Merge branch 'cm/remote-mediawiki-perlcritique'

* cm/remote-mediawiki-perlcritique: (31 commits)
  git-remote-mediawiki: make error message more precise
  git-remote-mediawiki: add a perlcritic rule in Makefile
  git-remote-mediawiki: add a .perlcriticrc file
  git-remote-mediawiki: clearly rewrite double dereference
  git-remote-mediawiki: fix a typo ("mediwiki" instead of "mediawiki")
  git-remote-mediawiki: put non-trivial numeric values in constants.
  git-remote-mediawiki: don't use quotes for empty strings
  git-remote-mediawiki: replace "unless" statements with negated "if" statements
  git-remote-mediawiki: brace file handles for print for more clarity
  git-remote-mediawiki: modify strings for a better coding-style
  git-remote-mediawiki: put long code into a subroutine
  git-remote-mediawiki: remove import of unused open2
  git-remote-mediawiki: check return value of open
  git-remote-mediawiki: assign a variable as undef and make proper indentation
  git-remote-mediawiki: rename a variable ($last) which has the name of a keyword
  git-remote-mediawiki: remove unused variable $entry
  git-remote-mediawiki: turn double-negated expressions into simple expressions
  git-remote-mediawiki: change the name of a variable
  git-remote-mediawiki: add newline in the end of die() error messages
  git-remote-mediawiki: change style in a regexp
  ...

3 files changed, 320 insertions, 247 deletions

diff --git a/contrib/mw-to-git/.perlcriticrc b/contrib/mw-to-git/.perlcriticrc
new file mode 100644
index 000000000..5a9955d75
--- /dev/null
+++ b/contrib/mw-to-git/.perlcriticrc
@@ -0,0 +1,28 @@
+# These 3 rules demand to add the s, m and x flag to *every* regexp. This is
+# overkill and would be harmful for readability.
+[-RegularExpressions::RequireExtendedFormatting]
+[-RegularExpressions::RequireDotMatchAnything]
+[-RegularExpressions::RequireLineBoundaryMatching]
+
+# This rule says that builtin functions should not be called with parentheses
+# e.g.: (taken from CPAN's documentation)
+# open($handle, '>', $filename); #not ok
+# open $handle, '>', $filename;  #ok
+# Applying such a rule would mean modifying a huge number of lines for a
+# question of style.
+[-CodeLayout::ProhibitParensWithBuiltins]
+
+# This rule states that each system call should have its return value checked
+# The problem is that it includes the print call. Checking every print call's
+# return value would be harmful to the code readabilty.
+# This configuration keeps all default function but print.
+[InputOutput::RequireCheckedSyscalls]
+functions = open say close
+
+# This rules demands to add a dependancy for the Readonly module. This is not
+# wished.
+[-ValuesAndExpressions::ProhibitConstantPragma]
+
+# This rule is not really useful (rather a question of style) and produces many
+# warnings among the code.
+[-ValuesAndExpressions::ProhibitNoisyQuotes]
diff --git a/contrib/mw-to-git/Makefile b/contrib/mw-to-git/Makefile
index f14971987..1fb242448 100644
--- a/contrib/mw-to-git/Makefile
+++ b/contrib/mw-to-git/Makefile
@@ -15,3 +15,5 @@ all: build
 build install clean:
 	$(MAKE) -C $(GIT_ROOT_DIR) SCRIPT_PERL=$(SCRIPT_PERL_FULL) \
                 $@-perl-script
+perlcritic:
+	perlcritic -2 *.perl
diff --git a/contrib/mw-to-git/git-remote-mediawiki.perl b/contrib/mw-to-git/git-remote-mediawiki.perl
index c1a967b3d..71baf8ace 100755
--- a/contrib/mw-to-git/git-remote-mediawiki.perl
+++ b/contrib/mw-to-git/git-remote-mediawiki.perl
@@ -15,18 +15,16 @@ use strict;
 use MediaWiki::API;
 use Git;
 use DateTime::Format::ISO8601;
+use warnings;
 
 # By default, use UTF-8 to communicate with Git and the user
-binmode STDERR, ":utf8";
-binmode STDOUT, ":utf8";
+binmode STDERR, ':encoding(UTF-8)';
+binmode STDOUT, ':encoding(UTF-8)';
 
 use URI::Escape;
-use IPC::Open2;
-
-use warnings;
 
 # Mediawiki filenames can contain forward slashes. This variable decides by which pattern they should be replaced
-use constant SLASH_REPLACEMENT => "%2F";
+use constant SLASH_REPLACEMENT => '%2F';
 
 # It's not always possible to delete pages (may require some
 # privileges). Deleted pages are replaced with this content.
@@ -37,11 +35,23 @@ use constant DELETED_CONTENT => "[[Category:Deleted]]\n";
 use constant EMPTY_CONTENT => "<!-- empty page -->\n";
 
 # used to reflect file creation or deletion in diff.
-use constant NULL_SHA1 => "0000000000000000000000000000000000000000";
+use constant NULL_SHA1 => '0000000000000000000000000000000000000000';
 
 # Used on Git's side to reflect empty edit messages on the wiki
 use constant EMPTY_MESSAGE => '*Empty MediaWiki Message*';
 
+use constant EMPTY => q{};
+
+# Number of pages taken into account at once in submodule get_mw_page_list
+use constant SLICE_SIZE => 50;
+
+# Number of linked mediafile to get at once in get_linked_mediafiles
+# The query is split in small batches because of the MW API limit of
+# the number of links to be returned (500 links max).
+use constant BATCH_SIZE => 10;
+
+use constant HTTP_CODE_OK => 200;
+
 if (@ARGV != 2) {
 	exit_error_usage();
 }
@@ -51,35 +61,35 @@ my $url = $ARGV[1];
 
 # Accept both space-separated and multiple keys in config file.
 # Spaces should be written as _ anyway because we'll use chomp.
-my @tracked_pages = split(/[ \n]/, run_git("config --get-all remote.". $remotename .".pages"));
+my @tracked_pages = split(/[ \n]/, run_git("config --get-all remote.${remotename}.pages"));
 chomp(@tracked_pages);
 
 # Just like @tracked_pages, but for MediaWiki categories.
-my @tracked_categories = split(/[ \n]/, run_git("config --get-all remote.". $remotename .".categories"));
+my @tracked_categories = split(/[ \n]/, run_git("config --get-all remote.${remotename}.categories"));
 chomp(@tracked_categories);
 
 # Import media files on pull
-my $import_media = run_git("config --get --bool remote.". $remotename .".mediaimport");
+my $import_media = run_git("config --get --bool remote.${remotename}.mediaimport");
 chomp($import_media);
-$import_media = ($import_media eq "true");
+$import_media = ($import_media eq 'true');
 
 # Export media files on push
-my $export_media = run_git("config --get --bool remote.". $remotename .".mediaexport");
+my $export_media = run_git("config --get --bool remote.${remotename}.mediaexport");
 chomp($export_media);
-$export_media = !($export_media eq "false");
+$export_media = !($export_media eq 'false');
 
-my $wiki_login = run_git("config --get remote.". $remotename .".mwLogin");
+my $wiki_login = run_git("config --get remote.${remotename}.mwLogin");
 # Note: mwPassword is discourraged. Use the credential system instead.
-my $wiki_passwd = run_git("config --get remote.". $remotename .".mwPassword");
-my $wiki_domain = run_git("config --get remote.". $remotename .".mwDomain");
+my $wiki_passwd = run_git("config --get remote.${remotename}.mwPassword");
+my $wiki_domain = run_git("config --get remote.${remotename}.mwDomain");
 chomp($wiki_login);
 chomp($wiki_passwd);
 chomp($wiki_domain);
 
