* Add support for using git instead of subversion as the RCS backend,

  tremendous thanks to Recai Oktaş for this.
* Doc updates for git.

1 files changed, 491 insertions, 0 deletions

diff --git a/IkiWiki/Rcs/git.pm b/IkiWiki/Rcs/git.pm
new file mode 100644
index 000000000..374904fd3
--- /dev/null
+++ b/IkiWiki/Rcs/git.pm
@@ -0,0 +1,491 @@
+#!/usr/bin/perl
+# Git backend for IkiWiki.
+# Copyright 2006  Recai Oktaş <roktas@debian.org>
+#
+# Licensed under the same terms as IkiWiki.
+
+use warnings;
+use strict;
+use IkiWiki;
+
+package IkiWiki;
+
+my $origin_branch    = 'origin';            # Git ref for main repository
+my $master_branch    = 'master';            # Working branch
+my $sha1_pattern     = qr/[0-9a-fA-F]{40}/; # pattern to validate Git sha1sums
+my $dummy_commit_msg = 'dummy commit';      # will be used in all dummy commits
+				            # and skipped in recent changes list
+my $web_commit_msg   = qr/^web commit by (\w+):?(.*)/; # pattern for web commits
+
+sub _safe_git (&@) { #{{{
+	# Start a child process safely without resorting /bin/sh.
+	# Return command output or success state (in scalar context).
+
+	my ($error_handler, @cmdline) = @_;
+
+	my $pid = open my $OUT, "-|";
+
+	error("Cannot fork: $!") if !defined $pid;
+
+	if (!$pid) {
+		# In child.
+		open STDERR, ">&STDOUT"
+		    or error("Cannot dup STDOUT: $!");
+		# Git commands want to be in wc.
+		chdir $config{srcdir}
+		    or error("Cannot chdir to $config{srcdir}: $!");
+		exec @cmdline or error("Cannot exec '@cmdline': $!");
+	}
+	# In parent.
+
+	my @lines;
+	while (<$OUT>) {
+		chomp;
+		push @lines, $_;
+	}
+
+	close $OUT;
+
+	($error_handler || sub { })->("'@cmdline' failed: $!") if $?;
+
+	return wantarray ? @lines : ($? == 0);
+}
+# Convenient wrappers.
+sub run_or_die ($@) { _safe_git(\&IkiWiki::error, @_) }
+sub run_or_cry ($@) { _safe_git(sub { warn @_ },  @_) }
+sub run_or_non ($@) { _safe_git(undef,            @_) }
+#}}}
+
+sub _merge_past ($$$) { #{{{
+	# Unlike with Subversion, Git cannot make a 'svn merge -rN:M file'.
+	# Git merge commands work with the committed changes, except in the
+	# implicit case of '-m' of git-checkout(1).  So we should invent a
+	# kludge here.  In principle, we need to create a throw-away branch
+	# in preparing for the merge itself.  Since branches are cheap (and
+	# branching is fast), this shouldn't cost high.
+	#
+	# The main problem is the presence of _uncommitted_ local changes.  One
+	# possible approach to get rid of this situation could be that we first
+	# make a temporary commit in the master branch and later restore the
+	# initial state (this is possible since Git has the ability to undo a
+	# commit, i.e. 'git-reset --soft HEAD^').  The method can be summarized
+	# as follows:
+	#
+	# 	- create a diff of HEAD:current-sha1
+	# 	- dummy commit
+	# 	- create a dummy branch and switch to it
+	# 	- rewind to past (reset --hard to the current-sha1)
+	# 	- apply the diff and commit
+	# 	- switch to master and do the merge with the dummy branch
+	# 	- make a soft reset (undo the last commit of master)
+	#
+	# The above method has some drawbacks: (1) it needs a redundant commit
+	# just to get rid of local changes, (2) somewhat slow because of the
+	# required system forks.  Until someone points a more straight method
+	# (which I would be grateful) I have implemented an alternative method.
+	# In this approach, we hide all the modified files from Git by renaming
+	# them (using the 'rename' builtin) and later restore those files in
+	# the throw-away branch (that is, we put the files themselves instead
+	# of applying a patch).
+
+	my ($sha1, $file, $message) = @_;
+
+	my @undo;      # undo stack for cleanup in case of an error
+	my $conflict;  # file content with conflict markers
+
+	eval {
+		# Hide local changes from Git by renaming the modified file.
+		# Relative paths must be converted to absolute for renaming.
+		my ($target, $hidden) = (
+		    "$config{srcdir}/${file}", "$config{srcdir}/${file}.${sha1}"
+		);
+		rename($target, $hidden)
+		    or error("rename '$target' to '$hidden' failed: $!");
+		# Ensure to restore the renamed file on error.
