directory(3) BSD Library Functions Manual directory(3)
NAME
closedir, dirfd, opendir, readdir, readdir_r, rewinddir, seekdir, telldir
-- directory operations
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <dirent.h>
int
closedir(DIR *dirp);
int
dirfd(DIR *dirp);
DIR *
opendir(const char *dirname);
struct dirent *
readdir(DIR *dirp);
int
readdir_r(DIR *restrict dirp, struct dirent *restrict entry,
struct dirent **restrict result);
void
rewinddir(DIR *dirp);
void
seekdir(DIR *dirp, long loc);
long
telldir(DIR *dirp);
DESCRIPTION
The opendir() function opens the directory named by dirname, 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 dirname cannot be accessed or if it cannot malloc(3) enough
memory to hold the whole thing.
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.
readdir_r() 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. readdir_r() 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 (e.g., 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;
LEGACY SYNOPSIS
#include <sys/types.h>
#include <dirent.h>
<sys/types.h> is necessary for these functions.
SEE ALSO
close(2), lseek(2), open(2), read(2), compat(5), dir(5)
HISTORY
The closedir(), dirfd(), opendir(), readdir(), rewinddir(), seekdir(),
and telldir() functions appeared in 4.2BSD.
BSD June 4, 1993 BSD
Mac OS X 10.5 - Generated Sun Oct 28 21:28:58 EDT 2007