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If a directory pool contains pipes or sockets, a pool start can fail or hang: https://bugzilla.redhat.com/show_bug.cgi?id=589577 We already try to avoid these special files, but only attempt after opening the path, which is where the problems lie. Unify volume opening into helper functions, which use the proper open() flags to avoid error, followed by fstat to validate storage mode. Previously, virStorageBackendUpdateVolTargetInfoFD attempted to enforce the storage mode check, but allowed callers to detect this case and silently continue. In practice, only the FS backend was using this feature, the rest were treating unknown mode as an error condition. Unfortunately the InfoFD function wasn't raising an error message here, so error reporting was busted. This patch adds 2 functions: virStorageBackendVolOpen, and virStorageBackendVolOpenModeSkip. The latter retains the original opt out semantics, the former now throws an explicit error. This patch maintains the previous volume mode checks: allowing specific modes for specific pool types requires a bit of surgery, since VolOpen is called through several different helper functions. v2: Use ATTRIBUTE_NONNULL. Drop stat check, just open with O_NONBLOCK|O_NOCTTY. v3: Move mode check logic back to VolOpen. Use 2 VolOpen functions with different error semantics. v4: Make second VolOpen function more extensible. Didn't opt to change FS backend defaults, this can just be to fix the original bug. v5: Prefix default flags with VIR_, use ATTRIBUTE_RETURN_CHECK
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>