git: avoid Perl5 internal scratchpad target cache

Creating a scalar ref directly off substr() seemed to be causing
the underlying non-ref scalar to end up in Perl's scratchpad.
Assign the substr result to a local variable seems sufficient to
prevent multi-megabyte SVs from lingering indefinitely when a
read-only daemon serves rare, oversized blobs.

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index 374a3b4dd71d9849aea7a1c7dee2e8d2e2d8d1f6..4078dd5b7cfe79f8bf1c0d29cfbe4b3cba35aae5 100644 (file)
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -158,7 +158,8 @@ sub my_read ($$$) {
                        return; # unrecoverable error
                }
        }
-       \substr($$rbuf, 0, $len, '');
+       my $no_pad = substr($$rbuf, 0, $len, '');
+       \$no_pad;
 }
 
 sub my_readline ($$) {