[PATCH 2/4] perf tools: Add functions which can get or set perf config variables.

[Taeung Song]

This patch consists of functions
which can get, set specific config variables.
For the syntax examples,

   perf config [options] [section.subkey[=value] ...]

   display key-value pairs of specific config variables
   # perf config report.queue-size report.children

   set specific config variables
   # perf config report.queue-size=100M report.children=true

Signed-off-by: Taeung Song <treeze.taeung@xxxxxxxxx>
---
 tools/perf/Documentation/perf-config.txt |   2 +
 tools/perf/builtin-config.c              | 276 ++++++++++++++++++++++++++++++-
 tools/perf/util/cache.h                  |  17 ++
 tools/perf/util/config.c                 |  30 +++-
 4 files changed, 320 insertions(+), 5 deletions(-)

diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt
index 489c2c6..b2b3321 100644
--- a/tools/perf/Documentation/perf-config.txt
+++ b/tools/perf/Documentation/perf-config.txt
@@ -8,6 +8,8 @@ perf-config - Get and set variables in configuration file.
 SYNOPSIS
 --------
 [verse]
+'perf config' [section.subkey[=value] ...]
+or
 'perf config' -l | --list
 
 DESCRIPTION
diff --git a/tools/perf/builtin-config.c b/tools/perf/builtin-config.c
index 9e4ba72..99292f6 100644
--- a/tools/perf/builtin-config.c
+++ b/tools/perf/builtin-config.c
@@ -15,10 +15,14 @@
 
 static struct {
 	bool list_action;
+	bool get_action;
+	bool set_action;
 } params;
 
+struct list_head *sections;
+
 static const char * const config_usage[] = {
-	"perf config [options]",
+	"perf config [options] [section.subkey[=value] ...]",
 	NULL
 };
 static const struct option config_options[] = {
@@ -27,6 +31,74 @@ static const struct option config_options[] = {
 	OPT_END()
 };
 
+static struct config_section *find_config_section(const char *section_name)
+{
+	struct config_section *section_node;
+	list_for_each_entry(section_node, sections, list)
+		if (!strcmp(section_node->name, section_name))
+			return section_node;
+
+	return NULL;
+}
+
+static struct config_element *find_config_element(const char *subkey,
+						  struct config_section *section_node)
+{
+	struct config_element *element_node;
+
+	list_for_each_entry(element_node, &section_node->element_head, list)
+		if (!strcmp(element_node->subkey, subkey))
+			return element_node;
+
+	return NULL;
+}
+
+static struct config_section *init_config_section(const char *section_name)
+{
+	struct config_section *section_node;
+
+	section_node = zalloc(sizeof(*section_node));
+	if (!section_node)
+		return NULL;
+
+	INIT_LIST_HEAD(&section_node->element_head);
+	section_node->name = strdup(section_name);
+	if (!section_node->name) {
+		pr_err("%s: strdup failed\n", __func__);
+		free(section_node);
+		return NULL;
+	}
+
+	return section_node;
+}
+
+static int add_config_element(struct list_head *head,
+			      const char *subkey, const char *value)
+{
+	struct config_element *element_node;
+	element_node = zalloc(sizeof(*element_node));
+	element_node->subkey = strdup(subkey);
+	if (!element_node->subkey) {
+		pr_err("%s: strdup failed\n", __func__);
+		goto out_free;
+	}
+	if (value) {
+		element_node->value = strdup(value);
+		if (!element_node->value) {
+			pr_err("%s: strdup failed\n", __func__);
+			goto out_free;
+		}
+	} else
+		element_node->value = NULL;
+
+	list_add_tail(&element_node->list, head);
+	return 0;
+
+out_free:
+	free(element_node);
+	return -1;
+}
+
 static int show_config(const char *key, const char *value,
 		       void *cb __maybe_unused)
 {
@@ -38,12 +110,211 @@ static int show_config(const char *key, const char *value,
 	return 0;
 }
 
