DIRECTORY(3)             BSD Library Functions Manual             DIRECTORY(3)

NAME
     opendir, fdopendir, readdir, readdir_r, telldir, seekdir, rewinddir,
     closedir, 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
     dirfd(DIR *dirp);

DESCRIPTION
     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 pointer NULL is
     returned if filename cannot be accessed, or if it cannot malloc(3) enough
     memory to hold the whole thing, and sets the global variable errno to
     indicate the error.

     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.

     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 success-
     ful call to fdopendir().

     The readdir() function returns a pointer to the next directory entry.  It
     returns NULL upon reaching the end of the directory or on error.  In the
     event of an error, errno may be set to any of the values documented for
     the getdirentries(2) system call.  Note that the order of the directory
     entries vended by readdir() is not specified. Some filesystems may return
     entries in lexicographic sort order and others may not.

     The readdir_r() function provides the same functionality as readdir(),
     but the caller must provide a directory entry buffer to store the results
     in.  If the read succeeds, result is pointed at the entry; upon reaching
     the end of the directory result is set to NULL.  The readdir_r() function
     returns 0 on success or an error number to indicate failure.

     The telldir() function returns the current location associated with the
     named directory stream.  Values returned by telldir() are good only for
     the lifetime of the DIR pointer, dirp, from which they are derived.  If
     the directory is closed and then reopened, prior values returned by
     telldir() will no longer be valid.

     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 the dirp pointer, returning 0 on success.  On
     failure, -1 is returned and the global variable errno is set to indicate
     the error.

     The dirfd() function returns the integer file descriptor associated with
     the named directory stream, see open(2).  On failure, -1 is returned and
     the global variable errno is set to indicate the error.

     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);

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

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

BSD                             April 16, 2008                             BSD