DragonFly On-Line Manual Pages

GETDIRENTRIES(2)         DragonFly System Calls Manual        GETDIRENTRIES(2)

NAME
     getdirentries, getdents -- get directory entries in a filesystem indepen-
     dent format

LIBRARY
     Standard C Library (libc, -lc)

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

     int
     getdirentries(int fd, char *buf, int nbytes, long *basep);

     int
     getdents(int fd, char *buf, int nbytes);

     size_t
     _DIRENT_DIRSIZ(struct dirent *dp);

     struct dirent *
     _DIRENT_NEXT(struct dirent *dp);

DESCRIPTION
     The getdirentries() and getdents() functions read directory entries from
     the directory referenced by the file descriptor fd into the buffer
     pointed to by buf, in a filesystem independent format.  Up to nbytes of
     data will be transferred.  The nbytes argument must be greater than or
     equal to the block size associated with the file, see stat(2).  Some
     filesystems may not support these functions with buffers smaller than
     this size.

     The data in the buffer is a series of dirent structures each containing
     the following entries:

           ino_t     d_fileno;
           u_int8_t  d_type;
           u_int8_t  d_namlen;
           char      d_name[...];  /* see below */

     The d_fileno entry is a number which is unique for each distinct file in
     the filesystem.  Files that are linked by hard links (see link(2)) have
     the same d_fileno.  The d_type entry is the type of the file pointed to
     by the directory record.  The file type values are defined in
     <sys/dirent.h>.  The d_name entry contains a null terminated file name.
     The d_namlen entry specifies the length of the file name excluding the
     null byte.  Thus the actual size of d_name may vary from 1 to MAXNAMELEN
     + 1.

     Entries may be separated by extra space.  To get the total size of a
     dirent structure, use the _DIRENT_DIRSIZ macro, or use _DIRENT_NEXT to
     get a pointer to the following dirent structure.

     The actual number of bytes transferred is returned.  The current position
     pointer associated with fd is set to point to the next block of entries.
     The pointer may not advance by the number of bytes returned by
     getdirentries() or getdents().  A value of zero is returned when the end
     of the directory has been reached.

     The getdirentries() function writes the position of the block read into
     the location pointed to by basep.  Alternatively, the current position
     pointer may be set and retrieved by lseek(2).  The current position
     pointer should only be set to a value returned by lseek(2), a value
     returned in the location pointed to by basep (getdirentries() only) or
     zero.

RETURN VALUES
     If successful, the number of bytes actually transferred is returned.
     Otherwise, -1 is returned and the global variable errno is set to indi-
     cate the error.

ERRORS
     Getdirentries() will fail if:

     [EBADF]            fd is not a valid file descriptor open for reading.

     [EFAULT]           Either buf or basep point outside the allocated
                        address space.

     [EINVAL]           The file referenced by fd is not a directory, or
                        nbytes is too small for returning a directory entry or
                        block of entries, or the current position pointer is
                        invalid.

     [EIO]              An I/O error occurred while reading from or writing to
                        the file system.

SEE ALSO
     lseek(2), open(2)

HISTORY
     The getdirentries() function first appeared in 4.4BSD.  The getdents()
     function first appeared in FreeBSD 3.0.

BUGS
     Unfortunately, *basep is only 32 bits wide on 32 bit platforms and may
     not be wide enough to accommodate the directory position cookie.  Modern
     users should use lseek(2).  to retrieve and set the seek position within
     the directory.  The seek offset is 64 bits wide on all platforms.

DragonFly 3.5                    July 31, 2006                   DragonFly 3.5