libbb: introduce and use safe_waitpid (loops in EINTR)

*: use more approproate (shorter) versions of wait()

function                                             old     new   delta
safe_waitpid                                           -      48     +48
wait_any_nohang                                        -      17     +17
send_tree                                            365     369      +4
processorstop                                        432     435      +3
text_yank                                            110     108      -2
make_human_readable_str                              202     200      -2
crond_main                                          1368    1366      -2
handle_sigchld                                        49      43      -6
reapchild                                            166     159      -7
custom                                               260     250     -10
checkscript                                          191     177     -14
wait_nohang                                           17       -     -17
wait_pid                                              43       -     -43
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 2/7 up/down: 72/-103)           Total: -31 bytes

18 files changed, 51 insertions, 55 deletions

diff --git a/archival/tar.c b/archival/tar.c
index 5b19093e8..64975c428 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -610,7 +610,7 @@ static int writeTarFile(const int tar_fd, const int verboseFlag,
 
         if (gzipPid) {
                 int status;
-                if (waitpid(gzipPid, &status, 0) == -1)
+                if (safe_waitpid(gzipPid, &status, 0) == -1)
                         bb_perror_msg("waitpid");
                 else if (!WIFEXITED(status) || WEXITSTATUS(status))
                         /* gzip was killed or has exited with nonzero! */
@@ -688,7 +688,7 @@ static void handle_SIGCHLD(int status)
         /* Actually, 'status' is a signo. We reuse it for other needs */
 
         /* Wait for any child without blocking */
-        if (waitpid(-1, &status, WNOHANG) < 0)
+        if (wait_any_nohang(&status) < 0)
                 /* wait failed?! I'm confused... */
                 return;
 
diff --git a/include/libbb.h b/include/libbb.h
index f35f85c33..fef8fe2e0 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -587,9 +587,9 @@ pid_t xspawn(char **argv);
  *      if (rc < 0) bb_perror_msg("%s", argv[0]);
  *      if (rc > 0) bb_error_msg("exit code: %d", rc);
  */
+int safe_waitpid(int pid, int *wstat, int options);
 int wait4pid(int pid);
-int wait_pid(int *wstat, int pid);
-int wait_nohang(int *wstat);
+int wait_any_nohang(int *wstat);
 #define wait_crashed(w) ((w) & 127)
 #define wait_exitcode(w) ((w) >> 8)
 #define wait_stopsig(w) ((w) >> 8)
diff --git a/init/init.c b/init/init.c
index 51125f348..68a59d88e 100644
--- a/init/init.c
+++ b/init/init.c
@@ -95,9 +95,14 @@ static const char *const environment[] = {
 
 /* Function prototypes */
 static void delete_init_action(struct init_action *a);
-static int waitfor(pid_t pid);
 static void halt_reboot_pwoff(int sig) ATTRIBUTE_NORETURN;
 
+/* TODO: move to libbb? */
+static int waitfor(pid_t runpid)
+{
+        return safe_waitpid(runpid, NULL, 0);
+}
+
 static void loop_forever(void) ATTRIBUTE_NORETURN;
 static void loop_forever(void)
 {
@@ -465,19 +470,6 @@ static pid_t run(const struct init_action *a)
         _exit(-1);
 }
 
-static int waitfor(pid_t runpid)
-{
-        int status, wpid;
-
-        while (1) {
-                wpid = waitpid(runpid, &status, 0);
-                if (wpid == -1 && errno == EINTR)
-                        continue;
-                break;
-        }
-        return wpid;
-}
-
 /* Run all commands of a particular type */
 static void run_actions(int action)
 {
@@ -520,7 +512,7 @@ static void init_reboot(unsigned long magic)
                 reboot(magic);
                 _exit(0);
         }
-        waitpid(pid, NULL, 0);
+        waitfor(pid);
 }
 
 static void kill_all_processes(void)
@@ -980,7 +972,7 @@ int init_main(int argc, char **argv)
                 /* Don't consume all CPU time -- sleep a bit */
                 sleep(1);
 
-                /* Wait for a child process to exit */
+                /* Wait for any child process to exit */
                 wpid = wait(NULL);
                 while (wpid > 0) {
                         /* Find out who died and clean up their corpse */
@@ -995,7 +987,7 @@ int init_main(int argc, char **argv)
                                 }
                         }
                         /* see if anyone else is waiting to be reaped */
-                        wpid = waitpid(-1, NULL, WNOHANG);
+                        wpid = wait_any_nohang(NULL);
                 }
         }
 }
diff --git a/ipsvd/tcpudp.c b/ipsvd/tcpudp.c
index fc29274d2..6187eb985 100644
--- a/ipsvd/tcpudp.c
+++ b/ipsvd/tcpudp.c
@@ -121,7 +121,7 @@ static void sig_child_handler(int sig)
         int wstat;
         int pid;
 
