man2/getdents.2

   1 .\" Copyright (C) 1995 Andries Brouwer (aeb@cwi.nl)
   2 .\"
   3 .\" Permission is granted to make and distribute verbatim copies of this
   4 .\" manual provided the copyright notice and this permission notice are
   5 .\" preserved on all copies.
   6 .\"
   7 .\" Permission is granted to copy and distribute modified versions of this
   8 .\" manual under the conditions for verbatim copying, provided that the
   9 .\" entire resulting derived work is distributed under the terms of a
  10 .\" permission notice identical to this one.
  11 .\"
  12 .\" Since the Linux kernel and libraries are constantly changing, this
  13 .\" manual page may be incorrect or out-of-date.  The author(s) assume no
  14 .\" responsibility for errors or omissions, or for damages resulting from
  15 .\" the use of the information contained herein.  The author(s) may not
  16 .\" have taken the same level of care in the production of this manual,
  17 .\" which is licensed free of charge, as they might when working
  18 .\" professionally.
  19 .\"
  20 .\" Formatted or processed versions of this manual, if unaccompanied by
  21 .\" the source, must acknowledge the copyright and authors of this work.
  22 .\"
  23 .\" Written 11 June 1995 by Andries Brouwer <aeb@cwi.nl>
  24 .\" Modified 22 July 1995 by Michael Chastain <mec@duracef.shout.net>:
  25 .\"   Derived from 'readdir.2'.
  26 .\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
  27 .TH GETDENTS 2  2008-06-22 "Linux" "Linux Programmer's Manual"
  28 .SH NAME
  29 getdents \- get directory entries
  30 .SH SYNOPSIS
  31 .nf
  32 .B #include <unistd.h>
  33 .B #include <linux/types.h>
  34 .B #include <linux/dirent.h>
  35 .B #include <linux/unistd.h>
  36 .B #include <errno.h>
  37 .sp
  38 .BI "int getdents(unsigned int " fd ", struct dirent *" dirp ", unsigned int " count );
  39 .fi
  40 .SH DESCRIPTION
  41 This is not the function you are interested in.
  42 Look at
  43 .BR readdir (3)
  44 for the POSIX conforming C library interface.
  45 This page documents the bare kernel system call interface.
  46 .PP
  47 The system call
  48 .BR getdents ()
  49 reads several
  50 .I dirent
  51 structures from the directory
  52 referred to by the open file descriptor
  53 .I fd
  54 into the buffer pointed to by
  55 .IR dirp .
  56 The parameter
  57 .I count
  58 is the size of the memory area.
  59 .PP
  60 The
  61 .I dirent
  62 structure is declared as follows:
  63 .PP
  64 .in +4n
  65 .nf
  66 struct linux_dirent {
  67     unsigned long  d_ino;     /* Inode number */
  68     unsigned long  d_off;     /* Offset to next \fIdirent\fP */
  69     unsigned short d_reclen;  /* Length of this \fIdirent\fP */
  70     char           d_name []; /* Filename (null-terminated) */
  71                         /* length is actually (d_reclen \- 2 \-
  72                            offsetof(struct linux_dirent, d_name) */
  73     /* char        pad;          Zero padding byte */
  74     /* char        d_type;       File type (only since Linux 2.6.4;
  75                                  offset is (d_reclen \- 1)) */
  76
  77 }
  78 .fi
  79 .in
  80 .PP
  81 .I d_ino
  82 is an inode number.
  83 .I d_off
  84 is the distance from the start of the directory to the start of the next
  85 .IR dirent .
  86 .I d_reclen
  87 is the size of this entire
  88 .IR dirent .
  89 .I d_name
  90 is a null-terminated filename.
  91
  92 .I d_type
  93 is a byte at the end of the structure that indicates the file type.
  94 It returns one of the following values:
  95 .TP 12
  96 .B DT_BLK
  97 This is a block device.
  98 .TP
  99 .B DT_CHR
 100 This is a character device.
 101 .TP
 102 .B DT_DIR
 103 This is a directory.
 104 .TP
 105 .B DT_FIFO
 106 This is a named pipe (FIFO).
 107 .TP
 108 .B DT_LNK
 109 This is a symbolic link.
 110 .TP
 111 .B DT_REG
 112 This is a regular file.
 113 .TP
 114 .B DT_SOCK
 115 This is a Unix domain socket.
 116 .TP
 117 .B DT_UNKNOWN
 118 The file type is unknown.
 119 .SH "RETURN VALUE"
 120 On success, the number of bytes read is returned.
 121 On end of directory, 0 is returned.
 122 On error, \-1 is returned, and
 123 .I errno
 124 is set appropriately.
 125 .SH ERRORS
 126 .TP
 127 .B EBADF
 128 Invalid file descriptor
 129 .IR fd .
 130 .TP
 131 .B EFAULT
 132 Argument points outside the calling process's address space.
 133 .TP
 134 .B EINVAL
 135 Result buffer is too small.
 136 .TP
 137 .B ENOENT
 138 No such directory.
 139 .TP
 140 .B ENOTDIR
 141 File descriptor does not refer to a directory.
 142 .SH "CONFORMING TO"
 143 SVr4.
 144 .\" SVr4 documents additional ENOLINK, EIO error conditions.
 145 .SH NOTES
 146 Glibc does not provide a wrapper for this system call; call it using
 147 .BR syscall (2).
 148
 149 This call supersedes
 150 .BR readdir (2).
 151 .SH "SEE ALSO"
 152 .BR readdir (2),
 153 .BR readdir (3)