svlogd: if processor's stdin can not be opened, do not try ad infinitum

function                                             old     new   delta
processorstart                                       426     423      -3

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

1 files changed, 18 insertions, 5 deletions

diff --git a/runit/svlogd.c b/runit/svlogd.c
index 294e31aca..4490492e3 100644
--- a/runit/svlogd.c
+++ b/runit/svlogd.c
@@ -412,19 +412,32 @@ static void processorstart(struct logdir *ld)
                 int fd;
 
                 /* child */
-                /* Non-ignored signals revert to SIG_DFL on exec anyway */
+                /* Non-ignored signals revert to SIG_DFL on exec anyway.
+                 * But we can get signals BEFORE execl(), this is unlikely
+                 * but wouldn't be good...
+                 */
                 /*bb_signals(0
                         + (1 << SIGTERM)
+                        //+ (1 << SIGCHLD)
                         + (1 << SIGALRM)
                         + (1 << SIGHUP)
                         , SIG_DFL);*/
-                sig_unblock(SIGTERM);
-                sig_unblock(SIGALRM);
-                sig_unblock(SIGHUP);
+                /* runit 2.1.2 does not unblock SIGCHLD, a bug? we do: */
+                sigprocmask(SIG_UNBLOCK, &blocked_sigset, NULL);
 
                 if (verbose)
                         bb_error_msg(INFO"processing: %s/%s", ld->name, ld->fnsave);
-                fd = xopen(ld->fnsave, O_RDONLY|O_NDELAY);
+
+                fd = open_or_warn(ld->fnsave, O_RDONLY|O_NDELAY);
+                /* Used to have xopen() above, but it causes infinite restarts of processor
+                 * if file is gone - which can happen even because of _us_!
+                 * Users report that if on reboot, time is reset to before existing
+                 * logfiles creation time, rmoldest() deletes the newest logfile (!)
+                 * and we end up here trying to open this now-deleted file.
+                 */
+                if (fd < 0)
+                        _exit(0); /* fake "success": do not run processor again */
+
                 xmove_fd(fd, 0);
                 ld->fnsave[26] = 't'; /* <- that's why we need sv_ch! */
                 fd = xopen(ld->fnsave, O_WRONLY|O_NDELAY|O_TRUNC|O_CREAT);