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>

3 files changed, 5 insertions, 5 deletions

diff --git a/loginutils/chpasswd.c b/loginutils/chpasswd.c
index 4b3602e..dd0532c 100644
--- a/loginutils/chpasswd.c
+++ b/loginutils/chpasswd.c
@@ -114,7 +114,7 @@ int chpasswd_main(int argc UNUSED_PARAM, char **argv)
 		if (rc < 0)
 			bb_error_msg_and_die("an error occurred updating password for %s", name);
 		if (rc)
-			bb_error_msg("password for '%s' changed", name);
+			bb_info_msg("password for '%s' changed", name);
 		logmode = LOGMODE_STDIO;
 		free(name);
 		free(free_me);
diff --git a/loginutils/passwd.c b/loginutils/passwd.c
index 30e0964..6c643d3 100644
--- a/loginutils/passwd.c
+++ b/loginutils/passwd.c
@@ -228,7 +228,7 @@ int passwd_main(int argc UNUSED_PARAM, char **argv)
 	/* LOGMODE_BOTH */
 	if (rc < 0)
 		bb_error_msg_and_die("can't update password file %s", filename);
-	bb_error_msg("password for %s changed by %s", name, myname);
+	bb_info_msg("password for %s changed by %s", name, myname);
 
 	/*if (ENABLE_FEATURE_CLEAN_UP) free(newp); - can't, it may be non-malloced */
  skip:
diff --git a/loginutils/sulogin.c b/loginutils/sulogin.c
index 27ea5df..9bb4d36 100644
--- a/loginutils/sulogin.c
+++ b/loginutils/sulogin.c
@@ -68,17 +68,17 @@ int sulogin_main(int argc UNUSED_PARAM, char **argv)
 		);
 		if (r < 0) {
 			/* ^D, ^C, timeout, or read error */
-			bb_error_msg("normal startup");
+			bb_info_msg("normal startup");
 			return 0;
 		}
 		if (r > 0) {
 			break;
 		}
 		bb_do_delay(LOGIN_FAIL_DELAY);
-		bb_error_msg("Login incorrect");
+		bb_info_msg("Login incorrect");
 	}
 
-	bb_error_msg("starting shell for system maintenance");
+	bb_info_msg("starting shell for system maintenance");
 
 	IF_SELINUX(renew_current_security_context());