-int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
+static void find_config(struct config_section **section_node, struct config_element **element_node,
+			const char *given_section_name, const char *given_subkey)
+{
+	*section_node = find_config_section(given_section_name);
+
+	if (*section_node != NULL)
+		*element_node = find_config_element(given_subkey, *section_node);
+	else
+		*element_node = NULL;
+}
+
+static int show_spec_config(const char *section_name, const char *subkey,
+			    const char *value __maybe_unused)
+{
+	struct config_section *section_node = NULL;
+	struct config_element *element_node = NULL;
+	char key[BUFSIZ];
+
+	find_config(&section_node, &element_node, section_name, subkey);
+
+	if (section_node && element_node) {
+		scnprintf(key, sizeof(key), "%s.%s", section_node->name, element_node->subkey);
+		show_config(key, element_node->value, NULL);
+	} else
+		pr_err("Error: Failed to find the variable.\n");
+
+	return 0;
+}
+
+static int set_config(const char *section_name, const char *subkey,
+		      const char *value)
+{
+	struct config_section *section_node = NULL;
+	struct config_element *element_node = NULL;
+
+	find_config(&section_node, &element_node, section_name, subkey);
+
+	/* if there isn't existent section, add a new section */
+	if (!section_node) {
+		section_node = init_config_section(section_name);
+		if (!section_node)
+			return -1;
+		list_add_tail(&section_node->list, sections);
+	}
+	/* if nothing to replace, add a new element which contains key-value pair. */
+	if (!element_node)
+		return add_config_element(&section_node->element_head, subkey, value);
+	else
+		element_node->value = (char *)value;
+
+	return 0;
+}
+
+static int set_spec_config(const char *section_name, const char *subkey,
+			   const char *value)
 {
 	int ret = 0;
+	ret += set_config(section_name, subkey, value);
+	ret += perf_configset_write_in_full();
+
+	return ret;
+}
+
+static void parse_key(const char *var, const char **section_name, const char **subkey)
+{
+	char *key = strdup(var);
+
+	if (!key)
+		die("%s: strdup failed\n", __func__);
+
+	*section_name = strsep(&key, ".");
+	*subkey = strsep(&key, ".");
+}
+
+static int collect_config(const char *var, const char *value,
+			  void *cb __maybe_unused)
+{
+	struct config_section *section_node;
+	const char *section_name, *subkey;
+
+	parse_key(var, &section_name, &subkey);
+
+	section_node = find_config_section(section_name);
+	if (!section_node) {
+		/* Add a new section */
+		section_node = init_config_section(section_name);
+		if (!section_node)
+			return -1;
+		list_add_tail(&section_node->list, sections);
+	}
+
+	return add_config_element(&section_node->element_head, subkey, value);
+}
+
+static int perf_configset_with_option(configset_fn_t fn, const char *var)
+{
+	int i, num_dot = 0, num_equals = 0;
+	static char *given_section_name;
+	static char *given_subkey;
+	static char *given_value;
+	const char *last_dot;
+	char *key = strdup(var);
+
+	if (!key) {
+		pr_err("%s: strdup failed\n", __func__);
+		return -1;
+	}
+	last_dot = strrchr(key, '.');
+	/*
+	 * Since "key" actually contains the section name and the real
+	 * key name separated by a dot, we have to know where the dot is.
+	 */
+	if (last_dot == NULL || last_dot == key) {
+		pr_err("The config variable does not contain a section: %s\n", key);
+		return -1;
+	}
+	if (!last_dot[1]) {
+		pr_err("The config varible does not contain variable name: %s\n", key);
+		return -1;
+	}
+	for (i = 0; key[i]; i++) {
+		if (i == 0 && !isalpha(key[i++]))
+			goto out_err;
+
+		switch (key[i]) {
+		case '.':
+			num_dot += 1;
+			if (!isalpha(key[++i]))
+				goto out_err;
+			break;
+		case '=':
+			num_equals += 1;
+			break;
+		default:
+			if (!isalpha(key[i]) && !isalnum(key[i]))
+				goto out_err;
+		}
+	}
+
+	if (num_equals > 1 || num_dot > 1)
+		goto out_err;
+
+	given_value = strchr(key, '=');
+	if (given_value == NULL || given_value == key)
+		given_value = NULL;
+	else {
+		if (!given_value[1]) {
+			pr_err("The config variable does not contain a value: %s\n", key);
+			return -1;
+		} else
+			given_value++;
+	}
+	given_section_name = strsep(&key, ".");
+	given_subkey = strsep(&key, ".");
+
+	if (given_value)
+		given_subkey = strsep(&given_subkey, "=");
+
+	if (!sections) {
+		sections = zalloc(sizeof(*sections));
+		if (!sections)
+			return -1;
+
+		INIT_LIST_HEAD(sections);
+		perf_config(collect_config, NULL);
+	}
+
+	return fn(given_section_name, given_subkey, given_value);
+
+out_err:
+	pr_err("invalid key: %s", var);
+	return -1;
+}
+
+int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
+{
+	int i, ret = 0;
+	int origin_argc = argc - 1;
+	char *value;
+	bool is_option;
 
