HardenedBSD/lib/libpathconv/rel2abs.3
Julian Elischer 0f7f3352c8 This little BSD licensed library has been kicking around for years.
It allows one to trivially convert an absolute path to a relative path
and the reverse. The test programs themselves are very useful in scripts
but the real use comes shortly with the -r and -a arguments to ln.
These are sometimes known as the --relative and --absolute flags and
can force a symlink to be relative when you only have an absolue path.
Another place these are sometimes used is to add -a and -r args to 'realpath'.
Incredibly useful in Makefiles.

I was going to just add the files in with 'ln' but a library makes more sense.
The test programs may come out in their own right some day for scripting.

released under a BSD 2-clause:
 * Copyright (c) 1997 Shigio Yamaguchi. All rights reserved.
 * Copyright (c) 1999 Tama Communications Corporation. All rights reserved.

The test directry does not conform to any framework.
Not connected to build.
doc people may want to play with the manual pages.

Obtained from:  https://www.tamacom.com/pathconvert.html  Shigio Yamaguchi.
MFC after: 1 month
Relnotes:       yes
Sponsored by:   Panzura, Tama Communications Corporation
2016-11-23 07:57:52 +00:00

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2.9 KiB
Groff

.\"
.\" Copyright (c) 1997 Shigio Yamaguchi. All rights reserved.
.\" Copyright (c) 1999 Tama Communications Corporation. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" $FreeBSD$
.\"
.Dd Dec 3, 1997"
.Dt REL2ABS 3
.Os
.Sh NAME
.Nm rel2abs
.Nd make an absolute path name from a relative path name
.Sh SYNOPSIS
.Ft "char *"
.Fn rel2abs "const char *path" "const char *base" "char *result" "size_t size"
.Sh DESCRIPTION
The
.Fn rel2abs
function makes an absolute path name from a relative path name
.Fa path
based on a directory
.Fa base
and copies the resulting path name into the memory referenced by
.Fa result .
The
.Fa result
argument must refer to a buffer capable of storing at least
.Fa size
character
The resulting path name may include symbolic links.
.Fn abs2rel
doesn't check whether or not any path exists.
.Sh "RETURN VALUES"
The
.Fn rel2abs
function returns absolute path name on success.
If an error occurs, it returns
.Dv NULL .
.Sh ERRORS
The
.Fn rel2abs
function may fail and set the external variable
.Va errno
to indicate the error.
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa base
directory isn't an absolute path name or the
.Fa size
argument is zero.
.It Bq Er ERANGE
The
.Fa size
argument is greater than zero but smaller than the length of the pathname plus 1
.Sh EXAMPLE
char result[MAXPATHLEN];
char *path = rel2abs("../../src/sys", "/usr/local/lib", result, MAXPATHLEN);
yields:
path == "/usr/src/sys"
Similarly,
path1 = rel2abs("src/sys", "/usr", result, MAXPATHLEN);
path2 = rel2abs(".", "/usr/src/sys", result, MAXPATHLEN);
yields:
path1 == "/usr/src/sys"
path2 == "/usr/src/sys"
.Sh "SEE ALSO"
.Xr abs2rel 3
.Sh AUTHORS
Shigio Yamaguchi (shigio@tamacom.com)