 # Import only last revisions (both for clone and fetch)
-my $shallow_import = run_git("config --get --bool remote.". $remotename .".shallow");
+my $shallow_import = run_git("config --get --bool remote.${remotename}.shallow");
 chomp($shallow_import);
-$shallow_import = ($shallow_import eq "true");
+$shallow_import = ($shallow_import eq 'true');
 
 # Fetch (clone and pull) by revisions instead of by pages. This behavior
 # is more efficient when we have a wiki with lots of pages and we fetch
@@ -87,15 +97,18 @@ $shallow_import = ($shallow_import eq "true");
 # Possible values:
 # - by_rev: perform one query per new revision on the remote wiki
 # - by_page: query each tracked page for new revision
-my $fetch_strategy = run_git("config --get remote.$remotename.fetchStrategy");
-unless ($fetch_strategy) {
-	$fetch_strategy = run_git("config --get mediawiki.fetchStrategy");
+my $fetch_strategy = run_git("config --get remote.${remotename}.fetchStrategy");
+if (!$fetch_strategy) {
+	$fetch_strategy = run_git('config --get mediawiki.fetchStrategy');
 }
 chomp($fetch_strategy);
-unless ($fetch_strategy) {
-	$fetch_strategy = "by_page";
+if (!$fetch_strategy) {
+	$fetch_strategy = 'by_page';
 }
 
+# Remember the timestamp corresponding to a revision id.
+my %basetimestamps;
+
 # Dumb push: don't update notes and mediawiki ref to reflect the last push.
 #
 # Configurable with mediawiki.dumbPush, or per-remote with
@@ -110,48 +123,25 @@ unless ($fetch_strategy) {
 # will get the history with information lost). If the import is
 # deterministic, this means everybody gets the same sha1 for each
 # MediaWiki revision.
-my $dumb_push = run_git("config --get --bool remote.$remotename.dumbPush");
-unless ($dumb_push) {
-	$dumb_push = run_git("config --get --bool mediawiki.dumbPush");
+my $dumb_push = run_git("config --get --bool remote.${remotename}.dumbPush");
+if (!$dumb_push) {
+	$dumb_push = run_git('config --get --bool mediawiki.dumbPush');
 }
 chomp($dumb_push);
-$dumb_push = ($dumb_push eq "true");
+$dumb_push = ($dumb_push eq 'true');
 
 my $wiki_name = $url;
-$wiki_name =~ s/[^\/]*:\/\///;
+$wiki_name =~ s{[^/]*://}{};
 # If URL is like http://user:password@example.com/, we clearly don't
 # want the password in $wiki_name. While we're there, also remove user
 # and '@' sign, to avoid author like MWUser@HTTPUser@host.com
 $wiki_name =~ s/^.*@//;
 
 # Commands parser
-my $entry;
-my @cmd;
 while (<STDIN>) {
 	chomp;
-	@cmd = split(/ /);
-	if (defined($cmd[0])) {
-		# Line not blank
-		if ($cmd[0] eq "capabilities") {
-			die("Too many arguments for capabilities") unless (!defined($cmd[1]));
-			mw_capabilities();
-		} elsif ($cmd[0] eq "list") {
-			die("Too many arguments for list") unless (!defined($cmd[2]));
-			mw_list($cmd[1]);
-		} elsif ($cmd[0] eq "import") {
-			die("Invalid arguments for import") unless ($cmd[1] ne "" && !defined($cmd[2]));
-			mw_import($cmd[1]);
-		} elsif ($cmd[0] eq "option") {
-			die("Too many arguments for option") unless ($cmd[1] ne "" && $cmd[2] ne "" && !defined($cmd[3]));
-			mw_option($cmd[1],$cmd[2]);
-		} elsif ($cmd[0] eq "push") {
-			mw_push($cmd[1]);
-		} else {
-			print STDERR "Unknown command. Aborting...\n";
-			last;
-		}
-	} else {
-		# blank line: we should terminate
+
+	if (!parse_command($_)) {
 		last;
 	}
 
@@ -172,6 +162,40 @@ sub exit_error_usage {
 	    "Then, use git commit, push and pull as with every normal git repository.\n";
 }
 
+sub parse_command {
+	my ($line) = @_;
+	my @cmd = split(/ /, $line);
+	if (!defined $cmd[0]) {
+		return 0;
+	}
+	if ($cmd[0] eq 'capabilities') {
+		die("Too many arguments for capabilities\n")
+		    if (defined($cmd[1]));
+		mw_capabilities();
+	} elsif ($cmd[0] eq 'list') {
+		die("Too many arguments for list\n") if (defined($cmd[2]));
+		mw_list($cmd[1]);
+	} elsif ($cmd[0] eq 'import') {
+		die("Invalid argument for import\n")
+		    if ($cmd[1] eq EMPTY);
+		die("Too many arguments for import\n")
+		    if (defined($cmd[2]));
+		mw_import($cmd[1]);
+	} elsif ($cmd[0] eq 'option') {
+		die("Invalid arguments for option\n")
+		    if ($cmd[1] eq EMPTY || $cmd[2] eq EMPTY);
+		die("Too many arguments for option\n")
+		    if (defined($cmd[3]));
+		mw_option($cmd[1],$cmd[2]);
+	} elsif ($cmd[0] eq 'push') {
+		mw_push($cmd[1]);
+	} else {
+		print {*STDERR} "Unknown command. Aborting...\n";
+		return 0;
+	}
+	return 1;
+}
+
 # MediaWiki API instance, created lazily.
 my $mediawiki;
 
@@ -180,7 +204,7 @@ sub mw_connect_maybe {
 		return;
 	}
 	$mediawiki = MediaWiki::API->new;
-	$mediawiki->{config}->{api_url} = "$url/api.php";
+	$mediawiki->{config}->{api_url} = "${url}/api.php";
 	if ($wiki_login) {
 		my %credential = (
 			'url' => $url,
@@ -193,16 +217,17 @@ sub mw_connect_maybe {
 			       lgdomain => $wiki_domain};
 		if ($mediawiki->login($request)) {
 			Git::credential(\%credential, 'approve');
-			print STDERR "Logged in mediawiki user \"$credential{username}\".\n";
+			print {*STDERR} qq(Logged in mediawiki user "$credential{username}".\n);
 		} else {
-			print STDERR "Failed to log in mediawiki user \"$credential{username}\" on $url\n";
-			print STDERR "  (error " .
+			print {*STDERR} qq(Failed to log in mediawiki user "$credential{username}" on ${url}\n);
+			print {*STDERR} '  (error ' .
 				$mediawiki->{error}->{code} . ': ' .
 				$mediawiki->{error}->{details} . ")\n";
 			Git::credential(\%credential, 'reject');
 			exit 1;
 		}
 	}
+	return;
 }
 
 sub fatal_mw_error {
@@ -225,21 +250,23 @@ sub fatal_mw_error {
 sub get_mw_tracked_pages {
 	my $pages = shift;
 	get_mw_page_list(\@tracked_pages, $pages);
+	return;
 }
 
