nsenter,unshare: share common code; fix a bug of not closing all fds

function                                             old     new   delta
xvfork_parent_waits_and_exits                          -      64     +64
exec_prog_or_SHELL                                     -      39     +39
unshare_main                                         873     810     -63
nsenter_main                                         663     596     -67
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 0/2 up/down: 106/-130)          Total: -27 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/libbb/xfuncs_printf.c b/libbb/xfuncs_printf.c
index 4aa1b5ce2..e9222f690 100644
--- a/libbb/xfuncs_printf.c
+++ b/libbb/xfuncs_printf.c
@@ -659,3 +659,19 @@ pid_t FAST_FUNC xfork(void)
         return pid;
 }
 #endif
+
+void FAST_FUNC xvfork_parent_waits_and_exits(void)
+{
+        pid_t pid;
+
+        fflush_all();
+        pid = xvfork();
+        if (pid > 0) {
+                /* Parent */
+                int exit_status = wait_for_exitstatus(pid);
+                if (WIFSIGNALED(exit_status))
+                        kill_myself_with_sig(WTERMSIG(exit_status));
+                _exit(WEXITSTATUS(exit_status));
+        }
+        /* Child continues */
+}