lei_mirror+fetch: don't slurp `git show-ref' output

While uncommon, some git repos have hundreds of thousands of
refs and slurping that output into memory can bloat the heap.
Introduce a sha_all sub in PublicInbox::SHA to loop until EOF
and rely on autodie for checking sysread errors.

1 files changed, 2 insertions, 4 deletions

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index 476dcf30..9c26d8bf 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -23,7 +23,7 @@ use PublicInbox::ProcessIONBF;
 use PublicInbox::Tmpfile;
 use IO::Poll qw(POLLIN);
 use Carp qw(croak carp);
-use PublicInbox::SHA ();
+use PublicInbox::SHA qw(sha_all);
 our %HEXLEN2SHA = (40 => 1, 64 => 256);
 our %OFMT2HEXLEN = (sha1 => 40, sha256 => 64);
 our @EXPORT_OK = qw(git_unquote git_quote %HEXLEN2SHA %OFMT2HEXLEN read_all);
@@ -620,10 +620,8 @@ sub manifest_entry {
                         $ent->{reference} = $buf;
                 }
         }
-        my $dig = PublicInbox::SHA->new(1);
-        while (CORE::read($sr, $buf, 65536)) { $dig->add($buf) }
+        $ent->{fingerprint} = sha_all(1, $sr)->hexdigest;
         CORE::close $sr or return; # empty, uninitialized git repo
-        $ent->{fingerprint} = $dig->hexdigest;
         $ent->{modified} = modified(undef, $mod);
         chomp($buf = <$own> // '');
         utf8::decode($buf);