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1cddaea7ae
Since there isn't a single libc API to get this value, this patch supplies one which gets the value by grabbing current time, then converting that into a struct tm with gmtime_r(), then back to a time_t using mktime. The returned value is the difference between UTC and localtime in seconds. If localtime is ahead of UTC (east) the offset will be a positive number, and if localtime is behind UTC (west) the offset will be negative. This function should be POSIX-compliant, and is threadsafe, but not async signal safe. If it was ever necessary to know this value in a child process, we could cache it with a one-time init function when libvirtd starts, then just supply the cached value, but that complexity isn't needed for current usage; that would also have the problem that it might not be accurate after a local daylight savings boundary. (If it weren't for DST, we could simply replace this entire function with "-timezone"; timezone contains the offset of the current timezone (negated from what we want) but doesn't account for DST. And in spite of being guaranteed by POSIX, it isn't available on older versions of mingw.) Signed-off-by: Eric Blake <eblake@redhat.com>
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>