gen/FreeBSD/getcwd.3

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  28 .\"     @(#)getcwd.3    8.2 (Berkeley) 12/11/93
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  31 .Dd April 17, 2010
  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 and
  64 .Fa size
  65 is ignored.
  66 This space may later be
  67 .Xr free 3 Ns 'd .
  68 .Pp
  69 The function
  70 .Fn getwd
  71 is a compatibility routine which calls
  72 .Fn getcwd
  73 with its
  74 .Fa buf
  75 argument and a size of
  76 .Dv MAXPATHLEN
  77 (as defined in the include
  78 file
  79 .In sys/param.h ) .
  80 Obviously,
  81 .Fa buf
  82 should be at least
  83 .Dv MAXPATHLEN
  84 bytes in length.
  85 .Pp
  86 These routines have traditionally been used by programs to save the
  87 name of a working directory for the purpose of returning to it.
  88 A much faster and less error-prone method of accomplishing this is to
  89 open the current directory
  90 .Pq Ql .\&
  91 and use the
  92 .Xr fchdir 2
  93 function to return.
  94 .Sh RETURN VALUES
  95 Upon successful completion, a pointer to the pathname is returned.
  96 Otherwise a
  97 .Dv NULL
  98 pointer is returned and the global variable
  99 .Va errno
 100 is set to indicate the error.
 101 In addition,
 102 .Fn getwd
 103 copies the error message associated with
 104 .Va errno
 105 into the memory referenced by
 106 .Fa buf .
 107 .Sh ERRORS
 108 The
 109 .Fn getcwd
 110 function
 111 will fail if:
 112 .Bl -tag -width Er
 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 .Pp
 128 The
 129 .Fn getcwd
 130 function
 131 may fail if:
 132 .Bl -tag -width Er
 133 .It Bq Er EACCES
 134 Read or search permission was denied for a component of the pathname.
 135 This is only checked in limited cases, depending on implementation details.
 136 .El
 137 .Sh SEE ALSO
 138 .Xr chdir 2 ,
 139 .Xr fchdir 2 ,
 140 .Xr malloc 3 ,
 141 .Xr strerror 3
 142 .Sh STANDARDS
 143 The
 144 .Fn getcwd
 145 function
 146 conforms to
 147 .St -p1003.1-90 .
 148 The ability to specify a
 149 .Dv NULL
 150 pointer and have
 151 .Fn getcwd
 152 allocate memory as necessary is an extension.
 153 .Sh HISTORY
 154 The
 155 .Fn getwd
 156 function appeared in
 157 .Bx 4.0 .
 158 .Sh BUGS
 159 The
 160 .Fn getwd
 161 function
 162 does not do sufficient error checking and is not able to return very
 163 long, but valid, paths.
 164 It is provided for compatibility.