cygwin: run, sh: mangle termination status word.

* stream.c (run): On Cygwin, the spawnvp function is
returning a 16 bit termination status word where the upper
8 bits is the termination status if the termination is normal,
otherwise the lower 8 bits holds a termination signal.
Let's massage it so that the function returns an integer
termnation status, or nil if the termination was abnormal,
same as we do on POSIX platforms with fork/wait.

1 files changed, 10 insertions, 0 deletions

diff --git a/stream.c b/stream.c
index d1d615e9..bf90613e 100644
--- a/stream.c
+++ b/stream.c
@@ -4751,6 +4751,16 @@ static val run(val command, val args)
 #else
     status = w_spawnvp(_P_WAIT, c_str(command, self), nargs, wargv);
 #endif
+#ifdef __CYGWIN__
+    /* Cygwin spawnvp reports regular termination status in upper 8 bits, and
+     * termination signal in lower 8 bits. Let's massage it so that we produce
+     * the same behavior as on Linux.
+     */
+    if (status && status < 0x100)
+      status = -1;      /* ensure nil return */
+    else
+      status >>= 8;
+#endif
   }
 
   free(strip_qual(wchar_t **, wargv));