syslogd: make "-O -" log to stdout

function                                             old     new   delta
packed_usage                                       29871   29908     +37
log_locally                                          404     440     +36
syslogd_main                                        1966    1956     -10
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 73/-10)             Total: 63 bytes

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

1 files changed, 45 insertions, 36 deletions

diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index f75851085..d80447bd7 100644
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -21,31 +21,31 @@
 //usage:       "(this version of syslogd ignores /etc/syslog.conf)\n"
 //usage:        )
 //usage:     "\n        -n              Run in foreground"
-//usage:     "\n        -O FILE         Log to FILE (default:/var/log/messages)"
-//usage:     "\n        -l N            Log only messages more urgent than prio N (1-8)"
-//usage:     "\n        -S              Smaller output"
-//usage:        IF_FEATURE_ROTATE_LOGFILE(
-//usage:     "\n        -s SIZE         Max size (KB) before rotation (default:200KB, 0=off)"
-//usage:     "\n        -b N            N rotated logs to keep (default:1, max=99, 0=purge)"
-//usage:        )
 //usage:        IF_FEATURE_REMOTE_LOG(
 //usage:     "\n        -R HOST[:PORT]  Log to HOST:PORT (default PORT:514)"
 //usage:     "\n        -L              Log locally and via network (default is network only if -R)"
 //usage:        )
-//usage:        IF_FEATURE_SYSLOGD_DUP(
-//usage:     "\n        -D              Drop duplicates"
-//usage:        )
 //usage:        IF_FEATURE_IPC_SYSLOG(
 /* NB: -Csize shouldn't have space (because size is optional) */
 //usage:     "\n        -C[size_kb]     Log to shared mem buffer (use logread to read it)"
 //usage:        )
+//usage:        IF_FEATURE_KMSG_SYSLOG(
+//usage:     "\n        -K              Log to kernel printk buffer (use dmesg to read it)"
+//usage:        )
+//usage:     "\n        -O FILE         Log to FILE (default:/var/log/messages, stdout if -)"
+//usage:        IF_FEATURE_ROTATE_LOGFILE(
+//usage:     "\n        -s SIZE         Max size (KB) before rotation (default:200KB, 0=off)"
+//usage:     "\n        -b N            N rotated logs to keep (default:1, max=99, 0=purge)"
+//usage:        )
+//usage:     "\n        -l N            Log only messages more urgent than prio N (1-8)"
+//usage:     "\n        -S              Smaller output"
+//usage:        IF_FEATURE_SYSLOGD_DUP(
+//usage:     "\n        -D              Drop duplicates"
+//usage:        )
 //usage:        IF_FEATURE_SYSLOGD_CFG(
 //usage:     "\n        -f FILE         Use FILE as config (default:/etc/syslog.conf)"
 //usage:        )
 /* //usage:  "\n        -m MIN          Minutes between MARK lines (default:20, 0=off)" */
-//usage:        IF_FEATURE_KMSG_SYSLOG(
-//usage:     "\n        -K              Log to kernel printk buffer (use dmesg to read it)"
-//usage:        )
 //usage:
 //usage:#define syslogd_example_usage
 //usage:       "$ syslogd -R masterlog:514\n"
@@ -585,7 +585,9 @@ static void log_locally(time_t now, char *msg, logFile_t *log_file)
 #endif
         int len = strlen(msg);
 
-        if (log_file->fd >= 0) {
+        /* fd can't be 0 (we connect fd 0 to /dev/log socket) */
+        /* fd is 1 if "-O -" is in use */
+        if (log_file->fd > 1) {
                 /* Reopen log file every second. This allows admin
                  * to delete the file and not worry about restarting us.
                  * This costs almost nothing since it happens
@@ -598,29 +600,38 @@ static void log_locally(time_t now, char *msg, logFile_t *log_file)
                         close(log_file->fd);
                         goto reopen;
                 }
-        } else {
+        }
+        else if (log_file->fd == 1) {
+                /* We are logging to stdout: do nothing */
+        }
+        else {
+                if (LONE_DASH(log_file->path)) {
+                        log_file->fd = 1;
+                        /* log_file->isRegular = 0; - already is */
+                } else {
  reopen:
-                log_file->fd = open(log_file->path, O_WRONLY | O_CREAT
+                        log_file->fd = open(log_file->path, O_WRONLY | O_CREAT
                                         | O_NOCTTY | O_APPEND | O_NONBLOCK,
                                         0666);
-                if (log_file->fd < 0) {
-                        /* cannot open logfile? - print to /dev/console then */
-                        int fd = device_open(DEV_CONSOLE, O_WRONLY | O_NOCTTY | O_NONBLOCK);
-                        if (fd < 0)
-                                fd = 2; /* then stderr, dammit */
-                        full_write(fd, msg, len);
-                        if (fd != 2)
-                                close(fd);
-                        return;
-                }
+                        if (log_file->fd < 0) {
+                                /* cannot open logfile? - print to /dev/console then */
+                                int fd = device_open(DEV_CONSOLE, O_WRONLY | O_NOCTTY | O_NONBLOCK);
+                                if (fd < 0)
+                                        fd = 2; /* then stderr, dammit */
+                                full_write(fd, msg, len);
+                                if (fd != 2)
+                                        close(fd);
+                                return;
+                        }
 #if ENABLE_FEATURE_ROTATE_LOGFILE
-                {
-                        struct stat statf;
-                        log_file->isRegular = (fstat(log_file->fd, &statf) == 0 && S_ISREG(statf.st_mode));
-                        /* bug (mostly harmless): can wrap around if file > 4gb */
-                        log_file->size = statf.st_size;
-                }
+                        {
+                                struct stat statf;
+                                log_file->isRegular = (fstat(log_file->fd, &statf) == 0 && S_ISREG(statf.st_mode));
+                                /* bug (mostly harmless): can wrap around if file > 4gb */
+                                log_file->size = statf.st_size;
+                        }
 #endif
+                }
         }
 
 #ifdef SYSLOGD_WRLOCK
@@ -865,7 +876,6 @@ static int try_to_resolve_remote(remoteHost_t *rh)
 static void do_syslogd(void) NORETURN;
 static void do_syslogd(void)
 {
-        int sock_fd;
 #if ENABLE_FEATURE_REMOTE_LOG
         llist_t *item;
 #endif
@@ -886,7 +896,7 @@ static void do_syslogd(void)
         signal(SIGALRM, do_mark);
         alarm(G.markInterval);
 #endif
-        sock_fd = create_socket();
+        xmove_fd(create_socket(), STDIN_FILENO);
 
         if (option_mask32 & OPT_circularlog)
                 ipcsyslog_init();
@@ -907,7 +917,7 @@ static void do_syslogd(void)
                         recvbuf = G.recvbuf;
 #endif
  read_again:
-                sz = read(sock_fd, recvbuf, MAX_READ - 1);
+                sz = read(STDIN_FILENO, recvbuf, MAX_READ - 1);
                 if (sz < 0) {
                         if (!bb_got_signal)
                                 bb_perror_msg("read from %s", _PATH_LOG);
@@ -978,7 +988,6 @@ static void do_syslogd(void)
         } /* while (!bb_got_signal) */
 
         timestamp_and_log_internal("syslogd exiting");
-        puts("syslogd exiting");
         remove_pidfile(CONFIG_PID_FILE_PATH "/syslogd.pid");
         ipcsyslog_cleanup();
         if (option_mask32 & OPT_kmsg)