runsvdir: conditionalize "log in argiment" (mis)feature. By Vladimir.

 with:
runsv                                                139     141      +2
runsvdir_main                                       1583    1513     -70

 without:
warn2_cannot                                          14      27     +13
runsv                                                139     141      +2
warnx                                                 28      16     -12
warn3x                                                23       -     -23
runsvdir_main                                       1583    1125    -458

2 files changed, 88 insertions, 64 deletions

diff --git a/runit/Config.in b/runit/Config.in
index 8a7deea..beff1e7 100644
--- a/runit/Config.in
+++ b/runit/Config.in
@@ -20,6 +20,15 @@ config RUNSVDIR
 	  a directory, in the services directory dir, up to a limit of 1000
 	  subdirectories, and restarts a runsv process if it terminates.
 
+config FEATURE_RUNSVDIR_LOG
+	bool "Enable scrolling argument log"
+	depends on RUNSVDIR
+	default n
+	help
+	  Enable feature where second parameter of runsvdir holds last error
+	  message (viewable via top/ps). Otherwise (feature is off
+	  or no parameter), error messages go to stderr only.
+
 config SV
 	bool "sv"
 	default n
diff --git a/runit/runsvdir.c b/runit/runsvdir.c
index 0dedd5c..8099ebf 100644
--- a/runit/runsvdir.c
+++ b/runit/runsvdir.c
@@ -35,8 +35,13 @@ ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #define MAXSERVICES 1000
 
+/* Should be not needed - all dirs are on same FS, right? */
+#define CHECK_DEVNO_TOO 0
+
 struct service {
+#if CHECK_DEVNO_TOO
 	dev_t dev;
+#endif
 	ino_t ino;
 	pid_t pid;
 	smallint isgone;
@@ -45,28 +50,30 @@ struct service {
 struct globals {
 	struct service *sv;
 	char *svdir;
-	char *rplog;
 	int svnum;
+#if ENABLE_FEATURE_RUNSVDIR_LOG
+	char *rplog;
 	int rploglen;
 	struct fd_pair logpipe;
 	struct pollfd pfd[1];
 	unsigned stamplog;
-	smallint check; /* = 1; */
+#endif
+	smallint need_rescan; /* = 1; */
 	smallint set_pgrp;
 };
 #define G (*(struct globals*)&bb_common_bufsiz1)
-#define sv        (G.sv        )
-#define svdir     (G.svdir     )
-#define rplog     (G.rplog     )
-#define svnum     (G.svnum     )
-#define rploglen  (G.rploglen  )
-#define logpipe   (G.logpipe   )
-#define pfd       (G.pfd       )
-#define stamplog  (G.stamplog  )
-#define check     (G.check     )
-#define set_pgrp  (G.set_pgrp  )
+#define sv          (G.sv          )
+#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    )
+#define need_rescan (G.need_rescan )
+#define set_pgrp    (G.set_pgrp    )
 #define INIT_G() do { \
-	check = 1; \
+	need_rescan = 1; \
 } while (0)
 
 static void fatal2_cannot(const char *m1, const char *m2)
@@ -82,10 +89,12 @@ static void warn2_cannot(const char *m1, const char *m2)
 {
 	warn3x("cannot ", m1, m2);
 }
+#if ENABLE_FEATURE_RUNSVDIR_LOG
 static void warnx(const char *m1)
 {
 	warn3x(m1, "", "");
 }
+#endif
 
 static void runsv(int no, const char *name)
 {
@@ -116,7 +125,7 @@ static void runsv(int no, const char *name)
 	sv[no].pid = pid;
 }
 
-static void runsvdir(void)
+static void do_rescan(void)
 {
 	DIR *dir;
 	direntry *d;
@@ -140,13 +149,16 @@ static void runsvdir(void)
 			continue;
 		if (stat(d->d_name, &s) == -1) {
 			warn2_cannot("stat ", d->d_name);
-			errno = 0;
 			continue;
 		}
 		if (!S_ISDIR(s.st_mode))
 			continue;
 		for (i = 0; i < svnum; i++) {
-			if ((sv[i].ino == s.st_ino) && (sv[i].dev == s.st_dev)) {
+			if ((sv[i].ino == s.st_ino)
+#if CHECK_DEVNO_TOO
+			 && (sv[i].dev == s.st_dev)
+#endif
+			) {
 				sv[i].isgone = 0;
 				if (!sv[i].pid)
 					runsv(i, d->d_name);
@@ -157,66 +169,43 @@ static void runsvdir(void)
 			/* new service */
 			struct service *svnew = realloc(sv, (i+1) * sizeof(*sv));
 			if (!svnew) {
-				warn3x("cannot start runsv ", d->d_name,
-						" too many services");
+				warn2_cannot("start runsv ", d->d_name);
 				continue;
 			}
 			sv = svnew;
 			svnum++;
 			memset(&sv[i], 0, sizeof(sv[i]));
 			sv[i].ino = s.st_ino;
+#if CHECK_DEVNO_TOO
 			sv[i].dev = s.st_dev;
+#endif
 			/*sv[i].pid = 0;*/
 			/*sv[i].isgone = 0;*/
 			runsv(i, d->d_name);
-			check = 1;
+			need_rescan = 1;
 		}
 	}
-	if (errno) {
+	i = errno;
+	closedir(dir);
+	if (i) {
 		warn2_cannot("read directory ", svdir);
-		closedir(dir);
-		check = 1;
+		need_rescan = 1;
 		return;
 	}
-	closedir(dir);
 
