[PATCH] Add git-relink-script to fix up missing hardlinks

This will scan 2 or more object repositories and look for common objects, check
if they are hardlinked, and replace one with a hardlink to the other if not.

This version warns when skipping files because of size differences, and
handle more than 2 repositories automatically.

Signed-off-by: Ryan Anderson <ryan@michonline.com>
Cheered-on-by: Jeff Garzik <jgarzik@pobox.com>
Acked-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/Makefile b/Makefile
index d9aae01f5598d4a349732f13bed2c1ac5bdc694a..e74b90bfeb3652ff2e8224b5771ce8d3df502e8f 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -25,7 +25,7 @@ SCRIPTS=git git-apply-patch-script git-merge-one-file-script git-prune-script \
        git-deltafy-script git-fetch-script git-status-script git-commit-script \
        git-log-script git-shortlog git-cvsimport-script git-diff-script \
        git-reset-script git-add-script git-checkout-script git-clone-script \
-       gitk git-cherry git-rebase-script
+       gitk git-cherry git-rebase-script git-relink-script
 
 PROG=   git-update-cache git-diff-files git-init-db git-write-tree \
        git-read-tree git-commit-tree git-cat-file git-fsck-cache \

diff --git a/git-relink-script b/git-relink-script
new file mode 100644 (file)
index 0000000..f6b4f6a
--- /dev/null
+++ b/git-relink-script
@@ -0,0 +1,173 @@
+#!/usr/bin/env perl
+# Copyright 2005, Ryan Anderson <ryan@michonline.com>
+# Distribution permitted under the GPL v2, as distributed
+# by the Free Software Foundation.
+# Later versions of the GPL at the discretion of Linus Torvalds
+#
+# Scan two git object-trees, and hardlink any common objects between them.
+
+use 5.006;
+use strict;
+use warnings;
+use Getopt::Long;
+
+sub get_canonical_form($);
+sub do_scan_directory($$$);
+sub compare_two_files($$);
+sub usage();
+sub link_two_files($$);
+
+# stats
+my $total_linked = 0;
+my $total_already = 0;
+my ($linked,$already);
+
+my $fail_on_different_sizes = 0;
+my $help = 0;
+GetOptions("safe" => \$fail_on_different_sizes,
+          "help" => \$help);
+
+usage() if $help;
+
+my (@dirs) = @ARGV;
+
+usage() if (!defined $dirs[0] || !defined $dirs[1]);
+
+$_ = get_canonical_form($_) foreach (@dirs);
+
+my $master_dir = pop @dirs;
+
+opendir(D,$master_dir . "objects/")
+       or die "Failed to open $master_dir/objects/ : $!";
+
+my @hashdirs = grep !/^\.{1,2}$/, readdir(D);
+
+foreach my $repo (@dirs) {
+       $linked = 0;
+       $already = 0;
+       printf("Searching '%s' and '%s' for common objects and hardlinking them...\n",
+               $master_dir,$repo);
+
+       foreach my $hashdir (@hashdirs) {
+               do_scan_directory($master_dir, $hashdir, $repo);
+       }
+
+       printf("Linked %d files, %d were already linked.\n",$linked, $already);
+
+       $total_linked += $linked;
+       $total_already += $already;
+}
+
+printf("Totals: Linked %d files, %d were already linked.\n",
+       $total_linked, $total_already);
+
+
+sub do_scan_directory($$$) {
+       my ($srcdir, $subdir, $dstdir) = @_;
+
+       my $sfulldir = sprintf("%sobjects/%s/",$srcdir,$subdir);
+       my $dfulldir = sprintf("%sobjects/%s/",$dstdir,$subdir);
+
+       opendir(S,$sfulldir)
+               or die "Failed to opendir $sfulldir: $!";
+
+       foreach my $file (grep(!/\.{1,2}$/, readdir(S))) {
+               my $sfilename = $sfulldir . $file;
+               my $dfilename = $dfulldir . $file;
+
+               compare_two_files($sfilename,$dfilename);
+
+       }
+       closedir(S);
+}
+
+sub compare_two_files($$) {
+       my ($sfilename, $dfilename) = @_;
+
+       # Perl's stat returns relevant information as follows:
+       # 0 = dev number
+       # 1 = inode number
+       # 7 = size
+       my @sstatinfo = stat($sfilename);
+       my @dstatinfo = stat($dfilename);
+
+       if (@sstatinfo == 0 && @dstatinfo == 0) {
+               die sprintf("Stat of both %s and %s failed: %s\n",$sfilename, $dfilename, $!);
+
+       } elsif (@dstatinfo == 0) {
+               return;
+       }
+
+       if ( ($sstatinfo[0] == $dstatinfo[0]) &&
+            ($sstatinfo[1] != $dstatinfo[1])) {
+               if ($sstatinfo[7] == $dstatinfo[7]) {
+                       link_two_files($sfilename, $dfilename);
+
+               } else {
+                       my $err = sprintf("ERROR: File sizes are not the same, cannot relink %s to %s.\n",
+                               $sfilename, $dfilename);
+                       if ($fail_on_different_sizes) {
+                               die $err;
+                       } else {
+                               warn $err;
+                       }
+               }
+
+       } elsif ( ($sstatinfo[0] == $dstatinfo[0]) &&
+            ($sstatinfo[1] == $dstatinfo[1])) {
+               $already++;
+       }
+}
+
+sub get_canonical_form($) {
+       my $dir = shift;
+       my $original = $dir;
+
+       die "$dir is not a directory." unless -d $dir;
+
+       $dir .= "/" unless $dir =~ m#/$#;
+       $dir .= ".git/" unless $dir =~ m#\.git/$#;
+
+       die "$original does not have a .git/ subdirectory.\n" unless -d $dir;
+
+       return $dir;
+}
+
+sub link_two_files($$) {
+       my ($sfilename, $dfilename) = @_;
+       my $tmpdname = sprintf("%s.old",$dfilename);
+       rename($dfilename,$tmpdname)
+               or die sprintf("Failure renaming %s to %s: %s",
+                       $dfilename, $tmpdname, $!);
+
+       if (! link($sfilename,$dfilename)) {
+               my $failtxt = "";
+               unless (rename($tmpdname,$dfilename)) {
+                       $failtxt = sprintf(
+                               "Git Repository containing %s is probably corrupted, " .
+                               "please copy '%s' to '%s' to fix.\n",
+                               $tmpdname, $dfilename);
+               }
+
+               die sprintf("Failed to link %s to %s: %s\n%s" .
+                       $sfilename, $dfilename,
+                       $!, $dfilename, $failtxt);
+       }
+
+       unlink($tmpdname)
+               or die sprintf("Unlink of %s failed: %s\n",
+                       $dfilename, $!);
+
+       $linked++;
+}
+
+
+sub usage() {
+       print("Usage: $0 [--safe] <dir> [<dir> ...] <master_dir> \n");
+       print("All directories should contain a .git/objects/ subdirectory.\n");
+       print("Options\n");
+       print("\t--safe\t" .
+               "Stops if two objects with the same hash exist but " .
+               "have different sizes.  Default is to warn and continue.\n");
+       exit(1);
+}