ash: fix TRACE commands

2 files changed, 81 insertions, 9 deletions

diff --git a/shell/ash.c b/shell/ash.c
index a8383d805..d969b20a2 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -39,7 +39,7 @@
  * When debugging is on, debugging info will be written to ./trace and
  * a quit signal will generate a core dump.
  */
-#define DEBUG 0
+#define DEBUG 2
 /* Tweak debug output verbosity here */
 #define DEBUG_TIME 0
 #define DEBUG_PID 1
@@ -3834,7 +3834,8 @@ dowait(int wait_flags, struct job *job)
 	 * NB: _not_ safe_waitpid, we need to detect EINTR */
 	pid = waitpid(-1, &status,
 			(doing_jobctl ? (wait_flags | WUNTRACED) : wait_flags));
-	TRACE(("wait returns pid=%d, status=0x%x\n", pid, status));
+	TRACE(("wait returns pid=%d, status=0x%x, errno=%d(%s)\n",
+				pid, status, errno, strerror(errno)));
 	if (pid <= 0)
 		return pid;
 
@@ -8003,7 +8004,7 @@ dotrap(void)
 		want_exexit = evalstring(t, SKIPEVAL);
 		exitstatus = savestatus;
 		if (want_exexit) {
-			TRACE(("dotrap returns %d\n", skip));
+			TRACE(("dotrap returns %d\n", want_exexit));
 			return want_exexit;
 		}
 	}
@@ -8051,11 +8052,13 @@ evaltree(union node *n, int flags)
 		if (err) {
 			/* if it was a signal, check for trap handlers */
 			if (exception_type == EXSIG) {
-				TRACE(("exception %d (EXSIG) in evaltree, err=%d\n", exception, err));
+				TRACE(("exception %d (EXSIG) in evaltree, err=%d\n",
+						exception_type, err));
 				goto out;
 			}
 			/* continue on the way out */
-			TRACE(("exception %d in evaltree, propagating err=%d\n", exception, err));
+			TRACE(("exception %d in evaltree, propagating err=%d\n",
+					exception_type, err));
 			exception_handler = savehandler;
 			longjmp(exception_handler->loc, err);
 		}
diff --git a/shell/ash_doc.txt b/shell/ash_doc.txt
index d8a48c114..2aa44434c 100644
--- a/shell/ash_doc.txt
+++ b/shell/ash_doc.txt
@@ -46,8 +46,77 @@ done
 of exiting. (true) in subshell does not seem to matter, as another user
 reports the same with:
 
-while true
-do
-  echo Kill me
-  sleep 1
+trap "echo USR1" USR1
+while true; do
+    echo Sleeping
+    sleep 5
 done
+
+Compat note.
+Bash version 3.2.0(1) exits this script at the receipt of SIGINT
+_only_ if it had two last children die from it.
+The following trace was obtained while periodically running
+"killall -SIGINT sleep; sleep 0.1; kill -SIGINT <bash_PID>":
+
+23:48:32.376707 clone(...) = 13528
+23:48:32.388706 waitpid(-1, 0xffc832ec, 0) = ? ERESTARTSYS (To be restarted)
+23:48:32.459761 --- SIGINT (Interrupt) @ 0 (0) ---
+    kill -SIGINT <bash_PID> is ignored, back to waiting:
+23:48:32.463706 waitpid(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 13528
+    sleep exited with 0
+23:48:37.377557 --- SIGCHLD (Child exited) @ 0 (0) ---
+23:48:37.378451 clone(...) = 13538
+23:48:37.390708 waitpid(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGINT}], 0) = 13538
+    sleep was killed by "killall -SIGINT sleep"
+23:48:38.523944 --- SIGCHLD (Child exited) @ 0 (0) ---
+23:48:38.524861 clone(...) = 13542
+23:48:38.538706 waitpid(-1, 0xffc832ec, 0) = ? ERESTARTSYS (To be restarted)
+23:48:38.624761 --- SIGINT (Interrupt) @ 0 (0) ---
+    kill -SIGINT <bash_PID> is ignored, back to waiting:
+23:48:38.628706 waitpid(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 13542
+    sleep exited with 0
+23:48:43.525674 --- SIGCHLD (Child exited) @ 0 (0) ---
+23:48:43.526563 clone(...) = 13545
+23:48:43.538709 waitpid(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGINT}], 0) = 13545
+    sleep was killed by "killall -SIGINT sleep"
+23:48:44.466848 --- SIGCHLD (Child exited) @ 0 (0) ---
+23:48:44.467735 clone(...) = 13549
+23:48:44.481706 waitpid(-1, 0xffc832ec, 0) = ? ERESTARTSYS (To be restarted)
+23:48:44.567757 --- SIGINT (Interrupt) @ 0 (0) ---
+    kill -SIGINT <bash_PID> is ignored, back to waiting:
+23:48:44.571706 waitpid(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 13549
+    sleep exited with 0
+23:48:49.468553 --- SIGCHLD (Child exited) @ 0 (0) ---
+23:48:49.469445 clone(...) = 13551
+23:48:49.481708 waitpid(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGINT}], 0) = 13551
+    sleep was killed by "killall -SIGINT sleep"
+23:48:50.515837 --- SIGCHLD (Child exited) @ 0 (0) ---
+23:48:50.516718 clone(...) = 13555
+23:48:50.530706 waitpid(-1, 0xffc832ec, 0) = ? ERESTARTSYS (To be restarted)
+23:48:50.615761 --- SIGINT (Interrupt) @ 0 (0) ---
+    kill -SIGINT <bash_PID> is ignored, back to waiting:
+23:48:50.619705 waitpid(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGINT}], 0) = 13555
+    sleep was killed by "killall -SIGINT sleep".
+    This is the second one in a row. Kill ourself:
+23:48:51.504604 kill(13515, SIGINT)     = 0
+23:48:51.504689 --- SIGINT (Interrupt) @ 0 (0) ---
+23:48:51.504915 +++ killed by SIGINT +++
+
+As long as there is at least one "sleep 5" which exited successfully
+(not killed by SIGINT), bash continues. This is not documented anywhere
+AFAIKS.
+
+Why keyboard ^C acts differently?
+
+00:08:07.655985 clone(...) = 14270
+00:08:07.669707 waitpid(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 14270
+00:08:12.656872 --- SIGCHLD (Child exited) @ 0 (0) ---
+00:08:12.657743 clone(...) = 14273
+00:08:12.671708 waitpid(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGINT}], 0) = 14273
+00:08:13.810778 --- SIGINT (Interrupt) @ 0 (0) ---
+00:08:13.818705 kill(14269, SIGINT)     = 0
+00:08:13.820103 --- SIGINT (Interrupt) @ 0 (0) ---
+00:08:13.820925 +++ killed by SIGINT +++
+
+Perhaps because at the moment bash got SIGINT it had no children?
+(it did not manage to spawn new sleep yet, see the trace)