 	argc = parse_options(argc, argv, config_options, config_usage,
 			     PARSE_OPT_STOP_AT_NON_OPTION);
+	if (origin_argc > argc)
+		is_option = true;
+	else
+		is_option = false;
+
+	if (!is_option && argc >= 0) {
+		switch (argc) {
+		case 0:
+			break;
+		default:
+			for (i = 0; argv[i]; i++) {
+				value = strrchr(argv[i], '=');
+				if (value == NULL || value == argv[i])
+					ret = perf_configset_with_option(show_spec_config, argv[i]);
+				else
+					ret = perf_configset_with_option(set_spec_config, argv[i]);
+				if (ret < 0)
+					break;
+			}
+			goto out;
+		}
+	}
 
 	if (params.list_action && argc == 0)
 		ret = perf_config(show_config, NULL);
@@ -52,5 +323,6 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
 		usage_with_options(config_usage, config_options);
 	}
 
+out:
 	return ret;
 }
diff --git a/tools/perf/util/cache.h b/tools/perf/util/cache.h
index fbcca21..d333753 100644
--- a/tools/perf/util/cache.h
+++ b/tools/perf/util/cache.h
@@ -1,6 +1,7 @@
 #ifndef __PERF_CACHE_H
 #define __PERF_CACHE_H
 
+#include <linux/list.h>
 #include <stdbool.h>
 #include "util.h"
 #include "strbuf.h"
@@ -19,6 +20,22 @@
 #define PERF_DEBUGFS_ENVIRONMENT "PERF_DEBUGFS_DIR"
 #define PERF_TRACEFS_ENVIRONMENT "PERF_TRACEFS_DIR"
 
+struct config_element {
+	char *subkey;
+	char *value;
+	struct list_head list;
+};
+
+struct config_section {
+	char *name;
+	struct list_head element_head;
+	struct list_head list;
+};
+
+extern struct list_head *sections;
+
+typedef int (*configset_fn_t)(const char *, const char *, const char*);
+extern int perf_configset_write_in_full(void);
 typedef int (*config_fn_t)(const char *, const char *, void *);
 extern int perf_default_config(const char *, const char *, void *);
 extern int perf_config(config_fn_t fn, void *);
diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
index e18f653..71294ef 100644
--- a/tools/perf/util/config.c
+++ b/tools/perf/util/config.c
@@ -21,7 +21,7 @@
 char buildid_dir[MAXPATHLEN]; /* root dir for buildid, binary cache */
 
 static FILE *config_file;
-static const char *config_file_name;
+static char *config_file_name;
 static int config_linenr;
 static int config_file_eof;
 
@@ -420,12 +420,11 @@ static int perf_config_from_file(config_fn_t fn, const char *filename, void *dat
 	ret = -1;
 	if (f) {
 		config_file = f;
-		config_file_name = filename;
+		config_file_name = strdup(filename);
 		config_linenr = 1;
 		config_file_eof = 0;
 		ret = perf_parse_file(fn, data);
 		fclose(f);
-		config_file_name = NULL;
 	}
 	return ret;
 }
@@ -502,6 +501,31 @@ out:
 	return ret;
 }
 
+int perf_configset_write_in_full(void)
+{
+	struct config_section *section_node;
+	struct config_element *element_node;
+	const char *first_line = "# this file is auto-generated.";
+	FILE *fp = fopen(config_file_name, "w");
+
+	if (!fp)
+		return -1;
+
+	fprintf(fp, "%s\n", first_line);
+	/* overwrite configvariables */
+	list_for_each_entry(section_node, sections, list) {
+		fprintf(fp, "[%s]\n", section_node->name);
+		list_for_each_entry(element_node, &section_node->element_head, list) {
+			if (element_node->value)
+				fprintf(fp, "\t%s = %s\n",
+					element_node->subkey, element_node->value);
+		}
+	}
+	fclose(fp);
+
+	return 0;
+}
+
 /*
  * Call this to report error for your variable that should not
  * get a boolean value (i.e. "[my] var" means "true").
-- 
1.9.1

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