gitweb: make gitweb_check_feature a boolean wrapper

The gitweb_get_feature() function retrieves the configuration parameters
for the feature (such as the list of snapshot formats or the list of
additional actions), but it is very often used to see if feature is
enabled (which is returned as the first element in the list).

Because accepting the returned list in the scalar context by mistake
yields the number of elements in the array, which is non-zero in all
cases, such a mistake would result in a bug for the latter use, with
disabled features appearing enabled.  All existing callers that call the
function for this purpose assign the return value in the list context to
retrieve the first element, but that is only because we fixed careless
callers recently.

This adds gitweb_check_feature() as a wrapper to gitweb_get_feature() that
can be called safely in the scalar context to see if a feature is enabled
to reduce the risk of future bugs.  Callers of "get" that use the call
only to see if the feature is enabled are updated to call this wrapper.

Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 36 insertions, 20 deletions

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 756b248..acc4cfd 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -190,7 +190,7 @@ our %feature = (
 	# if there is no 'sub' key (no feature-sub), then feature cannot be
 	# overriden
 	#
-	#
+	# use gitweb_check_feature(<feature>) to check if <feature> is enabled
 
 	# Enable the 'blame' blob view, showing the last commit that modified
 	# each line in the file. This can be very CPU-intensive.
@@ -344,6 +344,22 @@ sub gitweb_get_feature {
 	return $sub->(@defaults);
 }
 
+# A wrapper to check if a given feature is enabled.
+# With this, you can say
+#
+#   my $bool_feat = gitweb_check_feature('bool_feat');
+#   gitweb_check_feature('bool_feat') or somecode;
+#
+# instead of
+#
+#   my ($bool_feat) = gitweb_get_feature('bool_feat');
+#   (gitweb_get_feature('bool_feat'))[0] or somecode;
+#
+sub gitweb_check_feature {
+	return (gitweb_get_feature(@_))[0];
+}
+
+
 sub feature_blame {
 	my ($val) = git_get_project_config('blame', '--bool');
 
@@ -810,7 +826,7 @@ sub href (%) {
 		}
 	}
 
-	my ($use_pathinfo) = gitweb_get_feature('pathinfo');
+	my $use_pathinfo = gitweb_check_feature('pathinfo');
 	if ($use_pathinfo) {
 		# try to put as many parameters as possible in PATH_INFO:
 		#   - project name
@@ -2101,7 +2117,7 @@ sub git_get_projects_list {
 	$filter ||= '';
 	$filter =~ s/\.git$//;
 
-	my ($check_forks) = gitweb_get_feature('forks');
+	my $check_forks = gitweb_check_feature('forks');
 
 	if (-d $projects_list) {
 		# search in directory
@@ -2947,7 +2963,7 @@ EOF
 	}
 	print "</div>\n";
 
-	my ($have_search) = gitweb_get_feature('search');
+	my $have_search = gitweb_check_feature('search');
 	if (defined $project && $have_search) {
 		if (!defined $searchtext) {
 			$searchtext = "";
@@ -2961,7 +2977,7 @@ EOF
 			$search_hash = "HEAD";
 		}
 		my $action = $my_uri;
-		my ($use_pathinfo) = gitweb_get_feature('pathinfo');
+		my $use_pathinfo = gitweb_check_feature('pathinfo');
 		if ($use_pathinfo) {
 			$action .= "/".esc_url($project);
 		}
@@ -3454,7 +3470,7 @@ sub is_patch_split {
 sub git_difftree_body {
 	my ($difftree, $hash, @parents) = @_;
 	my ($parent) = $parents[0];
-	my ($have_blame) = gitweb_get_feature('blame');
+	my $have_blame = gitweb_check_feature('blame');
 	print "<div class=\"list_head\">\n";
 	if ($#{$difftree} > 10) {
 		print(($#{$difftree} + 1) . " files changed:\n");
@@ -3914,7 +3930,7 @@ sub fill_project_list_info {
 	my ($projlist, $check_forks) = @_;
 	my @projects;
 
-	my ($show_ctags) = gitweb_get_feature('ctags');
+	my $show_ctags = gitweb_check_feature('ctags');
  PROJECT:
 	foreach my $pr (@$projlist) {
 		my (@activity) = git_get_last_activity($pr->{'path'});
@@ -3968,7 +3984,7 @@ sub git_project_list_body {
 	# actually uses global variable $project
 	my ($projlist, $order, $from, $to, $extra, $no_header) = @_;
 
-	my ($check_forks) = gitweb_get_feature('forks');
+	my $check_forks = gitweb_check_feature('forks');
 	my @projects = fill_project_list_info($projlist, $check_forks);
 
