Add 'git svn reset' to unwind 'git svn fetch'

Add a command to unwind the effects of fetch by moving the rev_map
and refs/remotes/git-svn back to an old SVN revision.  This allows
revisions to be re-fetched.  Ideally SVN revs would be immutable,
but permissions changes in the SVN repository or indiscriminate use
of '--ignore-paths' can create situations where fetch cannot make
progress.

Signed-off-by: Ben Jackson <ben@ben.com>
Acked-by: Eric Wong <normalperson@yhbt.net>

diff --git a/Documentation/git-svn.txt b/Documentation/git-svn.txt
index 5027f9fbd727ab996ce1fb48a21f34296950e471..3f0fa5e6f1b3485232cc5045252e251a575f9111 100644 (file)
--- a/Documentation/git-svn.txt
+++ b/Documentation/git-svn.txt
@@ -216,7 +216,7 @@ config key: svn.commiturl (overwrites all svn-remote.<name>.commiturl options)
 The following features from `svn log' are supported:
 +
 --
---revision=<n>[:<n>];;
+-r/--revision=<n>[:<n>];;
        is supported, non-numeric args are not:
        HEAD, NEXT, BASE, PREV, etc ...
 -v/--verbose;;
@@ -314,6 +314,63 @@ Any other arguments are passed directly to 'git-log'
        Shows the Subversion externals.  Use -r/--revision to specify a
        specific revision.
 
+'reset'::
+       Undoes the effects of 'fetch' back to the specified revision.
+       This allows you to re-'fetch' an SVN revision.  Normally the
+       contents of an SVN revision should never change and 'reset'
+       should not be necessary.  However, if SVN permissions change,
+       or if you alter your --ignore-paths option, a 'fetch' may fail
+       with "not found in commit" (file not previously visible) or
+       "checksum mismatch" (missed a modification).  If the problem
+       file cannot be ignored forever (with --ignore-paths) the only
+       way to repair the repo is to use 'reset'.
+
+Only the rev_map and refs/remotes/git-svn are changed.  Follow 'reset'
+with a 'fetch' and then 'git-reset' or 'git-rebase' to move local
+branches onto the new tree.
+
+-r/--revision=<n>;;
+       Specify the most recent revision to keep.  All later revisions
+       are discarded.
+-p/--parent;;
+       Discard the specified revision as well, keeping the nearest
+       parent instead.
+Example:;;
+Assume you have local changes in "master", but you need to refetch "r2".
+
+------------
+    r1---r2---r3 remotes/git-svn
+                \
+                 A---B master
+------------
+
+Fix the ignore-paths or SVN permissions problem that caused "r2" to
+be incomplete in the first place.  Then:
+
+[verse]
+git svn reset -r2 -p
+git svn fetch
+
+------------
+    r1---r2'--r3' remotes/git-svn
+      \
+       r2---r3---A---B master
+------------
+
+Then fixup "master" with 'git-rebase'.
+Do NOT use 'git-merge' or your history will not be compatible with a
+future 'dcommit'!
+
+[verse]
+git rebase --onto remotes/git-svn A^ master
+
+------------
+    r1---r2'--r3' remotes/git-svn
+                \
+                 A'--B' master
+------------
+
+
 --
 
 OPTIONS

diff --git a/git-svn.perl b/git-svn.perl
index f9a672d772e4d586edd18556aa653950b985ec5b..b1245cbab2ec7303482d7405e594ba666dfc3f58 100755 (executable)
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -211,6 +211,10 @@ my %cmd = (
        'blame' => [ \&Git::SVN::Log::cmd_blame,
                    "Show what revision and author last modified each line of a file",
                    { 'git-format' => \$_git_format } ],
+       'reset' => [ \&cmd_reset,
+                    "Undo fetches back to the specified SVN revision",
+                    { 'revision|r=s' => \$_revision,
+                      'parent|p' => \$_fetch_parent } ],
 );
 
 my $cmd;
@@ -1054,6 +1058,20 @@ sub cmd_info {
        print $result, "\n";
 }
 
+sub cmd_reset {
+       my $target = shift || $_revision or die "SVN revision required\n";
+       $target = $1 if $target =~ /^r(\d+)$/;
+       $target =~ /^\d+$/ or die "Numeric SVN revision expected\n";
+       my ($url, $rev, $uuid, $gs) = working_head_info('HEAD');
+       unless ($gs) {
+               die "Unable to determine upstream SVN information from ".
+                   "history\n";
+       }
+       my ($r, $c) = $gs->find_rev_before($target, not $_fetch_parent);
+       $gs->rev_map_set($r, $c, 'reset', $uuid);
+       print "r$r = $c ($gs->{ref_id})\n";
+}
+
 ########################### utility functions #########################
 
 sub rebase_cmd {
@@ -3023,6 +3041,14 @@ sub _rev_map_set {
          croak "write: $!";
 }
 
