[dpdk-dev] [PATCH v7 4/4] log: add option argument help

[Thomas Monjalon <thomas@monjalon.net>]

The option --log-level was not completely described in the usage text,
and it was difficult to guess the names of the log types and levels.

A new value "help" is accepted after --log-level to give more details
about the syntax and listing the log types and levels.

The array "levels" used for level name parsing is replaced with
a (modified) existing function which was used in rte_log_dump().

The new function rte_log_list_types() is exported in the API
for allowing an application to give this info to the user
if not exposing the EAL option --log-level.
The list of log types cannot include all drivers if not linked in the
application (shared object plugin case).

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
---
 lib/librte_eal/common/eal_common_log.c     | 54 ++++++++++++++++++++--
 lib/librte_eal/common/eal_common_options.c | 44 ++++++++++++------
 lib/librte_eal/common/eal_log.h            |  5 ++
 lib/librte_eal/include/rte_log.h           | 11 +++++
 lib/librte_eal/version.map                 |  1 +
 5 files changed, 97 insertions(+), 18 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_log.c b/lib/librte_eal/common/eal_common_log.c
index b9b982fdb5..4c1d514770 100644
--- a/lib/librte_eal/common/eal_common_log.c
+++ b/lib/librte_eal/common/eal_common_log.c
@@ -397,12 +397,12 @@ RTE_INIT_PRIO(log_init, LOG)
 	rte_logs.dynamic_types_len = RTE_LOGTYPE_FIRST_EXT_ID;
 }
 
-static const char *
-loglevel_to_string(uint32_t level)
+const char *
+eal_log_level2str(uint32_t level)
 {
 	switch (level) {
 	case 0: return "disabled";
-	case RTE_LOG_EMERG: return "emerg";
+	case RTE_LOG_EMERG: return "emergency";
 	case RTE_LOG_ALERT: return "alert";
 	case RTE_LOG_CRIT: return "critical";
 	case RTE_LOG_ERR: return "error";
@@ -414,6 +414,50 @@ loglevel_to_string(uint32_t level)
 	}
 }
 
+static int
+log_type_compare(const void *a, const void *b)
+{
+	const struct rte_log_dynamic_type *type_a = a;
+	const struct rte_log_dynamic_type *type_b = b;
+
+	if (type_a->name == NULL && type_b->name == NULL)
+		return 0;
+	if (type_a->name == NULL)
+		return -1;
+	if (type_b->name == NULL)
+		return 1;
+	return strcmp(type_a->name, type_b->name);
+}
+
+/* Dump name of each logtype, one per line. */
+void
+rte_log_list_types(FILE *out, const char *prefix)
+{
+	struct rte_log_dynamic_type *sorted_types;
+	const size_t type_size = sizeof(rte_logs.dynamic_types[0]);
+	const size_t type_count = rte_logs.dynamic_types_len;
+	const size_t total_size = type_size * type_count;
+	size_t type;
+
+	sorted_types = malloc(total_size);
+	if (sorted_types == NULL) {
+		/* no sorting - unlikely */
+		sorted_types = rte_logs.dynamic_types;
+	} else {
+		memcpy(sorted_types, rte_logs.dynamic_types, total_size);
+		qsort(sorted_types, type_count, type_size, log_type_compare);
+	}
+
+	for (type = 0; type < type_count; ++type) {
+		if (sorted_types[type].name == NULL)
+			continue;
+		fprintf(out, "%s%s\n", prefix, sorted_types[type].name);
+	}
+
+	if (sorted_types != rte_logs.dynamic_types)
+		free(sorted_types);
+}
+
 /* dump global level and registered log types */
 void
 rte_log_dump(FILE *f)
@@ -421,14 +465,14 @@ rte_log_dump(FILE *f)
 	size_t i;
 
 	fprintf(f, "global log level is %s\n",
-		loglevel_to_string(rte_log_get_global_level()));
+		eal_log_level2str(rte_log_get_global_level()));
 
 	for (i = 0; i < rte_logs.dynamic_types_len; i++) {
 		if (rte_logs.dynamic_types[i].name == NULL)
 			continue;
 		fprintf(f, "id %zu: %s, level is %s\n",
 			i, rte_logs.dynamic_types[i].name,
-			loglevel_to_string(rte_logs.dynamic_types[i].loglevel));
+			eal_log_level2str(rte_logs.dynamic_types[i].loglevel));
 	}
 }
 
diff --git a/lib/librte_eal/common/eal_common_options.c b/lib/librte_eal/common/eal_common_options.c
index 7075a051b8..2951b1aca2 100644
--- a/lib/librte_eal/common/eal_common_options.c
+++ b/lib/librte_eal/common/eal_common_options.c
@@ -1227,19 +1227,31 @@ eal_parse_syslog(const char *facility, struct internal_config *conf)
 }
 #endif
 
