runsvdir: (almost) close a signal race

We could lose a signal while processing previous one

function                                             old     new   delta
runsvdir_main                                       1088    1077     -11

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

1 files changed, 28 insertions, 25 deletions

diff --git a/runit/runsvdir.c b/runit/runsvdir.c
index af7e75ba7..809c48a51 100644
--- a/runit/runsvdir.c
+++ b/runit/runsvdir.c
@@ -59,7 +59,6 @@ struct globals {
         int svnum;
 #if ENABLE_FEATURE_RUNSVDIR_LOG
         char *rplog;
-        int rploglen;
         struct fd_pair logpipe;
         struct pollfd pfd[1];
         unsigned stamplog;
@@ -70,7 +69,6 @@ struct globals {
 #define svdir       (G.svdir       )
 #define svnum       (G.svnum       )
 #define rplog       (G.rplog       )
-#define rploglen    (G.rploglen    )
 #define logpipe     (G.logpipe     )
 #define pfd         (G.pfd         )
 #define stamplog    (G.stamplog    )
@@ -219,15 +217,11 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
         struct stat s;
         dev_t last_dev = last_dev; /* for gcc */
         ino_t last_ino = last_ino; /* for gcc */
-        time_t last_mtime = 0;
-        int wstat;
+        time_t last_mtime;
         int curdir;
-        pid_t pid;
-        unsigned deadline;
-        unsigned now;
         unsigned stampcheck;
         int i;
-        int need_rescan = 1;
+        int need_rescan;
         char *opt_s_argv[3];
 
         INIT_G();
@@ -257,8 +251,7 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
         /* setup log */
         if (*argv) {
                 rplog = *argv;
-                rploglen = strlen(rplog);
-                if (rploglen < 7) {
+                if (strlen(rplog) < 7) {
                         warnx("log must have at least seven characters");
                 } else if (piped_pair(logpipe)) {
                         warnx("can't create pipe for log");
@@ -287,11 +280,16 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
         close_on_exec_on(curdir);
 
         stampcheck = monotonic_sec();
+        need_rescan = 1;
+        last_mtime = 0;
 
         for (;;) {
+                unsigned now;
+                unsigned sig;
+
                 /* collect children */
                 for (;;) {
-                        pid = wait_any_nohang(&wstat);
+                        pid_t pid = wait_any_nohang(NULL);
                         if (pid <= 0)
                                 break;
                         for (i = 0; i < svnum; i++) {
@@ -345,15 +343,17 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
                 }
                 pfd[0].revents = 0;
 #endif
-                deadline = (need_rescan ? 1 : 5);
-                sig_block(SIGCHLD);
+                {
+                        unsigned deadline = (need_rescan ? 1 : 5);
+                        sig_block(SIGCHLD);
 #if ENABLE_FEATURE_RUNSVDIR_LOG
-                if (rplog)
-                        poll(pfd, 1, deadline*1000);
-                else
+                        if (rplog)
+                                poll(pfd, 1, deadline*1000);
+                        else
 #endif
-                        sleep(deadline);
-                sig_unblock(SIGCHLD);
+                                sleep(deadline);
+                        sig_unblock(SIGCHLD);
+                }
 
 #if ENABLE_FEATURE_RUNSVDIR_LOG
                 if (pfd[0].revents & POLLIN) {
@@ -361,21 +361,25 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
                         while (read(logpipe.rd, &ch, 1) > 0) {
                                 if (ch < ' ')
                                         ch = ' ';
-                                for (i = 6; i < rploglen; i++)
+                                for (i = 6; rplog[i] != '\0'; i++)
                                         rplog[i-1] = rplog[i];
-                                rplog[rploglen-1] = ch;
+                                rplog[i-1] = ch;
                         }
                 }
 #endif
-                if (!bb_got_signal)
+                sig = bb_got_signal;
+                if (!sig)
                         continue;
+                bb_got_signal = 0;
 
                 /* -s SCRIPT: useful if we are init.
                  * In this case typically script never returns,
                  * it halts/powers off/reboots the system. */
                 if (opt_s_argv[0]) {
+                        pid_t pid;
+
                         /* Single parameter: signal# */
-                        opt_s_argv[1] = utoa(bb_got_signal);
+                        opt_s_argv[1] = utoa(sig);
                         pid = spawn(opt_s_argv);
                         if (pid > 0) {
                                 /* Remembering to wait for _any_ children,
@@ -385,7 +389,7 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
                         }
                 }
 
-                if (bb_got_signal == SIGHUP) {
+                if (sig == SIGHUP) {
                         for (i = 0; i < svnum; i++)
                                 if (sv[i].pid)
                                         kill(sv[i].pid, SIGTERM);
@@ -393,9 +397,8 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
                 /* SIGHUP or SIGTERM (or SIGUSRn if we are init) */
                 /* Exit unless we are init */
                 if (getpid() != 1)
-                        return (SIGHUP == bb_got_signal) ? 111 : EXIT_SUCCESS;
+                        return (SIGHUP == sig) ? 111 : EXIT_SUCCESS;
 
                 /* init continues to monitor services forever */
-                bb_got_signal = 0;
         } /* for (;;) */
 }