DIRECTORY(3X) SysV DIRECTORY(3X)
NAME
directory: opendir, readdir, telldir, seekdir, rewinddir, closedir -
directory operations
SYNOPSIS
#include <sys/types.h>
#include <dirent.h>
DIR *opendir (filename)
char *filename;
struct dirent *readdir (dirp)
DIR *dirp;
long telldir (dirp)
DIR *dirp;
void seekdir (dirp, loc)
DIR *dirp;
long loc;
void rewinddir (dirp)
DIR *dirp;
void closedir(dirp)
DIR *dirp;
DESCRIPTION
opendir opens the directory named by filename and associates a directory
stream with it. opendir 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 is not a directory, or if it cannot
malloc(3X) enough memory to hold a DIR structure or a buffer for the
directory entries.
readdir returns a pointer to the next active directory entry. No
inactive entries are returned. It returns NULL upon reaching the end of
the directory or upon detecting an invalid location in the directory.
telldir returns the current location associated with the named directory
stream.
seekdir 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 from which loc was obtained was
performed. Values returned by telldir are good only if the directory has
not changed due to compaction or expansion. This is not a problem with
System V, but it may be with some file system types.
rewinddir resets the position of the named directory stream to the
beginning of the directory.
closedir closes the named directory stream and frees the DIR structure.
The following errors can occur as a result of these operations.
opendir:
[ENOTDIR] A component of filename is not a directory.
[EACCES] A component of filename denies search permission.
[EMFILE] The maximum number of file descriptors are currently open.
[EFAULT] filename points outside the allocated address space.
readdir:
[ENOENT] The current file pointer for the directory is not located
at a valid entry.
[EBADF] The file descriptor determined by the DIR stream is no
longer valid. This results if the DIR stream has been
closed.
telldir, seekdir, and closedir:
[EBADF] The file descriptor determined by the DIR stream is no
longer valid. This results if the DIR stream has been
closed.
EXAMPLE
Sample code which searches a directory for entry name:
dirp = opendir( "." );
while ( (dp = readdir( dirp )) != NULL )
if ( strcmp( dp->d_name, name ) == 0 )
{
closedir( dirp );
return FOUND;
}
closedir( dirp );
return NOT_FOUND;
SEE ALSO
getdents(2), dirent(4).
WARNINGS
rewinddir is implemented as a macro, so its function address cannot be
taken.