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, 10 insertions, 1 deletions

diff --git a/libbb/executable.c b/libbb/executable.c
index 85ecc3e6c..05e70312f 100644
--- a/libbb/executable.c
+++ b/libbb/executable.c
@@ -83,10 +83,19 @@ int FAST_FUNC BB_EXECVP(const char *file, char *const argv[])
 }
 #endif
 
-int FAST_FUNC BB_EXECVP_or_die(char **argv)
+void FAST_FUNC BB_EXECVP_or_die(char **argv)
 {
         BB_EXECVP(argv[0], argv);
         /* SUSv3-mandated exit codes */
         xfunc_error_retval = (errno == ENOENT) ? 127 : 126;
         bb_perror_msg_and_die("can't execute '%s'", argv[0]);
 }
+
+/* Typical idiom for applets which exec *optional* PROG [ARGS] */
+void FAST_FUNC exec_prog_or_SHELL(char **argv)
+{
+        if (argv[0]) {
+                BB_EXECVP_or_die(argv);
+        }
+        run_shell(getenv("SHELL"), /*login:*/ 1, NULL, NULL);
+}