build: preserve original .po header when updating from templates to reduce diff noise

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

diff --git a/build/i18n-update.pl b/build/i18n-update.pl
index 16b82e8dddc126d4223f251dfac42bd2794605f8..4106c6da4c1c5a1cb06294ef87129c2b8497c3c5 100755 (executable)
--- a/build/i18n-update.pl
+++ b/build/i18n-update.pl
@@ -5,7 +5,7 @@
 my $source  = shift @ARGV;
 my $pattern = shift @ARGV || '*.po';
 
-sub fixup_header_order
+sub read_header
 {
        my $file = shift || return;
        local $/;
@@ -14,7 +14,34 @@ sub fixup_header_order
        my $data = readline P;
        close P;
 
-       $data =~ s/("Language-Team: .*?\\n"\n)(.+?)("Language: .*?\\n"\n)/$1$3$2/s;
+       $data =~ /
+               ^ (
+               msgid \s "" \n
+               msgstr \s "" \n
+               (?: " [^\n]+ " \n )+
+               \n )
+       /mx;
+
+       return $1;
+}
+
+sub write_header
+{
+       my $file = shift || return;
+       my $head = shift || return;
+       local $/;
+
+       open P, "< $file" || die "open(): $!";
+       my $data = readline P;
+       close P;
+
+       $data =~ s/
+               ^ (
+               msgid \s "" \n
+               msgstr \s "" \n
+               (?: " [^\n]+ " \n )+
+               \n )
+       /$head/mx;
 
        open P, "> $file" || die "open(): $!";
        print P $data;
@@ -29,9 +56,12 @@ if( open F, "find $source -type f -name '$pattern' |" )
                
                if( -f "$source/templates/$basename.pot" )
                {
+                       my $head = read_header($file);
+
                        printf "Updating %-40s", $file;
                        system("msgmerge", "-U", "-N", $file, "$source/templates/$basename.pot");
-                       fixup_header_order($file);
+
+                       write_header($file, $head);
                }
        }