+		push @undo, sub {
+			return if ! -e "$hidden"; # already renamed
+			rename($hidden, $target)
+			   or debug("rename '$hidden' to '$target' failed: $!");
+		};
+
+		my $branch = "throw_away_${sha1}"; # supposed to be unique
+
+		# Create a throw-away branch and rewind backward.
+		push @undo, sub { run_or_cry('git-branch', '-D', $branch) };
+		run_or_die('git-branch', $branch, $sha1);
+
+		# Switch to throw-away branch for the merge operation.
+		push @undo, sub {
+			if (!run_or_cry('git-checkout', $master_branch)) {
+				run_or_cry('git-checkout','-f',$master_branch);
+			}
+		};
+		run_or_die('git-checkout', $branch);
+
+		# Put the modified file in _this_ branch.
+		rename($hidden, $target)
+		    or error("rename '$hidden' to '$target' failed: $!");
+
+		# _Silently_ commit all modifications in the current branch.
+		run_or_non('git-commit', '-m', $message, '-a');
+		# ... and re-switch to master.
+		run_or_die('git-checkout', $master_branch);
+
+		# Attempt to merge without complaining.
+		if (!run_or_non('git-pull', '--no-commit', '.', $branch)) {
+			$conflict = readfile($target);
+			run_or_die('git-reset', '--hard');
+		}
+	};
+	my $failure = $@;
+
+	# Process undo stack (in reverse order).  By policy cleanup
+	# actions should normally print a warning on failure.
+	while (my $handle = pop @undo) {
+		$handle->();
+	}
+
+	error("Git merge failed!\n$failure\n") if $failure;
+
+	return $conflict;
+} #}}}
+
+sub _parse_diff_tree (@) { #{{{
+	# Parse the raw diff tree chunk and return the info hash.
+	# See git-diff-tree(1) for the syntax.
+
+	my ($dt_ref) = @_;
+
+	# End of stream?
+	return if !defined @{ $dt_ref } || !length @{ $dt_ref }[0];
+
+	my %ci;
+
+	# Header line.
+	HEADER: while (my $line = shift @{ $dt_ref }) {
+		return if $line !~ m/^diff-tree (\S+)/;
+
+		my $sha1 = $1;
+		$ci{'sha1'} = $sha1;
+		last HEADER;
+	}
+
+	# Identification lines for the commit.
+	IDENT: while (my $line = shift @{ $dt_ref }) {
+		# Regexps are semi-stolen from gitweb.cgi.
+		if ($line =~ m/^tree ([0-9a-fA-F]{40})$/) {
+			$ci{'tree'} = $1;
+		} elsif ($line =~ m/^parent ([0-9a-fA-F]{40})$/) {
+			# XXX: collecting in reverse order
+			push @{ $ci{'parents'} }, $1;
+		} elsif ($line =~ m/^(author|committer) (.*) ([0-9]+) (.*)$/) {
+			my ($who, $name, $epoch, $tz) =
+			   ($1,   $2,    $3,     $4 );
+
+			$ci{  $who          } = $name;
+			$ci{ "${who}_epoch" } = $epoch;
+			$ci{ "${who}_tz"    } = $tz;
+
+			if ($name =~ m/^([^<]+) <([^@]+)/) {
+				my ($fullname, $username) = ($1, $2);
+				$ci{"${who}_fullname"}    = $fullname;
+				$ci{"${who}_username"}    = $username;
+			} else {
+				$ci{"${who}_fullname"} =
+					$ci{"${who}_username"} = $name;
+			}
+		} elsif ($line =~ m/^$/) {
+			# Trailing empty line signals next section.
+			last IDENT;
+		}
+	}
+
+	error("No 'tree' or 'parents' seen in diff-tree output")
+	    if !defined $ci{'tree'} || !defined $ci{'parents'};
+
+	$ci{'parent'} = @{ $ci{'parents'} }[0];
+
+	# Commit message.
+	COMMENT: while (my $line = shift @{ $dt_ref }) {
+		if ($line =~ m/^$/) {
+			# Trailing empty line signals next section.
+			last COMMENT;
+		};
+		$line =~ s/^    //;
+		push @{ $ci{'comment'} }, $line;
+	}
+
+	# Modified files.
