http-backend: respect CONTENT_LENGTH for receive-pack

Push passes to another commands, as described in
https://public-inbox.org/git/20171129032214.GB32345@sigill.intra.peff.net/

As it gets complicated to correctly track the data length, instead transfer
the data through parent process and cut the pipe as the specified length is
reached. Do it only when CONTENT_LENGTH is set, otherwise pass the input
directly to the forked commands.

Add tests for cases:

* CONTENT_LENGTH is set, script's stdin has more data, with all combinations
  of variations: fetch or push, plain or compressed body, correct or truncated
  input.

* CONTENT_LENGTH is specified to a value which does not fit into ssize_t.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Max Kirillov <max@max630.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/t/t5562/invoke-with-content-length.pl b/t/t5562/invoke-with-content-length.pl
new file mode 100755
index 0000000000..6c2aae7692
--- /dev/null
+++ b/t/t5562/invoke-with-content-length.pl
@@ -0,0 +1,37 @@
+#!/usr/bin/perl
+use 5.008;
+use strict;
+use warnings;
+
+my $body_filename = $ARGV[0];
+my @command = @ARGV[1 .. $#ARGV];
+
+# read data
+my $body_size = -s $body_filename;
+$ENV{"CONTENT_LENGTH"} = $body_size;
+open(my $body_fh, "<", $body_filename) or die "Cannot open $body_filename: $!";
+my $body_data;
+defined read($body_fh, $body_data, $body_size) or die "Cannot read $body_filename: $!";
+close($body_fh);
+
+my $exited = 0;
+$SIG{"CHLD"} = sub {
+        $exited = 1;
+};
+
+# write data
+my $pid = open(my $out, "|-", @command);
+{
+        # disable buffering at $out
+        my $old_selected = select;
+        select $out;
+        $| = 1;
+        select $old_selected;
+}
+print $out $body_data or die "Cannot write data: $!";
+
+sleep 60; # is interrupted by SIGCHLD
+if (!$exited) {
+        close($out);
+        die "Command did not exit after reading whole body";
+}