bpo-40094: Add os.waitstatus_to_exitcode() (GH-19201)

Add os.waitstatus_to_exitcode() function to convert a wait status to an
exitcode.

Suggest waitstatus_to_exitcode() usage in the documentation when
appropriate.

Use waitstatus_to_exitcode() in:

* multiprocessing, os, subprocess and _bootsubprocess modules;
* test.support.wait_process();
* setup.py: run_command();
* and many tests.

1 files changed, 6 insertions, 12 deletions

diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index c8db387..1eeccea 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1838,23 +1838,17 @@ class Popen(object):
                 raise child_exception_type(err_msg)
 
 
-        def _handle_exitstatus(self, sts, _WIFSIGNALED=os.WIFSIGNALED,
-                _WTERMSIG=os.WTERMSIG, _WIFEXITED=os.WIFEXITED,
-                _WEXITSTATUS=os.WEXITSTATUS, _WIFSTOPPED=os.WIFSTOPPED,
-                _WSTOPSIG=os.WSTOPSIG):
+        def _handle_exitstatus(self, sts,
+                               waitstatus_to_exitcode=os.waitstatus_to_exitcode,
+                               _WIFSTOPPED=os.WIFSTOPPED,
+                               _WSTOPSIG=os.WSTOPSIG):
             """All callers to this function MUST hold self._waitpid_lock."""
             # This method is called (indirectly) by __del__, so it cannot
             # refer to anything outside of its local scope.
-            if _WIFSIGNALED(sts):
-                self.returncode = -_WTERMSIG(sts)
-            elif _WIFEXITED(sts):
-                self.returncode = _WEXITSTATUS(sts)
-            elif _WIFSTOPPED(sts):
+            if _WIFSTOPPED(sts):
                 self.returncode = -_WSTOPSIG(sts)
             else:
-                # Should never happen
-                raise SubprocessError("Unknown child exit status!")
-
+                self.returncode = waitstatus_to_exitcode(sts)
 
         def _internal_poll(self, _deadstate=None, _waitpid=os.waitpid,
                 _WNOHANG=os.WNOHANG, _ECHILD=errno.ECHILD):