[gparted] Fix gparted scans forever blank disk in virtual machine (#697518)

[Mike Fleetwood <mfleetwo src gnome org>]

commit 51b8e241bcf674cde34495df9b0af07ffcdf9ac2
Author: Curtis Gedak <gedakc gmail com>
Date:   Thu Apr 18 13:20:05 2013 -0600

    Fix gparted scans forever blank disk in virtual machine (#697518)
    
    In some circumstances gparted would appear to scan forever if it
    encountered a blank hard disk.  This would happen if the timing of
    events was right and gparted encountered a disk without a partition
    table.  The missing partition table would cause a call to the
    exception handler, which could get stuck in a thread waiting position.
    
    The problem was traced back to the ped_exception_handler
    and a cond.signal() call missing the requisite mutex.lock() and
    mutex.unlock() around the signal call.
    
    Closes Bug #697518 - gparted scans forever blank disk in virtualbox

 src/GParted_Core.cc | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/src/GParted_Core.cc b/src/GParted_Core.cc
index 40d5b54..515ab9e 100644
--- a/src/GParted_Core.cc
+++ b/src/GParted_Core.cc
@@ -3502,7 +3502,9 @@ static bool _ped_exception_handler( struct ped_exception_ctx *ctx )
        if( optcount == 1 && ctx->e->type != PED_EXCEPTION_BUG && ctx->e->type != PED_EXCEPTION_FATAL )
        {
                ctx->ret = (PedExceptionOption)opt;
+               ctx->mutex.lock();
                ctx->cond.signal();
+               ctx->mutex.unlock();
                return false;
        }
        PedExceptionMsg msg( *ctx->e );