-        while ((pid = wait_nohang(&wstat)) > 0) {
+        while ((pid = wait_any_nohang(&wstat)) > 0) {
                 if (max_per_host)
                         ipsvd_perhost_remove(pid);
                 if (cnum)
diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c
index d6e233ac3..4e6ecde67 100644
--- a/libbb/vfork_daemon_rexec.c
+++ b/libbb/vfork_daemon_rexec.c
@@ -66,6 +66,21 @@ pid_t xspawn(char **argv)
         return pid;
 }
 
+int safe_waitpid(int pid, int *wstat, int options)
+{
+        int r;
+
+        do
+                r = waitpid(pid, wstat, options);
+        while ((r == -1) && (errno == EINTR));
+        return r;
+}
+
+int 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 wait4pid(int pid)
 {
@@ -76,28 +91,18 @@ int wait4pid(int pid)
                 /* we expect errno to be already set from failed [v]fork/exec */
                 return -1;
         }
-        if (waitpid(pid, &status, 0) == -1)
+        if (safe_waitpid(pid, &status, 0) == -1)
                 return -1;
         if (WIFEXITED(status))
                 return WEXITSTATUS(status);
         if (WIFSIGNALED(status))
                 return WTERMSIG(status) + 1000;
         return 0;
-}
-
-int wait_nohang(int *wstat)
-{
-        return waitpid(-1, wstat, WNOHANG);
-}
-
-int wait_pid(int *wstat, int pid)
-{
-        int r;
-
-        do
-                r = waitpid(pid, wstat, 0);
-        while ((r == -1) && (errno == EINTR));
-        return r;
+        if (WIFEXITED(status))
+                return WEXITSTATUS(status);
+        if (WIFSIGNALED(status))
+                return WTERMSIG(status) + 1000;
+        return 0;
 }
 
 #if ENABLE_FEATURE_PREFER_APPLETS
diff --git a/miscutils/crond.c b/miscutils/crond.c
index 8ee7e5837..6056cb065 100644
--- a/miscutils/crond.c
+++ b/miscutils/crond.c
@@ -756,7 +756,7 @@ static int CheckJobs(void)
                         for (line = file->cf_LineBase; line; line = line->cl_Next) {
                                 if (line->cl_Pid > 0) {
                                         int status;
-                                        int r = wait4(line->cl_Pid, &status, WNOHANG, NULL);
+                                        int r = waitpid(line->cl_Pid, &status, WNOHANG);
 
                                         if (r < 0 || r == line->cl_Pid) {
                                                 EndJob(file->cf_User, line);
diff --git a/networking/httpd.c b/networking/httpd.c
index 87dc4b7da..72949755a 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -1152,7 +1152,7 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
                 count = safe_poll(pfd, 3, -1);
                 if (count <= 0) {
 #if 0
-                        if (waitpid(pid, &status, WNOHANG) <= 0) {
+                        if (safe_waitpid(pid, &status, WNOHANG) <= 0) {
                                 /* Weird. CGI didn't exit and no fd's
                                  * are ready, yet poll returned?! */
                                 continue;
diff --git a/networking/ifupdown.c b/networking/ifupdown.c
index 31911cd21..68ea01a67 100644
--- a/networking/ifupdown.c
+++ b/networking/ifupdown.c
@@ -944,7 +944,7 @@ static int doit(char *str)
                         execle(DEFAULT_SHELL, DEFAULT_SHELL, "-c", str, NULL, my_environ);
                         exit(127);
                 }
-                waitpid(child, &status, 0);
+                safe_waitpid(child, &status, 0);
                 if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
                         return 0;
                 }
@@ -1068,7 +1068,7 @@ static char *run_mapping(char *physical, struct mapping_defn_t * map)
                 fprintf(in, "%s\n", map->mapping[i]);
         }
         fclose(in);
-        waitpid(pid, &status, 0);
+        safe_waitpid(pid, &status, 0);
 
         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
                 /* If the mapping script exited successfully, try to
diff --git a/networking/inetd.c b/networking/inetd.c
index a9c9397f5..d643dc6e0 100644
--- a/networking/inetd.c
+++ b/networking/inetd.c
@@ -1161,7 +1161,7 @@ static void reapchild(int sig ATTRIBUTE_UNUSED)
         servtab_t *sep;
 
         for (;;) {
-                pid = wait3(&status, WNOHANG, NULL);
+                pid = wait_any_nohang(&status);
                 if (pid <= 0)
                         break;
                 for (sep = servtab; sep; sep = sep->se_next)
diff --git a/networking/telnetd.c b/networking/telnetd.c
index 108bbf44f..0201d2636 100644
--- a/networking/telnetd.c
+++ b/networking/telnetd.c
@@ -394,7 +394,7 @@ static void handle_sigchld(int sig)
 
