perf config: Make show_config() use perf_config_set

Currently show_config() has a problem when user and system config files
have the same config variables i.e.:

  # cat ~/.perfconfig
  [top]
          children = false

When $(sysconfdir) is /usr/local/etc

  # cat /usr/local/etc/perfconfig
  [top]
          children = true

Before:

  # perf config --user --list
  top.children=false

  # perf config --system --list
  top.children=true

  # perf config --list
  top.children=true
   top.children=false

Because perf_config() can call show_config() each the config file (user
and system).  Fix it.

After:

  # perf config --user --list
  top.children=false

  # perf config --system --list
  top.children=true

  # perf config --list
  top.children=false

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1460620401-23430-3-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-config.c

@@ -12,6 +12,7 @@
 #include <subcmd/parse-options.h>
 #include "util/util.h"
 #include "util/debug.h"
+#include "util/config.h"
 
 static bool use_system_config, use_user_config;
 
@@ -32,13 +33,28 @@ static struct option config_options[] = {
 	OPT_END()
 };
 
-static int show_config(const char *key, const char *value,
-		       void *cb __maybe_unused)
+static int show_config(struct perf_config_set *set)
 {
-	if (value)
-		printf("%s=%s\n", key, value);
-	else
-		printf("%s\n", key);
+	struct perf_config_section *section;
+	struct perf_config_item *item;
+	struct list_head *sections;
+
+	if (set == NULL)
+		return -1;
+
+	sections = &set->sections;
+	if (list_empty(sections))
+		return -1;
+
+	list_for_each_entry(section, sections, node) {
+		list_for_each_entry(item, &section->items, node) {
+			char *value = item->value;
+
+			if (value)
+				printf("%s.%s=%s\n", section->name,
+				       item->name, value);
+		}
+	}
 
 	return 0;
 }
@@ -46,6 +62,7 @@ static int show_config(const char *key, const char *value,
 int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
 {
 	int ret = 0;
+	struct perf_config_set *set;
 	char *user_config = mkpath("%s/.perfconfig", getenv("HOME"));
 
 	argc = parse_options(argc, argv, config_options, config_usage,
@@ -63,13 +80,19 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
 	else if (use_user_config)
 		config_exclusive_filename = user_config;
 
+	set = perf_config_set__new();
+	if (!set) {
+		ret = -1;
+		goto out_err;
+	}
+
 	switch (actions) {
 	case ACTION_LIST:
 		if (argc) {
 			pr_err("Error: takes no arguments\n");
 			parse_options_usage(config_usage, config_options, "l", 1);
 		} else {
-			ret = perf_config(show_config, NULL);
+			ret = show_config(set);
 			if (ret < 0) {
 				const char * config_filename = config_exclusive_filename;
 				if (!config_exclusive_filename)
@@ -83,5 +106,7 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
 		usage_with_options(config_usage, config_options);
 	}
 
+	perf_config_set__delete(set);
+out_err:
 	return ret;
 }