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28 .\" @(#)directory.3 8.1 (Berkeley) 6/4/93
44 .Nd directory operations
50 .Fn opendir "const char *filename"
52 .Fn fdopendir "int fd"
54 .Fn readdir "DIR *dirp"
56 .Fn readdir_r "DIR *dirp" "struct dirent *entry" "struct dirent **result"
58 .Fn telldir "DIR *dirp"
60 .Fn seekdir "DIR *dirp" "long loc"
62 .Fn rewinddir "DIR *dirp"
64 .Fn closedir "DIR *dirp"
66 .Fn fdclosedir "DIR *dirp"
73 interface is deprecated
74 because it cannot be used correctly unless
82 opens the directory named by
88 returns a pointer to be used to identify the
90 in subsequent operations.
95 cannot be accessed, or if it cannot
97 enough memory to hold the whole thing.
101 function is equivalent to the
103 function except that the directory is specified by a file descriptor
105 rather than by a name.
106 The file offset associated with the file descriptor at the time of the call
107 determines which entries are returned.
109 Upon successful return from
111 the file descriptor is under the control of the system,
112 and if any attempt is made to close the file descriptor,
113 or to modify the state of the associated description other than by means
120 the behavior is undefined.
123 the file descriptor is closed.
126 flag is set on the file descriptor by a successful call to
132 returns a pointer to the next directory entry.
133 The directory entry remains valid until the next call to
138 .Em directory stream .
141 upon reaching the end of the directory or on error.
142 In the event of an error,
144 may be set to any of the values documented for the
151 provides the same functionality as
153 but the caller must provide a directory
155 buffer to store the results in.
156 The buffer must be large enough for a
163 If the read succeeds,
167 upon reaching the end of the directory
174 returns 0 on success or an error number to indicate failure.
179 returns a token representing the current location associated with the named
180 .Em directory stream .
183 are good only for the lifetime of the
187 from which they are derived.
188 If the directory is closed and then
189 reopened, prior values returned by
191 will no longer be valid.
194 are also invalidated by a call to
200 sets the position of the next
203 .Em directory stream .
204 The new position reverts to the one associated with the
208 operation was performed.
213 resets the position of the named
215 to the beginning of the directory.
222 and frees the structure associated with the
225 returning 0 on success.
226 On failure, \-1 is returned and the global variable
228 is set to indicate the error.
232 function is equivalent to the
234 function except that this function returns directory file descriptor instead of
240 returns the integer file descriptor associated with the named
241 .Em directory stream ,
245 Sample code which searches a directory for entry ``name'' is:
246 .Bd -literal -offset indent
251 while ((dp = readdir(dirp)) != NULL) {
252 if (dp->d_namlen == len && strcmp(dp->d_name, name) == 0) {
253 (void)closedir(dirp);
257 (void)closedir(dirp);
263 function will fail if:
266 Search permission is denied for the component of the path prefix of
268 or read permission is denied for
271 A loop exists in symbolic links encountered during resolution of the
274 .It Bq Er ENAMETOOLONG
280 a pathname component is longer than
285 does not name an existing directory or
296 function will fail if:
301 argument is not a valid file descriptor open for reading.
305 is not associated with a directory.
312 functions may also fail and set
314 for any of the errors specified for the routine
319 function may also fail and set
321 for any of the errors specified for the routine
326 function may also fail and set
328 for any of the errors specified for the routine
348 functions are expected to conform to
359 are non-standard, and should not be used in portable programs.
370 functions appeared in
384 is likely to be wrong if there are parallel unlinks happening
385 and the directory is larger than one page.
386 There is code to ensure that a
388 to the location given by a
390 immediately before the last
392 will always set the correct location to return the same value as that last
395 This is enough for some applications which want to
396 "push back the last entry read", e.g., Samba.
397 Seeks back to any other location,
398 other than the beginning of the directory,
399 may result in unexpected behaviour if deletes are present.
400 It is hoped that this situation will be resolved with changes to