From: Michal Nazarewicz <min...@mina86.com>
The command_close_bidi_pipe() function will insist on closing both
input and output pipes returned by command_bidi_pipe(). With this
change it is possible to close one of the pipes in advance and
pass undef as an argument.
Signed-off-by: Michal Nazarewicz <min...@mina86.com>
---
perl/Git.pm | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
> On Wed, Feb 06, 2013 at 09:47:04PM +0100, Michal Nazarewicz wrote:
>> This allows for something like:
>>
>> my ($pid, $in, $out, $ctx) = command_bidi_pipe(...);
>> print $out "write data";
>> close $out;
>> # ... do stuff with $in
>> command_close_bidi_pipe($pid, $in, undef, $ctx);
On Thu, Feb 07 2013, Jeff King <p...@peff.net> wrote:
> Should this part go into the documentation for command_close_bidi_pipe
> in Git.pm?
Done.
diff --git a/perl/Git.pm b/perl/Git.pm
index 11f310a..9dded54 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -426,13 +426,26 @@ Note that you should not rely on whatever actually is in
C<CTX>;
currently it is simply the command name but in future the context might
have more complicated structure.
+C<PIPE_IN> and C<PIPE_OUT> may be C<undef> if they have been closed prior to
+calling this function. This may be useful in a query-response type of
+commands where caller first writes a query and later reads response, eg:
+
+ my ($pid, $in, $out, $ctx) = $r->command_bidi_pipe('cat-file
--batch-check');
+ print $out "000000000\n";
+ close $out;
+ while (<$in>) { ... }
+ $r->command_close_bidi_pipe($pid, $in, undef, $ctx);
+
+This idiom may prevent potential dead locks caused by data sent to the output
+pipe not being flushed and thus not reaching the executed command.
+
=cut
sub command_close_bidi_pipe {
local $?;
my ($self, $pid, $in, $out, $ctx) = _maybe_self(@_);
foreach my $fh ($in, $out) {
- unless (close $fh) {
+ if (defined $fh && !close $fh) {
if ($!) {
carp "error closing pipe: $!";
} elsif ($? >> 8) {
--
1.8.1.2.549.g1d13f9f
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