git svn: attempt to create empty dirs on clone+rebase

We parse unhandled.log files for empty_dir statements and make a
best effort attempt to recreate empty directories on fresh
clones and rebase.  This should cover the majority of cases
where users work off a single branch or for projects where
branches do not differ in empty directories.

Since this cannot affect "normal" git commands like "checkout"
or "reset", so users switching between branches in a single
working directory should use the new "git svn mkdirs" command
after switching branches.

Signed-off-by: Eric Wong <normalperson@yhbt.net>

4 files changed, 139 insertions, 2 deletions

diff --git a/Documentation/git-svn.txt b/Documentation/git-svn.txt
index 1812890a7e..db00ed43b7 100644
--- a/Documentation/git-svn.txt
+++ b/Documentation/git-svn.txt
@@ -320,6 +320,13 @@ Any other arguments are passed directly to 'git log'
 	directories.  The output is suitable for appending to
 	the $GIT_DIR/info/exclude file.
 
+'mkdirs'::
+	Attempts to recreate empty directories that core git cannot track
+	based on information in $GIT_DIR/svn/<refname>/unhandled.log files.
+	Empty directories are automatically recreated when using
+	"git svn clone" and "git svn rebase", so "mkdirs" is intended
+	for use after commands like "git checkout" or "git reset".
+
 'commit-diff'::
 	Commits the diff of two tree-ish arguments from the
 	command-line.  This command does not rely on being inside an `git svn
diff --git a/git-svn.perl b/git-svn.perl
index ea922ace1d..ab0a8dd099 100755
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -168,6 +168,9 @@ my %cmd = (
 			     'Create a .gitignore per svn:ignore',
 			     { 'revision|r=i' => \$_revision
 			     } ],
+	'mkdirs' => [ \&cmd_mkdirs ,
+	              "recreate empty directories after a checkout",
+	              { 'revision|r=i' => \$_revision } ],
         'propget' => [ \&cmd_propget,
 		       'Print the value of a property on a file or directory',
 		       { 'revision|r=i' => \$_revision } ],
@@ -769,6 +772,7 @@ sub cmd_rebase {
 		$_fetch_all ? $gs->fetch_all : $gs->fetch;
 	}
 	command_noisy(rebase_cmd(), $gs->refname);
+	$gs->mkemptydirs;
 }
 
 sub cmd_show_ignore {
@@ -830,6 +834,12 @@ sub cmd_create_ignore {
 	});
 }
 
+sub cmd_mkdirs {
+	my ($url, $rev, $uuid, $gs) = working_head_info('HEAD');
+	$gs ||= Git::SVN->new;
+	$gs->mkemptydirs($_revision);
+}
+
 sub canonicalize_path {
 	my ($path) = @_;
 	my $dot_slash_added = 0;
@@ -1196,6 +1206,7 @@ sub post_fetch_checkout {
 	command_noisy(qw/read-tree -m -u -v HEAD HEAD/);
 	print STDERR "Checked out HEAD:\n  ",
 	             $gs->full_url, " r", $gs->last_rev, "\n";
+	$gs->mkemptydirs($gs->last_rev);
 }
 
 sub complete_svn_url {
@@ -2724,6 +2735,34 @@ sub do_fetch {
 	$self->make_log_entry($rev, \@parents, $ed);
 }
 
+sub mkemptydirs {
+	my ($self, $r) = @_;
+	my %empty_dirs = ();
+
+	open my $fh, '<', "$self->{dir}/unhandled.log" or return;
+	binmode $fh or croak "binmode: $!";
+	while (<$fh>) {
+		if (defined $r && /^r(\d+)$/) {
+			last if $1 > $r;
+		} elsif (/^  \+empty_dir: (.+)$/) {
+			$empty_dirs{$1} = 1;
+		} elsif (/^  \-empty_dir: (.+)$/) {
+			delete $empty_dirs{$1};
+		}
+	}
+	close $fh;
+	foreach my $d (sort keys %empty_dirs) {
+		$d = uri_decode($d);
+		next if -d $d;
+		if (-e _) {
+			warn "$d exists but is not a directory\n";
+		} else {
+			print "creating empty directory: $d\n";
+			mkpath([$d]);
+		}
+	}
+}
+
 sub get_untracked {
 	my ($self, $ed) = @_;
 	my @out;
@@ -3556,6 +3595,12 @@ sub uri_encode {
 	$f
 }
 
