ash,hush: add comment about masked SIGCHLD, handle SIG_IGNed SIGHUP as in bash
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash.c b/shell/ash.c
index ff59405..fea4b10 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -4307,8 +4307,19 @@
#if 1
sigfillset(&mask);
sigprocmask2(SIG_SETMASK, &mask); /* mask is updated */
- while (!got_sigchld && !pending_sig)
+ while (!got_sigchld && !pending_sig) {
sigsuspend(&mask);
+ /* ^^^ add "sigdelset(&mask, SIGCHLD);" before sigsuspend
+ * to make sure SIGCHLD is not masked off?
+ * It was reported that this:
+ * fn() { : | return; }
+ * shopt -s lastpipe
+ * fn
+ * exec ash SCRIPT
+ * under bash 4.4.23 runs SCRIPT with SIGCHLD masked,
+ * making "wait" commands in SCRIPT block forever.
+ */
+ }
sigprocmask(SIG_SETMASK, &mask, NULL);
#else /* unsafe: a signal can set pending_sig after check, but before pause() */
while (!got_sigchld && !pending_sig)
@@ -14170,11 +14181,6 @@
sigmode[SIGCHLD - 1] = S_DFL; /* ensure we install handler even if it is SIG_IGNed */
setsignal(SIGCHLD);
- /* bash re-enables SIGHUP which is SIG_IGNed on entry.
- * Try: "trap '' HUP; bash; echo RET" and type "kill -HUP $$"
- */
- signal(SIGHUP, SIG_DFL);
-
{
char **envp;
const char *p;
@@ -14512,6 +14518,14 @@
}
#endif
state4: /* XXX ??? - why isn't this before the "if" statement */
+
+ /* Interactive bash re-enables SIGHUP which is SIG_IGNed on entry.
+ * Try:
+ * trap '' hup; bash; echo RET # type "kill -hup $$", see SIGHUP having effect
+ * trap '' hup; bash -c 'kill -hup $$; echo ALIVE' # here SIGHUP is SIG_IGNed
+ */
+ signal(SIGHUP, SIG_DFL);
+
cmdloop(1);
}
#if PROFILE