ash: hopefully close bug 4324. With testcase.

function                                             old     new   delta
evaltree                                             621     869    +248
popstring                                            134     140      +6

3 files changed, 57 insertions, 17 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 11174683e..5348e9572 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -203,7 +203,7 @@ struct globals_misc {
 #define S_RESET 5               /* temporary - to reset a hard ignored sig */
 
         /* indicates specified signal received */
-        char gotsig[NSIG - 1];
+        char gotsig[NSIG - 1]; /* offset by 1: "signal" 0 is meaningless */
         char *trap[NSIG];
 
         /* Rarely referenced stuff */
@@ -7846,12 +7846,12 @@ dotrap(void)
         pendingsig = 0;
         xbarrier();
 
-        for (i = 0, q = gotsig; i < NSIG - 1; i++, q++) {
+        for (i = 1, q = gotsig; i < NSIG; i++, q++) {
                 if (!*q)
                         continue;
                 *q = '\0';
 
-                p = trap[i + 1];
+                p = trap[i];
                 if (!p)
                         continue;
                 skip = evalstring(p, SKIPEVAL);
@@ -7881,16 +7881,33 @@ static void prehash(union node *);
 static void
 evaltree(union node *n, int flags)
 {
+
+        struct jmploc *volatile savehandler = exception_handler;
+        struct jmploc jmploc;
         int checkexit = 0;
         void (*evalfn)(union node *, int);
-        unsigned isor;
         int status;
+
         if (n == NULL) {
                 TRACE(("evaltree(NULL) called\n"));
-                goto out;
+                goto out1;
         }
         TRACE(("pid %d, evaltree(%p: %d, %d) called\n",
                         getpid(), n, n->type, flags));
+
+        exception_handler = &jmploc;
+        {
+                int err = setjmp(jmploc.loc);
+                if (err) {
+                        /* if it was a signal, check for trap handlers */
+                        if (exception == EXSIG)
+                                goto out;
+                        /* continue on the way out */
+                        exception_handler = savehandler;
+                        longjmp(exception_handler->loc, err);
+                }
+        }
+
         switch (n->type) {
         default:
 #if DEBUG
@@ -7936,19 +7953,20 @@ evaltree(union node *n, int flags)
                 goto calleval;
         case NAND:
         case NOR:
-        case NSEMI:
+        case NSEMI: {
+
 #if NAND + 1 != NOR
 #error NAND + 1 != NOR
 #endif
 #if NOR + 1 != NSEMI
 #error NOR + 1 != NSEMI
 #endif
-                isor = n->type - NAND;
+                unsigned is_or = is_or = n->type - NAND;
                 evaltree(
                         n->nbinary.ch1,
-                        (flags | ((isor >> 1) - 1)) & EV_TESTED
+                        (flags | ((is_or >> 1) - 1)) & EV_TESTED
                 );
-                if (!exitstatus == isor)
+                if (!exitstatus == is_or)
                         break;
                 if (!evalskip) {
                         n = n->nbinary.ch2;
@@ -7959,6 +7977,7 @@ evaltree(union node *n, int flags)
                         break;
                 }
                 break;
+        }
         case NIF:
                 evaltree(n->nif.test, EV_TESTED);
                 if (evalskip)
@@ -7979,8 +7998,11 @@ evaltree(union node *n, int flags)
                 exitstatus = status;
                 break;
         }
+
  out:
-        if ((checkexit & exitstatus))
+        exception_handler = savehandler;
+ out1:
+        if (checkexit & exitstatus)
                 evalskip |= SKIPEVAL;
         else if (pendingsig && dotrap())
                 goto exexit;
@@ -11907,18 +11929,15 @@ trapcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
         if (!*ap) {
                 for (signo = 0; signo < NSIG; signo++) {
                         if (trap[signo] != NULL) {
-                                const char *sn;
-
-                                sn = get_signame(signo);
                                 out1fmt("trap -- %s %s\n",
-                                        single_quote(trap[signo]), sn);
+                                                single_quote(trap[signo]),
+                                                get_signame(signo));
                         }
                 }
                 return 0;
         }
-        if (!ap[1])
-                action = NULL;
-        else
+        action = NULL;
+        if (ap[1])
                 action = *ap++;
         while (*ap) {
                 signo = get_signum(*ap);
diff --git a/shell/ash_test/ash-signals/signal2.right b/shell/ash_test/ash-signals/signal2.right
new file mode 100644
index 000000000..96d2d6ad3
--- /dev/null
+++ b/shell/ash_test/ash-signals/signal2.right
@@ -0,0 +1,3 @@
+sleeping
+child exits as expected
+parent exits
diff --git a/shell/ash_test/ash-signals/signal2.tests b/shell/ash_test/ash-signals/signal2.tests
new file mode 100755
index 000000000..04f981c2d
--- /dev/null
+++ b/shell/ash_test/ash-signals/signal2.tests
@@ -0,0 +1,18 @@
+#!/bin/sh
+
+$THIS_SH -c '
+cleanup() {
+    echo "child exits as expected"
+    exit
+}
+trap cleanup HUP
+echo "sleeping"
+sleep 1
+echo "BAD exit from child!"
+' &
+
+child=$!
+sleep 0.1 # let child install handler first
+kill -HUP $child
+wait
+echo "parent exits"