1.\" Copyright (c) 1983, 1991, 1993
2.\" The Regents of the University of California. All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\" notice, this list of conditions and the following disclaimer in the
11.\" documentation and/or other materials provided with the distribution.
12.\" 3. All advertising materials mentioning features or use of this software
13.\" must display the following acknowledgement:
14.\" This product includes software developed by the University of
15.\" California, Berkeley and its contributors.
16.\" 4. Neither the name of the University nor the names of its contributors
17.\" may be used to endorse or promote products derived from this software
18.\" without specific prior written permission.
19.\"
20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30.\" SUCH DAMAGE.
31.\"
32.\" @(#)directory.3 8.1 (Berkeley) 6/4/93
33.\" $FreeBSD: head/lib/libc/gen/directory.3 53872 1999-11-29 06:12:22Z wes $
34.\"
35.Dd June 4, 1993
36.Dt DIRECTORY 3
37.Os BSD 4.2
38.Sh NAME
39.Nm opendir ,
40.Nm readdir ,
41.Nm readdir_r ,
42.Nm telldir ,
43.Nm seekdir ,
44.Nm rewinddir ,
45.Nm closedir ,
46.Nm dirfd
47.Nd directory operations
48.Sh SYNOPSIS
49.Fd #include <sys/types.h>
50.Fd #include <dirent.h>
51.Ft DIR *
52.Fn opendir "const char *filename"
53.Ft struct dirent *
54.Fn readdir "DIR *dirp"
55.Ft int
56.Fn readdir_r "DIR *dirp" "struct dirent *entry" "struct dirent **result"
57.Ft long
58.Fn telldir "const DIR *dirp"
59.Ft void
60.Fn seekdir "DIR *dirp" "long loc"
61.Ft void
62.Fn rewinddir "DIR *dirp"
63.Ft int
64.Fn closedir "DIR *dirp"
65.Ft int
66.Fn dirfd "DIR *dirp"
67.Sh DESCRIPTION
68The
69.Fn opendir
70function
71opens the directory named by
72.Fa filename ,
73associates a
74.Em directory stream
75with it
76and
77returns a pointer to be used to identify the
78.Em directory stream
79in subsequent operations. The pointer
80.Dv NULL
81is returned if
82.Fa filename
83cannot be accessed, or if it cannot
84.Xr malloc 3
85enough memory to hold the whole thing.
86.Pp
87The
88.Fn readdir
89function
90returns a pointer to the next directory entry. It returns
91.Dv NULL
92upon reaching the end of the directory or detecting an invalid
93.Fn seekdir
94operation.
95.Pp
96.Fn readdir_r
97provides the same functionality as
98.Fn readdir ,
99but the caller must provide a directory
100.Fa entry
101buffer to store the results in. If the read succeeds,
102.Fa result
103is pointed at the
104.Fa entry ;
105upon reaching the end of the directory
106.Fa result
107is set to
108.Dv NULL .
109.Fn readdir_r
110returns 0 on success or an error number to indicate failure.
111.Pp
112The
113.Fn telldir
114function
115returns the current location associated with the named
116.Em directory stream .
117Values returned by
118.Fn telldir
119are good only for the lifetime of the
120.Dv DIR
121pointer,
122.Fa dirp ,
123from which they are derived. If the directory is closed and then
124reopened, prior values returned by
125.Fn telldir
126will no longer be valid.
127.Pp
128The
129.Fn seekdir
130function
131sets the position of the next
132.Fn readdir
133operation on the
134.Em directory stream .
135The new position reverts to the one associated with the
136.Em directory stream
137when the
138.Fn telldir
139operation was performed.
140.Pp
141The
142.Fn rewinddir
143function
144resets the position of the named
145.Em directory stream
146to the beginning of the directory.
147.Pp
148The
149.Fn closedir
150function
151closes the named
152.Em directory stream
153and frees the structure associated with the
154.Fa dirp
155pointer,
156returning 0 on success.
157On failure, \-1 is returned and the global variable
158.Va errno
159is set to indicate the error.
160.Pp
161The
162.Fn dirfd
163function
164returns the integer file descriptor associated with the named
165.Em directory stream ,
166see
167.Xr open 2 .
168.Pp
169Sample code which searches a directory for entry ``name'' is:
170.Bd -literal -offset indent
171len = strlen(name);
172dirp = opendir(".");
173while ((dp = readdir(dirp)) != NULL)
174 if (dp->d_namlen == len && !strcmp(dp->d_name, name)) {
175 (void)closedir(dirp);
176 return FOUND;
177 }
178(void)closedir(dirp);
179return NOT_FOUND;
180.Ed
181.Sh SEE ALSO
182.Xr close 2 ,
183.Xr lseek 2 ,
184.Xr open 2 ,
185.Xr read 2 ,
186.Xr dir 5
187.Sh HISTORY
188The
189.Fn opendir ,
190.Fn readdir ,
191.Fn telldir ,
192.Fn seekdir ,
193.Fn rewinddir ,
194.Fn closedir ,
195and
196.Fn dirfd
197functions appeared in
198.Bx 4.2 .
