Applets send errors to syslog during normal, successful operation

[Tito]

On 04/02/2018 19:53, Denys Vlasenko wrote:
> On Thu, Nov 30, 2017 at 9:51 PM, Tito <farmatito at tiscali.it> wrote:
>> On 11/30/2017 08:26 PM, Deweloper wrote:
>>> Many applets are daemons (or can be run as daemons) and send messages to
>>> syslog. The problem is that the messages don't have accurate, individually
>>> assigned severity; they are all LOG_ERR. Effectively, system administrator sees
>>> a lot of ERRORs in the log even when everything goes well. It seems that libbb
>>> provides only bb_error_msg() as a convenient way to print a message (including
>>> sending it to syslog), while a more generic function taking severity as well
>>> would be needed instead. grep -r 'syslog(' shows that only some loginutils call
>>> syslog() directly. In other places bb_error_msg() is used even for
>>> informational or verbose debugging messages. Just have a look at output of
>>> grep -r 'bb_error_msg('
>>>
>>> Do you have an idea how to clean this up? Shouldn't these messages be sent to a
>>> new function, e.g. bb_msg(), which would additionally take "severity" argument?
> 
> The "severity" arg usually ends up being a PITA.
> For example, it's rather unreadable.
> Then, it tends to proliferate: after you have errors/not-errors,
> then someone wants critical/errors/not-errors/debug - which adds
> another dimension to coding every error message: "what severity is it?!"
> 
> 
>> 4) create a function that changes syslog_level to LOG_INFO, add it to libbb,
>>     and then change the code of the applets accordingly, for example:
>>
>> void FAST_FUNC bb_info_msg(const char *s, ...)
>> {
>>          va_list p;
>> #if ENABLE_FEATURE_SYSLOG
>>          smallint syslog_level_old =  syslog_level;
>>          syslog_level = LOG_INFO;
>> #endif
>>          va_start(p, s);
>>          bb_verror_msg(s, p, NULL);
>> #if ENABLE_FEATURE_SYSLOG
>>          syslog_level = syslog_level_old;
>> #endif
>>          va_end(p);
>> }
> 
> I like this. Feel free to send patches doing this.
> 
>> I wonder if the compiler could be so smart to see that this is
>> the same as bb_error_msg when  ENABLE_FEATURE_SYSLOG is not set
>> and optimize it out.
> 
> #if !ENABLE_FEATURE_SYSLOG
> #define bb_info_msg(...) bb_error_msg(__VA_ARGS__)
> #endif
> 

Hi,
attached you will find a patch that adds bb_info_msg function to libbb.
This patch is tested with and without CONFIG_SYSLOG
set but there are no users yet.

Ciao,
Tito

--- include/libbb.h.orig	2018-02-04 23:27:22.000000000 +0100
+++ include/libbb.h	2018-02-04 23:43:08.054064117 +0100
@@ -1277,6 +1277,11 @@ extern void (*die_func)(void);
 extern void xfunc_die(void) NORETURN FAST_FUNC;
 extern void bb_show_usage(void) NORETURN FAST_FUNC;
 extern void bb_error_msg(const char *s, ...) __attribute__ ((format (printf, 1, 2))) FAST_FUNC;
+#if ENABLE_FEATURE_SYSLOG
+extern void bb_info_msg(const char *s, ...) __attribute__ ((format (printf, 1, 2))) FAST_FUNC;
+#else
+#define bb_info_msg(...)	bb_error_msg(__VA_ARGS__)
+#endif
 extern void bb_error_msg_and_die(const char *s, ...) __attribute__ ((noreturn, format (printf, 1, 2))) FAST_FUNC;
 extern void bb_perror_msg(const char *s, ...) __attribute__ ((format (printf, 1, 2))) FAST_FUNC;
 extern void bb_simple_perror_msg(const char *s) FAST_FUNC;
--- libbb/verror_msg.c.orig	2017-07-24 00:27:51.000000000 +0200
+++ libbb/verror_msg.c	2018-02-05 00:54:09.587081933 +0100
@@ -180,3 +180,17 @@ void FAST_FUNC bb_error_msg(const char *
 	bb_verror_msg(s, p, NULL);
 	va_end(p);
 }
+
+#if ENABLE_FEATURE_SYSLOG
+void FAST_FUNC bb_info_msg(const char *s, ...)
+{
+	va_list p;
+	smallint syslog_level_old =  syslog_level;
+
+	syslog_level = LOG_INFO;
+	va_start(p, s);
+	bb_verror_msg(s, p, NULL);
+	syslog_level = syslog_level_old;
+	va_end(p);
+}
+#endif
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