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virnetserver: handle sigaction correctly

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POSIX says that sa_sigaction is only safe to use if sa_flags
includes SA_SIGINFO; conversely, sa_handler is only safe to
use when flags excludes that bit.  Gnulib doesn't guarantee
an implementation of SA_SIGINFO, but does guarantee that
if SA_SIGINFO is undefined, we can safely define it to 0 as
long as we don't dereference the 2nd or 3rd argument of
any handler otherwise registered via sa_sigaction.

Based on a report by Wen Congyang.

* src/rpc/virnetserver.c (SA_SIGINFO): Stub for mingw.
(virNetServerSignalHandler): Avoid bogus dereference.
(virNetServerFatalSignal, virNetServerNew): Set flags properly.
(virNetServerAddSignalHandler): Drop unneeded #ifdef.
This commit is contained in:
Eric Blake 2012-04-19 21:41:27 -06:00 committed by Cole Robinson
parent 8a55d381ae
commit ac620c2e4a
1 changed files with 21 additions and 9 deletions
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30
src/rpc/virnetserver.c
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@ -1,7 +1,7 @@
/*
* virnetserver.c: generic network RPC server
*
* Copyright (C) 2006-2011 Red Hat, Inc.
* Copyright (C) 2006-2012 Red Hat, Inc.
* Copyright (C) 2006 Daniel P. Berrange
*
* This library is free software; you can redistribute it and/or
@ -43,6 +43,10 @@
# include <dbus/dbus.h>
#endif
#ifndef SA_SIGINFO
# define SA_SIGINFO 0
#endif
#define VIR_FROM_THIS VIR_FROM_RPC
#define virNetError(code, ...) \
virReportErrorHelper(VIR_FROM_THIS, code, __FILE__, \
@ -277,8 +281,9 @@ error:
}
static void virNetServerFatalSignal(int sig, siginfo_t *siginfo ATTRIBUTE_UNUSED,
void *context ATTRIBUTE_UNUSED)
static void
virNetServerFatalSignal(int sig, siginfo_t *siginfo ATTRIBUTE_UNUSED,
void *context ATTRIBUTE_UNUSED)
{
struct sigaction sig_action;
int origerrno;
@ -293,6 +298,7 @@ static void virNetServerFatalSignal(int sig, siginfo_t *siginfo ATTRIBUTE_UNUSED
#ifdef SIGUSR2
if (sig != SIGUSR2) {
#endif
memset(&sig_action, 0, sizeof(sig_action));
sig_action.sa_handler = SIG_DFL;
sigaction(sig, &sig_action, NULL);
raise(sig);
@ -390,6 +396,7 @@ virNetServerPtr virNetServerNew(size_t min_workers,
* debugging purposes or testing
*/
sig_action.sa_sigaction = virNetServerFatalSignal;
sig_action.sa_flags = SA_SIGINFO;
sigaction(SIGFPE, &sig_action, NULL);
sigaction(SIGSEGV, &sig_action, NULL);
sigaction(SIGILL, &sig_action, NULL);
@ -455,17 +462,24 @@ static sig_atomic_t sigErrors = 0;
static int sigLastErrno = 0;
static int sigWrite = -1;
static void virNetServerSignalHandler(int sig, siginfo_t * siginfo,
void* context ATTRIBUTE_UNUSED)
static void
virNetServerSignalHandler(int sig, siginfo_t * siginfo,
void* context ATTRIBUTE_UNUSED)
{
int origerrno;
int r;
siginfo_t tmp;
if (SA_SIGINFO)
tmp = *siginfo;
else
memset(&tmp, 0, sizeof(tmp));
/* set the sig num in the struct */
siginfo->si_signo = sig;
tmp.si_signo = sig;
origerrno = errno;
r = safewrite(sigWrite, siginfo, sizeof(*siginfo));
r = safewrite(sigWrite, &tmp, sizeof(tmp));
if (r == -1) {
sigErrors++;
sigLastErrno = errno;
@ -568,9 +582,7 @@ int virNetServerAddSignalHandler(virNetServerPtr srv,
memset(&sig_action, 0, sizeof(sig_action));
sig_action.sa_sigaction = virNetServerSignalHandler;
#ifdef SA_SIGINFO
sig_action.sa_flags = SA_SIGINFO;
#endif
sigemptyset(&sig_action.sa_mask);
sigaction(signum, &sig_action, &sigdata->oldaction);