From 712c6adaeece262121c185a55e83a5074e2a8ea6 Mon Sep 17 00:00:00 2001 From: Joshua Clayton Date: Fri, 22 Feb 2013 13:01:18 -0800 Subject: [PATCH] Git.pm: fix cat_blob crashes on large files Read and write each 1024 byte buffer, rather than trying to buffer the entire content of the file. We are only copying the contents to a file descriptor and do not use it ourselves. 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 Reviewed-by: Jeff King Signed-off-by: Junio C Hamano --- perl/Git.pm | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/perl/Git.pm b/perl/Git.pm index 497f420178..cebf8f34c2 100644 --- a/perl/Git.pm +++ b/perl/Git.pm @@ -890,20 +890,22 @@ 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. @@ -918,11 +920,6 @@ 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; }