Re: Detecting CR eol

On Wednesday 08 Sep 2010, Csaba Raduly wrote:
> Hi Giulio,
>
> On Wed, Sep 8, 2010 at 10:25 AM, Giulio Troccoli wrote:
> > I am writing a pre-commit hook script in perl. One of the requirement is
> > that all files (luckily they are all text files) have the svn:eol-style
> > property set to LF and the actual eol is indeed LF. If that's not the
> > case I will reject the commit and direct the user to a page on our
> > intranet to explain what to do to fix it.
> >
> > My problem is how to detect whether the eol is LF and nothing else. I'm
> > developing on Linux (Centos 5) and Perl 5.10. Subversion is 1.6.9, if it
> > matters.
> >
> > I thought about using the dos2unix utility (we only use Windows or Linux)
> > and then check that the file hasn't changed, but it seems a lot of
> > processing.
> >
> > My second idea was to use a regular expression to check each line of each
> > file. This way at least I would stop as soon as I find an eol that is not
> > LF, saving some processing. I still need to svn cat each file into an
> > array I think.
>
> You need to use svnlook cat, but there is no need to read all its
> output into memory. You can process it line-by-line.
> Here's an outline (completely untested)
>
> #!/usr/bin/perl -w
> use strict;
>
> my ($REPOS, $TXN) = @ARGV;
>
> my $crlf = 0;
>
> ... determine the list of files
> my @files = `svnlook changed -t $TXN $REPOS`;
> chomp @files; # remove the newline at the end
> s/^U\s+// for @files; # remove the leading U
>
> FILE:
> foreach my $file (@files) {
> open (SVN, "svnlook cat $file |") or die "open pipe failed: $!"
> while (<SVN>) # read from the pipe, one line at a time
> {
> chomp; # cut the platform-specific line end. On Unix, this drops
> the \n but keeps the \r
> if ( /^M$/ ) { # last character is a \r (a.k.a. Control-M)
> $crlf = 1; last FILE;
> }
> }
> close(SVN) or die "close pipe failed: $!" # it is very important to
> check the close on pipes
> }
>
> if ($crlf)
> {
> die "$file contains DOS line endings";
> }

I don't believe you have to go to so much trouble in the pre-commit hook. If
you have set the svn:eol-style property then subversion will ensure the file
has those line endings on checkout and update them when committing into the
repository. So all the hook needs to do is check for the property. See the
book for more details

http://svnbook.red-bean.com/nightly/en/svn-book.html#svn.advanced.props.special.eol-style

I'd also normally expect the line ending style to be set to native so windows
and unix users don't trample the existing incompatible line endings. The only
reason perhaps for checking each file explicitly would be if there was
something else needing the files to be in a particular format, ie releases to
customers from a developer machine rather than an official build server that
would check out a clean copy each time.

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