DIRECTORY(S) UNIX System V DIRECTORY(S)
Name
directory: opendir, readdir, telldir, seekdir, rewinddir,
closedir - directory operations
Syntax
#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
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, loc , is the
position associated with the directory stream when the
telldir operation 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stream is no longer valid.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stream is no longer valid.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(S), dirent(F)
Warnings
rewinddir is implemented as a macro, so its function address
cannot be taken.
Standards Conformance
closedir, opendir, readdir and rewinddir are conformant
with:
AT&T SVID Issue 2, Select Code 307-127;
The X/Open Portability Guide II of January 1987;
IEEE POSIX Std 1003.1-1988 with C Standard Language-
Dependent System Support;
and NIST FIPS 151-1.
seekdir and telldir are conformant with:
AT&T SVID Issue 2, Select Code 307-127;
and The X/Open Portability Guide II of January 1987.
(printed 6/20/89)