+sub uri_decode {
+	my ($f) = @_;
+	$f =~ s#%([0-9a-fA-F]{2})#chr(hex($1))#eg;
+	$f
+}
+
 sub remove_username {
 	$_[0] =~ s{^([^:]*://)[^@]+@}{$1};
 }
diff --git a/t/t9115-git-svn-dcommit-funky-renames.sh b/t/t9115-git-svn-dcommit-funky-renames.sh
index 9be7aefaee..767799e7a7 100755
--- a/t/t9115-git-svn-dcommit-funky-renames.sh
+++ b/t/t9115-git-svn-dcommit-funky-renames.sh
@@ -19,7 +19,7 @@ test_expect_success 'init and fetch repository' '
 	'
 
 test_expect_success 'create file in existing ugly and empty dir' '
-	mkdir "#{bad_directory_name}" &&
+	mkdir -p "#{bad_directory_name}" &&
 	echo hi > "#{bad_directory_name}/ foo" &&
 	git update-index --add "#{bad_directory_name}/ foo" &&
 	git commit -m "new file in ugly parent" &&
@@ -37,7 +37,7 @@ test_expect_success 'rename pretty file' '
 	git update-index --add pretty &&
 	git commit -m "pretty :x" &&
 	git svn dcommit &&
-	mkdir regular_dir_name &&
+	mkdir -p regular_dir_name &&
 	git mv pretty regular_dir_name/pretty &&
 	git commit -m "moved pretty file" &&
 	git svn dcommit
diff --git a/t/t9146-git-svn-empty-dirs.sh b/t/t9146-git-svn-empty-dirs.sh
new file mode 100755
index 0000000000..5948544ec5
--- /dev/null
+++ b/t/t9146-git-svn-empty-dirs.sh
@@ -0,0 +1,85 @@
+#!/bin/sh
+#
+# Copyright (c) 2009 Eric Wong
+
+test_description='git svn creates empty directories'
+. ./lib-git-svn.sh
+
+test_expect_success 'initialize repo' '
+	for i in a b c d d/e d/e/f "weird file name"
+	do
+		svn_cmd mkdir -m "mkdir $i" "$svnrepo"/"$i"
+	done
+'
+
+test_expect_success 'clone' 'git svn clone "$svnrepo" cloned'
+
+test_expect_success 'empty directories exist' '
+	(
+		cd cloned &&
+		for i in a b c d d/e d/e/f "weird file name"
+		do
+			if ! test -d "$i"
+			then
+				echo >&2 "$i does not exist"
+				exit 1
+			fi
+		done
+	)
+'
+
+test_expect_success 'more emptiness' '
+	svn_cmd mkdir -m "bang bang"  "$svnrepo"/"! !"
+'
+
+test_expect_success 'git svn rebase creates empty directory' '
+	( cd cloned && git svn rebase )
+	test -d cloned/"! !"
+'
+
+test_expect_success 'git svn mkdirs recreates empty directories' '
+	(
+		cd cloned &&
+		rm -r * &&
+		git svn mkdirs &&
+		for i in a b c d d/e d/e/f "weird file name" "! !"
+		do
+			if ! test -d "$i"
+			then
+				echo >&2 "$i does not exist"
+				exit 1
+			fi
+		done
+	)
+'
+
+test_expect_success 'git svn mkdirs -r works' '
+	(
+		cd cloned &&
+		rm -r * &&
+		git svn mkdirs -r7 &&
+		for i in a b c d d/e d/e/f "weird file name"
+		do
+			if ! test -d "$i"
+			then
+				echo >&2 "$i does not exist"
+				exit 1
+			fi
+		done
+
+		if test -d "! !"
+		then
+			echo >&2 "$i should not exist"
+			exit 1
+		fi
+
+		git svn mkdirs -r8 &&
+		if ! test -d "! !"
+		then
+			echo >&2 "$i not exist"
+			exit 1
+		fi
+	)
+'
+
+test_done