Revision control
++ #!/usr/bin/perl -w
++ ####################################################################################################
++ #
++ # git-qt-grafts
++ #
++ # Sets up the proper grafts for a Qt repository
++ #
++ # Copyright (C) 2015 The Qt Company Ltd.
++ # Contact: http://www.qt.io/licensing/
++ #
++ ####################################################################################################
++
++ use File::Basename;
++ use Cwd 'abs_path';
++ use strict;
++
++ my $history_location;
++
++ # Syntax: fileContents(filename)
++ # Returns: String with contents of the file, or empty string if file
++ # doens't exist.
++ sub fileContents {
++ my ($filename) = @_;
++ my $filecontents = "";
++ if (-e $filename) {
++ my $FD;
++ open($FD, "< $filename") || die "Could not open $filename for reading, read block?";
++ local $/;
++ binmode $FD;
++ $filecontents = <$FD>;
++ close $FD;
++ }
++ return $filecontents;
++ }
++
++ sub fileContains {
++ my ($filename, $text) = @_;
++ # purposely not using perl grep here
++ foreach my $line (split /\n/, fileContents("$filename")) {
++ return 1 if ("$line" eq "$text");
++ }
++ return 0;
++ }
++
++ sub showUsage {
++ my $prg = basename($0);
++ print "Usage: $prg <path to Qt history>:\n";
++ }
++
++ while ( @ARGV ) {
++ my $arg = shift @ARGV;
++ if ($arg eq "-?" || $arg eq "-h" || $arg eq "-help" || $arg eq "?") {
++ showUsage();
++ exit 0;
++ } elsif (!$history_location) {
++ $history_location = $arg;
++ } else {
++ print "Unknown option: $arg\n\n";
++ showUsage();
++ exit 1;
++ }
++ }
++
++ # Get current git-dir
++ my $git_dir = `git rev-parse --git-dir`;
++ chomp $git_dir;
++ if (!$git_dir) {
++ print "Cannot find any Git dir!\n";
++ exit 1;
++ }
++
++ # validate path for history repo
++ if (!$history_location || !-e $history_location) {
++ print "You need to provide a path to the monolithic Qt repo!\n";
++ exit 1;
++ }
++ my $history_git_dir = `cd $history_location && git rev-parse --git-dir`;
++ chomp $history_git_dir;
++ if (!$history_git_dir || !-e "$history_location/$history_git_dir/objects") {
++ print "Monolithic Qt repo path is not a valid Git repo!\n";
++ exit 1;
++ }
++ $history_git_dir = abs_path("$history_location/$history_git_dir");
++ my $history_alternates_objects = "$history_git_dir/objects";
++
++ # check if we already point to this alternate object store
++ my $git_alternates_file = "$git_dir/objects/info/alternates";
++ my $found_alternate = fileContains($git_alternates_file, $history_alternates_objects);
++
++ # get first commit SHA1 of this repo which mentions branching from a commit
++ my $GIT_REVLIST;
++ my $git_pid = open($GIT_REVLIST, "git rev-list --reverse --grep='Branched from .*at commit' HEAD |")
++ or die ("Failed to launch Git");
++ my @commits;
++ while (<$GIT_REVLIST>) {
++ chomp;
++ push(@commits, $_);
++ }
++ close($GIT_REVLIST);
++
++ my $found_any_grafts = 0;
++ mkdir("$git_dir/info");
++ my $graft_file = "$git_dir/info/grafts";
++ my @graft_lines;
++
++ foreach my $commit (@commits) {
++ # find the graft point which the commit mentions
++ my $commit_msg = `git show -s --format=%b $commit`;
++ my $graft_to_commit = $commit_msg;
++ $graft_to_commit =~ s/^.+Branched from .+at commit\n([a-f0-9]+)\n.*/$1/s;
++ next if (!$graft_to_commit || $graft_to_commit eq $commit_msg);
++
++ # Preserve any existing parents of the commit.
++ my @existing_parents;
++ my $GIT_CAT_FILE;
++ open($GIT_CAT_FILE, "git cat-file commit $commit |") or die ("Failed to launch Git");
++ while (<$GIT_CAT_FILE>) {
++ if (/^parent ([0-9a-z]{40})/i) {
++ push(@existing_parents, $1);
++ }
++ }
++ close($GIT_CAT_FILE);
++
++ # check that we don't already have this graft already setup
++ my $graft_line = "$commit $graft_to_commit";
++ $graft_line .= " " . join(" ", @existing_parents) if (@existing_parents);
++ my $found_graft = fileContains($graft_file, $graft_line);
++ if ($found_graft) {
++ print "Graft for $commit already exists. Skipping...\n";
++ $found_any_grafts = 1;
++ next;
++ }
++
++ # verify that alternate object store contains the commit we want to graft to
++ if (system("cd $history_location && git cat-file -e $graft_to_commit") != 0) {
++ print "History repo ($history_location) does not contain commit $graft_to_commit!\n";
++ print "Skipping this graft...\n";
++ next;
++ }
++
++ print "Grafted $commit -> $graft_to_commit\n";
++ push(@graft_lines, $graft_line);
++ $found_any_grafts = 1;
++ }
++ if (!$found_any_grafts) {
++ print "This repo does not refer to a graft point, so no grafts added!\n";
++ exit 0;
++ }
++
++ # if our alternates file didn't contain the "history repo" path already
++ # add its path now
++ if (!$found_alternate) {
++ my $ALTERNATES_FILE;
++ open($ALTERNATES_FILE, ">> $git_alternates_file") || die "Could not open $git_alternates_file for writing, wrong permissions?";
++ print $ALTERNATES_FILE "$history_alternates_objects\n";
++ # Add alternates from alternates file in the history repo, in case it has additional alternates.
++ my $HISTORY_ALTERNATES_FILE;
++ if (open($HISTORY_ALTERNATES_FILE, "< $history_git_dir/objects/info/alternates")) {
++ print("Reusing existing alternates in history repository\n");
++ while (<$HISTORY_ALTERNATES_FILE>) {
++ chomp;
++ print $ALTERNATES_FILE $_ if (!fileContains($git_alternates_file, $_));
++ }
++ close($HISTORY_ALTERNATES_FILE);
++ }
++ close($ALTERNATES_FILE);
++ }
++
++ # Add graft lines from graft file in the history repo, in case it has additional grafts.
++ my $HISTORY_GRAFT_FILE;
++ if (open($HISTORY_GRAFT_FILE, "< $history_git_dir/info/grafts")) {
++ print("Reusing existing grafts in history repository\n");
++ while (<$HISTORY_GRAFT_FILE>) {
++ chomp;
++ push(@graft_lines, $_) if (!fileContains($graft_file, $_));
++ }
++ close($HISTORY_GRAFT_FILE);
++ }
++
++ # add graft
++ if (@graft_lines) {
++ my $GRAFT_FILE;
++ open($GRAFT_FILE, ">> $graft_file") || die "Could not open $graft_file for writing, wrong permissions?";
++ print $GRAFT_FILE join("\n", @graft_lines) . "\n";
++ close($GRAFT_FILE);
++ }