Allow module / function specific debug logging

Just setting mce to debug mode generates so much noise it is no
longer useful for debugging. After the changes for example

  mce -T -l'tklock.c:*datapipe_*' -l'tklock.c:*except*'

can be utilized to get debug logging only from datapipe changes
seen by tklock module and the exception state machine activity
resulting from them.

mce-log.c

@@ -18,6 +18,11 @@
  * You should have received a copy of the GNU Lesser General Public
  * License along with mce.  If not, see <http://www.gnu.org/licenses/>.
  */
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include <fnmatch.h>
+
 #include <glib.h>
 #include <glib/gprintf.h>
 
@@ -111,7 +116,7 @@ void mce_log_file(loglevel_t loglevel, const char *const file,
 
 	loglevel = mce_log_level_normalize(loglevel);
 
-	if( mce_log_p(loglevel) ) {
+	if( mce_log_p_(loglevel, file, function) ) {
 		gchar *msg = 0;
 
 		va_start(args, fmt);
@@ -181,6 +186,45 @@ void mce_log_close(void)
 		closelog();
 }
 
+static GSList     *mce_log_patterns = 0;
+static GHashTable *mce_log_functions = 0;
+
+void mce_log_add_pattern(const char *pat)
+{
+    // NB these are never released by desing
+
+    mce_log_patterns = g_slist_prepend(mce_log_patterns, strdup(pat));
+
+    if( !mce_log_functions )
+	mce_log_functions = g_hash_table_new_full(g_str_hash, g_str_equal,
+						  free, 0);
+}
+
+static bool mce_log_check_pattern(const char *func)
+{
+    gpointer hit = 0;
+
+    if( !mce_log_functions )
+	goto EXIT;
+
+    if( (hit = g_hash_table_lookup(mce_log_functions, func)) )
+	goto EXIT;
+
+    hit = GINT_TO_POINTER(1);
+
+    for( GSList *item = mce_log_patterns; item; item = item->next ) {
+	const char *pat = item->data;
+	if( fnmatch(pat, func, 0) != 0 )
+	    continue;
+	hit = GINT_TO_POINTER(2);
+	break;
+    }
+    g_hash_table_replace(mce_log_functions, strdup(func), hit);
+
+EXIT:
+    return GPOINTER_TO_INT(hit) > 1;
+}
+
 /**
  * Log level testing predicate
  *
@@ -191,11 +235,21 @@ void mce_log_close(void)
  *
  * @return 1 if logging at givel level is enabled, 0 if not
  */
-int mce_log_p(const loglevel_t loglevel)
+int mce_log_p_(const loglevel_t loglevel,
+	       const char *const file,
+	       const char *const func)
 {
-	if( loglevel < LL_CRIT )
-		return logverbosity >= LL_NOTICE;
-	return logverbosity >= loglevel;
+    if( mce_log_functions && file && func ) {
+	char temp[256];
+	snprintf(temp, sizeof temp, "%s:%s", file, func);
+	if( mce_log_check_pattern(temp) )
+	    return true;
+    }
+
+    if( loglevel < LL_CRIT )
+	return logverbosity >= LL_NOTICE;
+
+    return logverbosity >= loglevel;
 }
 
 #endif /* OSSOLOG_COMPILE */

mce-log.h

@@ -40,6 +40,8 @@ typedef enum {
 	LL_DEFAULT = LL_WARN,		/**< Default log level */
 } loglevel_t;
 
+void mce_log_add_pattern(const char *pat);
+
 #ifdef OSSOLOG_COMPILE
 void mce_log_file(loglevel_t loglevel, const char *const file,
 		  const char *const function, const char *const fmt, ...)
@@ -49,7 +51,8 @@ void mce_log_file(loglevel_t loglevel, const char *const file,
 void mce_log_set_verbosity(const int verbosity);
 void mce_log_open(const char *const name, const int facility, const int type);
 void mce_log_close(void);
-int mce_log_p(const loglevel_t loglevel);
+int mce_log_p_(const loglevel_t loglevel, const char *const file, const char *const function);
+#define mce_log_p(LEV_) mce_log_p_(LEV_,__FILE__,__FUNCTION__)
 #else
 /** Dummy version used when logging is disabled at compile time */
 #define mce_log(_loglevel, _fmt, ...)			do {} while (0)
@@ -62,5 +65,4 @@ int mce_log_p(const loglevel_t loglevel);
 /** Dummy version used when logging is disabled at compile time */
 #define mce_log_p(_loglevel)				0
 #endif /* OSSOLOG_COMPILE */
-
 #endif /* _MCE_LOG_H_ */

mce.c

@@ -187,6 +187,7 @@ static const char usage_fmt[] =
 "  -v, --verbose              increase debug message verbosity\n"
 "  -t, --trace=<what>         enable domain specific debug logging;\n"
 "                               supported values: \"wakelocks\"\n"
+"  -l, --log-function=<file:func>  add function logging override\n"
 "  -h, --help                 display this help and exit\n"
 "  -V, --version              output version information and exit\n"
 "\n"
@@ -764,7 +765,7 @@ int main(int argc, char **argv)
 	gboolean debugmode = FALSE;
 	gboolean systemd_notify = FALSE;
 
-	const char optline[] = "dsTSMDqvhVt:n";
+	const char optline[] = "dsTSMDqvhVt:l:n";
 
 	struct option const options[] = {
 		{ "systemd",          no_argument,       0, 'n' },
@@ -779,6 +780,7 @@ int main(int argc, char **argv)
 		{ "help",             no_argument,       0, 'h' },
 		{ "version",          no_argument,       0, 'V' },
 		{ "trace",            required_argument, 0, 't' },
+		{ "log-function",     required_argument, 0, 'l' },
 		{ 0, 0, 0, 0 }
         };
 
@@ -839,6 +841,9 @@ int main(int argc, char **argv)
 			if( !mce_enable_trace(optarg) )
 				exit(EXIT_FAILURE);
 			break;
+		case 'l':
+			mce_log_add_pattern(optarg);
+			break;
 		default:
 			usage();
 			exit(EXIT_FAILURE);