 sub get_mw_page_list {
 	my $page_list = shift;
 	my $pages = shift;
-	my @some_pages = @$page_list;
+	my @some_pages = @{$page_list};
 	while (@some_pages) {
-		my $last = 50;
-		if ($#some_pages < $last) {
-			$last = $#some_pages;
+		my $last_page = SLICE_SIZE;
+		if ($#some_pages < $last_page) {
+			$last_page = $#some_pages;
 		}
-		my @slice = @some_pages[0..$last];
+		my @slice = @some_pages[0..$last_page];
 		get_mw_first_pages(\@slice, $pages);
-		@some_pages = @some_pages[51..$#some_pages];
+		@some_pages = @some_pages[(SLICE_SIZE + 1)..$#some_pages];
 	}
+	return;
 }
 
 sub get_mw_tracked_categories {
@@ -249,7 +276,7 @@ sub get_mw_tracked_categories {
 			# Mediawiki requires the Category
 			# prefix, but let's not force the user
 			# to specify it.
-			$category = "Category:" . $category;
+			$category = "Category:${category}";
 		}
 		my $mw_pages = $mediawiki->list( {
 			action => 'query',
@@ -257,11 +284,12 @@ sub get_mw_tracked_categories {
 			cmtitle => $category,
 			cmlimit => 'max' } )
 			|| die $mediawiki->{error}->{code} . ': '
-				. $mediawiki->{error}->{details};
+				. $mediawiki->{error}->{details} . "\n";
 		foreach my $page (@{$mw_pages}) {
 			$pages->{$page->{title}} = $page;
 		}
 	}
+	return;
 }
 
 sub get_mw_all_pages {
@@ -278,6 +306,7 @@ sub get_mw_all_pages {
 	foreach my $page (@{$mw_pages}) {
 		$pages->{$page->{title}} = $page;
 	}
+	return;
 }
 
 # queries the wiki for a set of pages. Meant to be used within a loop
@@ -300,18 +329,19 @@ sub get_mw_first_pages {
 	}
 	while (my ($id, $page) = each(%{$mw_pages->{query}->{pages}})) {
 		if ($id < 0) {
-			print STDERR "Warning: page $page->{title} not found on wiki\n";
+			print {*STDERR} "Warning: page $page->{title} not found on wiki\n";
 		} else {
 			$pages->{$page->{title}} = $page;
 		}
 	}
+	return;
 }
 
 # Get the list of pages to be fetched according to configuration.
 sub get_mw_pages {
 	mw_connect_maybe();
 
-	print STDERR "Listing pages on remote wiki...\n";
+	print {*STDERR} "Listing pages on remote wiki...\n";
 
 	my %pages; # hash on page titles to avoid duplicates
 	my $user_defined;
@@ -329,14 +359,14 @@ sub get_mw_pages {
 		get_mw_all_pages(\%pages);
 	}
 	if ($import_media) {
-		print STDERR "Getting media files for selected pages...\n";
+		print {*STDERR} "Getting media files for selected pages...\n";
 		if ($user_defined) {
 			get_linked_mediafiles(\%pages);
 		} else {
 			get_all_mediafiles(\%pages);
 		}
 	}
-	print STDERR (scalar keys %pages) . " pages found.\n";
+	print {*STDERR} (scalar keys %pages) . " pages found.\n";
 	return %pages;
 }
 
@@ -344,9 +374,13 @@ sub get_mw_pages {
 #        $out = run_git("command args", "raw"); # don't interpret output as UTF-8.
 sub run_git {
 	my $args = shift;
-	my $encoding = (shift || "encoding(UTF-8)");
-	open(my $git, "-|:$encoding", "git " . $args);
-	my $res = do { local $/; <$git> };
+	my $encoding = (shift || 'encoding(UTF-8)');
+	open(my $git, "-|:${encoding}", "git ${args}")
+	    or die "Unable to fork: $!\n";
+	my $res = do {
+		local $/ = undef;
+		<$git>
+	};
 	close($git);
 
 	return $res;
@@ -361,27 +395,26 @@ sub get_all_mediafiles {
 	my $mw_pages = $mediawiki->list({
 		action => 'query',
 		list => 'allpages',
-		apnamespace => get_mw_namespace_id("File"),
+		apnamespace => get_mw_namespace_id('File'),
 		aplimit => 'max'
 	});
 	if (!defined($mw_pages)) {
-		print STDERR "fatal: could not get the list of pages for media files.\n";
-		print STDERR "fatal: '$url' does not appear to be a mediawiki\n";
-		print STDERR "fatal: make sure '$url/api.php' is a valid page.\n";
+		print {*STDERR} "fatal: could not get the list of pages for media files.\n";
+		print {*STDERR} "fatal: '$url' does not appear to be a mediawiki\n";
+		print {*STDERR} "fatal: make sure '$url/api.php' is a valid page.\n";
 		exit 1;
 	}
 	foreach my $page (@{$mw_pages}) {
 		$pages->{$page->{title}} = $page;
 	}
+	return;
 }
 
 sub get_linked_mediafiles {
 	my $pages = shift;
-	my @titles = map $_->{title}, values(%{$pages});
+	my @titles = map { $_->{title} } values(%{$pages});
 
-	# The query is split in small batches because of the MW API limit of
-	# the number of links to be returned (500 links max).
-	my $batch = 10;
+	my $batch = BATCH_SIZE;
 	while (@titles) {
 		if ($#titles < $batch) {
 			$batch = $#titles;
@@ -397,7 +430,7 @@ sub get_linked_mediafiles {
 			action => 'query',
 			prop => 'links|images',
 			titles => $mw_titles,
-			plnamespace => get_mw_namespace_id("File"),
+			plnamespace => get_mw_namespace_id('File'),
 			pllimit => 'max'
 		};
 		my $result = $mediawiki->api($query);
@@ -405,11 +438,13 @@ sub get_linked_mediafiles {
 		while (my ($id, $page) = each(%{$result->{query}->{pages}})) {
 			my @media_titles;
 			if (defined($page->{links})) {
-				my @link_titles = map $_->{title}, @{$page->{links}};
+				my @link_titles
+				    = map { $_->{title} } @{$page->{links}};
 				push(@media_titles, @link_titles);
 			}
 			if (defined($page->{images})) {
-				my @image_titles = map $_->{title}, @{$page->{images}};
+				my @image_titles
+				    = map { $_->{title} } @{$page->{images}};
 				push(@media_titles, @image_titles);
 			}
 			if (@media_titles) {
@@ -419,6 +454,7 @@ sub get_linked_mediafiles {
 
 		@titles = @titles[($batch+1)..$#titles];
 	}
+	return;
 }
 
 sub get_mw_mediafile_for_page_revision {
@@ -432,7 +468,7 @@ sub get_mw_mediafile_for_page_revision {
 	my $query = {
 		action => 'query',
 		prop => 'imageinfo',
-		titles => "File:" . $filename,
+		titles => "File:${filename}",
 		iistart => $timestamp,
 		iiend => $timestamp,
 		iiprop => 'timestamp|archivename|url',
@@ -450,47 +486,44 @@ sub get_mw_mediafile_for_page_revision {
 		$mediafile{timestamp} = $fileinfo->{timestamp};
 		# Mediawiki::API's download function doesn't support https URLs
 		# and can't download old versions of files.
-		print STDERR "\tDownloading file $mediafile{title}, version $mediafile{timestamp}\n";
+		print {*STDERR} "\tDownloading file $mediafile{title}, version $mediafile{timestamp}\n";
 		$mediafile{content} = download_mw_mediafile($fileinfo->{url});
 	}
 	return %mediafile;
 }
 
 sub download_mw_mediafile {
-	my $url = shift;
+	my $download_url = shift;
 
