[builtin/wait] Fix blocking after stopped process.

BEFORE calling WaitForOne(), we should examine the shell state and see
if we're already there.

Addresses issue #1005.

osh/builtin_process.py

@@ -129,22 +129,23 @@ def _Run(self, cmd_val):
     if arg.n:
       # Loop until there is one fewer process running, there's nothing to wait
       # for, or there's a signal
-      target = self.job_state.NumRunning() - 1
-      status = 0
-      while True:
-        result = self.waiter.WaitForOne()
-        if result == process.W1_OK:
-          status = self.waiter.last_status
-        elif result == process.W1_ECHILD:
-          # nothing to wait for, or interrupted
-          status = 127
-          break  
-        elif result >= 0 and result != pyos.UNTRAPPED_SIGWINCH:  # signal
-          status = 128 + result
-          break
-
-        if self.job_state.NumRunning() == target:
-          break
+      n = self.job_state.NumRunning()
+      if n == 0:
+        status = 127
+      else:
+        target = n - 1
+        status = 0
+        while self.job_state.NumRunning() > target:
+          result = self.waiter.WaitForOne()
+          if result == process.W1_OK:
+            status = self.waiter.last_status
+          elif result == process.W1_ECHILD:
+            # nothing to wait for, or interrupted
+            status = 127
+            break  
+          elif result >= 0 and result != pyos.UNTRAPPED_SIGWINCH:  # signal
+            status = 128 + result
+            break
 
       return status
 
@@ -156,7 +157,7 @@ def _Run(self, cmd_val):
       # But how to fix this?
 
       status = 0
-      while True:
+      while self.job_state.NumRunning() != 0:
         result = self.waiter.WaitForOne()
         if result == process.W1_ECHILD:
           # nothing to wait for, or interrupted.  status is 0
@@ -165,9 +166,6 @@ def _Run(self, cmd_val):
           status = 128 + result
           break
 
-        if self.job_state.NumRunning() == 0:
-          break
-
       return status
 
     # Get list of jobs.  Then we need to check if they are ALL stopped.

osh/cmd_eval.py

@@ -1361,6 +1361,9 @@ def _Execute(self, node):
 
     Also runs trap handlers.
     """
+    # TODO: Do this in "leaf" nodes?  SimpleCommand, DBracket, DParen should
+    # call self.DoTick()?  That will RunPendingTraps and check the Ctrl-C flag,
+    # and maybe throw an exception.
     self.RunPendingTraps()
 
     # This has to go around redirect handling because the process sub could be

spec/stateful/job_control.py

@@ -95,7 +95,6 @@ def bug_721(sh):
 
   time.sleep(0.1)
 
-  log('Ctrl-C')
   ctrl_c(sh)
   expect_prompt(sh)
 
@@ -108,7 +107,6 @@ def bug_721(sh):
   sh.sendline('fg')
   expect_no_job(sh)
 
-  log('End')
   sh.sendline('')
   expect_prompt(sh)
 
@@ -122,13 +120,37 @@ def bug_1005(sh):
   sh.sendline('sleep 10')
 
   time.sleep(0.1)
+  if 1:  # TODO: remove hack for OSH
+    stop_process__hack('sleep')
+  else:
+    ctrl_z(sh)
 
-  ctrl_z(sh)
   sh.expect(r'.*Stopped.*')
 
   sh.sendline('wait')
   sh.sendline('echo status=$?')
-  sh.expect(r"status=0")
+  sh.expect('status=0')
+
+
+@register(skip_shells=['dash'])
+def bug_1005_wait_n(sh):
+  'sleep 10 then Ctrl-Z then wait -n should not hang'
+
+  expect_prompt(sh)
+
+  sh.sendline('sleep 10')
+
+  time.sleep(0.1)
+  if 1:  # TODO: remove hack for OSH
+    stop_process__hack('sleep')
+  else:
+    ctrl_z(sh)
+
+  sh.expect(r'.*Stopped.*')
+
+  sh.sendline('wait -n')
+  sh.sendline('echo status=$?')
+  sh.expect('status=127')
 
 
 @register()

test/stateful.sh

@@ -37,7 +37,7 @@ run() {
 readonly FIRST=''
 
 signals-quick() {
-  spec/stateful/signals.py $FIRST --osh-failures-allowed 1 \
+  spec/stateful/signals.py $FIRST \
     $OSH bash "$@"
 }