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 <sys/types.h>
#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.
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 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 detecting an
invalid seekdir() operation.
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).
Sample code which searches a directory for entry ``name'' is:
len = strlen(name);
dirp = opendir(".");
while ((dp = readdir(dirp)) != NULL)
if (dp->d_namlen == len && !strcmp(dp->d_name, name)) {
(void)closedir(dirp);
return FOUND;
}
(void)closedir(dirp);
return NOT_FOUND;
SEE ALSOclose(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