freebsd-dev/lib/libc/stdlib/realpath.3

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.\"     @(#)realpath.3	8.2 (Berkeley) 2/16/94
.\" $FreeBSD$
.\"
.Dd April 19, 2010
.Dt REALPATH 3
.Os
.Sh NAME
.Nm realpath
.Nd returns the canonicalized absolute pathname
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/param.h
.In stdlib.h
.Ft "char *"
.Fn realpath "const char *pathname" "char *resolved_path"
.Sh DESCRIPTION
The
.Fn realpath
function resolves all symbolic links, extra
.Dq /
characters and references to
.Pa /./
and
.Pa /../
in
.Fa pathname ,
and copies the resulting absolute pathname into
the memory pointed to by
.Fa resolved_path .
The
.Fa resolved_path
argument
.Em must
point to a buffer capable of storing at least
.Dv PATH_MAX
characters, or be
.Dv NULL .
.Pp
The
.Fn realpath
function will resolve both absolute and relative paths
and return the absolute pathname corresponding to
.Fa pathname .
All but the last component of
.Fa pathname
must exist when
.Fn realpath
is called.
.Sh "RETURN VALUES"
The
.Fn realpath
function returns
.Fa resolved_path
on success.
If the function was supplied
.Dv NULL
as
.Fa resolved_path ,
and operation did not cause errors, the returned value is
a null-terminated string in a buffer allocated by a call to
.Fn malloc 3 .
If an error occurs,
.Fn realpath
returns
.Dv NULL ,
and if
.Fa resolved_path
is not
.Dv NULL ,
the array that it points to contains the pathname which caused the problem.
.Sh ERRORS
The function
.Fn realpath
may fail and set the external variable
.Va errno
for any of the errors specified for the library functions
.Xr lstat 2 ,
.Xr readlink 2
and
.Xr getcwd 3 .
.Sh CAVEATS
This implementation of
.Fn realpath
differs slightly from the Solaris implementation.
The
.Bx 4.4
version always returns absolute pathnames,
whereas the Solaris implementation will,
under certain circumstances, return a relative
.Fa resolved_path
when given a relative
.Fa pathname .
.Sh "SEE ALSO"
.Xr getcwd 3
.Sh STANDARDS
The
.Fn realpath
function conforms to
.St -p1003.1-2001 .
.Sh HISTORY
The
.Fn realpath
function first appeared in
.Bx 4.4 .