Optionally re-introduce bb_info_msg()

Between Busybox 1.24.2 and 1.25.0 the bb_info_msg() function was
eliminated and calls to it changed to be bb_error_msg(). The downside of
this is that daemons now log all messages to syslog at the LOG_ERR level
which makes it hard to filter errors from informational messages.

This change optionally re-introduces bb_info_msg(), controlled by a new
option FEATURE_SYSLOG_INFO, restores all the calls to bb_info_msg() that
were removed (only in applets that set logmode to LOGMODE_SYSLOG or
LOGMODE_BOTH), and also changes informational messages in ifplugd and
ntpd.

The code size change of this is as follows (using 'defconfig' on x86_64
with gcc 7.3.0-27ubuntu1~18.04)

function                                             old     new   delta
bb_info_msg                                            -     182    +182
bb_vinfo_msg                                           -      27     +27
static.log7                                          194     198      +4
log8                                                 190     191      +1
log5                                                 190     191      +1
crondlog                                              45       -     -45
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 3/0 up/down: 215/-45)           Total: 170 bytes

If you don't care about everything being logged at LOG_ERR level
then when FEATURE_SYSLOG_INFO is disabled Busybox actually gets smaller:

function                                             old     new   delta
static.log7                                          194     200      +6
log8                                                 190     193      +3
log5                                                 190     193      +3
syslog_level                                           1       -      -1
bb_verror_msg                                        583     581      -2
crondlog                                              45       -     -45
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 3/1 up/down: 12/-48)            Total: -36 bytes

Signed-off-by: James Byrne <james.byrne@origamienergy.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 3 insertions, 5 deletions

diff --git a/miscutils/crond.c b/miscutils/crond.c
index 25e5503c7..b533a3991 100644
--- a/miscutils/crond.c
+++ b/miscutils/crond.c
@@ -181,9 +181,7 @@ static void crondlog(unsigned level, const char *msg, va_list va)
 		 * need not touch syslog_level
 		 * (they are ok with LOG_ERR default).
 		 */
-		syslog_level = LOG_INFO;
-		bb_verror_msg(msg, va, /* strerr: */ NULL);
-		syslog_level = LOG_ERR;
+		bb_vinfo_msg(msg, va);
 	}
 }
 
@@ -1108,7 +1106,7 @@ int crond_main(int argc UNUSED_PARAM, char **argv)
 		process_cron_update_file();
 		log5("wakeup dt=%ld", dt);
 		if (dt < -60 * 60 || dt > 60 * 60) {
-			bb_error_msg("time disparity of %ld minutes detected", dt / 60);
+			bb_info_msg("time disparity of %ld minutes detected", dt / 60);
 			/* and we do not run any jobs in this case */
 		} else if (dt > 0) {
 			/* Usual case: time advances forward, as expected */
diff --git a/miscutils/devfsd.c b/miscutils/devfsd.c
index 3bf06b965..e4d104d0c 100644
--- a/miscutils/devfsd.c
+++ b/miscutils/devfsd.c
@@ -343,7 +343,7 @@ static const char bb_msg_variable_not_found[] ALIGN1 = "variable: %s not found";
 
 /* Busybox stuff */
 #if ENABLE_DEVFSD_VERBOSE || ENABLE_DEBUG
-#define info_logger(p, fmt, args...)                 bb_error_msg(fmt, ## args)
+#define info_logger(p, fmt, args...)                 bb_info_msg(fmt, ## args)
 #define msg_logger(p, fmt, args...)                  bb_error_msg(fmt, ## args)
 #define msg_logger_and_die(p, fmt, args...)          bb_error_msg_and_die(fmt, ## args)
 #define error_logger(p, fmt, args...)                bb_perror_msg(fmt, ## args)