-	my $response = $mediawiki->{ua}->get($url);
-	if ($response->code == 200) {
+	my $response = $mediawiki->{ua}->get($download_url);
+	if ($response->code == HTTP_CODE_OK) {
 		return $response->decoded_content;
 	} else {
-		print STDERR "Error downloading mediafile from :\n";
-		print STDERR "URL: $url\n";
-		print STDERR "Server response: " . $response->code . " " . $response->message . "\n";
+		print {*STDERR} "Error downloading mediafile from :\n";
+		print {*STDERR} "URL: ${download_url}\n";
+		print {*STDERR} 'Server response: ' . $response->code . q{ } . $response->message . "\n";
 		exit 1;
 	}
 }
 
 sub get_last_local_revision {
 	# Get note regarding last mediawiki revision
-	my $note = run_git("notes --ref=$remotename/mediawiki show refs/mediawiki/$remotename/master 2>/dev/null");
+	my $note = run_git("notes --ref=${remotename}/mediawiki show refs/mediawiki/${remotename}/master 2>/dev/null");
 	my @note_info = split(/ /, $note);
 
 	my $lastrevision_number;
-	if (!(defined($note_info[0]) && $note_info[0] eq "mediawiki_revision:")) {
-		print STDERR "No previous mediawiki revision found";
+	if (!(defined($note_info[0]) && $note_info[0] eq 'mediawiki_revision:')) {
+		print {*STDERR} 'No previous mediawiki revision found';
 		$lastrevision_number = 0;
 	} else {
 		# Notes are formatted : mediawiki_revision: #number
 		$lastrevision_number = $note_info[1];
 		chomp($lastrevision_number);
-		print STDERR "Last local mediawiki revision found is $lastrevision_number";
+		print {*STDERR} "Last local mediawiki revision found is ${lastrevision_number}";
 	}
 	return $lastrevision_number;
 }
 
-# Remember the timestamp corresponding to a revision id.
-my %basetimestamps;
-
 # Get the last remote revision without taking in account which pages are
 # tracked or not. This function makes a single request to the wiki thus
 # avoid a loop onto all tracked pages. This is useful for the fetch-by-rev
@@ -519,7 +552,7 @@ sub get_last_remote_revision {
 
 	my $max_rev_num = 0;
 
-	print STDERR "Getting last revision id on tracked pages...\n";
+	print {*STDERR} "Getting last revision id on tracked pages...\n";
 
 	foreach my $page (@pages) {
 		my $id = $page->{pageid};
@@ -540,7 +573,7 @@ sub get_last_remote_revision {
 		$max_rev_num = ($lastrev->{revid} > $max_rev_num ? $lastrev->{revid} : $max_rev_num);
 	}
 
-	print STDERR "Last remote revision found is $max_rev_num.\n";
+	print {*STDERR} "Last remote revision found is $max_rev_num.\n";
 	return $max_rev_num;
 }
 
@@ -551,7 +584,7 @@ sub mediawiki_clean {
 	# Mediawiki does not allow blank space at the end of a page and ends with a single \n.
 	# This function right trims a string and adds a \n at the end to follow this rule
 	$string =~ s/\s+$//;
-	if ($string eq "" && $page_created) {
+	if ($string eq EMPTY && $page_created) {
 		# Creating empty pages is forbidden.
 		$string = EMPTY_CONTENT;
 	}
@@ -562,15 +595,15 @@ sub mediawiki_clean {
 sub mediawiki_smudge {
 	my $string = shift;
 	if ($string eq EMPTY_CONTENT) {
-		$string = "";
+		$string = EMPTY;
 	}
 	# This \n is important. This is due to mediawiki's way to handle end of files.
-	return $string."\n";
+	return "${string}\n";
 }
 
 sub mediawiki_clean_filename {
 	my $filename = shift;
-	$filename =~ s/@{[SLASH_REPLACEMENT]}/\//g;
+	$filename =~ s{@{[SLASH_REPLACEMENT]}}{/}g;
 	# [, ], |, {, and } are forbidden by MediaWiki, even URL-encoded.
 	# Do a variant of URL-encoding, i.e. looks like URL-encoding,
 	# but with _ added to prevent MediaWiki from thinking this is
@@ -584,16 +617,17 @@ sub mediawiki_clean_filename {
 
 sub mediawiki_smudge_filename {
 	my $filename = shift;
-	$filename =~ s/\//@{[SLASH_REPLACEMENT]}/g;
+	$filename =~ s{/}{@{[SLASH_REPLACEMENT]}}g;
 	$filename =~ s/ /_/g;
 	# Decode forbidden characters encoded in mediawiki_clean_filename
-	$filename =~ s/_%_([0-9a-fA-F][0-9a-fA-F])/sprintf("%c", hex($1))/ge;
+	$filename =~ s/_%_([0-9a-fA-F][0-9a-fA-F])/sprintf('%c', hex($1))/ge;
 	return $filename;
 }
 
 sub literal_data {
 	my ($content) = @_;
-	print STDOUT "data ", bytes::length($content), "\n", $content;
+	print {*STDOUT} 'data ', bytes::length($content), "\n", $content;
+	return;
 }
 
 sub literal_data_raw {
@@ -601,33 +635,37 @@ sub literal_data_raw {
 	my ($content) = @_;
 	# Avoid confusion between size in bytes and in characters
 	utf8::downgrade($content);
-	binmode STDOUT, ":raw";
-	print STDOUT "data ", bytes::length($content), "\n", $content;
-	binmode STDOUT, ":utf8";
+	binmode {*STDOUT}, ':raw';
+	print {*STDOUT} 'data ', bytes::length($content), "\n", $content;
+	binmode {*STDOUT}, ':encoding(UTF-8)';
+	return;
 }
 
 sub mw_capabilities {
 	# Revisions are imported to the private namespace
 	# refs/mediawiki/$remotename/ by the helper and fetched into
 	# refs/remotes/$remotename later by fetch.
-	print STDOUT "refspec refs/heads/*:refs/mediawiki/$remotename/*\n";
-	print STDOUT "import\n";
-	print STDOUT "list\n";
-	print STDOUT "push\n";
-	print STDOUT "\n";
+	print {*STDOUT} "refspec refs/heads/*:refs/mediawiki/${remotename}/*\n";
+	print {*STDOUT} "import\n";
+	print {*STDOUT} "list\n";
+	print {*STDOUT} "push\n";
+	print {*STDOUT} "\n";
+	return;
 }
 
 sub mw_list {
 	# MediaWiki do not have branches, we consider one branch arbitrarily
 	# called master, and HEAD pointing to it.
-	print STDOUT "? refs/heads/master\n";
-	print STDOUT "\@refs/heads/master HEAD\n";
-	print STDOUT "\n";
+	print {*STDOUT} "? refs/heads/master\n";
+	print {*STDOUT} "\@refs/heads/master HEAD\n";
+	print {*STDOUT} "\n";
+	return;
 }
 
 sub mw_option {
-	print STDERR "remote-helper command 'option $_[0]' not yet implemented\n";
-	print STDOUT "unsupported\n";
+	print {*STDERR} "remote-helper command 'option $_[0]' not yet implemented\n";
+	print {*STDOUT} "unsupported\n";
+	return;
 }
 
 sub fetch_mw_revisions_for_page {
@@ -658,15 +696,15 @@ sub fetch_mw_revisions_for_page {
 			push(@page_revs, $page_rev_ids);
 			$revnum++;
 		}
-		last unless $result->{'query-continue'};
+		last if (!$result->{'query-continue'});
 		$query->{rvstartid} = $result->{'query-continue'}->{revisions}->{rvstartid};
 	}
 	if ($shallow_import && @page_revs) {
-		print STDERR "  Found 1 revision (shallow import).\n";
+		print {*STDERR} "  Found 1 revision (shallow import).\n";
 		@page_revs = sort {$b->{revid} <=> $a->{revid}} (@page_revs);
 		return $page_revs[0];
 	}
-	print STDERR "  Found ", $revnum, " revision(s).\n";
+	print {*STDERR} "  Found ${revnum} revision(s).\n";
 	return @page_revs;
 }
 