-	/* SIGTERM removed runsv's */
+	/* Send SIGTERM to runsv whose directories were not found (removed) */
 	for (i = 0; i < svnum; i++) {
 		if (!sv[i].isgone)
 			continue;
 		if (sv[i].pid)
 			kill(sv[i].pid, SIGTERM);
-		sv[i] = sv[--svnum];
-/* BUG? we deleted sv[i] by copying over sv[last], but we will not check this newly-copied one! */
-		check = 1;
+		svnum--;
+		sv[i] = sv[svnum];
+		i--; /* so that we don't skip new sv[i] (bug was here!) */
+		need_rescan = 1;
 	}
 }
 
-static int setup_log(void)
-{
-	rploglen = strlen(rplog);
-	if (rploglen < 7) {
-		warnx("log must have at least seven characters");
-		return 0;
-	}
-	if (piped_pair(logpipe)) {
-		warnx("cannot create pipe for log");
-		return -1;
-	}
-	close_on_exec_on(logpipe.rd);
-	close_on_exec_on(logpipe.wr);
-	ndelay_on(logpipe.rd);
-	ndelay_on(logpipe.wr);
-	if (dup2(logpipe.wr, 2) == -1) {
-		warnx("cannot set filedescriptor for log");
-		return -1;
-	}
-	pfd[0].fd = logpipe.rd;
-	pfd[0].events = POLLIN;
-	stamplog = monotonic_sec();
-	return 1;
-}
-
 int runsvdir_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int runsvdir_main(int argc UNUSED_PARAM, char **argv)
 {
@@ -230,7 +219,6 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
 	unsigned deadline;
 	unsigned now;
 	unsigned stampcheck;
-	char ch;
 	int i;
 
 	INIT_G();
@@ -241,13 +229,35 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
 
 	bb_signals_recursive((1 << SIGTERM) | (1 << SIGHUP), record_signo);
 	svdir = *argv++;
-	if (argv && *argv) {
+
+#if ENABLE_FEATURE_RUNSVDIR_LOG
+	/* setup log */
+	if (*argv) {
 		rplog = *argv;
-		if (setup_log() != 1) {
-			rplog = 0;
-			warnx("log service disabled");
+		rploglen = strlen(rplog);
+		if (rploglen < 7) {
+			warnx("log must have at least seven characters");
+		} else if (piped_pair(logpipe)) {
+			warnx("cannot create pipe for log");
+		} else {
+			close_on_exec_on(logpipe.rd);
+			close_on_exec_on(logpipe.wr);
+			ndelay_on(logpipe.rd);
+			ndelay_on(logpipe.wr);
+			if (dup2(logpipe.wr, 2) == -1) {
+				warnx("cannot set filedescriptor for log");
+			} else {
+				pfd[0].fd = logpipe.rd;
+				pfd[0].events = POLLIN;
+				stamplog = monotonic_sec();
+				goto run;
+			}
 		}
+		rplog = NULL;
+		warnx("log service disabled");
 	}
+run:
+#endif
 	curdir = open_read(".");
 	if (curdir == -1)
 		fatal2_cannot("open current directory", "");
@@ -265,7 +275,7 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
 				if (pid == sv[i].pid) {
 					/* runsv has gone */
 					sv[i].pid = 0;
-					check = 1;
+					need_rescan = 1;
 					break;
 				}
 			}
@@ -277,7 +287,7 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
 			stampcheck = now + 1;
 
 			if (stat(svdir, &s) != -1) {
-				if (check || s.st_mtime != last_mtime
+				if (need_rescan || s.st_mtime != last_mtime
 				 || s.st_ino != last_ino || s.st_dev != last_dev
 				) {
 					/* svdir modified */
@@ -285,10 +295,10 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
 						last_mtime = s.st_mtime;
 						last_dev = s.st_dev;
 						last_ino = s.st_ino;
-						check = 0;
+						need_rescan = 0;
 						//if (now <= mtime)
 						//	sleep(1);
-						runsvdir();
+						do_rescan();
 						while (fchdir(curdir) == -1) {
 							warn2_cannot("change directory, pausing", "");
 							sleep(5);
@@ -300,23 +310,28 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
 				warn2_cannot("stat ", svdir);
 		}
 
+#if ENABLE_FEATURE_RUNSVDIR_LOG
 		if (rplog) {
 			if ((int)(now - stamplog) >= 0) {
 				write(logpipe.wr, ".", 1);
 				stamplog = now + 900;
 			}
 		}
-
 		pfd[0].revents = 0;
+#endif
 		sig_block(SIGCHLD);
-		deadline = (check ? 1 : 5);
+		deadline = (need_rescan ? 1 : 5);
+#if ENABLE_FEATURE_RUNSVDIR_LOG
 		if (rplog)
 			poll(pfd, 1, deadline*1000);
 		else
+#endif
 			sleep(deadline);
 		sig_unblock(SIGCHLD);
 
+#if ENABLE_FEATURE_RUNSVDIR_LOG
 		if (pfd[0].revents & POLLIN) {
+			char ch;
 			while (read(logpipe.rd, &ch, 1) > 0) {
 				if (ch) {
 					for (i = 6; i < rploglen; i++)
@@ -325,7 +340,7 @@ int runsvdir_main(int argc UNUSED_PARAM, char **argv)
 				}
 			}
 		}
-
+#endif
 		switch (bb_got_signal) {
 		case SIGHUP:
 			for (i = 0; i < svnum; i++)