--- /dev/null
+git-cvsexportcommit(1)
+================
+
+NAME
+----
+git-cvsexportcommit - Export a commit to a CVS checkout
+
+
+SYNOPSIS
+--------
+git-cvsapplycommmit.perl
+ [ -h ] [ -v ] [ -c ] [ -p ] [PARENTCOMMIT] COMMITID
+
+
+DESCRIPTION
+-----------
+Exports a commit from GIT to a CVS checkout, making it easier
+to merge patches from a git repository into a CVS repository.
+
+Execute it from the root of the CVS working copy. GIT_DIR must be defined.
+
+It does its best to do the safe thing, it will check that the files are
+unchanged and up to date in the CVS checkout, and it will not autocommit
+by default.
+
+Supports file additions, removals, and commits that affect binary files.
+
+If the commit is a merge commit, you must tell git-cvsapplycommit what parent
+should the changeset be done against.
+
+OPTIONS
+-------
+
+-c::
+ Commit automatically if the patch applied cleanly. It will not
+ commit if any hunks fail to apply or there were other problems.
+
+-p::
+ Be pedantic (paranoid) when applying patches. Invokes patch with
+ --fuzz=0
+
+-v::
+ Verbose.
+
+Author
+------
+Written by Martin Langhoff <martin@catalyst.net.nz>
+
+Documentation
+--------------
+Documentation by Martin Langhoff <martin@catalyst.net.nz>
+
+GIT
+---
+Part of the gitlink:git[7] suite
+
--- /dev/null
+#!/usr/bin/perl -w
+
+use strict;
+use Getopt::Std;
+use File::Temp qw(tempdir);
+use Data::Dumper;
+
+unless ($ENV{GIT_DIR} && -r $ENV{GIT_DIR}){
+ die "GIT_DIR is not defined or is unreadable";
+}
+
+our ($opt_h, $opt_p, $opt_v, $opt_c );
+
+getopt('hpvc');
+
+$opt_h && usage();
+
+die "Need at least one commit identifier!" unless @ARGV;
+
+# setup a tempdir
+our ($tmpdir, $tmpdirname) = tempdir('git-cvsapplycommit-XXXXXX',
+ TMPDIR => 1,
+ CLEANUP => 1);
+
+print Dumper(@ARGV);
+# resolve target commit
+my $commit;
+$commit = pop @ARGV;
+$commit = `git-rev-parse --verify "$commit"^0`;
+chomp $commit;
+if ($?) {
+ die "The commit reference $commit did not resolve!";
+}
+
+# resolve what parent we want
+my $parent;
+if (@ARGV) {
+ $parent = pop @ARGV;
+ $parent = `git-rev-parse --verify "$parent"^0"`;
+ chomp $parent;
+ if ($?) {
+ die "The parent reference did not resolve!";
+ }
+}
+
+# find parents from the commit itself
+my @commit = `git-cat-file commit $commit`;
+my @parents;
+foreach my $p (@commit) {
+ if ($p =~ m/^$/) { # end of commit headers, we're done
+ last;
+ }
+ if ($p =~ m/^parent (\w{40})$/) { # found a parent
+ push @parents, $1;
+ }
+}
+
+if ($parent) {
+ # double check that it's a valid parent
+ foreach my $p (@parents) {
+ my $found;
+ if ($p eq $parent) {
+ $found = 1;
+ last;
+ }; # found it
+ die "Did not find $parent in the parents for this commit!";
+s }
+} else { # we don't have a parent from the cmdline...
+ if (@parents == 1) { # it's safe to get it from the commit
+ $parent = $parents[0];
+ } else { # or perhaps not!
