DIRECTORY(3)           FreeBSD Library Functions Manual           DIRECTORY(3)

NAME

     opendir, fdopendir, readdir, readdir_r, telldir, seekdir, rewinddir,
     closedir, fdclosedir, dirfd - directory operations

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <dirent.h>

     DIR *
     opendir(const char *filename);

     DIR *
     fdopendir(int fd);

     struct dirent *
     readdir(DIR *dirp);

     int
     readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result);

     long
     telldir(DIR *dirp);

     void
     seekdir(DIR *dirp, long loc);

     void
     rewinddir(DIR *dirp);

     int
     closedir(DIR *dirp);

     int
     fdclosedir(DIR *dirp);

     int
     dirfd(DIR *dirp);

DESCRIPTION

     The readdir_r() interface is deprecated because it cannot be used
     correctly unless {NAME_MAX} is a fixed value.

     The opendir() function opens the directory named by filename, associates
     a directory stream with it and returns a pointer to be used to identify
     the directory stream in subsequent operations.

     The fdopendir() function is equivalent to the opendir() function except
     that the directory is specified by a file descriptor fd rather than by a
     name.  The file offset associated with the file descriptor at the time of
     the call determines which entries are returned.

     Upon successful return from fdopendir(), the file descriptor is under the
     control of the system, and if any attempt is made to close the file
     descriptor, or to modify the state of the associated description other
     than by means of closedir(), readdir(), readdir_r(), or rewinddir(), the
     behavior is undefined.  Upon calling closedir() the file descriptor is
     closed.  The FD_CLOEXEC flag is set on the file descriptor by a
     successful call to fdopendir().

     The readdir() function returns a pointer to the next directory entry.
     The directory entry remains valid until the next call to readdir() or
     closedir() on the same directory stream.

     The readdir_r() function provides the same functionality as readdir(),
     but the caller must provide a directory entry buffer to store the results
     in.  The buffer must be large enough for a struct dirent with a d_name
     array with {NAME_MAX} + 1 elements.  If the read succeeds, result is
     pointed at the entry; upon reaching the end of the directory result is
     set to NULL.

     The telldir() function returns a token representing the current location
     associated with the named directory stream.  Values returned by telldir()
     are good only for the lifetime of the directory stream from which they
     are derived.  If the directory is closed and then reopened, prior values
     returned by telldir() will no longer be valid.  Values returned by
     telldir() are also invalidated by a call to rewinddir().

     The seekdir() function sets the position of the next readdir() operation
     on the directory stream.  The new position reverts to the one associated
     with the directory stream when the telldir() operation was performed.

     The rewinddir() function resets the position of the named directory
     stream to the beginning of the directory.

     The closedir() function closes the named directory stream and frees the
     structure associated with dirp.

     The fdclosedir() function is equivalent to the closedir() function except
     that it returns the file descriptor associated with dirp instead of
     closing it.

     The dirfd() function returns the file descriptor associated with dirp.

EXAMPLES

     Sample code which searches a directory for entry ``name'' is:

           dirp = opendir(".");
           if (dirp == NULL)
                   return (ERROR);
           len = strlen(name);
           while ((dp = readdir(dirp)) != NULL) {
                   if (dp->d_namlen == len && strcmp(dp->d_name, name) == 0) {
                           (void)closedir(dirp);
                           return (FOUND);
                   }
           }
           (void)closedir(dirp);
           return (NOT_FOUND);

RETURN VALUES

     The opendir() and fdopendir() functions return a pointer to the new
     directory stream on success and NULL on failure.

     The readdir() function returns a pointer to a directory entry on success
     and NULL on failure.  The readdir_r() function returns 0 on success and
     an error number on failure.

     The telldir() function returns a nonnegative value on success and -1 on
     failure.

     The closedir() function returns 0 on success and -1 on failure.  The
     fdclosedir() and dirfd() functions return an open file descriptor on
     success and -1 on failure.

ERRORS

     The opendir() function will fail if:

     [EACCES]           Search permission is denied for the component of the
                        path prefix of filename or read permission is denied
                        for filename.

     [ELOOP]            A loop exists in symbolic links encountered during
                        resolution of the filename argument.

     [ENAMETOOLONG]     The length of the filename argument exceeds {PATH_MAX}
                        or a pathname component is longer than {NAME_MAX}.

     [ENOENT]           A component of filename does not name an existing
                        directory or filename is an empty string.

     [ENOTDIR]          A component of filename is not a directory.

     The fdopendir() function will fail if:

     [EBADF]            The fd argument is not a valid file descriptor open
                        for reading.

     [ENOTDIR]          The descriptor fd is not associated with a directory.

     The readdir() and readdir_r() functions may also fail and set errno for
     any of the errors specified for the routine getdents(2).

     The telldir() function may also fail and set errno for any of the errors
     specified for the routine realloc(3).

     The closedir() function may also fail and set errno for any of the errors
     specified for the routine close(2).

     The dirfd() function will fail if:

     [EINVAL]           The dirp argument does not refer to a valid directory
                        stream.

SEE ALSO

     close(2), lseek(2), open(2), read(2), dir(5)

STANDARDS

     The closedir(), dirfd(), fdopendir(), opendir(), readdir(), readdir_r(),
     rewinddir(), seekdir() and telldir() functions are expected to conform to
     IEEE Std 1003.1-2008 ("POSIX.1").  The fdclosedir() function and the
     d_off, d_reclen and d_type fields of struct dirent are non-standard, and
     should not be used in portable programs.

HISTORY

     The opendir(), readdir(), telldir(), seekdir(), rewinddir(), closedir(),
     and dirfd() functions appeared in 4.2BSD.  The fdopendir() function
     appeared in FreeBSD 8.0.  fdclosedir() function appeared in FreeBSD 10.0.

BUGS

     The behaviour of telldir() and seekdir() is likely to be wrong if there
     are parallel unlinks happening and the directory is larger than one page.
     There is code to ensure that a seekdir() to the location given by a
     telldir() immediately before the last readdir() will always set the
     correct location to return the same value as that last readdir()
     performed.  This is enough for some applications which want to "push back
     the last entry read", e.g., Samba.  Seeks back to any other location,
     other than the beginning of the directory, may result in unexpected
     behaviour if deletes are present.  It is hoped that this situation will
     be resolved with changes to getdirentries() and the VFS.

FreeBSD 15.1-STABLE-HBSD       January 31, 2026                   DIRECTORY(3)