gen/FreeBSD/getcwd.3

   1 .\" Copyright (c) 1991, 1993
   2 .\"     The Regents of the University of California.  All rights reserved.
   3 .\"
   4 .\" Redistribution and use in source and binary forms, with or without
   5 .\" modification, are permitted provided that the following conditions
   6 .\" are met:
   7 .\" 1. Redistributions of source code must retain the above copyright
   8 .\"    notice, this list of conditions and the following disclaimer.
   9 .\" 2. Redistributions in binary form must reproduce the above copyright
  10 .\"    notice, this list of conditions and the following disclaimer in the
  11 .\"    documentation and/or other materials provided with the distribution.
  12 .\" 4. Neither the name of the University nor the names of its contributors
  13 .\"    may be used to endorse or promote products derived from this software
  14 .\"    without specific prior written permission.
  15 .\"
  16 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  17 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  20 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26 .\" SUCH DAMAGE.
  27 .\"
  28 .\"     @(#)getcwd.3    8.2 (Berkeley) 12/11/93
  29 .\" $FreeBSD: src/lib/libc/gen/getcwd.3,v 1.17 2007/01/09 00:27:53 imp Exp $
  30 .\"
  31 .Dd November 24, 1997
  32 .Dt GETCWD 3
  33 .Os
  34 .Sh NAME
  35 .Nm getcwd ,
  36 .Nm getwd
  37 .Nd get working directory pathname
  38 .Sh LIBRARY
  39 .Lb libc
  40 .Sh SYNOPSIS
  41 .In unistd.h
  42 .Ft char *
  43 .Fn getcwd "char *buf" "size_t size"
  44 .Ft char *
  45 .Fn getwd "char *buf"
  46 .Sh DESCRIPTION
  47 The
  48 .Fn getcwd
  49 function copies the absolute pathname of the current working directory
  50 into the memory referenced by
  51 .Fa buf
  52 and returns a pointer to
  53 .Fa buf .
  54 The
  55 .Fa size
  56 argument is the size, in bytes, of the array referenced by
  57 .Fa buf .
  58 .Pp
  59 If
  60 .Fa buf
  61 is
  62 .Dv NULL ,
  63 space is allocated as necessary to store the pathname.
  64 This space may later be
  65 .Xr free 3 Ns 'd .
  66 .Pp
  67 The function
  68 .Fn getwd
  69 is a compatibility routine which calls
  70 .Fn getcwd
  71 with its
  72 .Fa buf
  73 argument and a size of
  74 .Dv MAXPATHLEN
  75 (as defined in the include
  76 file
  77 .In sys/param.h ) .
  78 Obviously,
  79 .Fa buf
  80 should be at least
  81 .Dv MAXPATHLEN
  82 bytes in length.
  83 .Pp
  84 These routines have traditionally been used by programs to save the
  85 name of a working directory for the purpose of returning to it.
  86 A much faster and less error-prone method of accomplishing this is to
  87 open the current directory
  88 .Pq Ql .\&
  89 and use the
  90 .Xr fchdir 2
  91 function to return.
  92 .Sh RETURN VALUES
  93 Upon successful completion, a pointer to the pathname is returned.
  94 Otherwise a
  95 .Dv NULL
  96 pointer is returned and the global variable
  97 .Va errno
  98 is set to indicate the error.
  99 In addition,
 100 .Fn getwd
 101 copies the error message associated with
 102 .Va errno
 103 into the memory referenced by
 104 .Fa buf .
 105 .Sh ERRORS
 106 The
 107 .Fn getcwd
 108 function
 109 will fail if:
 110 .Bl -tag -width Er
 111 .It Bq Er EACCES
 112 Read or search permission was denied for a component of the pathname.
 113 .It Bq Er EINVAL
 114 The
 115 .Fa size
 116 argument is zero.
 117 .It Bq Er ENOENT
 118 A component of the pathname no longer exists.
 119 .It Bq Er ENOMEM
 120 Insufficient memory is available.
 121 .It Bq Er ERANGE
 122 The
 123 .Fa size
 124 argument is greater than zero but smaller than the length of the pathname
 125 plus 1.
 126 .El
 127 .Sh SEE ALSO
 128 .Xr chdir 2 ,
 129 .Xr fchdir 2 ,
 130 .Xr malloc 3 ,
 131 .Xr strerror 3
 132 .Sh STANDARDS
 133 The
 134 .Fn getcwd
 135 function
 136 conforms to
 137 .St -p1003.1-90 .
 138 The ability to specify a
 139 .Dv NULL
 140 pointer and have
 141 .Fn getcwd
 142 allocate memory as necessary is an extension.
 143 .Sh HISTORY
 144 The
 145 .Fn getwd
 146 function appeared in
 147 .Bx 4.0 .
 148 .Sh BUGS
 149 The
 150 .Fn getwd
 151 function
 152 does not do sufficient error checking and is not able to return very
 153 long, but valid, paths.
 154 It is provided for compatibility.