 	$order ||= $default_projects_order;
@@ -3988,7 +4004,7 @@ sub git_project_list_body {
 		@projects = sort {$a->{$oi->{'key'}} <=> $b->{$oi->{'key'}}} @projects;
 	}
 
-	my ($show_ctags) = gitweb_get_feature('ctags');
+	my $show_ctags = gitweb_check_feature('ctags');
 	if ($show_ctags) {
 		my %ctags;
 		foreach my $p (@projects) {
@@ -4428,7 +4444,7 @@ sub git_summary {
 	my @taglist  = git_get_tags_list(16);
 	my @headlist = git_get_heads_list(16);
 	my @forklist;
-	my ($check_forks) = gitweb_get_feature('forks');
+	my $check_forks = gitweb_check_feature('forks');
 
 	if ($check_forks) {
 		@forklist = git_get_projects_list($project);
@@ -4457,7 +4473,7 @@ sub git_summary {
 	}
 
 	# Tag cloud
-	my ($show_ctags) = gitweb_get_feature('ctags');
+	my $show_ctags = gitweb_check_feature('ctags');
 	if ($show_ctags) {
 		my $ctags = git_get_project_ctags($project);
 		my $cloud = git_populate_project_tagcloud($ctags);
@@ -4559,7 +4575,7 @@ sub git_blame {
 	my $fd;
 	my $ftype;
 
-	gitweb_get_feature('blame')[0]
+	gitweb_check_feature('blame')
 	    or die_error(403, "Blame view not allowed");
 
 	die_error(400, "No file name given") unless $file_name;
@@ -4747,7 +4763,7 @@ sub git_blob {
 		$expires = "+1d";
 	}
 
-	my ($have_blame) = gitweb_get_feature('blame');
+	my $have_blame = gitweb_check_feature('blame');
 	open my $fd, "-|", git_cmd(), "cat-file", "blob", $hash
 		or die_error(500, "Couldn't cat $file_name, $hash");
 	my $mimetype = blob_mimetype($fd, $file_name);
@@ -4840,7 +4856,7 @@ sub git_tree {
 	my $ref = format_ref_marker($refs, $hash_base);
 	git_header_html();
 	my $basedir = '';
-	my ($have_blame) = gitweb_get_feature('blame');
+	my $have_blame = gitweb_check_feature('blame');
 	if (defined $hash_base && (my %co = parse_commit($hash_base))) {
 		my @views_nav = ();
 		if (defined $file_name) {
@@ -5610,7 +5626,7 @@ sub git_history {
 }
 
 sub git_search {
-	gitweb_get_feature('search')[0] or die_error(403, "Search is disabled");
+	gitweb_check_feature('search') or die_error(403, "Search is disabled");
 	if (!defined $searchtext) {
 		die_error(400, "Text field is empty");
 	}
@@ -5629,11 +5645,11 @@ sub git_search {
 	if ($searchtype eq 'pickaxe') {
 		# pickaxe may take all resources of your box and run for several minutes
 		# with every query - so decide by yourself how public you make this feature
-		gitweb_get_feature('pickaxe')[0]
+		gitweb_check_feature('pickaxe')
 		    or die_error(403, "Pickaxe is disabled");
 	}
 	if ($searchtype eq 'grep') {
-		gitweb_get_feature('grep')[0]
+		gitweb_check_feature('grep')
 		    or die_error(403, "Grep is disabled");
 	}
 
@@ -5838,7 +5854,7 @@ insensitive).</p>
 <dt><b>commit</b></dt>
 <dd>The commit messages and authorship information will be scanned for the given pattern.</dd>
 EOT
-	my ($have_grep) = gitweb_get_feature('grep');
+	my $have_grep = gitweb_check_feature('grep');
 	if ($have_grep) {
 		print <<EOT;
 <dt><b>grep</b></dt>
@@ -5855,7 +5871,7 @@ EOT
 <dt><b>committer</b></dt>
 <dd>Name and e-mail of the committer and date of commit will be scanned for the given pattern.</dd>
 EOT
-	my ($have_pickaxe) = gitweb_get_feature('pickaxe');
+	my $have_pickaxe = gitweb_check_feature('pickaxe');
 	if ($have_pickaxe) {
 		print <<EOT;
 <dt><b>pickaxe</b></dt>
@@ -5907,7 +5923,7 @@ sub git_shortlog {
 
 sub git_feed {
 	my $format = shift || 'atom';
-	my ($have_blame) = gitweb_get_feature('blame');
+	my $have_blame = gitweb_check_feature('blame');
 
 	# Atom: http://www.atomenabled.org/developers/syndication/
 	# RSS:  http://www.notestips.com/80256B3A007F2692/1/NAMO5P9UPQ