win32: convert exit codes

Add two utility functions to convert Windows process exit codes.

- exit_code_to_wait_status() converts to a POSIX wait status.
  This is used in ash and the implementations of system(3) and
  mingw_wait3().

- exit_code_to_posix() converts to a POSIX exit code.  (Not that
  POSIX has much to say about them.)

As a result it's possible for more applets to report when child
processes are killed as if by a signal.  'time', 'drop' and 'su -W',
for example.

Adds 64-80 bytes.

1 files changed, 2 insertions, 13 deletions

diff --git a/shell/ash.c b/shell/ash.c
index dcc73031f..f0480f723 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -4960,7 +4960,7 @@ waitpid_child(int *status, int wait_flags)
         HANDLE *proclist;
         pid_t pid = -1;
         DWORD win_status, idx;
-        int i, sig;
+        int i;
 
         for (jb = curjob; jb; jb = jb->prev_job) {
                 if (jb->state != JOBDONE)
@@ -4992,18 +4992,7 @@ waitpid_child(int *status, int wait_flags)
                                 wait_flags&WNOHANG ? 1 : INFINITE);
         if (idx < pid_nr) {
                 GetExitCodeProcess(proclist[idx], &win_status);
-                if (win_status == 0xc0000005)
-                        win_status = SIGSEGV << 24;
-                else if (win_status == 0xc000013a)
-                        win_status = SIGINT << 24;
-
-                // When a process is terminated as if by a signal the exit
-                // code is zero apart from the signal in its topmost byte.
-                sig = win_status >> 24;
-                if (sig != 0 && win_status == sig << 24 && is_valid_signal(sig))
-                        *status = sig;
-                else
-                        *status = (int)win_status << 8;
+                *status = exit_code_to_wait_status(win_status);
                 pid = pidlist[idx];
         }
  done: