[fix] W1_OK shouldn't be 0.

W1_OK and W1_ECHILD shouldn't overlap with the range of valid signals.

sig_num == 0 is technically not valid, but I'm working on it.
SigwinchHandler doesn't set it if self.user_handler isn't set.

Fixes spec/oil-xtrace.

Author: Andy C

core/process.py

@@ -1355,8 +1355,8 @@ def NoneAreRunning(self):
 
 # WaitForOne() return values
 
-W1_OK = 0      # waitpid(-1) returned
-W1_ECHILD = -1  # no processes to wait for
+W1_OK = -2      # waitpid(-1) returned
+W1_ECHILD = -3  # no processes to wait for
 # result > 0:   # a signal number that we exited with!
 
 

osh/builtin_process.py

@@ -168,7 +168,8 @@ def _Run(self, cmd_val):
         # Not sure it matters since you can now Ctrl-C it.
 
         result = self.waiter.WaitForOne()
-        if result == process.W1_ECHILD:  # nothing to wait for, or interrupted.  status is 0
+        if result == process.W1_ECHILD:
+          # nothing to wait for, or interrupted.  status is 0
           break  
         elif result >= 0:  # signal
           status = 128 + result