+static void
+eal_log_usage(void)
+{
+	unsigned int level;
+
+	printf("Log type is a pattern matching items of this list"
+			" (plugins may be missing):\n");
+	rte_log_list_types(stdout, "\t");
+	printf("\n");
+	printf("Syntax using globbing pattern:     ");
+	printf("--"OPT_LOG_LEVEL" pattern:level\n");
+	printf("Syntax using regular expression:   ");
+	printf("--"OPT_LOG_LEVEL" regexp,level\n");
+	printf("Syntax for the global level:       ");
+	printf("--"OPT_LOG_LEVEL" level\n");
+	printf("Logs are emitted if allowed by both global and specific levels.\n");
+	printf("\n");
+	printf("Log level can be a number or the first letters of its name:\n");
+	for (level = 1; level <= RTE_LOG_MAX; level++)
+		printf("\t%d   %s\n", level, eal_log_level2str(level));
+}
+
 static int
 eal_parse_log_priority(const char *level)
 {
-	static const char * const levels[] = {
-		[RTE_LOG_EMERG]   = "emergency",
-		[RTE_LOG_ALERT]   = "alert",
-		[RTE_LOG_CRIT]    = "critical",
-		[RTE_LOG_ERR]     = "error",
-		[RTE_LOG_WARNING] = "warning",
-		[RTE_LOG_NOTICE]  = "notice",
-		[RTE_LOG_INFO]    = "info",
-		[RTE_LOG_DEBUG]   = "debug",
-	};
 	size_t len = strlen(level);
 	unsigned long tmp;
 	char *end;
@@ -1250,7 +1262,7 @@ eal_parse_log_priority(const char *level)
 
 	/* look for named values, skip 0 which is not a valid level */
 	for (i = 1; i <= RTE_LOG_MAX; i++) {
-		if (strncmp(levels[i], level, len) == 0)
+		if (strncmp(eal_log_level2str(i), level, len) == 0)
 			return i;
 	}
 
@@ -1274,6 +1286,11 @@ eal_parse_log_level(const char *arg)
 	char *str, *level;
 	int priority;
 
+	if (strcmp(arg, "help") == 0) {
+		eal_log_usage();
+		exit(EXIT_SUCCESS);
+	}
+
 	str = strdup(arg);
 	if (str == NULL)
 		return -1;
@@ -2068,9 +2085,10 @@ eal_common_usage(void)
 #ifndef RTE_EXEC_ENV_WINDOWS
 	       "  --"OPT_SYSLOG"            Set syslog facility\n"
 #endif
-	       "  --"OPT_LOG_LEVEL"=<int>   Set global log level\n"
-	       "  --"OPT_LOG_LEVEL"=<type-match>:<int>\n"
+	       "  --"OPT_LOG_LEVEL"=<level> Set global log level\n"
+	       "  --"OPT_LOG_LEVEL"=<type-match>:<level>\n"
 	       "                      Set specific log level\n"
+	       "  --"OPT_LOG_LEVEL"=help    Show log types and levels\n"
 #ifndef RTE_EXEC_ENV_WINDOWS
 	       "  --"OPT_TRACE"=<regex-match>\n"
 	       "                      Enable trace based on regular expression trace name.\n"
diff --git a/lib/librte_eal/common/eal_log.h b/lib/librte_eal/common/eal_log.h
index 684650a17b..c784fa6043 100644
--- a/lib/librte_eal/common/eal_log.h
+++ b/lib/librte_eal/common/eal_log.h
@@ -24,4 +24,9 @@ void eal_log_set_default(FILE *default_log);
 int eal_log_save_regexp(const char *regexp, uint32_t level);
 int eal_log_save_pattern(const char *pattern, uint32_t level);
 
+/*
+ * Convert log level to string.
+ */
+const char *eal_log_level2str(uint32_t level);
+
 #endif /* EAL_LOG_H */
diff --git a/lib/librte_eal/include/rte_log.h b/lib/librte_eal/include/rte_log.h
index 424dfa3fd0..ccbb7ccd81 100644
--- a/lib/librte_eal/include/rte_log.h
+++ b/lib/librte_eal/include/rte_log.h
@@ -240,6 +240,17 @@ int rte_log_register(const char *name);
 __rte_experimental
 int rte_log_register_type_and_pick_level(const char *name, uint32_t level_def);
 
+/**
+ * Dump name of each logtype, one per line.
+ *
+ * @param out
+ *   Stream where the list is sent.
+ * @param prefix
+ *   String preceding each logtype in the output.
+ */
+__rte_experimental
+void rte_log_list_types(FILE *out, const char *prefix);
+
 /**
  * Dump log information.
  *
diff --git a/lib/librte_eal/version.map b/lib/librte_eal/version.map
index fc305c1c71..aa86b9e4fb 100644
--- a/lib/librte_eal/version.map
+++ b/lib/librte_eal/version.map
@@ -412,6 +412,7 @@ EXPERIMENTAL {
 
 	# added in 21.05
 	rte_intr_callback_unregister_sync;
+	rte_log_list_types;
 	rte_thread_key_create;
 	rte_thread_key_delete;
 	rte_thread_value_get;
-- 
2.31.1