+	FILE: while (my $line = shift @{ $dt_ref }) {
+		if ($line =~ m{^
+			:([0-7]{6})[ ]       # from mode
+			([0-7]{6})[ ]        # to mode
+			([0-9a-fA-F]{40})[ ] # from sha1
+			([0-9a-fA-F]{40})[ ] # to sha1
+			(.)                  # status
+			([0-9]{0,3})\t       # similarity
+			(.*)                 # file
+		$}xo) {
+			my ($sha1_from, $sha1_to, $file) =
+			   ($3,         $4,       $7   );
+
+			if ($file =~ m/^"(.*)"$/) {
+				($file=$1) =~ s/\\([0-7]{1,3})/chr(oct($1))/eg;
+			}
+			if (length $file) {
+				push @{ $ci{'details'} }, {
+					'file'      => $file,
+					'sha1_from' => $sha1_from,
+					'sha1_to'   => $sha1_to,
+				};
+			}
+			next FILE;
+		};
+		last FILE;
+	}
+
+	error("No detail in diff-tree output") if !defined $ci{'details'};
+
+	return \%ci;
+} #}}}
+
+sub git_commit_info (;$$) { #{{{
+	# Return an array of commit info hashes of num commits (default: 1)
+	# starting from the given sha1sum (default: HEAD).
+
+	my ($sha1, $num) = @_;
+
+	$num ||= 1;
+
+	my @raw_lines =
+	    run_or_die(qq{git-rev-list --max-count=$num $sha1 |
+		git-diff-tree --stdin --pretty=raw -c -M -r});
+
+	my @ci;
+	while (my $parsed = _parse_diff_tree(\@raw_lines)) {
+		push @ci, $parsed;
+	}
+
+	return wantarray ? @ci : $ci[0];
+} #}}}
+
+sub git_sha1 (;$) { #{{{
+	# Return head sha1sum (of given file).
+
+	my $file = shift || q{--};
+
+	my ($sha1) = run_or_die('git-rev-list', '--max-count=1', 'HEAD', $file);
+	($sha1) = $sha1 =~ m/($sha1_pattern)/; # sha1sum is untainted now
+	debug("Empty sha1sum for '$file'.") if !length $sha1;
+	return $sha1;
+} #}}}
+
+sub rcs_update () { #{{{
+	# Update working directory.
+
+	run_or_cry('git-pull', $origin_branch);
+} #}}}
+
+sub rcs_prepedit ($) { #{{{
+	# Return the commit sha1sum of the file when editing begins.
+	# This will be later used in rcs_commit if a merge is required.
+
+	my ($file) = @_;
+
+	my $sha1 = git_sha1($file);
+	return defined $sha1 ? $sha1 : q{};
+} #}}}
+
+sub rcs_commit ($$$) { #{{{
+	# Try to commit the page; returns undef on _success_ and
+	# a version of the page with the rcs's conflict markers on
+	# failure.
+
+	my ($file, $message, $rcstoken) = @_;
+
+	# XXX: Wiki directory is in the unlocked state when starting this
+	# action.  But it takes time for a Git process to finish its job
+	# (especially if a merge required), so we must re-lock to prevent
+	# race conditions.  Only when the time of the real commit action
+	# (i.e. git-push(1)) comes, we'll unlock the directory.
+	lockwiki();
+
+	# Check to see if the page has been changed by someone else since
+	# rcs_prepedit was called.
+	my $cur    = git_sha1($file);
+	my ($prev) = $rcstoken =~ m/^$sha1_pattern$/; # untaint
+
+	if (defined $cur && defined $prev && $cur ne $prev) {
+		my $conflict = _merge_past($prev, $file, $dummy_commit_msg);
+		return $conflict if defined $conflict;
+	}
+
+	# git-commit(1) returns non-zero if file has not been really changed.
+	# so we should ignore its exit status (hence run_or_non).
+	if (run_or_non('git-commit', '-m', $message, '-i', $file)) {
+		unlockwiki();
+		run_or_cry('git-push', $origin_branch);
+	}
+
+	return undef; # success
+} #}}}
+
+sub rcs_add ($) { # {{{
+	# Add file to archive.
+
+	my ($file) = @_;
+
+	run_or_cry('git-add', $file);
+} #}}}
+
+sub rcs_recentchanges ($) { #{{{
+	# List of recent changes.
+
+	my ($num) = @_;
+
+	eval q{use CGI 'escapeHTML'};
+	eval q{use Date::Parse};
+	eval q{use Time::Duration};
+
+	my ($sha1, $type, $when, $diffurl, $user, @pages, @message, @rets);
+	INFO: foreach my $ci (git_commit_info('HEAD', $num)) {
+		my $title = @{ $ci->{'comment'} }[0];
+
+		# Skip redundant commits.
