Message-Id: <D743CFC4-CE7A-4F98-BDA1-D61CFB5C9178@gmail.com>
Date:	Sun, 19 Jul 2015 18:57:20 +0900
From:	Taewoong Song <treeze.taeung@...il.com>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	namhyung@...nel.org, Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v3 2/5] perf config: Add functions which can get or set perf config variables.


> On Jul 12, 2015, at 11:33 PM, Jiri Olsa <jolsa@...hat.com> wrote:
> 
> On Sun, Jul 12, 2015 at 02:10:56PM +0900, Taeung Song wrote:
>> This patch consists of functions
>> which can get, set specific config variables.
>> For the syntax examples,
>> 
>>   perf config [options] [section.name[=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
> 
> having just patch 1 and 2 applied:
> 
> [jolsa@...va perf]$ ./perf config
> [jolsa@...va perf]$ ./perf config report.queue-size report.children
> report.queue-size=0
> report.children=false
> [jolsa@...va perf]$ ./perf config report.queue-size=100M
> report.children=true
> [jolsa@...va perf]$ ./perf config report.queue-size report.children
> report.queue-size=0
> report.children=false
> 
> [jolsa@...va perf]$ ./perf config colors.normal
> colors.normal=lightgray, default
> [jolsa@...va perf]$ ./perf config colors.normal=blue
> [jolsa@...va perf]$ ./perf config colors.normal
> colors.normal=lightgray, default
> [jolsa@...va perf]$ ./perf config colors.normal=red
> [jolsa@...va perf]$ ./perf config colors.normal
> colors.normal=lightgray, default
> 
> also notice the 'default' for colors.normal while
> it's missing for report.children and report.queue-size
> above
> 
> jirka
> 

Thank you for your review.

I modified the patch following what you point out as below.

1. If some config value is default value, notice it is '(default)' as below
 
 :> ./perf config colors.normal
colors.normal=lightgray, default (default)

2. A bug about report.queue-size and report.children was because of config file path.
   If there aren't both global and system config file, can’t write config variables to the files. 
   So, I added new options which are '--global' and '--system' to be enable to select config file path to be used.
    (If there aren’t perfconfig files or can’t write to the file, print error a message.)

I sent PATCH v4 patch files.
If you have spare time, please recheck the patch v4. 


