Read and write each 1024 byte buffer, rather than trying to buffer
the entire content of the file.
Previous code would crash on all files > 2 Gib, when the offset variable
became negative (perhaps below the level of perl), resulting in a crash.
On a 32 bit system, or a system with low memory it might crash before
reaching 2 GiB due to memory exhaustion.
This code may leave a partial file behind in case of failure, where the
old code would leave a completely empty file.
Neither version verifies the correctness of the content.
Calling code must take care of verification and cleanup.

Signed-off-by: Joshua Clayton <stillcompil...@gmail.com>
Reviewed-by: Jeff King <p...@peff.net>
Reviewed-by: Junio C Hamano <gits...@pobox.com>
---
 perl/Git.pm |   17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/perl/Git.pm b/perl/Git.pm
index 931047c..db6e0a8 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -942,20 +942,22 @@ sub cat_blob {
        my $size = $1;
 
        my $blob;
-       my $bytesRead = 0;
+       my $bytesLeft = $size;
 
        while (1) {
-               my $bytesLeft = $size - $bytesRead;
                last unless $bytesLeft;
 
                my $bytesToRead = $bytesLeft < 1024 ? $bytesLeft : 1024;
-               my $read = read($in, $blob, $bytesToRead, $bytesRead);
+               my $read = read($in, $blob, $bytesToRead);
                unless (defined($read)) {
                        $self->_close_cat_blob();
                        throw Error::Simple("in pipe went bad");
                }
-
-               $bytesRead += $read;
+               unless (print $fh $blob) {
+                       $self->_close_cat_blob();
+                       throw Error::Simple("couldn't write to passed in 
filehandle");
+               }
+               $bytesLeft -= $read;
        }
 
        # Skip past the trailing newline.
@@ -970,11 +972,6 @@ sub cat_blob {
                throw Error::Simple("didn't find newline after blob");
        }
 
-       unless (print $fh $blob) {
-               $self->_close_cat_blob();
-               throw Error::Simple("couldn't write to passed in filehandle");
-       }
-
        return $size;
 }
 
-- 
1.7.10.4
I'm trying to send this with git-send-email this time around to beat
 the linewrapping problem.

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