+sub _rev_map_reset {
+       my ($fh, $rev, $commit) = @_;
+       my $c = _rev_map_get($fh, $rev);
+       $c eq $commit or die "_rev_map_reset(@_) commit $c does not match!\n";
+       my $offset = sysseek($fh, 0, SEEK_CUR) or croak "seek: $!";
+       truncate $fh, $offset or croak "truncate: $!";
+}
+
 sub mkfile {
        my ($path) = @_;
        unless (-e $path) {
@@ -3039,6 +3065,7 @@ sub rev_map_set {
        my $db = $self->map_path($uuid);
        my $db_lock = "$db.lock";
        my $sig;
+       $update_ref ||= 0;
        if ($update_ref) {
                $SIG{INT} = $SIG{HUP} = $SIG{TERM} = $SIG{ALRM} = $SIG{PIPE} =
                            $SIG{USR1} = $SIG{USR2} = sub { $sig = $_[0] };
@@ -3062,7 +3089,8 @@ sub rev_map_set {
 
        sysopen(my $fh, $db_lock, O_RDWR | O_CREAT)
             or croak "Couldn't open $db_lock: $!\n";
-       _rev_map_set($fh, $rev, $commit);
+       $update_ref eq 'reset' ? _rev_map_reset($fh, $rev, $commit) :
+                                _rev_map_set($fh, $rev, $commit);
        if ($sync) {
                $fh->flush or die "Couldn't flush $db_lock: $!\n";
                $fh->sync or die "Couldn't sync $db_lock: $!\n";
@@ -3070,7 +3098,9 @@ sub rev_map_set {
        close $fh or croak $!;
        if ($update_ref) {
                $_head = $self;
-               command_noisy('update-ref', '-m', "r$rev",
+               my $note = "";
+               $note = " ($update_ref)" if ($update_ref !~ /^\d*$/);
+               command_noisy('update-ref', '-m', "r$rev$note",
                              $self->refname, $commit);
        }
        rename $db_lock, $db or die "rev_map_set(@_): ", "Failed to rename: ",
@@ -3132,12 +3162,19 @@ sub rev_map_get {
        return undef unless -e $map_path;
 
        sysopen(my $fh, $map_path, O_RDONLY) or croak "open: $!";
+       my $c = _rev_map_get($fh, $rev);
+       close($fh) or croak "close: $!";
+       $c
+}
+
+sub _rev_map_get {
+       my ($fh, $rev) = @_;
+
        binmode $fh or croak "binmode: $!";
        my $size = (stat($fh))[7];
        ($size % 24) == 0 or croak "inconsistent size: $size";
 
        if ($size == 0) {
-               close $fh or croak "close: $fh";
                return undef;
        }
 
@@ -3155,11 +3192,9 @@ sub rev_map_get {
                } elsif ($r > $rev) {
                        $u = $i - 24;
                } else { # $r == $rev
-                       close($fh) or croak "close: $!";
                        return $c eq ('0' x 40) ? undef : $c;
                }
        }
-       close($fh) or croak "close: $!";
        undef;
 }
 

diff --git a/t/t9139-git-svn-reset.sh b/t/t9139-git-svn-reset.sh
new file mode 100755 (executable)
index 0000000..0735526
--- /dev/null
+++ b/t/t9139-git-svn-reset.sh
@@ -0,0 +1,66 @@
+#!/bin/sh
+#
+# Copyright (c) 2009 Ben Jackson
+#
+
+test_description='git svn reset'
+. ./lib-git-svn.sh
+
+test_expect_success 'setup test repository' '
+       svn_cmd co "$svnrepo" s &&
+       (
+               cd s &&
+               mkdir vis &&
+               echo always visible > vis/vis.txt &&
+               svn_cmd add vis &&
+               svn_cmd commit -m "create visible files" &&
+               mkdir hid &&
+               echo initially hidden > hid/hid.txt &&
+               svn_cmd add hid &&
+               svn_cmd commit -m "create initially hidden files" &&
+               svn_cmd up &&
+               echo mod >> vis/vis.txt &&
+               svn_cmd commit -m "modify vis" &&
+               svn_cmd up
+       )
+'
+
+test_expect_success 'clone SVN repository with hidden directory' '
+       git svn init "$svnrepo" g &&
+       ( cd g && git svn fetch --ignore-paths="^hid" )
+'
+
+test_expect_success 'modify hidden file in SVN repo' '
+       ( cd s &&
+         echo mod hidden >> hid/hid.txt &&
+         svn_cmd commit -m "modify hid" &&
+         svn_cmd up
+       )
+'
+
+test_expect_success 'fetch fails on modified hidden file' '
+       ( cd g &&
+         git svn find-rev refs/remotes/git-svn > ../expect &&
+         ! git svn fetch 2> ../errors &&
+         git svn find-rev refs/remotes/git-svn > ../expect2 ) &&
+       fgrep "not found in commit" errors &&
+       test_cmp expect expect2
+'
+
+test_expect_success 'reset unwinds back to r1' '
+       ( cd g &&
+         git svn reset -r1 &&
+         git svn find-rev refs/remotes/git-svn > ../expect2 ) &&
+       echo 1 >expect &&
+       test_cmp expect expect2
+'
+
+test_expect_success 'refetch succeeds not ignoring any files' '
+       ( cd g &&
+         git svn fetch &&
+         git svn rebase &&
+         fgrep "mod hidden" hid/hid.txt
+       )
+'
+
+test_done