2.\" The Regents of the University of California. All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\" notice, this list of conditions and the following disclaimer in the
11.\" documentation and/or other materials provided with the distribution.
12.\" 3. All advertising materials mentioning features or use of this software
13.\" must display the following acknowledgement:
14.\" This product includes software developed by the University of
15.\" California, Berkeley and its contributors.
16.\" 4. Neither the name of the University nor the names of its contributors
17.\" may be used to endorse or promote products derived from this software
18.\" without specific prior written permission.
19.\"
20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30.\" SUCH DAMAGE.
31.\"
32.\" @(#)directory.3 8.1 (Berkeley) 6/4/93
33.\" $FreeBSD: head/lib/libc/gen/directory.3 53872 1999-11-29 06:12:22Z wes $
34.\"
35.Dd June 4, 1993
36.Dt DIRECTORY 3
37.Os BSD 4.2
38.Sh NAME
39.Nm opendir ,
40.Nm readdir ,
41.Nm readdir_r ,
42.Nm telldir ,
43.Nm seekdir ,
44.Nm rewinddir ,
45.Nm closedir ,
46.Nm dirfd
47.Nd directory operations
48.Sh SYNOPSIS
49.Fd #include <sys/types.h>
50.Fd #include <dirent.h>
51.Ft DIR *
52.Fn opendir "const char *filename"
53.Ft struct dirent *
54.Fn readdir "DIR *dirp"
55.Ft int
56.Fn readdir_r "DIR *dirp" "struct dirent *entry" "struct dirent **result"
57.Ft long
58.Fn telldir "const DIR *dirp"
59.Ft void
60.Fn seekdir "DIR *dirp" "long loc"
61.Ft void
62.Fn rewinddir "DIR *dirp"
63.Ft int
64.Fn closedir "DIR *dirp"
65.Ft int
66.Fn dirfd "DIR *dirp"
67.Sh DESCRIPTION
68The
69.Fn opendir
70function
71opens the directory named by
72.Fa filename ,
73associates a
74.Em directory stream
75with it
76and
77returns a pointer to be used to identify the
78.Em directory stream
79in subsequent operations. The pointer
80.Dv NULL
81is returned if
82.Fa filename
83cannot be accessed, or if it cannot
84.Xr malloc 3
85enough memory to hold the whole thing.
86.Pp
87The
88.Fn readdir
89function
90returns a pointer to the next directory entry. It returns
91.Dv NULL
92upon reaching the end of the directory or detecting an invalid
93.Fn seekdir
94operation.
95.Pp
96.Fn readdir_r
97provides the same functionality as
98.Fn readdir ,
99but the caller must provide a directory
100.Fa entry
101buffer to store the results in. If the read succeeds,
102.Fa result
103is pointed at the
104.Fa entry ;
105upon reaching the end of the directory
106.Fa result
107is set to
108.Dv NULL .
109.Fn readdir_r
110returns 0 on success or an error number to indicate failure.
111.Pp
112The
113.Fn telldir
114function
115returns the current location associated with the named
116.Em directory stream .
117Values returned by
118.Fn telldir
119are good only for the lifetime of the
120.Dv DIR
121pointer,
122.Fa dirp ,
123from which they are derived. If the directory is closed and then
124reopened, prior values returned by
125.Fn telldir
126will no longer be valid.
127.Pp
128The
129.Fn seekdir
130function
131sets the position of the next
132.Fn readdir
133operation on the
134.Em directory stream .
135The new position reverts to the one associated with the
136.Em directory stream
137when the
138.Fn telldir
139operation was performed.
140.Pp
141The
142.Fn rewinddir
143function
144resets the position of the named
145.Em directory stream
146to the beginning of the directory.
147.Pp
148The
149.Fn closedir
150function
151closes the named
152.Em directory stream
153and frees the structure associated with the
154.Fa dirp
155pointer,
156returning 0 on success.
157On failure, \-1 is returned and the global variable
158.Va errno
159is set to indicate the error.
160.Pp
161The
162.Fn dirfd
163function
164returns the integer file descriptor associated with the named
165.Em directory stream ,
166see
167.Xr open 2 .
168.Pp
169Sample code which searches a directory for entry ``name'' is:
170.Bd -literal -offset indent
171len = strlen(name);
172dirp = opendir(".");
173while ((dp = readdir(dirp)) != NULL)
174 if (dp->d_namlen == len && !strcmp(dp->d_name, name)) {
175 (void)closedir(dirp);
176 return FOUND;
177 }
178(void)closedir(dirp);
179return NOT_FOUND;
180.Ed
181.Sh SEE ALSO
182.Xr close 2 ,
183.Xr lseek 2 ,
184.Xr open 2 ,
185.Xr read 2 ,
186.Xr dir 5
187.Sh HISTORY
188The
189.Fn opendir ,
190.Fn readdir ,
191.Fn telldir ,
192.Fn seekdir ,
193.Fn rewinddir ,
194.Fn closedir ,
195and
196.Fn dirfd
197functions appeared in
198.Bx 4.2 .