@@ -678,8 +716,7 @@ sub fetch_mw_revisions {
 	my $n = 1;
 	foreach my $page (@pages) {
 		my $id = $page->{pageid};
-
-		print STDERR "page $n/", scalar(@pages), ": ". $page->{title} ."\n";
+		print {*STDERR} "page ${n}/", scalar(@pages), ': ', $page->{title}, "\n";
 		$n++;
 		my @page_revs = fetch_mw_revisions_for_page($page, $id, $fetch_from);
 		@revisions = (@page_revs, @revisions);
@@ -693,7 +730,7 @@ sub fe_escape_path {
     $path =~ s/\\/\\\\/g;
     $path =~ s/"/\\"/g;
     $path =~ s/\n/\\n/g;
-    return '"' . $path . '"';
+    return qq("${path}");
 }
 
 sub import_file_revision {
@@ -713,42 +750,43 @@ sub import_file_revision {
 	my $author = $commit{author};
 	my $date = $commit{date};
 
-	print STDOUT "commit refs/mediawiki/$remotename/master\n";
-	print STDOUT "mark :$n\n";
-	print STDOUT "committer $author <$author\@$wiki_name> ", $date->epoch, " +0000\n";
+	print {*STDOUT} "commit refs/mediawiki/${remotename}/master\n";
+	print {*STDOUT} "mark :${n}\n";
+	print {*STDOUT} "committer ${author} <${author}\@${wiki_name}> " . $date->epoch . " +0000\n";
 	literal_data($comment);
 
 	# If it's not a clone, we need to know where to start from
 	if (!$full_import && $n == 1) {
-		print STDOUT "from refs/mediawiki/$remotename/master^0\n";
+		print {*STDOUT} "from refs/mediawiki/${remotename}/master^0\n";
 	}
 	if ($content ne DELETED_CONTENT) {
-		print STDOUT "M 644 inline " .
-		    fe_escape_path($title . ".mw") . "\n";
+		print {*STDOUT} 'M 644 inline ' .
+		    fe_escape_path("${title}.mw") . "\n";
 		literal_data($content);
 		if (%mediafile) {
-			print STDOUT "M 644 inline "
+			print {*STDOUT} 'M 644 inline '
 			    . fe_escape_path($mediafile{title}) . "\n";
 			literal_data_raw($mediafile{content});
 		}
-		print STDOUT "\n\n";
+		print {*STDOUT} "\n\n";
 	} else {
-		print STDOUT "D " . fe_escape_path($title . ".mw") . "\n";
+		print {*STDOUT} 'D ' . fe_escape_path("${title}.mw") . "\n";
 	}
 
 	# mediawiki revision number in the git note
 	if ($full_import && $n == 1) {
-		print STDOUT "reset refs/notes/$remotename/mediawiki\n";
+		print {*STDOUT} "reset refs/notes/${remotename}/mediawiki\n";
 	}
-	print STDOUT "commit refs/notes/$remotename/mediawiki\n";
-	print STDOUT "committer $author <$author\@$wiki_name> ", $date->epoch, " +0000\n";
-	literal_data("Note added by git-mediawiki during import");
+	print {*STDOUT} "commit refs/notes/${remotename}/mediawiki\n";
+	print {*STDOUT} "committer ${author} <${author}\@${wiki_name}> " . $date->epoch . " +0000\n";
+	literal_data('Note added by git-mediawiki during import');
 	if (!$full_import && $n == 1) {
-		print STDOUT "from refs/notes/$remotename/mediawiki^0\n";
+		print {*STDOUT} "from refs/notes/${remotename}/mediawiki^0\n";
 	}
-	print STDOUT "N inline :$n\n";
-	literal_data("mediawiki_revision: " . $commit{mw_revision});
-	print STDOUT "\n\n";
+	print {*STDOUT} "N inline :${n}\n";
+	literal_data("mediawiki_revision: $commit{mw_revision}");
+	print {*STDOUT} "\n\n";
+	return;
 }
 
 # parse a sequence of
@@ -761,23 +799,25 @@ sub get_more_refs {
 	my @refs;
 	while (1) {
 		my $line = <STDIN>;
-		if ($line =~ m/^$cmd (.*)$/) {
+		if ($line =~ /^$cmd (.*)$/) {
 			push(@refs, $1);
 		} elsif ($line eq "\n") {
 			return @refs;
 		} else {
-			die("Invalid command in a '$cmd' batch: ". $_);
+			die("Invalid command in a '$cmd' batch: $_\n");
 		}
 	}
+	return;
 }
 
 sub mw_import {
 	# multiple import commands can follow each other.
-	my @refs = (shift, get_more_refs("import"));
+	my @refs = (shift, get_more_refs('import'));
 	foreach my $ref (@refs) {
 		mw_import_ref($ref);
 	}
-	print STDOUT "done\n";
+	print {*STDOUT} "done\n";
+	return;
 }
 
 sub mw_import_ref {
@@ -787,40 +827,41 @@ sub mw_import_ref {
 	# Since HEAD is a symbolic ref to master (by convention,
 	# followed by the output of the command "list" that we gave),
 	# we don't need to do anything in this case.
-	if ($ref eq "HEAD") {
+	if ($ref eq 'HEAD') {
 		return;
 	}
 
 	mw_connect_maybe();
 
-	print STDERR "Searching revisions...\n";
+	print {*STDERR} "Searching revisions...\n";
 	my $last_local = get_last_local_revision();
 	my $fetch_from = $last_local + 1;
 	if ($fetch_from == 1) {
-		print STDERR ", fetching from beginning.\n";
+		print {*STDERR} ", fetching from beginning.\n";
 	} else {
-		print STDERR ", fetching from here.\n";
+		print {*STDERR} ", fetching from here.\n";
 	}
 
 	my $n = 0;
-	if ($fetch_strategy eq "by_rev") {
-		print STDERR "Fetching & writing export data by revs...\n";
+	if ($fetch_strategy eq 'by_rev') {
+		print {*STDERR} "Fetching & writing export data by revs...\n";
 		$n = mw_import_ref_by_revs($fetch_from);
-	} elsif ($fetch_strategy eq "by_page") {
-		print STDERR "Fetching & writing export data by pages...\n";
+	} elsif ($fetch_strategy eq 'by_page') {
+		print {*STDERR} "Fetching & writing export data by pages...\n";
 		$n = mw_import_ref_by_pages($fetch_from);
 	} else {
-		print STDERR "fatal: invalid fetch strategy \"$fetch_strategy\".\n";
-		print STDERR "Check your configuration variables remote.$remotename.fetchStrategy and mediawiki.fetchStrategy\n";
+		print {*STDERR} qq(fatal: invalid fetch strategy "${fetch_strategy}".\n);
+		print {*STDERR} "Check your configuration variables remote.${remotename}.fetchStrategy and mediawiki.fetchStrategy\n";
 		exit 1;
 	}
 
 	if ($fetch_from == 1 && $n == 0) {
-		print STDERR "You appear to have cloned an empty MediaWiki.\n";
+		print {*STDERR} "You appear to have cloned an empty MediaWiki.\n";
 		# Something has to be done remote-helper side. If nothing is done, an error is
 		# thrown saying that HEAD is referring to unknown object 0000000000000000000
 		# and the clone fails.
 	}
+	return;
 }
 
 sub mw_import_ref_by_pages {
@@ -832,7 +873,7 @@ sub mw_import_ref_by_pages {
 	my ($n, @revisions) = fetch_mw_revisions(\@pages, $fetch_from);
 