         /* Looping: more than one child may have exited */
         while (1) {
-                pid = waitpid(-1, NULL, WNOHANG);
+                pid = wait_any_nohang(NULL);
                 if (pid <= 0)
                         break;
                 ts = sessions;
diff --git a/networking/udhcp/script.c b/networking/udhcp/script.c
index 8a188988e..71f033328 100644
--- a/networking/udhcp/script.c
+++ b/networking/udhcp/script.c
@@ -232,7 +232,7 @@ void udhcp_run_script(struct dhcpMessage *packet, const char *name)
                        name, NULL, envp);
                 bb_perror_msg_and_die("script %s failed", client_config.script);
         }
-        waitpid(pid, NULL, 0);
+        safe_waitpid(pid, NULL, 0);
         for (curr = envp; *curr; curr++)
                 free(*curr);
         free(envp);
diff --git a/runit/runsv.c b/runit/runsv.c
index 8c5a4d4ea..84f5193f5 100644
--- a/runit/runsv.c
+++ b/runit/runsv.c
@@ -282,8 +282,7 @@ static unsigned custom(struct svdir *s, char c)
                                 execve(a, prog, environ);
                                 fatal_cannot("run control/?");
                         }
-                        while (wait_pid(&w, pid) == -1) {
-                                if (errno == EINTR) continue;
+                        while (safe_waitpid(pid, &w, 0) == -1) {
                                 warn_cannot("wait for child control/?");
                                 return 0;
                         }
@@ -593,7 +592,7 @@ int runsv_main(int argc, char **argv)
                         int child;
                         int wstat;
 
-                        child = wait_nohang(&wstat);
+                        child = wait_any_nohang(&wstat);
                         if (!child)
                                 break;
                         if ((child == -1) && (errno != EINTR))
diff --git a/runit/runsvdir.c b/runit/runsvdir.c
index 9e98ca6f8..838490376 100644
--- a/runit/runsvdir.c
+++ b/runit/runsvdir.c
@@ -252,7 +252,7 @@ int runsvdir_main(int argc, char **argv)
         for (;;) {
                 /* collect children */
                 for (;;) {
-                        pid = wait_nohang(&wstat);
+                        pid = wait_any_nohang(&wstat);
                         if (pid <= 0)
                                 break;
                         for (i = 0; i < svnum; i++) {
diff --git a/runit/sv.c b/runit/sv.c
index e31adffed..a89e24439 100644
--- a/runit/sv.c
+++ b/runit/sv.c
@@ -333,8 +333,7 @@ static int checkscript(void)
                 bb_perror_msg(WARN"cannot %s child %s/check", "run", *service);
                 return 0;
         }
-        while (wait_pid(&w, pid) == -1) {
-                if (errno == EINTR) continue;
+        while (safe_waitpid(pid, &w, 0) == -1) {
                 bb_perror_msg(WARN"cannot %s child %s/check", "wait for", *service);
                 return 0;
         }
diff --git a/runit/svlogd.c b/runit/svlogd.c
index 2dc8cb987..1d679c972 100644
--- a/runit/svlogd.c
+++ b/runit/svlogd.c
@@ -265,7 +265,7 @@ static unsigned processorstop(struct logdir *ld)
 
         if (ld->ppid) {
                 sig_unblock(SIGHUP);
-                while (wait_pid(&wstat, ld->ppid) == -1)
+                while (safe_waitpid(ld->ppid, &wstat, 0) == -1)
                         pause2cannot("wait for processor", ld->name);
                 sig_block(SIGHUP);
                 ld->ppid = 0;
@@ -794,7 +794,7 @@ static void sig_child_handler(int sig_no)
 
         if (verbose)
                 bb_error_msg(INFO"sig%s received", "child");
-        while ((pid = wait_nohang(&wstat)) > 0) {
+        while ((pid = wait_any_nohang(&wstat)) > 0) {
                 for (l = 0; l < dirn; ++l) {
                         if (dir[l].ppid == pid) {
                                 dir[l].ppid = 0;
diff --git a/shell/ash.c b/shell/ash.c
index a5b19c863..96563bf06 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -3768,7 +3768,7 @@ waitproc(int block, int *status)
 #endif
         if (block == 0)
                 flags |= WNOHANG;
-        return wait3(status, flags, (struct rusage *)NULL);
+        return waitpid(-1, status, flags); // safe_waitpid?
 }
 
 /*
diff --git a/shell/hush.c b/shell/hush.c
index cb2c3e98e..b08fe10b6 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1649,6 +1649,7 @@ static int checkjobs(struct pipe* fg_pipe)
 // + killall -STOP cat
 
  wait_more:
+// TODO: safe_waitpid?
         while ((childpid = waitpid(-1, &status, attributes)) > 0) {
                 const int dead = WIFEXITED(status) || WIFSIGNALED(status);
 
diff --git a/shell/msh.c b/shell/msh.c
index 9edf793ab..9e9b798a1 100644
--- a/shell/msh.c
+++ b/shell/msh.c
@@ -4162,7 +4162,7 @@ static int grave(int quoted)
                 return 0;
         }
         if (i != 0) {
-                waitpid(i, NULL, 0);
+                waitpid(i, NULL, 0); // safe_waitpid?
                 global_env.iop->argp->aword = ++cp;
                 close(pf[1]);
                 PUSHIO(afile, remap(pf[0]),