stdlib/FreeBSD/realpath.3

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   4 .\" This code is derived from software contributed to Berkeley by
   5 .\" Jan-Simon Pendry.
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  31 .\"     @(#)realpath.3  8.2 (Berkeley) 2/16/94
  32 .\" $FreeBSD: src/lib/libc/stdlib/realpath.3,v 1.14 2007/01/09 00:28:10 imp Exp $
  33 .\"
  34 .Dd April 5, 2008
  35 .Dt REALPATH 3
  36 .Os
  37 .Sh NAME
  38 .Nm realpath
  39 .Nd returns the canonicalized absolute pathname
  40 .\" .Sh LIBRARY
  41 .\" .Lb libc
  42 .Sh SYNOPSIS
  43 .In stdlib.h
  44 .Ft "char *"
  45 .Fo realpath
  46 .Fa "const char *restrict file_name"
  47 .Fa "char *restrict resolved_name"
  48 .Fc
  49 .Sh DESCRIPTION
  50 The
  51 .Fn realpath
  52 function resolves all symbolic links, extra
  53 .Dq /
  54 characters, and references to
  55 .Pa /./
  56 and
  57 .Pa /../
  58 in
  59 .Fa file_name .
  60 If the
  61 .Fa resolved_name
  62 argument
  63 is non-NULL, the resulting absolute pathname is copied there (it
  64 .Em must
  65 refer to a buffer capable of storing at least
  66 .Dv PATH_MAX
  67 characters).
  68 .Pp
  69 As a permitted extension to the standard, if
  70 .Fa resolved_name
  71 is NULL,
  72 memory is allocated for the resulting absolute pathname, and is returned by
  73 .Fn realpath .
  74 This memory should be freed by a call to
  75 .Xr free 3
  76 when no longer needed.
  77 .Pp
  78 The
  79 .Fn realpath
  80 function will resolve both absolute and relative paths
  81 and return the absolute pathname corresponding to
  82 .Fa file_name .
  83 All components of
  84 .Fa file_name
  85 must exist when
  86 .Fn realpath
  87 is called.
  88 .Sh "RETURN VALUES"
  89 On success, the
  90 .Fn realpath
  91 function returns the address of the resulting absolute pathname, which is
  92 .Fa resolved_name
  93 if it was non-NULL, or the address of newly allocated memory.
  94 If an error occurs,
  95 .Fn realpath
  96 returns
  97 .Dv NULL .
  98 If
  99 .Fa resolved_name
 100 was non-NULL, it will
 101 contains the pathname which caused the problem.
 102 .Sh VARIANTS
 103 Defining
 104 .Dv _DARWIN_C_SOURCE
 105 or
 106 .Dv _DARWIN_BETTER_REALPATH
 107 before including stdio.h will cause the provided implementation of
 108 .Fn realpath
 109 to use F_GETPATH from
 110 .Xr fcntl 2
 111 to discover the path.
 112 .Sh ERRORS
 113 The function
 114 .Fn realpath
 115 may fail and set the external variable
 116 .Va errno
 117 for any of the errors specified for the library functions
 118 .Xr alloca 3 ,
 119 .Xr getattrlist 2 ,
 120 .Xr getcwd 3 ,
 121 .Xr lstat 2 ,
 122 .Xr readlink 2 ,
 123 .Xr stat 2 ,
 124 and
 125 .Xr strdup 3 .
 126 .\" .Sh CAVEATS
 127 .\" This implementation of
 128 .\" .Fn realpath
 129 .\" differs slightly from the Solaris implementation.
 130 .\" The
 131 .\" .Bx 4.4
 132 .\" version always returns absolute pathnames,
 133 .\" whereas the Solaris implementation will,
 134 .\" under certain circumstances, return a relative
 135 .\" .Fa resolved_name
 136 .\" when given a relative
 137 .\" .Fa file_name .
 138 .Sh LEGACY SYNOPSIS
 139 .Fd #include <sys/param.h>
 140 .Fd #include <stdlib.h>
 141 .Pp
 142 The include file
 143 .In sys/param.h
 144 is necessary.
 145 .Sh LEGACY DESCRIPTION
 146 In legacy mode,
 147 the last component of
 148 .Fa file_name
 149 does not need to exist when
 150 .Fn realpath
 151 is called.
 152 .Sh "SEE ALSO"
 153 .Xr free 3 ,
 154 .Xr getcwd 3 ,
 155 .Xr compat 5
 156 .Sh HISTORY
 157 The
 158 .Fn realpath
 159 function first appeared in
 160 .Bx 4.4 .