+		next INFO if ($title eq $dummy_commit_msg);
+
+		$sha1 = $ci->{'sha1'};
+		$type = "web";
+		$when = concise(ago(time - $ci->{'author_epoch'}));
+
+		foreach my $bit (@{ $ci->{'details'} }) {
+			my $diffurl = $config{'diffurl'};
+			my $file    = $bit->{'file'};
+
+			$diffurl =~ s/\[\[file\]\]/$file/go;
+			$diffurl =~ s/\[\[sha1_parent\]\]/$ci->{'parent'}/go;
+			$diffurl =~ s/\[\[sha1_from\]\]/$bit->{'sha1_from'}/go;
+			$diffurl =~ s/\[\[sha1_to\]\]/$bit->{'sha1_to'}/go;
+
+			push @pages, {
+				link => htmllink("", pagename($file), 1),
+				diffurl => $diffurl,
+			},
+		}
+
+		push @message, { line => escapeHTML($title) };
+
+		if (defined $message[0] &&
+		    $message[0]->{line} =~ m/$web_commit_msg/) {
+			$user = "$1";
+			$message[0]->{line} = $2;
+		} else {
+			$type ="git";
+			$user = $ci->{'author_username'};
+		}
+
+		push @rets, {
+			rev        => $sha1,
+			user       => htmllink("", $user, 1),
+			committype => $type,
+			when       => $when,
+			message    => [@message],
+			pages      => [@pages],
+		} if @pages;
+
+		$sha1 = $type = $when = $diffurl = $user = undef;
+		@pages = @message = ();
+	}
+
+	return @rets;
+} #}}}
+
+sub rcs_notify () { #{{{
+	# Send notification mail to subscribed users.
+	#
+	# In usual Git usage, hooks/update script is presumed to send
+	# notification mails (see git-receive-pack(1)).  But we prefer
+	# hooks/post-update to support IkiWiki commits coming from a
+	# cloned repository (through command line) because post-update
+	# is called _after_ each ref in repository is updated (update
+	# hook is called _before_ the repository is updated).  Since
+	# post-update hook does not accept command line arguments, we
+	# don't have an $ENV variable in this function.
+	#
+	# Here, we rely on a simple fact: we can extract all parts of the
+	# notification content by parsing the "HEAD" commit (which also
+	# triggers a refresh of IkiWiki pages) and we can obtain the diff
+	# by comparing HEAD and HEAD^ (the previous commit).
+
+	my $sha1 = 'HEAD'; # the commit which triggers this action
+
+	my $ci = git_commit_info($sha1);
+	if (!defined $ci) {
+		warn "Cannot parse info for '$sha1' commit";
+		return;
+	}
+
+	my @changed_pages = map { $_->{'file'} } @{ $ci->{'details'} };
+
+	my ($user, $message);
+	if (@{ $ci->{'comment'} }[0] =~ m/$web_commit_msg/) {
+		$user    = "$1";
+		$message = $2;
+	} else {
+		$user    = $ci->{'author_username'};
+		$message = join "\n", @{ $ci->{'comment'} };
+	}
+
+	require IkiWiki::UserInfo;
+	my @email_recipients = commit_notify_list($user, @changed_pages);
+	return if !@email_recipients;
+
+	# TODO: if a commit spans multiple pages, this will send
+	# subscribers a diff that might contain pages they did not
+	# sign up for. Should separate the diff per page and
+	# reassemble into one mail with just the pages subscribed to.
+	my $diff = join "\n", run_or_die('git-diff', "${sha1}^", $sha1);
+
+	my $subject = "$config{wikiname} update of ";
+	if (@changed_pages > 2) {
+		$subject .= "$changed_pages[0] $changed_pages[1] etc";
+	} else {
+		$subject .= join " ", @changed_pages;
+	}
+	$subject .= " by $user";
+
+	my $template = HTML::Template->new(
+		filename => "$config{templatedir}/notifymail.tmpl"
+	);
+	$template->param(
+		wikiname => $config{wikiname},
+		diff     => $diff,
+		user     => $user,
+		message  => $message,
+	);
+
+	eval q{use Mail::Sendmail};
+	foreach my $email (@email_recipients) {
+		sendmail(
+			To      => $email,
+			From    => "$config{wikiname} <$config{adminemail}>",
+			Subject => $subject,
+			Message => $template->output,
+		) or error("Failed to send update notification mail: $!");
+	}
+} #}}}
+
+sub rcs_getctime ($) { #{{{
+	# Get the ctime of file.
+
+	my ($file) = @_;
+
+	my $sha1  = git_sha1($file);
+	my $ci    = git_commit_info($sha1);
+	my $ctime = $ci->{'author_epoch'};
+	debug("ctime for '$file': ". localtime($ctime) . "\n");
+
+	return $ctime;
+} #}}}
+
+1