[refactor] WaitForOne() returns signal number rather than exit code.

This should make it simpler to test for SIGWINCH.

Author: Andy C

core/process.py

@@ -918,7 +918,7 @@ def JobWait(self, waiter):
     while self.state == job_state_e.Running:
       result = waiter.WaitForOne()
 
-      if result > 0:  # signal
+      if result >= 0:  # signal
         return wait_status.Cancelled(result)
 
       if result == W1_ECHILD:
@@ -1079,7 +1079,7 @@ def JobWait(self, waiter):
     while self.state == job_state_e.Running:
       result = waiter.WaitForOne()
 
-      if result > 0:  # signal
+      if result >= 0:  # signal
         return wait_status.Cancelled(result)
 
       if result == W1_ECHILD:
@@ -1402,11 +1402,11 @@ def WaitForOne(self):
       will try again.
 
     Callers:
-      wait -n  -- WaitForOne() just once
-      wait     -- WaitForOne() in a loop
-      wait $!  -- job.JobWait()
-      Process::Wait()
-      Pipeline::Wait()
+      wait -n          -- loop until there is one fewer process (TODO)
+      wait             -- loop until there are no processes
+      wait $!          -- loop until job state is Done (process or pipeline)
+      Process::Wait()  -- loop until Process state is done
+      Pipeline::Wait() -- loop until Pipeline state is done
 
     Comparisons:
       bash: jobs.c waitchld() Has a special case macro(!) CHECK_WAIT_INTR for
@@ -1435,10 +1435,7 @@ def WaitForOne(self):
       if e.errno == ECHILD:
         return W1_ECHILD  # nothing to wait for caller should stop
       elif e.errno == EINTR:  # Bug #858 fix
-        # Examples:
-        # - 128 + SIGUSR1 = 128 + 10 = 138
-        # - 128 + SIGUSR2 = 128 + 12 = 140
-        return 128 + self.sig_state.last_sig_num
+        return self.sig_state.last_sig_num  # e.g. 1 for SIGHUP
       else:
         # The signature of waitpid() means this shouldn't happen
         raise AssertionError()

core/runtime.asdl

@@ -155,7 +155,7 @@ module runtime
     Proc(int code)
   | Pipeline(int* codes)
     -- because the 'wait' builtin is interruptible
-  | Cancelled(int code)
+  | Cancelled(int sig_num)
 
   -- For word splitting (in frontend/consts.py and osh/split.py)
   span = Black | Delim | Backslash

osh/builtin_process.py

@@ -147,13 +147,16 @@ def _Run(self, cmd_val):
       # But note that it can be interrupted by a signal and will return say
       # status=156 for SIGWINCH
 
+      # TODO: WaitForOne() in a loop and ignore SIGWINCH here.  We run until we
+      # reach a STATE.
+
       result = self.waiter.WaitForOne()
       if result == process.W1_OK:
         return self.waiter.last_status
       elif result == process.W1_ECHILD:  # nothing to wait for
         return 127
       else:
-        return result  # signal, e.g. SIGHUP is 129 = 128 + 1
+        return 128 + result  # signal, e.g. SIGHUP is 129 = 128 + 1
 
     if len(job_ids) == 0:
       #log('*** wait')
@@ -167,8 +170,8 @@ def _Run(self, cmd_val):
         result = self.waiter.WaitForOne()
         if result == process.W1_ECHILD:  # nothing to wait for, or interrupted.  status is 0
           break  
-        elif result > 0:  # signal
-          status = result
+        elif result >= 0:  # signal
+          status = 128 + result
           break
 
         i += 1
@@ -217,7 +220,7 @@ def _Run(self, cmd_val):
           status = wait_status.codes[-1]
         elif case(wait_status_e.Cancelled):
           wait_status = cast(wait_status__Cancelled, UP_wait_status)
-          status = wait_status.code
+          status = 128 + wait_status.sig_num
         else:
           raise AssertionError()