GitCatFile: use offset for read instead of appending

There is no need to perform string appends when the
"read" and "sysread" functions take an offset argument
to append to the given buffer.

This avoid needless string creation.

diff --git a/lib/PublicInbox/GitCatFile.pm b/lib/PublicInbox/GitCatFile.pm
index 8bc6a238d2ae2c8f09c5062091e2ae140245d0c6..9bffce2aa2a727db21e1e42431dafc66310133c2 100644 (file)
--- a/lib/PublicInbox/GitCatFile.pm
+++ b/lib/PublicInbox/GitCatFile.pm
@@ -68,17 +68,17 @@ sub cat_file {
 
        my $size = $1;
        my $bytes_left = $size;
-       my $buf;
+       my $offset = 0;
        my $rv = '';
 
        while ($bytes_left) {
-               my $read = read($in, $buf, $bytes_left);
-               defined($read) or die "read pipe failed: $!\n";
-               $rv .= $buf;
+               my $read = read($in, $rv, $bytes_left, $offset);
+               defined($read) or die "sysread pipe failed: $!\n";
                $bytes_left -= $read;
+               $offset += $read;
        }
 
-       my $read = read($in, $buf, 1);
+       my $read = read($in, my $buf, 1);
        defined($read) or die "read pipe failed: $!\n";
        if ($read != 1 || $buf ne "\n") {
                die "newline missing after blob\n";