Re: [PATCH 1/4] gitweb: Fix utf8 encoding for blob_plain, blobdiff_plain, commitdiff_plain, and patch

Jakub Narębski [off-list ref] writes:

On 08.04.2013, Junio C Hamano wrote:

quoted

jk@blackdown.de (Jürgen Kreileder) writes:

quoted

Fixes the encoding for several _plain actions and for text/* and */*+xml blobs. 

Signed-off-by: Jürgen Kreileder <redacted>

I see that this patch does (or tries to do) two _independent_ things,
and should be split into at least two separate commits:

Agreed.

quoted

quoted

---

Thanks, will queue but not hold until I hear something from Jakub.

quoted

 gitweb/gitweb.perl |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 1309196..9cfe5b5 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl

@@ -3823,7 +3823,7 @@ sub blob_contenttype {
 	my ($fd, $file_name, $type) = @_;
 
 	$type ||= blob_mimetype($fd, $file_name);
-	if ($type eq 'text/plain' && defined $default_text_plain_charset) {
+	if (($type =~ m!^text/\w[-\w]*$! || $type =~ m!^\w[-\w]*/\w[-\w]*\+xml$!) && defined $default_text_plain_charset) {
 		$type .= "; charset=$default_text_plain_charset";
 	}

First, it extends adding "; charset=$default_text_plain_charset" to
other mimetypes for 'blob_plain' view to all 'text/*' and '*/*+xml'
mimetypes (without changing name of variable... though this is more
complicated as it is configuration variable and we would want to
preserve backward compatibility, but at least a comment would be,
I think, needed).
 
Originally it applied only to 'text/plain' files, which can be
displayed inline by web browser, and which need charset in
'Content-Type:' HTTP header to be displayed correctly, as they
do not include such information inside the file.

What prompted the change is that some browsers (Chrome and Safari) also
display other file types inline: text/x-chdr, text/x-java, text/x-objc,
text/x-sh, ...

At least on my system these files do get served with charset set!
(ISO-8859-1 even though Apache has "AddDefaultCharset UTF-8"...)

    $ curl -I "https://git.blackdown.de/old.cgi?p=contactalbum.git;a=blob_plain;f=Classes/ContactAlbum.h;hb=HEAD"
    HTTP/1.1 200 OK
    Date: Tue, 09 Apr 2013 21:47:30 GMT
    Server: Apache
    Content-disposition: inline; filename="Classes/ContactAlbum.h"
    X-Frame-Options: SAMEORIGIN
    Vary: User-Agent
    X-UA-Compatible: IE=edge
    Strict-Transport-Security: max-age=31536000
    Content-Type: text/x-chdr; charset=ISO-8859-1

'text/html' and 'application/xhtml+xml' can include such information
inside them (meta http-equiv for 'text/html' and <?xml ...> for
'application/xhtml+xml').  I don't know what browser does when there
is conflicting information about charset, i.e. which one wins, but
it is certainly something to consider.

As shown above, even without my patch, this already can happen!

It might be a good change; I don't know what web browser do when
serving 'text/css', 'text/javascript', 'text/xml' to client to
view without media type known.


BTW I have noticed that we do $prevent_xss dance outside
blob_contenttype(), in it's only caller i.e. git_blob_plain()...
which for example means that 'text/html' converted to 'text/plain'
don't get '; charset=...' added.  I guess that it *might* be
what prompted this part of change... but if it is so, it needs
to be fixed at source, e.g. by moving $prevent_xss to
blob_contenttype() subroutine.

Jep.

[...]

Second it changes 'blobdiff_plain', 'commitdiff_plain' (which I think
that should be abandoned in favor of 'patch' view; but that is
a separate issue) and 'patch' views so they use binary-safe output.

Note that in all cases (I think) we use

   $cgi->header(
     -type => 'text/plain',
     -charset => 'utf-8',
     ...
   );

promising web browser that output is as whole in 'utf-8' encoding.

Yes.

It is not explained in the commit message what is the reason for this
change.  Is it better handing of a situation where files being diff-ed
being in other encoding (like for example in commit that changes
encoding of files from legacy encoding such like e.g. iso-8859-2
or cp1250 to utf-8)?

I do see encoding problems when comparing utf8 to utf8 files (i.e. no
encoding change).  For instance:
https://git.blackdown.de/old.cgi?p=contactalbum.git;a=commitdiff_plain;h=cc4eaa64c2b399dd9bdbf1f67f6d621aa24df5f8

I don't claim to be an expert in Perl's utf8 handling but I guess this
because Perl's internal utf8 form differs from the normal utf8 out from
git commands.  Switching to :raw fixes that: We write plain utf8 (and,
as noted above, charset is set to utf8 already)

With the patch: https://git.blackdown.de/?p=contactalbum.git;a=commitdiff_plain;h=cc4eaa64c2b399dd9bdbf1f67f6d621aa24df5f8

But what about -charset => 'utf-8'  then?

That's a good question.  I think I never tried git with anything besides
ISO-8859-1 (rarely), UTF8 (mostly), and UTF16 (some Xcode files).
(UTF16 definitely causes problems for gitweb.)

About implementation: I think after this change common code crosses
threshold for refactoring it into subroutine, for example:

  sub dump_fh_raw {
  	my $fh = shift;

  	local $/ = undef;
  	binmode STDOUT, ':raw';
  	print <$fh>;
  	binmode STDOUT, ':utf8'; # as set at the beginning of gitweb.cgi

  	return $fh;
  }

OK.

I'll submit an updated patch for the second part ('blobdiff_plain',
'commitdiff_plain', and 'plain') tomorrow.

Not sure how to proceed with the 'blob_plain' issue.


    Juergen

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