Libguestfs - Apr 2010 - [PATCH 1/2] SSH: Check for complete transfer of disk images

---
 lib/Sys/VirtV2V/Transfer/SSH.pm |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/lib/Sys/VirtV2V/Transfer/SSH.pm b/lib/Sys/VirtV2V/Transfer/SSH.pm
index 3b08716..ac5a384 100644
--- a/lib/Sys/VirtV2V/Transfer/SSH.pm
+++ b/lib/Sys/VirtV2V/Transfer/SSH.pm
@@ -82,6 +82,7 @@ sub transfer
     my $vol = $target->create_volume($name, $size);
     $vol->open();
 
+    my $written = 0;
     for (;;) {
         my $buffer;
         # Transfer in 8k chunks
@@ -93,10 +94,16 @@ sub transfer
         last if ($in == 0);
 
         $vol->write($buffer);
+        $written += length($buffer);
     }
 
     $vol->close();
 
+    die(user_message(__x("Didn't receive full volume. Received
{received} ".
+                         "of {total} bytes.",
+                         received => $written,
+                         total => $size))) unless ($written == $size);
+
     waitpid($pid, 0) == $pid or die("error reaping child: $!");
     # If the child returned an error, check for anything on its stderr
     if ($? != 0) {
-- 
1.6.6.1

SSH transfer contained a race due to use of buffered IO to read the initial
size, followed by sysread() to read the data. If data was available for reading
at the time the size was read, some of it would be consumed and buffered. It
would subsequently not be available to sysread(), meaning it wasn't copied.

Fix by using buffered IO consistently.
---
 lib/Sys/VirtV2V/Transfer/SSH.pm |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/lib/Sys/VirtV2V/Transfer/SSH.pm b/lib/Sys/VirtV2V/Transfer/SSH.pm
index ac5a384..0868b37 100644
--- a/lib/Sys/VirtV2V/Transfer/SSH.pm
+++ b/lib/Sys/VirtV2V/Transfer/SSH.pm
@@ -86,7 +86,7 @@ sub transfer
     for (;;) {
         my $buffer;
         # Transfer in 8k chunks
-        my $in = sysread($fh, $buffer, 8 * 1024);
+        my $in = read($fh, $buffer, 8 * 1024);
         die(user_message(__x("Error reading data from {path}:
{error}",
                              path => $path,
                              error => $!))) if (!defined($in));
-- 
1.6.6.1

On Thu, Apr 29, 2010 at 11:47:48AM +0100, Matthew Booth
wrote:
> ---
>  lib/Sys/VirtV2V/Transfer/SSH.pm |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
ACK both.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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