5 ,
59e0d9fe A	207	.Xr fts 3 ,
	208	.Xr malloc 3 ,
	209	.Xr opendir 3 ,
	210	.Xr readdir 3
	211	.Sh STANDARDS
	212	The
	213	.Fn ftw
	214	and
	215	.Fn nftw
	216	functions conform to
3d9156a7 A	217	.St -p1003.1-2001 and
	218	.St -susv3 .
	219	.Sh HISTORY
	220	Prior to MacOS X 10.4
	221	.Nm ftw
	222	did not follow symlinks.
59e0d9fe A	223	.Sh BUGS
	224	The
	225	.Fa maxfds
	226	argument is currently ignored.