 	@revisions = sort {$a->{revid} <=> $b->{revid}} @revisions;
-	my @revision_ids = map $_->{revid}, @revisions;
+	my @revision_ids = map { $_->{revid} } @revisions;
 
 	return mw_import_revids($fetch_from, \@revision_ids, \%pages_hash);
 }
@@ -859,7 +900,7 @@ sub mw_import_revids {
 	my $n_actual = 0;
 	my $last_timestamp = 0; # Placeholer in case $rev->timestamp is undefined
 
-	foreach my $pagerevid (@$revision_ids) {
+	foreach my $pagerevid (@{$revision_ids}) {
 	        # Count page even if we skip it, since we display
 		# $n/$total and $total includes skipped pages.
 		$n++;
@@ -875,7 +916,7 @@ sub mw_import_revids {
 		my $result = $mediawiki->api($query);
 
 		if (!$result) {
-			die "Failed to retrieve modified page for revision $pagerevid";
+			die "Failed to retrieve modified page for revision $pagerevid\n";
 		}
 
 		if (defined($result->{query}->{badrevids}->{$pagerevid})) {
@@ -884,7 +925,7 @@ sub mw_import_revids {
 		}
 
 		if (!defined($result->{query}->{pages})) {
-			die "Invalid revision $pagerevid.";
+			die "Invalid revision ${pagerevid}.\n";
 		}
 
 		my @result_pages = values(%{$result->{query}->{pages}});
@@ -894,8 +935,8 @@ sub mw_import_revids {
 		my $page_title = $result_page->{title};
 
 		if (!exists($pages->{$page_title})) {
-			print STDERR "$n/", scalar(@$revision_ids),
-				": Skipping revision #$rev->{revid} of $page_title\n";
+			print {*STDERR} "${n}/", scalar(@{$revision_ids}),
+				": Skipping revision #$rev->{revid} of ${page_title}\n";
 			next;
 		}
 
@@ -920,14 +961,14 @@ sub mw_import_revids {
 		my %mediafile;
 		if ($namespace) {
 			my $id = get_mw_namespace_id($namespace);
-			if ($id && $id == get_mw_namespace_id("File")) {
+			if ($id && $id == get_mw_namespace_id('File')) {
 				%mediafile = get_mw_mediafile_for_page_revision($filename, $rev->{timestamp});
 			}
 		}
 		# If this is a revision of the media page for new version
 		# of a file do one common commit for both file and media page.
 		# Else do commit only for that page.
-		print STDERR "$n/", scalar(@$revision_ids), ": Revision #$rev->{revid} of $commit{title}\n";
+		print {*STDERR} "${n}/", scalar(@{$revision_ids}), ": Revision #$rev->{revid} of $commit{title}\n";
 		import_file_revision(\%commit, ($fetch_from == 1), $n_actual, \%mediafile);
 	}
 
@@ -935,17 +976,17 @@ sub mw_import_revids {
 }
 
 sub error_non_fast_forward {
-	my $advice = run_git("config --bool advice.pushNonFastForward");
+	my $advice = run_git('config --bool advice.pushNonFastForward');
 	chomp($advice);
-	if ($advice ne "false") {
+	if ($advice ne 'false') {
 		# Native git-push would show this after the summary.
 		# We can't ask it to display it cleanly, so print it
 		# ourselves before.
-		print STDERR "To prevent you from losing history, non-fast-forward updates were rejected\n";
-		print STDERR "Merge the remote changes (e.g. 'git pull') before pushing again. See the\n";
-		print STDERR "'Note about fast-forwards' section of 'git push --help' for details.\n";
+		print {*STDERR} "To prevent you from losing history, non-fast-forward updates were rejected\n";
+		print {*STDERR} "Merge the remote changes (e.g. 'git pull') before pushing again. See the\n";
+		print {*STDERR} "'Note about fast-forwards' section of 'git push --help' for details.\n";
 	}
-	print STDOUT "error $_[0] \"non-fast-forward\"\n";
+	print {*STDOUT} qq(error $_[0] "non-fast-forward"\n);
 	return 0;
 }
 
@@ -956,11 +997,11 @@ sub mw_upload_file {
 	my $file_deleted = shift;
 	my $summary = shift;
 	my $newrevid;
-	my $path = "File:" . $complete_file_name;
+	my $path = "File:${complete_file_name}";
 	my %hashFiles = get_allowed_file_extensions();
 	if (!exists($hashFiles{$extension})) {
-		print STDERR "$complete_file_name is not a permitted file on this wiki.\n";
-		print STDERR "Check the configuration of file uploads in your mediawiki.\n";
+		print {*STDERR} "${complete_file_name} is not a permitted file on this wiki.\n";
+		print {*STDERR} "Check the configuration of file uploads in your mediawiki.\n";
 		return $newrevid;
 	}
 	# Deleting and uploading a file requires a priviledged user
@@ -972,18 +1013,18 @@ sub mw_upload_file {
 			reason => $summary
 		};
 		if (!$mediawiki->edit($query)) {
-			print STDERR "Failed to delete file on remote wiki\n";
-			print STDERR "Check your permissions on the remote site. Error code:\n";
-			print STDERR $mediawiki->{error}->{code} . ':' . $mediawiki->{error}->{details};
+			print {*STDERR} "Failed to delete file on remote wiki\n";
+			print {*STDERR} "Check your permissions on the remote site. Error code:\n";
+			print {*STDERR} $mediawiki->{error}->{code} . ':' . $mediawiki->{error}->{details};
 			exit 1;
 		}
 	} else {
 		# Don't let perl try to interpret file content as UTF-8 => use "raw"
-		my $content = run_git("cat-file blob $new_sha1", "raw");
-		if ($content ne "") {
+		my $content = run_git("cat-file blob ${new_sha1}", 'raw');
+		if ($content ne EMPTY) {
 			mw_connect_maybe();
 			$mediawiki->{config}->{upload_url} =
-				"$url/index.php/Special:Upload";
+				"${url}/index.php/Special:Upload";
 			$mediawiki->edit({
 				action => 'upload',
 				filename => $complete_file_name,
@@ -995,12 +1036,12 @@ sub mw_upload_file {
 			}, {
 				skip_encoding => 1
 			} ) || die $mediawiki->{error}->{code} . ':'
-				 . $mediawiki->{error}->{details};
+				 . $mediawiki->{error}->{details} . "\n";
 			my $last_file_page = $mediawiki->get_page({title => $path});
 			$newrevid = $last_file_page->{revid};
-			print STDERR "Pushed file: $new_sha1 - $complete_file_name.\n";
+			print {*STDERR} "Pushed file: ${new_sha1} - ${complete_file_name}.\n";
 		} else {
-			print STDERR "Empty file $complete_file_name not pushed.\n";
+			print {*STDERR} "Empty file ${complete_file_name} not pushed.\n";
 		}
 	}
 	return $newrevid;
@@ -1022,7 +1063,7 @@ sub mw_push_file {
 	my $newrevid;
 
