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NAME

     getdirentries, getdents - get directory entries in a file system
     independent 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);

DESCRIPTION

     The getdirentries() and getdents() system calls read directory entries
     from the directory referenced by the file descriptor fd into the buffer
     pointed to by buf, in a file system 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 file
     systems may not support these system calls with buffers smaller than this
     size.

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

           u_int32_t d_fileno;
           u_int16_t d_reclen;
           u_int8_t  d_type;
           u_int8_t  d_namlen;
           char    d_name[MAXNAMELEN + 1]; /* see below */

     The d_fileno entry is a number which is unique for each distinct file in
     the file system.  Files that are linked by hard links (see link(2)) have
     the same d_fileno.  The d_reclen entry is the length, in bytes, of the
     directory record.  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.  The d_reclen entry may be used
     as an offset from the start of a dirent structure to the next structure,
     if any.

     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() system call 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
     indicate the error.

ERRORS

     The getdirentries() system call will fail if:

     [EBADF]            The fd argument 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() system call first appeared in 4.4BSD.  The getdents()
     system call first appeared in FreeBSD 3.0.