On Thu, 2010-12-16 at 14:30 -0800, Jakub Narebski wrote:
> Sylvain Rabot <sylvain@xxxxxxxxxxxxxx> writes:
>
> > it happens that closing file descriptor fails whereas
> > the blob is perfectly readable.
> >
> > Signed-off-by: Sylvain Rabot <sylvain@xxxxxxxxxxxxxx>
> > ---
> > gitweb/gitweb.perl | 3 +--
> > 1 files changed, 1 insertions(+), 2 deletions(-)
> >
> > diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
> > index 9398475..9a885b1 100755
> > --- a/gitweb/gitweb.perl
> > +++ b/gitweb/gitweb.perl
> > @@ -3450,8 +3450,7 @@ sub run_highlighter {
> > my ($fd, $highlight, $syntax) = @_;
> > return $fd unless ($highlight && defined $syntax);
> >
> > - close $fd
> > - or die_error(404, "Reading blob failed");
> > + close $fd;
>
> Actually what I think happens is the following. "close $fh" cannot
> usually fail, unless (`perldoc -f close`):
>
> If the file handle came from a piped open, "close" will additionally
> return false if one of the other system calls involved fails, or if the
> program exits with non-zero status. (If the only problem was that the
> program exited non-zero, $! will be set to 0.) Closing a pipe also waits
> for the process executing on the pipe to complete, in case you want to
> look at the output of the pipe afterwards, and implicitly puts the exit
> status value of that command into $?.
>
> Prematurely closing the read end of a pipe (i.e. before the process writ-
> ing to it at the other end has closed it) will result in a SIGPIPE being
> delivered to the writer. If the other end can't handle that, be sure to
> read all the data before closing the pipe.
>
> In this place we close read end of pipe after at most reading a few
> bytes (what -T test does), so what might happen is that writer got
> SIGPIPE and "failed". But we are not interested in this, so we can
> safely ignore return from 'close'.
>
> I think that some from above explanation should make it to commit
> message.
Thanks for explaining it, I did not have any idea why it was failing.
Can I use your explanation as commit message ?
>
> > open $fd, quote_command(git_cmd(), "cat-file", "blob", $hash)." | ".
> > quote_command($highlight_bin).
> > " --xhtml --fragment --syntax $syntax |"
>
> P.S. A better solution would be to redirect opened $fd to highlighter,
> instead of closing and reopening a pipe... but I'm not sure how it
> could be implemented.
I don't know either.
>
--
Sylvain Rabot <sylvain@xxxxxxxxxxxxxx>
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