Re: [Libguestfs] [PATCH nbdkit] vddk: Suppress errors in can_extents test (RHBZ#1709211).

In can_extents we test whether the VDDK function VixDiskLib_QueryAllocatedBlocks works before declaring that extents are supported. This VDDK function can fail in several ways but most notable if the server doesn't support querying extents. In this case VDDK raises an error message through the error_function callback, which we turn into a call to nbdkit_error. In most cases this will cause something to be printed to stderr and/or logged noisily to syslog, which is not desirable. This commit adds a per-thread error suppression mechanism so that we can temporarily hide errors, especially while doing this test, but I guess it might be useful in future in other cases too. Note this only affects a narrow range of versions of VMware ESXi and VDDK. In particular to see this problem you would need VMware ESXi (server) <= 5.5 and VDDK (client) >= 6.7. --- plugins/vddk/vddk.c | 80 ++++++++++++++++++++++++++++++++++++--------- 1 file changed, 64 insertions(+), 16 deletions(-)