+ die "This commit has more than one parent -- please name the parent you want to use explicitly";
+ }
+}
+
+$opt_v && print "Applying to CVS commit $commit from parent $parent\n";
+
+# grab the commit message
+`git-cat-file commit $commit | sed -e '1,/^\$/d' > .msg`;
+$? && die "Error extraction the commit message";
+
+my (@afiles, @dfiles, @mfiles);
+my @files = `git-diff-tree -r $parent $commit`;
+print @files;
+$? && die "Error in git-diff-tree";
+foreach my $f (@files) {
+ chomp $f;
+ my @fields = split(m/\s+/, $f);
+ if ($fields[4] eq 'A') {
+ push @afiles, $fields[5];
+ }
+ if ($fields[4] eq 'M') {
+ push @mfiles, $fields[5];
+ }
+ if ($fields[4] eq 'R') {
+ push @dfiles, $fields[5];
+ }
+}
+$opt_v && print "The commit affects:\n ";
+$opt_v && print join ("\n ", @afiles,@mfiles,@dfiles) . "\n\n";
+undef @files; # don't need it anymore
+
+# check that the files are clean and up to date according to cvs
+my $dirty;
+foreach my $f (@afiles, @mfiles, @dfiles) {
+ # TODO:we need to handle removed in cvs and/or new (from git)
+ my $status = `cvs -q status "$f" | grep '^File: '`;
+
+ unless ($status =~ m/Status: Up-to-date$/) {
+ $dirty = 1;
+ warn "File $f not up to date in your CVS checkout!\n";
+ }
+}
+if ($dirty) {
+ die "Exiting: your CVS tree is not clean for this merge.";
+}
+
+###
+### NOTE: if you are planning to die() past this point
+### you MUST call cleanupcvs(@files) before die()
+###
+
+
+print "'Patching' binary files\n";
+
+my @bfiles = `git-diff-tree -p $parent $commit | grep '^Binary'`;
+@bfiles = map { chomp } @bfiles;
+foreach my $f (@bfiles) {
+ # check that the file in cvs matches the "old" file
+ # extract the file to $tmpdir and comparre with cmp
+ my $tree = `git-rev-parse $parent^{tree} `;
+ chomp $tree;
+ my $blob = `git-ls-tree $tree "$f" | cut -f 1 | cut -d ' ' -f 3`;
+ chomp $blob;
+ `git-cat-file blob $blob > $tmpdir/blob`;
+ `cmp -q $f $tmpdir/blob`;
+ if ($?) {
+ warn "Binary file $f in CVS does not match parent.\n";
+ $dirty = 1;
+ next;
+ }
+
+ # replace with the new file
+ `git-cat-file blob $blob > $f`;
+
+ # TODO: something smart with file modes
+
+}
+if ($dirty) {
+ cleanupcvs(@files);
+ die "Exiting: Binary files in CVS do not match parent";
+}
+
+## apply non-binary changes
+my $fuzz = $opt_p ? 0 : 2;
+
+print "Patching non-binary files\n";
+print `(git-diff-tree -p $parent -p $commit | patch -p1 -F $fuzz ) 2>&1`;
+
+my $dirtypatch = 0;
+if (($? >> 8) == 2) {
+ cleanupcvs(@files);
+ die "Exiting: Patch reported serious trouble -- you will have to apply this patch manually";
+} elsif (($? >> 8) == 1) { # some hunks failed to apply
+ $dirtypatch = 1;
+}
+
+foreach my $f (@afiles) {
+ `cvs add $f`;
+ if ($?) {
+ $dirty = 1;
+ warn "Failed to cvs add $f -- you may need to do it manually";
+ }
+}
+
+foreach my $f (@dfiles) {
+ `cvs rm -f $f`;
+ if ($?) {
+ $dirty = 1;
+ warn "Failed to cvs rm -f $f -- you may need to do it manually";
+ }
+}
+
+print "Commit to CVS\n";
+my $commitfiles = join(' ', @afiles, @mfiles, @dfiles);
+my $cmd = "cvs commit -F .msg $commitfiles";
+
+if ($dirtypatch) {
+ print "NOTE: One or more hunks failed to apply cleanly.\n";
+ print "Resolve the conflicts and then commit using:n";
+ print "\n $cmd\n\n";
+ exit;
+}
+
+
+if ($opt_c) {
+ print "Autocommit\n $cmd\n";
+ print `cvs commit -F .msg $commitfiles 2>&1`;
+ if ($?) {
+ cleanupcvs(@files);
+ die "Exiting: The commit did not succeed";
+ }
+ print "Committed successfully to CVS\n";
+} else {
+ print "Ready for you to commit, just run:\n\n $cmd\n";
+}
+sub usage {
+ print STDERR <<END;
+Usage: GIT_DIR=/path/to/.gi ${\basename $0} # fetch/update GIT from CVS
+ [-h] [-p] [ parent ] commit
+END
+ exit(1);
+}
+
+# ensure cvs is clean before we die
+sub cleanupcvs {
+ my @files = @_;
+ foreach my $f (@files) {
+ `cvs -q update -C "$f"`;
+ if ($?) {
+ warn "Warning! Failed to cleanup state of $f\n";
+ }
+ }
+}
+