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Re: [Qemu-devel] [PATCH] linux-user: Proper exit code for uncaught signa
From: |
Thiemo Seufer |
Subject: |
Re: [Qemu-devel] [PATCH] linux-user: Proper exit code for uncaught signals |
Date: |
Thu, 27 Nov 2008 12:42:33 +0100 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
Riku Voipio wrote:
> The proper exit code for dieing from an uncaught signal is -<signal>.
> The kernel doesn't allow exit() or _exit() to pass a negative value.
> To get the proper exit code we need to actually die from an uncaught
> signal.
>
> A default signal handler is installed, we send ourself a signal
> and we wait for it to arrive.
>
> Patch originates from Scratchbox
So, who holds the copyright (and deserves the credit)?
Thiemo
> Signed-off-by: Riku Voipio <address@hidden>
> ---
> linux-user/signal.c | 37 +++++++++++++++++++++++++------------
> 1 files changed, 25 insertions(+), 12 deletions(-)
>
> diff --git a/linux-user/signal.c b/linux-user/signal.c
> index e0f6aaf..dac9933 100644
> --- a/linux-user/signal.c
> +++ b/linux-user/signal.c
> @@ -24,6 +24,7 @@
> #include <unistd.h>
> #include <signal.h>
> #include <errno.h>
> +#include <assert.h>
> #include <sys/ucontext.h>
>
> #include "qemu.h"
> @@ -328,21 +329,33 @@ static inline void free_sigqueue(CPUState *env, struct
> sigqueue *q)
> static void __attribute((noreturn)) force_sig(int sig)
> {
> int host_sig;
> + struct sigaction act;
> host_sig = target_to_host_signal(sig);
> fprintf(stderr, "qemu: uncaught target signal %d (%s) - exiting\n",
> sig, strsignal(host_sig));
> -#if 1
> - _exit(-host_sig);
> -#else
> - {
> - struct sigaction act;
> - sigemptyset(&act.sa_mask);
> - act.sa_flags = SA_SIGINFO;
> - act.sa_sigaction = SIG_DFL;
> - sigaction(SIGABRT, &act, NULL);
> - abort();
> - }
> -#endif
> +
> + /* The proper exit code for dieing from an uncaught signal is
> + * -<signal>. The kernel doesn't allow exit() or _exit() to pass
> + * a negative value. To get the proper exit code we need to
> + * actually die from an uncaught signal. Here the default signal
> + * handler is installed, we send ourself a signal and we wait for
> + * it to arrive. */
> + sigfillset(&act.sa_mask);
> + act.sa_handler = SIG_DFL;
> + sigaction(host_sig, &act, NULL);
> +
> + /* For some reason raise(host_sig) doesn't send the signal when
> + * statically linked on x86-64. */
> + kill(getpid(), host_sig);
> +
> + /* Make sure the signal isn't masked (just reuse the mask inside
> + of act) */
> + sigdelset(&act.sa_mask, host_sig);
> + sigsuspend(&act.sa_mask);
> +
> + /* unreachable */
> + assert(0);
> +
> }
>
> /* queue a signal so that it will be send to the virtual CPU as soon
> --
> 1.5.6.5
>
>
> --
> "rm -rf" only sounds scary if you don't have backups
>