man3/opendir.3

   1 .\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
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  25 .\" References consulted:
  26 .\"     Linux libc source code
  27 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  28 .\"     386BSD man pages
  29 .\" Modified Sat Jul 24 18:46:01 1993 by Rik Faith (faith@cs.unc.edu)
  30 .\" Modified 11 June 1995 by Andries Brouwer (aeb@cwi.nl)
  31 .\" 2007-07-30 Ulrich Drepper <drepper@redhat.com>: document fdopendir().
  32 .TH OPENDIR 3  2017-09-15 "GNU" "Linux Programmer's Manual"
  33 .SH NAME
  34 opendir, fdopendir \- open a directory
  35 .SH SYNOPSIS
  36 .nf
  37 .B #include <sys/types.h>
  38 .B #include <dirent.h>
  39 .PP
  40 .BI "DIR *opendir(const char *" name );
  41 .BI "DIR *fdopendir(int " fd );
  42 .fi
  43 .PP
  44 .in -4n
  45 Feature Test Macro Requirements for glibc (see
  46 .BR feature_test_macros (7)):
  47 .in
  48 .PP
  49 .BR fdopendir ():
  50 .PD 0
  51 .ad l
  52 .RS 4
  53 .TP 4
  54 Since glibc 2.10:
  55 _POSIX_C_SOURCE\ >=\ 200809L
  56 .TP
  57 Before glibc 2.10:
  58 _GNU_SOURCE
  59 .RE
  60 .ad
  61 .PD
  62 .SH DESCRIPTION
  63 The
  64 .BR opendir ()
  65 function opens a directory stream corresponding to the
  66 directory \fIname\fP, and returns a pointer to the directory stream.
  67 The stream is positioned at the first entry in the directory.
  68 .PP
  69 The
  70 .BR fdopendir ()
  71 function
  72 is like
  73 .BR opendir (),
  74 but returns a directory stream for the directory referred
  75 to by the open file descriptor
  76 .IR fd .
  77 After a successful call to
  78 .BR fdopendir (),
  79 .I fd
  80 is used internally by the implementation,
  81 and should not otherwise be used by the application.
  82 .SH RETURN VALUE
  83 The
  84 .BR opendir ()
  85 and
  86 .BR fdopendir ()
  87 functions return a pointer to the directory stream.
  88 On error, NULL is returned, and
  89 .I errno
  90 is set appropriately.
  91 .SH ERRORS
  92 .TP
  93 .B EACCES
  94 Permission denied.
  95 .TP
  96 .B EBADF
  97 .I fd
  98 is not a valid file descriptor opened for reading.
  99 .TP
 100 .B EMFILE
 101 The per-process limit on the number of open file descriptors has been reached.
 102 .TP
 103 .B ENFILE
 104 The system-wide limit on the total number of open files has been reached.
 105 .TP
 106 .B ENOENT
 107 Directory does not exist, or \fIname\fP is an empty string.
 108 .TP
 109 .B ENOMEM
 110 Insufficient memory to complete the operation.
 111 .TP
 112 .B ENOTDIR
 113 \fIname\fP is not a directory.
 114 .SH VERSIONS
 115 .BR fdopendir ()
 116 is available in glibc since version 2.4.
 117 .SH ATTRIBUTES
 118 For an explanation of the terms used in this section, see
 119 .BR attributes (7).
 120 .TS
 121 allbox;
 122 lbw22 lb lb
 123 l l l.
 124 Interface       Attribute       Value
 125 T{
 126 .BR opendir (),
 127 .BR fdopendir ()
 128 T}      Thread safety   MT-Safe
 129 .TE
 130 .SH CONFORMING TO
 131 .BR opendir ()
 132 is present on SVr4, 4.3BSD, and specified in POSIX.1-2001.
 133 .BR fdopendir ()
 134 is specified in POSIX.1-2008.
 135 .SH NOTES
 136 Filename entries can be read from a directory stream using
 137 .BR readdir (3).
 138 .PP
 139 The underlying file descriptor of the directory stream can be obtained using
 140 .BR dirfd (3).
 141 .PP
 142 The
 143 .BR opendir ()
 144 function sets the close-on-exec flag for the file descriptor underlying the
 145 .IR "DIR *" .
 146 The
 147 .BR fdopendir ()
 148 function leaves the setting of the close-on-exec
 149 flag unchanged for the file descriptor,
 150 .IR fd .
 151 POSIX.1-200x leaves it unspecified whether a successful call to
 152 .BR fdopendir ()
 153 will set the close-on-exec flag for the file descriptor,
 154 .IR fd .
 155 .SH SEE ALSO
 156 .BR open (2),
 157 .BR closedir (3),
 158 .BR dirfd (3),
 159 .BR readdir (3),
 160 .BR rewinddir (3),
 161 .BR scandir (3),
 162 .BR seekdir (3),
 163 .BR telldir (3)