Re: Patch and Cygwin

[Eli Zaretskii <eliz at gnu dot org>]

> Date: Fri, 16 Dec 2005 01:07:30 +0100
> From: Lennart Borgman <lennart.borgman.073@student.lu.se>
> CC: cygwin@cygwin.com, Emacs Devel <emacs-devel@gnu.org>, 
>  Eli Zaretskii <eliz@gnu.org>

I urge people who participate in this thread to please keep
emacs-devel off the list of the addressees, as this issue is off-topic
there.

> This is a summary of my tests with Cygwin patch and different line 
> ending styles. (Only LF and CRLF are tested here.)
> 
> I have downloaded patch 2.5.9 from 
> ftp://alpha.gnu.org/gnu/diffutils/patch-2.5.9.tar.gz and compiled it 
> using Cygwin. I have used this patch and the patch that currently comes 
> with Cygwin to do some tests of patch and diff when the files to compare 
> and patch have different line ending styles. I have also made this test 
> using MSYS and GnuWin32 utilities.
> 
> The result is that the only option that seems to be able to handle the 
> mix of line endings is Cygwin using DOS line endings with patch 2.5.9. 
> (The only thing that did not work was preservation of line endings in 
> the patched file, but that seems to be a small problem here.)
> 
> To see more of the result see here: 
> http://ourcomments.org/GNU/patchcrlf/readme.txt

I don't use Cygwin, but I tried your tests with the GnuWin32 ports of
Diff and Patch (and `cat' from GnuWin32 port of Coreutils), and the
tests worked for me as I expected.  Here are the results:

    D:\gnu\patches>gnuwin32-test.cmd
    D:\gnu\patches\tempGNUWIN32

    D:/usr/bin/diff.EXE
    D:/usr/bin/patch.EXE

    patching file file-lf.txt
    patching file file-cr-lf.txt

    **** PATCHED file-cr-lf.txt: ********
    This is a test comparing two files^M
    with different line endings.^M
    the name of this file is file-lf.txt^M
    and it has lf line ending.^M
    No this is diffed against the other file^M
    using GnuWin32 diff.^M

    **** PATCHED file-lf.txt: ***********
    This is a test comparing two files^M
    with different line endings.^M
    the name of this file is file-cr-lf.txt^M
    and it has cr-lf line ending.^M
    No this is diffed against the other file^M
    using GnuWin32 diff.^M

    **** THE PATCH: ***********
    3,4c3,4^M
    < the name of this file is file-lf.txt^M
    < and it has lf line ending.^M
    ---^M
    > the name of this file is file-cr-lf.txt^M
    > and it has cr-lf line ending.^M

    D:\gnu\patches>

I think this is the result you expected.  Is that true?

If you wanted the patched file-lf.txt to retain its Unix-style EOL
format, then gnuwun32-test.cmd should be modified to say

    patch --binary file-lf.txt temp.diff

instead of

    patch file-lf.txt temp.diff

and then Patch will remove the CR characters from the patch file
temp.diff and produce a LF-only EOLs:

    D:\gnu\patches>gnuwin32-test.cmd
    D:\gnu\patches\tempGNUWIN32

    D:/usr/bin/diff.EXE
    D:/usr/bin/patch.EXE

    (Stripping trailing CRs from patch.)  <<<<<<<<<<<<<<=========
    patching file file-lf.txt
    patching file file-cr-lf.txt

    **** PATCHED file-cr-lf.txt: ********
    This is a test comparing two files^M
    with different line endings.^M
    the name of this file is file-lf.txt^M
    and it has lf line ending.^M
    No this is diffed against the other file^M
    using GnuWin32 diff.^M

    **** PATCHED file-lf.txt: ***********
    This is a test comparing two files   <<<<<<======== no ^M characters
    with different line endings.
    the name of this file is file-cr-lf.txt
    and it has cr-lf line ending.
    No this is diffed against the other file
    using GnuWin32 diff.

    **** THE PATCH: ***********
    3,4c3,4^M
    < the name of this file is file-lf.txt^M
    < and it has lf line ending.^M
    ---^M
    > the name of this file is file-cr-lf.txt^M
    > and it has cr-lf line ending.^M

    D:\gnu\patches>

The files on your site indicate that the GnuWin32 test failed, but I
think this is because you used a port of Diff that is not the GnuWin32
port.  You need to use a coherent set of ported utilities that behave
similarly wrt the line-endings issue, otherwise you _will_ get weird
and unexpected failures.

(Btw, when I downloaded file-cr-lf.txt from your site by
right-clicking on it and selecting "Save target as...", it wound up on
my machine with Unix-style LF-only EOLs.  So I'm afraid some people
that will try your tests might get incorrect results if they are not
careful enough to convert file-cr-lf.txt to DOS EOL format first.
Caveat emptor!)

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