 	if ($summary eq EMPTY_MESSAGE) {
-		$summary = '';
+		$summary = EMPTY;
 	}
 
 	my $new_sha1 = $diff_info_split[3];
@@ -1033,13 +1074,13 @@ sub mw_push_file {
 
 	my ($title, $extension) = $complete_file_name =~ /^(.*)\.([^\.]*)$/;
 	if (!defined($extension)) {
-		$extension = "";
+		$extension = EMPTY;
 	}
-	if ($extension eq "mw") {
+	if ($extension eq 'mw') {
 		my $ns = get_mw_namespace_id_for_page($complete_file_name);
-		if ($ns && $ns == get_mw_namespace_id("File") && (!$export_media)) {
-			print STDERR "Ignoring media file related page: $complete_file_name\n";
-			return ($oldrevid, "ok");
+		if ($ns && $ns == get_mw_namespace_id('File') && (!$export_media)) {
+			print {*STDERR} "Ignoring media file related page: ${complete_file_name}\n";
+			return ($oldrevid, 'ok');
 		}
 		my $file_content;
 		if ($page_deleted) {
@@ -1049,7 +1090,7 @@ sub mw_push_file {
 			# with this content instead:
 			$file_content = DELETED_CONTENT;
 		} else {
-			$file_content = run_git("cat-file blob $new_sha1");
+			$file_content = run_git("cat-file blob ${new_sha1}");
 		}
 
 		mw_connect_maybe();
@@ -1066,49 +1107,49 @@ sub mw_push_file {
 		if (!$result) {
 			if ($mediawiki->{error}->{code} == 3) {
 				# edit conflicts, considered as non-fast-forward
-				print STDERR 'Warning: Error ' .
+				print {*STDERR} 'Warning: Error ' .
 				    $mediawiki->{error}->{code} .
-				    ' from mediwiki: ' . $mediawiki->{error}->{details} .
+				    ' from mediawiki: ' . $mediawiki->{error}->{details} .
 				    ".\n";
-				return ($oldrevid, "non-fast-forward");
+				return ($oldrevid, 'non-fast-forward');
 			} else {
 				# Other errors. Shouldn't happen => just die()
 				die 'Fatal: Error ' .
 				    $mediawiki->{error}->{code} .
-				    ' from mediwiki: ' . $mediawiki->{error}->{details};
+				    ' from mediawiki: ' . $mediawiki->{error}->{details} . "\n";
 			}
 		}
 		$newrevid = $result->{edit}->{newrevid};
-		print STDERR "Pushed file: $new_sha1 - $title\n";
+		print {*STDERR} "Pushed file: ${new_sha1} - ${title}\n";
 	} elsif ($export_media) {
 		$newrevid = mw_upload_file($complete_file_name, $new_sha1,
 					   $extension, $page_deleted,
 					   $summary);
 	} else {
-		print STDERR "Ignoring media file $title\n";
+		print {*STDERR} "Ignoring media file ${title}\n";
 	}
 	$newrevid = ($newrevid or $oldrevid);
-	return ($newrevid, "ok");
+	return ($newrevid, 'ok');
 }
 
 sub mw_push {
 	# multiple push statements can follow each other
-	my @refsspecs = (shift, get_more_refs("push"));
+	my @refsspecs = (shift, get_more_refs('push'));
 	my $pushed;
 	for my $refspec (@refsspecs) {
 		my ($force, $local, $remote) = $refspec =~ /^(\+)?([^:]*):([^:]*)$/
-		    or die("Invalid refspec for push. Expected <src>:<dst> or +<src>:<dst>");
+		    or die("Invalid refspec for push. Expected <src>:<dst> or +<src>:<dst>\n");
 		if ($force) {
-			print STDERR "Warning: forced push not allowed on a MediaWiki.\n";
+			print {*STDERR} "Warning: forced push not allowed on a MediaWiki.\n";
 		}
-		if ($local eq "") {
-			print STDERR "Cannot delete remote branch on a MediaWiki\n";
-			print STDOUT "error $remote cannot delete\n";
+		if ($local eq EMPTY) {
+			print {*STDERR} "Cannot delete remote branch on a MediaWiki\n";
+			print {*STDOUT} "error ${remote} cannot delete\n";
 			next;
 		}
-		if ($remote ne "refs/heads/master") {
-			print STDERR "Only push to the branch 'master' is supported on a MediaWiki\n";
-			print STDOUT "error $remote only master allowed\n";
+		if ($remote ne 'refs/heads/master') {
+			print {*STDERR} "Only push to the branch 'master' is supported on a MediaWiki\n";
+			print {*STDOUT} "error ${remote} only master allowed\n";
 			next;
 		}
 		if (mw_push_revision($local, $remote)) {
@@ -1117,30 +1158,32 @@ sub mw_push {
 	}
 
 	# Notify Git that the push is done
-	print STDOUT "\n";
+	print {*STDOUT} "\n";
 
 	if ($pushed && $dumb_push) {
-		print STDERR "Just pushed some revisions to MediaWiki.\n";
-		print STDERR "The pushed revisions now have to be re-imported, and your current branch\n";
-		print STDERR "needs to be updated with these re-imported commits. You can do this with\n";
-		print STDERR "\n";
-		print STDERR "  git pull --rebase\n";
-		print STDERR "\n";
+		print {*STDERR} "Just pushed some revisions to MediaWiki.\n";
+		print {*STDERR} "The pushed revisions now have to be re-imported, and your current branch\n";
+		print {*STDERR} "needs to be updated with these re-imported commits. You can do this with\n";
+		print {*STDERR} "\n";
+		print {*STDERR} "  git pull --rebase\n";
+		print {*STDERR} "\n";
 	}
+	return;
 }
 
 sub mw_push_revision {
 	my $local = shift;
 	my $remote = shift; # actually, this has to be "refs/heads/master" at this point.
 	my $last_local_revid = get_last_local_revision();
-	print STDERR ".\n"; # Finish sentence started by get_last_local_revision()
+	print {*STDERR} ".\n"; # Finish sentence started by get_last_local_revision()
 	my $last_remote_revid = get_last_remote_revision();
 	my $mw_revision = $last_remote_revid;
 
 	# Get sha1 of commit pointed by local HEAD
-	my $HEAD_sha1 = run_git("rev-parse $local 2>/dev/null"); chomp($HEAD_sha1);
+	my $HEAD_sha1 = run_git("rev-parse ${local} 2>/dev/null");
+	chomp($HEAD_sha1);
 	# Get sha1 of commit pointed by remotes/$remotename/master
-	my $remoteorigin_sha1 = run_git("rev-parse refs/remotes/$remotename/master 2>/dev/null");
+	my $remoteorigin_sha1 = run_git("rev-parse refs/remotes/${remotename}/master 2>/dev/null");
 	chomp($remoteorigin_sha1);
 
