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28 .\" @(#)directory.3 8.1 (Berkeley) 6/4/93
45 .Nd directory operations
51 .Fn opendir "const char *filename"
53 .Fn fdopendir "int fd"
55 .Fn readdir "DIR *dirp"
57 .Fn readdir_r "DIR *dirp" "struct dirent *entry" "struct dirent **result"
59 .Fn telldir "DIR *dirp"
61 .Fn seekdir "DIR *dirp" "long loc"
63 .Fn rewinddir "DIR *dirp"
65 .Fn closedir "DIR *dirp"
67 .Fn fdclosedir "DIR *dirp"
74 opens the directory named by
80 returns a pointer to be used to identify the
82 in subsequent operations.
87 cannot be accessed, or if it cannot
89 enough memory to hold the whole thing.
93 function is equivalent to the
95 function except that the directory is specified by a file descriptor
97 rather than by a name.
98 The file offset associated with the file descriptor at the time of the call
99 determines which entries are returned.
101 Upon successful return from
103 the file descriptor is under the control of the system,
104 and if any attempt is made to close the file descriptor,
105 or to modify the state of the associated description other than by means
112 the behavior is undefined.
115 the file descriptor is closed.
118 flag is set on the file descriptor by a successful call to
124 returns a pointer to the next directory entry.
127 upon reaching the end of the directory or on error.
128 In the event of an error,
130 may be set to any of the values documented for the
137 provides the same functionality as
139 but the caller must provide a directory
141 buffer to store the results in.
142 If the read succeeds,
146 upon reaching the end of the directory
153 returns 0 on success or an error number to indicate failure.
158 returns a token representing the current location associated with the named
159 .Em directory stream .
162 are good only for the lifetime of the
166 from which they are derived.
167 If the directory is closed and then
168 reopened, prior values returned by
170 will no longer be valid.
173 are also invalidated by a call to
179 sets the position of the next
182 .Em directory stream .
183 The new position reverts to the one associated with the
187 operation was performed.
192 resets the position of the named
194 to the beginning of the directory.
201 and frees the structure associated with the
204 returning 0 on success.
205 On failure, \-1 is returned and the global variable
207 is set to indicate the error.
211 function is equivalent to the
213 function except that this function returns directory file descriptor instead of
219 returns the integer file descriptor associated with the named
220 .Em directory stream ,
224 Sample code which searches a directory for entry ``name'' is:
225 .Bd -literal -offset indent
230 while ((dp = readdir(dirp)) != NULL) {
231 if (dp->d_namlen == len && strcmp(dp->d_name, name) == 0) {
232 (void)closedir(dirp);
236 (void)closedir(dirp);
255 functions appeared in
269 is likely to be wrong if there are parallel unlinks happening
270 and the directory is larger than one page.
271 There is code to ensure that a
273 to the location given by a
275 immediately before the last
277 will always set the correct location to return the same value as that last
280 This is enough for some applications which want to "push back the last entry read" E.g. Samba.
281 Seeks back to any other location,
282 other than the beginning of the directory,
283 may result in unexpected behaviour if deletes are present.
284 It is hoped that this situation will be resolved with changes to