Re: [Libguestfs] [PATCH] tests: regressions: make test-big-heap use a temporary empty file

[adding qemu lists] On 03/21/2018 07:51 AM, Richard W.M. Jones wrote: > On Wed, Mar 21, 2018 at 01:44:17PM +0100, Pino Toscano wrote: >> Newer versions of qemu use file locking for the images by default, and >> apparently that does not work with /dev/null. Since this test just >> calls qemu-img to get the format of an empty image, create a temporary >> one instead. > > ACK, but feels like this is a bug in qemu-img to me. You're right that file locking on a character device like /dev/null is not going to work as expected, but is it a case where fcntl() actually fails, or is it worse where the fcntl() claiming the locks "succeeds" but doesn't do what we want? That is, what were the actual error messages you ran into?