[PATCH v5 4/9] linux-user: Only register handlers for core_dump_signal by default

[Richard Henderson]

The set of fatal signals is really immaterial.  If one arrives,
and is unhandled, then the qemu process dies and the parent gets
the correct signal.

It is only for those signals which we would like to perform a
guest core dump instead of a host core dump that we need to catch.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/signal.c | 43 ++++++++++++++-----------------------------
 1 file changed, 14 insertions(+), 29 deletions(-)

diff --git a/linux-user/signal.c b/linux-user/signal.c
index 9fadc51347..aab05f8eec 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -488,26 +488,6 @@ void target_to_host_siginfo(siginfo_t *info, const 
target_siginfo_t *tinfo)
     info->si_value.sival_ptr = (void *)(long)sival_ptr;
 }
 
-static int fatal_signal (int sig)
-{
-    switch (sig) {
-    case TARGET_SIGCHLD:
-    case TARGET_SIGURG:
-    case TARGET_SIGWINCH:
-        /* Ignored by default.  */
-        return 0;
-    case TARGET_SIGCONT:
-    case TARGET_SIGSTOP:
-    case TARGET_SIGTSTP:
-    case TARGET_SIGTTIN:
-    case TARGET_SIGTTOU:
-        /* Job control signals.  */
-        return 0;
-    default:
-        return 1;
-    }
-}
-
 /* returns 1 if given signal should dump core if not handled */
 static int core_dump_signal(int sig)
 {
@@ -602,8 +582,9 @@ void signal_init(void)
            SIGSEGV and SIGBUS, to detect exceptions.  We can not just
            trap all signals because it affects syscall interrupt
            behavior.  But do trap all default-fatal signals.  */
-        if (fatal_signal (i))
+        if (core_dump_signal(i)) {
             sigaction(host_sig, &act, NULL);
+        }
     }
 }
 
@@ -997,7 +978,6 @@ int do_sigaction(int sig, const struct target_sigaction 
*act,
                  struct target_sigaction *oact, abi_ulong ka_restorer)
 {
     struct target_sigaction *k;
-    struct sigaction act1;
     int host_sig;
     int ret = 0;
 
@@ -1057,22 +1037,27 @@ int do_sigaction(int sig, const struct target_sigaction 
*act,
             return 0;
         }
         if (host_sig != SIGSEGV && host_sig != SIGBUS) {
+            struct sigaction act1;
+
             sigfillset(&act1.sa_mask);
             act1.sa_flags = SA_SIGINFO;
-            if (k->sa_flags & TARGET_SA_RESTART)
-                act1.sa_flags |= SA_RESTART;
-            /* NOTE: it is important to update the host kernel signal
-               ignore state to avoid getting unexpected interrupted
-               syscalls */
             if (k->_sa_handler == TARGET_SIG_IGN) {
+                /*
+                 * It is important to update the host kernel signal ignore
+                 * state to avoid getting unexpected interrupted syscalls.
+                 */
                 act1.sa_sigaction = (void *)SIG_IGN;
             } else if (k->_sa_handler == TARGET_SIG_DFL) {
-                if (fatal_signal (sig))
+                if (core_dump_signal(sig)) {
                     act1.sa_sigaction = host_signal_handler;
-                else
+                } else {
                     act1.sa_sigaction = (void *)SIG_DFL;
+                }
             } else {
                 act1.sa_sigaction = host_signal_handler;
+                if (k->sa_flags & TARGET_SA_RESTART) {
+                    act1.sa_flags |= SA_RESTART;
+                }
             }
             ret = sigaction(host_sig, &act1, NULL);
         }
-- 
2.34.1