DIRECTORY(3) OpenBSD Programmer's Manual DIRECTORY(3)NAME
opendir, readdir, readdir_r, telldir, seekdir, rewinddir, closedir, dirfd
- directory operations
SYNOPSIS
#include <sys/types.h>
#include <dirent.h>
DIR *
opendir(const char *filename);
struct dirent *
readdir(DIR *dirp);
int
readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result);
long
telldir(const 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. On failure, NULL is
returned and errno is set to indicate the error.
The readdir() function returns a pointer to the next directory entry in
the named directory stream dirp. It returns NULL upon reaching the end
of the directory or detecting an invalid seekdir() operation.
The readdir_r() function (much like readdir()) initializes the dirent
structure referenced by entry to represent the next directory entry in
the named directory stream dirp, and stores a pointer to this structure
at the location referenced by result. The storage pointed to by entry
must be large enough for a dirent with a d_name array member containing
at least NAME_MAX plus one elements. On successful return, the pointer
returned at *result will have the same value as the argument entry. Upon
reaching the end of the directory stream, this pointer shall have the
value NULL.
The telldir() function returns the current location associated with the
named directory stream dirp. On failure, -1 is returned and errno is set
to indicate the error.
The seekdir() function sets the position of the next readdir() operation
on the named directory stream dirp. The new position reverts to the one
associated with the directory stream when the telldir() operation was
performed. 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, the telldir() value may be invalidated due
to undetected directory compaction.
The rewinddir() function resets the position of the named directory
stream dirp 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 dirp (see open(2)).
EXAMPLES
Sample code which searches a directory for entry ``name'' is:
len = strlen(name);
dirp = opendir(".");
if (dirp) {
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);
ERRORS
The opendir() function will fail if:
[ENOTDIR] The supplied filename is not a directory.
The opendir() function may also fail and set errno for any of the errors
specified for the routines fcntl(2), fstat(2), open(2), and malloc(3).
The readdir() and readdir_r() functions may also fail and set errno for
any of the errors specified for the routine getdirentries(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).
SEE ALSOclose(2), getdirentries(2), lseek(2), open(2), dir(5)HISTORY
The opendir(), readdir(), telldir(), seekdir(), rewinddir(), closedir(),
and dirfd() functions appeared in 4.2BSD.
OpenBSD 4.9 January 19, 2010 OpenBSD 4.9
