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. In the event of an error,
NULL is returned and errno will be set to reflect 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 on error. In the
event of an error, errno will be set to any of the values documented for
the getdirentries(2) system call.
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() func-
tion 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 on success, 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);
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 10.9.1 - Generated Tue Jan 7 09:12:05 CST 2014