libbb: introduce and use BB_EXECVP_or_die()

function                                             old     new   delta
BB_EXECVP_or_die                                       -      47     +47
time_main                                           1042    1043      +1
chrt_main                                            371     364      -7
ionice_main                                          292     282     -10
setsid_main                                           69      56     -13
nohup_main                                           236     223     -13
cttyhack_main                                        266     253     -13
chroot_main                                           94      81     -13
chpst_main                                           746     733     -13
timeout_main                                         297     279     -18
taskset_main                                         541     522     -19
vfork_child                                           67      45     -22
parse                                                975     953     -22
lpd_main                                             770     748     -22
launch_helper                                        192     170     -22
tcpudpsvd_main                                      1810    1782     -28
nice_main                                            190     156     -34
env_main                                             242     206     -36
run_command                                          221     174     -47
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/17 up/down: 48/-352)         Total: -304 bytes

Signed-off-by: Pascal Bellard <pascal.bellard@ads-lu.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index 6543721..275dd4b 100644
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -268,3 +268,37 @@ int FAST_FUNC tcsetattr_stdin_TCSANOW(const struct termios *tp)
 {
 	return tcsetattr(STDIN_FILENO, TCSANOW, tp);
 }
+
+pid_t FAST_FUNC safe_waitpid(pid_t pid, int *wstat, int options)
+{
+	pid_t r;
+
+	do
+		r = waitpid(pid, wstat, options);
+	while ((r == -1) && (errno == EINTR));
+	return r;
+}
+
+pid_t FAST_FUNC wait_any_nohang(int *wstat)
+{
+	return safe_waitpid(-1, wstat, WNOHANG);
+}
+
+// Wait for the specified child PID to exit, returning child's error return.
+int FAST_FUNC wait4pid(pid_t pid)
+{
+	int status;
+
+	if (pid <= 0) {
+		/*errno = ECHILD; -- wrong. */
+		/* we expect errno to be already set from failed [v]fork/exec */
+		return -1;
+	}
+	if (safe_waitpid(pid, &status, 0) == -1)
+		return -1;
+	if (WIFEXITED(status))
+		return WEXITSTATUS(status);
+	if (WIFSIGNALED(status))
+		return WTERMSIG(status) + 0x180;
+	return 0;
+}