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GETDENTS(2)                 BSD System Calls Manual                GETDENTS(2)

NAME
     getdents -- get directory entries in a filesystem independent format

SYNOPSIS
     #include <&lt;dirent.h>&gt;

     int
     getdents(int fd, void *buf, size_t nbytes);

DESCRIPTION
     getdents() reads 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.  nbytes
     must be greater than or equal to the block size associated with the file
     (see stat(2)).  Some filesystems may not support getdents() with buffers
     smaller than this size.

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

           ino_t           d_fileno;
           off_t           d_off;
           u_int16_t       d_reclen;
           u_int8_t        d_type;
           u_int8_t        d_namlen;
           char            d_name[MAXNAMLEN + 1]; /* 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_off entry is the file offset of the next entry.
     The d_reclen entry is the length, in bytes, of the directory record.

     The d_type is the type of file, where the following are possible types:
     DT_UNKNOWN, DT_FIFO, DT_CHR, DT_DIR, DT_BLK, DT_REG, DT_LNK, and DT_SOCK.

     The d_namlen entry specifies the length of the file name excluding the
     NUL byte.  Thus the actual size of d_name may vary from 1 to MAXNAMLEN +
     1.

     The d_name entry contains a NUL-terminated file name.

     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.

     Invalid entries with d_fileno set to 0 may be returned among regular
     entries.

     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
     getdents().

     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), the value of d_off from an entry, or zero.

RETURN VALUES
     If successful, the number of bytes actually transferred is returned.  A
     value of zero is returned when the end of the directory has been reached.
     Otherwise, -1 is returned and the global variable errno is set to indi-
     cate the error.

ERRORS
     getdents() will fail if:

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

     [EFAULT]           Part of buf points outside the process's 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), opendir(3), dirent(5)

STANDARDS
     The getdents() call is not a portable interface and should not be used
     directly by applications.  Use readdir(3) instead.

HISTORY
     The getdirentries() function first appeared in 4.4BSD.  In OpenBSD 5.5
     the d_off entry was added to struct dirent and getdirentries() was
     replaced with getdents().

BSD                             March 27, 2017                             BSD