 	if ($last_local_revid > 0 &&
@@ -1159,22 +1202,22 @@ sub mw_push_revision {
 	if ($last_local_revid > 0) {
 		my $parsed_sha1 = $remoteorigin_sha1;
 		# Find a path from last MediaWiki commit to pushed commit
-		print STDERR "Computing path from local to remote ...\n";
-		my @local_ancestry = split(/\n/, run_git("rev-list --boundary --parents $local ^$parsed_sha1"));
+		print {*STDERR} "Computing path from local to remote ...\n";
+		my @local_ancestry = split(/\n/, run_git("rev-list --boundary --parents ${local} ^${parsed_sha1}"));
 		my %local_ancestry;
 		foreach my $line (@local_ancestry) {
-			if (my ($child, $parents) = $line =~ m/^-?([a-f0-9]+) ([a-f0-9 ]+)/) {
-				foreach my $parent (split(' ', $parents)) {
+			if (my ($child, $parents) = $line =~ /^-?([a-f0-9]+) ([a-f0-9 ]+)/) {
+				foreach my $parent (split(/ /, $parents)) {
 					$local_ancestry{$parent} = $child;
 				}
-			} elsif (!$line =~ m/^([a-f0-9]+)/) {
-				die "Unexpected output from git rev-list: $line";
+			} elsif (!$line =~ /^([a-f0-9]+)/) {
+				die "Unexpected output from git rev-list: ${line}\n";
 			}
 		}
 		while ($parsed_sha1 ne $HEAD_sha1) {
 			my $child = $local_ancestry{$parsed_sha1};
 			if (!$child) {
-				printf STDERR "Cannot find a path in history from remote commit to last commit\n";
+				print {*STDERR} "Cannot find a path in history from remote commit to last commit\n";
 				return error_non_fast_forward($remote);
 			}
 			push(@commit_pairs, [$parsed_sha1, $child]);
@@ -1183,12 +1226,12 @@ sub mw_push_revision {
 	} else {
 		# No remote mediawiki revision. Export the whole
 		# history (linearized with --first-parent)
-		print STDERR "Warning: no common ancestor, pushing complete history\n";
-		my $history = run_git("rev-list --first-parent --children $local");
-		my @history = split('\n', $history);
+		print {*STDERR} "Warning: no common ancestor, pushing complete history\n";
+		my $history = run_git("rev-list --first-parent --children ${local}");
+		my @history = split(/\n/, $history);
 		@history = @history[1..$#history];
 		foreach my $line (reverse @history) {
-			my @commit_info_split = split(/ |\n/, $line);
+			my @commit_info_split = split(/[ \n]/, $line);
 			push(@commit_pairs, \@commit_info_split);
 		}
 	}
@@ -1196,12 +1239,12 @@ sub mw_push_revision {
 	foreach my $commit_info_split (@commit_pairs) {
 		my $sha1_child = @{$commit_info_split}[0];
 		my $sha1_commit = @{$commit_info_split}[1];
-		my $diff_infos = run_git("diff-tree -r --raw -z $sha1_child $sha1_commit");
+		my $diff_infos = run_git("diff-tree -r --raw -z ${sha1_child} ${sha1_commit}");
 		# TODO: we could detect rename, and encode them with a #redirect on the wiki.
 		# TODO: for now, it's just a delete+add
 		my @diff_info_list = split(/\0/, $diff_infos);
 		# Keep the subject line of the commit message as mediawiki comment for the revision
-		my $commit_msg = run_git("log --no-walk --format=\"%s\" $sha1_commit");
+		my $commit_msg = run_git(qq(log --no-walk --format="%s" ${sha1_commit}));
 		chomp($commit_msg);
 		# Push every blob
 		while (@diff_info_list) {
@@ -1213,7 +1256,7 @@ sub mw_push_revision {
 			my $info = shift(@diff_info_list);
 			my $file = shift(@diff_info_list);
 			($mw_revision, $status) = mw_push_file($info, $file, $commit_msg, $mw_revision);
-			if ($status eq "non-fast-forward") {
+			if ($status eq 'non-fast-forward') {
 				# we may already have sent part of the
 				# commit to MediaWiki, but it's too
 				# late to cancel it. Stop the push in
@@ -1221,17 +1264,17 @@ sub mw_push_revision {
 				# accurate error message.
 				return error_non_fast_forward($remote);
 			}
-			if ($status ne "ok") {
-				die("Unknown error from mw_push_file()");
+			if ($status ne 'ok') {
+				die("Unknown error from mw_push_file()\n");
 			}
 		}
-		unless ($dumb_push) {
-			run_git("notes --ref=$remotename/mediawiki add -f -m \"mediawiki_revision: $mw_revision\" $sha1_commit");
-			run_git("update-ref -m \"Git-MediaWiki push\" refs/mediawiki/$remotename/master $sha1_commit $sha1_child");
+		if (!$dumb_push) {
+			run_git(qq(notes --ref=${remotename}/mediawiki add -f -m "mediawiki_revision: ${mw_revision}" ${sha1_commit}));
+			run_git(qq(update-ref -m "Git-MediaWiki push" refs/mediawiki/${remotename}/master ${sha1_commit} ${sha1_child}));
 		}
 	}
 
-	print STDOUT "ok $remote\n";
+	print {*STDOUT} "ok ${remote}\n";
 	return 1;
 }
 
@@ -1244,8 +1287,8 @@ sub get_allowed_file_extensions {
 		siprop => 'fileextensions'
 		};
 	my $result = $mediawiki->api($query);
-	my @file_extensions= map $_->{ext},@{$result->{query}->{fileextensions}};
-	my %hashFile = map {$_ => 1}@file_extensions;
+	my @file_extensions = map { $_->{ext}} @{$result->{query}->{fileextensions}};
+	my %hashFile = map { $_ => 1 } @file_extensions;
 
 	return %hashFile;
 }
@@ -1267,8 +1310,8 @@ sub get_mw_namespace_id {
 		# Look at configuration file, if the record for that namespace is
 		# already cached. Namespaces are stored in form:
 		# "Name_of_namespace:Id_namespace", ex.: "File:6".
-		my @temp = split(/[\n]/, run_git("config --get-all remote."
-						. $remotename .".namespaceCache"));
+		my @temp = split(/\n/,
+				 run_git("config --get-all remote.${remotename}.namespaceCache"));
 		chomp(@temp);
 		foreach my $ns (@temp) {
 			my ($n, $id) = split(/:/, $ns);
@@ -1282,7 +1325,7 @@ sub get_mw_namespace_id {
 	}
 
 	if (!exists $namespace_id{$name}) {
-		print STDERR "Namespace $name not found in cache, querying the wiki ...\n";
+		print {*STDERR} "Namespace ${name} not found in cache, querying the wiki ...\n";
 		# NS not found => get namespace id from MW and store it in
 	        # configuration file.
 	        my $query = {
@@ -1306,8 +1349,8 @@ sub get_mw_namespace_id {
 	my $ns = $namespace_id{$name};
 	my $id;
 
-	unless (defined $ns) {
-		print STDERR "No such namespace $name on MediaWiki.\n";
+	if (!defined $ns) {
+		print {*STDERR} "No such namespace ${name} on MediaWiki.\n";
 		$ns = {is_namespace => 0};
 		$namespace_id{$name} = $ns;
 	}
@@ -1321,15 +1364,15 @@ sub get_mw_namespace_id {
 
 	# Store explicitely requested namespaces on disk
 	if (!exists $cached_mw_namespace_id{$name}) {
-		run_git("config --add remote.". $remotename
-			.".namespaceCache \"". $name .":". $store_id ."\"");
+		run_git(qq(config --add remote.${remotename}.namespaceCache "${name}:${store_id}"));
 		$cached_mw_namespace_id{$name} = 1;
 	}
 	return $id;
 }
 
 sub get_mw_namespace_id_for_page {
-	if (my ($namespace) = $_[0] =~ /^([^:]*):/) {
+	my $namespace = shift;
+	if ($namespace =~ /^([^:]*):/) {
 		return get_mw_namespace_id($namespace);
 	} else {
 		return;