+extern char **environ;
+
+#if defined(HAVE_SPAWNVE) && defined(HAVE_SPAWNVPE)
+/* Implementation of pex->exec_child using the Cygwin spawn operation. */
+
+/* Subroutine of pex_unix_exec_child. Move OLD_FD to a new file descriptor
+ to be stored in *PNEW_FD, save the flags in *PFLAGS, and arrange for the
+ saved copy to be close-on-exec. Move CHILD_FD into OLD_FD. If CHILD_FD
+ is -1, OLD_FD is to be closed. Return -1 on error. */
+
+static int
+save_and_install_fd(int *pnew_fd, int *pflags, int old_fd, int child_fd)
+{
+ int new_fd, flags;
+
+ flags = fcntl (old_fd, F_GETFD);
+
+ /* If we could not retrieve the flags, then OLD_FD was not open. */
+ if (flags < 0)
+ {
+ new_fd = -1, flags = 0;
+ if (child_fd >= 0 && dup2 (child_fd, old_fd) < 0)
+ return -1;
+ }
+ /* If we wish to close OLD_FD, just mark it CLOEXEC. */
+ else if (child_fd == -1)
+ {
+ new_fd = old_fd;
+ if ((flags & FD_CLOEXEC) == 0 && fcntl (old_fd, F_SETFD, FD_CLOEXEC) < 0)
+ return -1;
+ }
+ /* Otherwise we need to save a copy of OLD_FD before installing CHILD_FD. */
+ else
+ {
+#ifdef F_DUPFD_CLOEXEC
+ new_fd = fcntl (old_fd, F_DUPFD_CLOEXEC, 3);
+ if (new_fd < 0)
+ return -1;
+#else
+ /* Prefer F_DUPFD over dup in order to avoid getting a new fd
+ in the range 0-2, right where a new stderr fd might get put. */
+ new_fd = fcntl (old_fd, F_DUPFD, 3);
+ if (new_fd < 0)
+ return -1;
+ if (fcntl (new_fd, F_SETFD, FD_CLOEXEC) < 0)
+ return -1;
+#endif
+ if (dup2 (child_fd, old_fd) < 0)
+ return -1;
+ }
+
+ *pflags = flags;
+ if (pnew_fd)
+ *pnew_fd = new_fd;
+ else if (new_fd != old_fd)
+ abort ();
+
+ return 0;
+}
+
+/* Subroutine of pex_unix_exec_child. Move SAVE_FD back to OLD_FD
+ restoring FLAGS. If SAVE_FD < 0, OLD_FD is to be closed. */
+
+static int
+restore_fd(int old_fd, int save_fd, int flags)
+{
+ /* For SAVE_FD < 0, all we have to do is restore the
+ "closed-ness" of the original. */
+ if (save_fd < 0)
+ return close (old_fd);
+
+ /* For SAVE_FD == OLD_FD, all we have to do is restore the
+ original setting of the CLOEXEC flag. */
+ if (save_fd == old_fd)
+ {
+ if (flags & FD_CLOEXEC)
+ return 0;
+ return fcntl (old_fd, F_SETFD, flags);
+ }
+
+ /* Otherwise we have to move the descriptor back, restore the flags,
+ and close the saved copy. */
+#ifdef HAVE_DUP3
+ if (flags == FD_CLOEXEC)
+ {
+ if (dup3 (save_fd, old_fd, O_CLOEXEC) < 0)
+ return -1;
+ }
+ else
+#endif
+ {
+ if (dup2 (save_fd, old_fd) < 0)
+ return -1;
+ if (flags != 0 && fcntl (old_fd, F_SETFD, flags) < 0)
+ return -1;
+ }
+ return close (save_fd);
+}
+
+static pid_t
+pex_unix_exec_child (struct pex_obj *obj ATTRIBUTE_UNUSED,
+ int flags, const char *executable,
+ char * const * argv, char * const * env,
+ int in, int out, int errdes, int toclose,