2010/4/26 Eric Blake <eblake@redhat.com>:
On 04/25/2010 05:32 AM, Matthias Bolte wrote:
--- examples/domain-events/events-c/event-test.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/examples/domain-events/events-c/event-test.c b/examples/domain-events/events-c/event-test.c index 53a3195..74eabba 100644 --- a/examples/domain-events/events-c/event-test.c +++ b/examples/domain-events/events-c/event-test.c @@ -380,10 +380,11 @@ int main(int argc, char **argv) int callback5ret = -1; int callback6ret = -1; int callback7ret = -1; + struct sigaction action_stop;
- struct sigaction action_stop = { - .sa_handler = stop - }; + memset(&action_stop, 0, sizeof action_stop); + + action_stop.sa_handler = stop;
ACK. By the way, the "for some reason" boils down to how sa_handler is declared in <signal.h> on the two platforms. On cygwin, sa_handler happens to be a member of an anonymous union (exploiting a gcc extension); whereas on Linux, it is a macro that accesses a member of a named union. If I read POSIX correctly, both behaviors for the declaration of sa_handler are permitted. But dotted assignment only works in the case of a named union. Whether it is a gcc bug that you can't use dotted assignment to access a member of an anonymous union, or a cygwin bug for having a header that does not allow compilation like Linux (when cygwin's stated goal is to be Linux-compatible) is debatable.
By the way, this use of memset() to initialize action_stop assumes that the null pointer is all 0 bits (which is probably okay for all platforms that libvirt will ever run on). There is currently a discussion on gnulib on the fact that to be portable to C99, where a null pointer might not be all 0 bits, you would instead have to use the more drawn-out sequence:
You say null pointer, but where's the pointer in this example? Do you really refer to pointers or to the initialization of memory? I wonder what's the use case for this.
static struct sigaction zero_sigaction = {0}; struct sigaction action_stop = zero_sigaction; action_stop.sa_handler = stop;
But don't go changing this commit just for that theoretical platform.
Thanks, pushed. Matthias