[PATCH 4/3 v2 (bugfix)] gitweb: Fix fallback mode of to_utf8 subroutine
e5d3de5 (gitweb: use Perl built-in utf8 function for UTF-8 decoding., 2007-12-04) was meant to make gitweb faster by using Perl's internals (see subsection "Messing with Perl's Internals" in Encode(3pm) manpage)
Simple benchmark confirms that (old = 00f429a, new = this version): note that it is synthetic benchmark of standalone subroutines, not of gitweb itself (where probably no visible difference in performace will show)
Rate old new
old 1582/s -- -64%
new 4453/s 181% --
Unfortunately it made fallback mode of to_utf8 do not work... except for default value 'latin1' of $fallback_encoding (because 'latin1' is Perl native encoding), which is probably why it was not noticed for so long.
utf8::valid(STRING) is an internal function that tests whether STRING is in a _consistent state_ regarding UTF-8. It returns true is well-formed UTF-8 and has the UTF-8 flag on _*or*_ if string is held as bytes (both these states are 'consistent').
For gitweb in most cases the second option was true, as output from git commands is opened without ':utf8' layer. So utf8::valid is not useful for to_utf8.
What made it look as if to_utf8() fallback mode worked correctly (though only for $fallback_encoding at its default value 'latin1') was the fact that utf8::decode(STRING) turns on UTF-8 flag only if source string^W octets form a valid UTF-8 and it contains multi-byte UTF-8 characters... this means that if string was not valid UTF-8 it didn't get UTF-8 flag.
When string doesn't have UTF-8 flag set, it is treated as if it was in native Perl encoding, which is 'latin1' (unless native encoding is EBCDIC ;-)). So it was ':utf8' layer that actually converted 'latin1' (no UTF-8 flag == native == 'latin1) to 'utf8', and not to_utf8() subroutine. Fallback mode was never triggered.
Let's make use of the fact that utf8::decode(STRING) returns false if STRING is invalid as UTF-8 to check whether to enable fallback mode.
Note however that if STRING has UTF-8 flag set already, then utf8::decode also returns false, which could cause problems if given string was already converted with to_utf8(). Such double conversion can happen in gitweb. Therefore we have to check if STRING has UTF-8 flag set with utf8::is_utf8(); if this subroutine returns true then we have already decoded (converted) string, and don't have to do it second time.
Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---
Jakub Narebski wrote:
Show 17 quoted lines
> P.S. I started to get strange errors
>
> XML Parsing Error: xml processing instruction not at start of external entity
> Location: http://localhost/cgi-bin/gitweb/gitweb.cgi
> Line Number 37, Column 1:
> <?xml version="1.0" encoding="utf-8"?>
> ^
>
> while "show source" shows that '<?xml version="1.0" encoding="utf-8"?>'
> is the first line. WTF?!?
>
> P.P.S. Now I am getting errors when running gitweb, but only in some
> cases (via mod_cgi not as standalone script, only when using lynx),
> namely it looks like it falls back to 'latin1' when doing content
> which is valid UTF-8.
>
> Will investigate.
Now it is fixed; the error was caused by to_utf8 not dealing with double encoding for strings outside 7bit ASCII.
gitweb/gitweb.perl | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
Show changes to gitweb/gitweb.perl +2 −2
diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index d24763b..fc41b07 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -1443,8 +1443,8 @@ sub validate_refname {
sub to_utf8 {
my $str = shift;
return undef unless defined $str;
- if (utf8::valid($str)) {
- utf8::decode($str);
+
+ if (utf8::is_utf8($str) || utf8::decode($str)) {
return $str;
} else {
return decode($fallback_encoding, $str, Encode::FB_DEFAULT);
--
1.7.6
Jakub Narebski