directory(3Cbsd)

Synopsis

   /usr/ucb/cc [flag . . . ] file . . .
   

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

   DIR *opendir(const char *filename);
   

   struct direct *readdir(DIR *dirp);
   

   long telldir(DIR *dirp);
   

   void seekdir(DIR *dirp, long loc);
   

   void rewinddir(DIR *dirp);
   

   int closedir(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 directory stream is positioned at the first entry. A null pointer 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 and positions the directory stream at the next 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. readdir buffers several directory entries per actual read operation; readdir marks for update the st_atime field of the directory each time the directory is actually read.

telldir returns the current location associated with the named directory stream.

seekdir sets the position of the next read operation on the directory stream. The new position reverts to the position associated with the directory stream at the time the telldir operation that provides loc was performed. Values returned by telldir are valid only if the directory has not changed because of compaction or expansion. This situation is not a problem with System V, but it may be a problem with some file system types.

rewinddir resets the position of the named directory stream to the beginning of the directory. It also causes the directory stream to refer to the current state of the corresponding directory, as a call to opendir would.

closedir closes the named directory stream and frees the DIR structure.

The following errors can occur as a result of these operations.

opendir returns NULL on failure and sets errno to one of the following values:

ENOTDIR

A component of filename is not a directory.

EACCES

A component of filename denies search permission.

EACCES

Read permission is denied on the specified directory.

EMFILE

The maximum number of file descriptors are currently open.

ENFILE

The system file table is full.

EFAULT

filename points outside the allocated address space.

ELOOP

Too many symbolic links were encountered in translating filename.

ENAMETOOLONG

The length of the filename argument exceeds {PATH_MAX}, or the length of a filename component exceeds {NAME_MAX} while {_POSIX_NO_TRUNC} is in effect.

ENOENT

A component of filename does not exist or is a null pathname.

readdir returns NULL on failure and sets errno to one of the following values:

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 result occurs if the DIR stream has been closed.

closedir returns -1 on failure and sets errno to the following value:

EBADF

The file descriptor determined by the DIR stream is no longer valid. This results if the DIR stream has been closed.

Examples

   #include <stdio.h>
   #include <sys/types.h>
   #include <sys/dir.h>
   

   main()
   {
   	DIR *dirp;
   	struct direct *directp;
   

   	dirp = opendir( "." );
   	while ( (directp = readdir( dirp )) != NULL )
   		(void)printf( "%s\n", directp->d_name );
   	closedir( dirp );
   	return (0);
   }

References

References

cc(1bsd), ld(1bsd), directory(3C), getdents(2)

Notices