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DIRECTORY(3) Library Functions Manual DIRECTORY(3)

fdopendir, opendir, readdir, readdir_r, telldir, seekdir, rewinddir, closedir, dirfd — directory operations

library “libc”

#include <sys/types.h>
#include <dirent.h>

DIR *
fdopendir(int fd);

DIR *
opendir(const char *filename);

struct dirent *
readdir(DIR *dirp);

int
readdir_r(DIR * restrict dirp, struct dirent * restrict entry, struct dirent ** restrict result);

long
telldir(DIR *dirp);

void
seekdir(DIR *dirp, long loc);

void
rewinddir(DIR *dirp);

int
closedir(DIR *dirp);

int
dirfd(DIR *dirp);

The () 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 () function associates a directory stream with the directory file descriptor fd. The file offset associated with fd at the time of the call determines which entries are returned. The file descriptor must not be used further by the caller in any way.

The () 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 () 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 () 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 () 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 () function resets the position of the named directory stream to the beginning of the directory.

The () 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 () 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;

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

The opendir(), readdir(), telldir(), seekdir(), rewinddir(), closedir(), and dirfd() functions appeared in 4.2BSD.

February 22, 2018 DragonFly-5.6.1