readdir(3) - NetBSD Manual Pages

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DIRECTORY(3)            NetBSD Library Functions Manual           DIRECTORY(3)


NAME
opendir, readdir, readdir_r, telldir, seekdir, rewinddir, closedir, dirfd -- directory operations
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <dirent.h> 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);
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 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. 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. 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 cannot be re-used. 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).
EXAMPLES
Sample code which searches a directory for entry ``name'' is: len = strlen(name); dirp = opendir("."); if (dirp != NULL) { 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 ALSO
close(2), lseek(2), open(2), read(2), dir(5)
STANDARDS
The opendir(), readdir(), rewinddir() and closedir() functions conform to ISO/IEC 9945-1:1990 (``POSIX.1'').
HISTORY
The opendir(), readdir(), telldir(), seekdir(), rewinddir(), closedir(), and dirfd() functions appeared in 4.2BSD. NetBSD 5.0 May 18, 2006 NetBSD 5.0
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