Thanks,
Taeung

> 
>> 
>> Signed-off-by: Taeung Song <treeze.taeung@...il.com>
>> ---
>> tools/perf/Documentation/perf-config.txt |   2 +
>> tools/perf/builtin-config.c              | 550 ++++++++++++++++++++++++++++++-
>> tools/perf/util/cache.h                  |  17 +
>> tools/perf/util/config.c                 |  30 +-
>> 4 files changed, 594 insertions(+), 5 deletions(-)
>> 
>> diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt
>> index afda861..f3dae23 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 a configuration file.
>> SYNOPSIS
>> --------
>> [verse]
>> +'perf config' [section.name[=value] ...]
>> +or
>> 'perf config' -l | --list
>> 
>> DESCRIPTION
>> diff --git a/tools/perf/builtin-config.c b/tools/perf/builtin-config.c
>> index e7784ed..2d1278d 100644
>> --- a/tools/perf/builtin-config.c
>> +++ b/tools/perf/builtin-config.c
>> @@ -16,7 +16,7 @@
>> static int actions;
>> 
>> static const char * const config_usage[] = {
>> -	"perf config [options]",
>> +	"perf config [options] [section.name[=value] ...]",
>> 	NULL
>> };
>> 
>> @@ -28,6 +28,353 @@ static const struct option config_options[] = {
>> 	OPT_END()
>> };
>> 
>> +/* section names */
>> +#define COLORS "colors"
>> +#define TUI "tui"
>> +#define BUILDID "buildid"
>> +#define ANNOTATE "annotate"
>> +#define GTK "gtk"
>> +#define PAGER "pager"
>> +#define HELP "help"
>> +#define HIST "hist"
>> +#define UI "ui"
>> +#define CALL_GRAPH "call-graph"
>> +#define REPORT "report"
>> +#define TOP "top"
>> +#define MAN "man"
>> +#define KMEM "kmem"
>> +
>> +/* config variable types */
>> +#define TYPE_INT "int"
>> +#define TYPE_LONG "long"
>> +#define TYPE_DIRNAME "dirname"
>> +#define TYPE_BOOL "bool"
>> +#define TYPE_ON_OFF "on_off"
>> +
>> +static struct default_configset {
>> +	const char *section_name;
>> +	const char *name, *value, *type;
>> +
>> +} default_configsets[] = {
>> +	{
>> +		.section_name = COLORS,
>> +		.name = "top",
>> +		.value = "red, default",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = COLORS,
>> +		.name = "medium",
>> +		.value = "green, default",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = COLORS,
>> +		.name = "normal",
>> +		.value = "lightgray, default",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = COLORS,
>> +		.name = "selected",
>> +		.value = "white, lightgray",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = COLORS,
>> +		.name = "code",
>> +		.value = "blue, default",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = COLORS,
>> +		.name = "addr",
>> +		.value = "magenta, default",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = COLORS,
>> +		.name = "root",
>> +		.value = "white, blue",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = TUI,
>> +		.name = "report",
>> +		.value = "on",
>> +		.type = TYPE_ON_OFF,
>> +	},
>> +	{
>> +		.section_name = TUI,
>> +		.name = "annotate",
>> +		.value = "on",
>> +		.type = TYPE_ON_OFF,
>> +	},
>> +	{
>> +		.section_name = TUI,
>> +		.name = "top",
>> +		.value = "on",
>> +		.type = TYPE_ON_OFF,
>> +	},
>> +	{
>> +		.section_name = BUILDID,
>> +		.name = "dir",
>> +		.value = "~/.debug",
>> +		.type = TYPE_DIRNAME,
>> +	},
>> +	{
>> +		.section_name = ANNOTATE,
>> +		.name = "hide_src_code",
>> +		.value = "false",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = ANNOTATE,
>> +		.name = "use_offset",
>> +		.value = "true",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = ANNOTATE,
>> +		.name = "jump_arrows",
>> +		.value = "true",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = ANNOTATE,
>> +		.name = "show_nr_jumps",
>> +		.value = "false",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = GTK,
>> +		.name = "annotate",
>> +		.value = "off",
>> +		.type = TYPE_ON_OFF,
>> +	},
>> +	{
>> +		.section_name = GTK,
>> +		.name = "report",
>> +		.value = "off",
>> +		.type = TYPE_ON_OFF,
>> +	},
>> +	{
>> +		.section_name = GTK,
>> +		.name = "top",
>> +		.value = "off",
>> +		.type = TYPE_ON_OFF,
>> +	},
>> +	{
>> +		.section_name = PAGER,
>> +		.name = "cmd",
>> +		.value = "true",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = PAGER,
>> +		.name = "report",
>> +		.value = "true",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = PAGER,
>> +		.name = "annotate",
>> +		.value = "true",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = PAGER,
>> +		.name = "record",
>> +		.value = "true",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = PAGER,
>> +		.name = "top",
>> +		.value = "true",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = PAGER,
>> +		.name = "diff",
>> +		.value = "true",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = HELP,
>> +		.name = "format",
>> +		.value = "man",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = HELP,
>> +		.name = "autocorrect",
>> +		.value = "0",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = HIST,
>> +		.name = "percentage",
>> +		.value = "absolute",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = UI,
>> +		.name = "show-headers",
>> +		.value = "true",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = CALL_GRAPH,
>> +		.name = "record-mode",
>> +		.value = "fp",
>> +	},
>> +	{
>> +		.section_name = CALL_GRAPH,
>> +		.name = "dump-size",
>> +		.value = "8192",
>> +		.type = TYPE_INT,
>> +	},
>> +	{
>> +		.section_name = CALL_GRAPH,
>> +		.name = "print-type",
>> +		.value = "fractal",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = CALL_GRAPH,
>> +		.name = "order",
>> +		.value = "caller",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = CALL_GRAPH,
>> +		.name = "sort-key",
>> +		.value = "function",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = CALL_GRAPH,
>> +		.name = "threshold",
>> +		.value = "0.5",
>> +		.type = TYPE_LONG,
>> +	},
>> +	{
>> +		.section_name = CALL_GRAPH,
>> +		.name = "print-limit",
>> +		.value = "0",
>> +		.type = TYPE_INT,
>> +	},
>> +	{
>> +		.section_name = REPORT,
>> +		.name = "children",
>> +		.value = "false",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = REPORT,
>> +		.name = "percent-limit",
>> +		.value = "0",
>> +		.type = TYPE_INT,
>> +	},
>> +	{
>> +		.section_name = REPORT,
>> +		.name = "queue-size",
>> +		.value = "0",
>> +		.type = TYPE_INT,
>> +	},
>> +	{
>> +		.section_name = TOP,
>> +		.name = "children",
>> +		.value = "false",
>> +		.type = TYPE_BOOL,
>> +	},
>> +	{
>> +		.section_name = MAN,
>> +		.name = "viewer",
>> +		.value = "man",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = KMEM,
>> +		.name = "default",
>> +		.value = "page",
>> +		.type = NULL,
>> +	},
>> +	{
>> +		.section_name = NULL,
>> +		.name = NULL,
>> +		.value = NULL,
>> +		.type = NULL,
>> +	},
>> +};
>> +
>> +static struct config_section *find_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_element(const char *name,
>> +					   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->name, name))
>> +			return element_node;
>> +
>> +	return NULL;
>> +}
>> +
>> +static struct config_section *init_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_element(struct list_head *head,
>> +			      const char *name, const char *value)
>> +{
>> +	struct config_element *element_node;
>> +
>> +	element_node = zalloc(sizeof(*element_node));
>> +	element_node->name = strdup(name);
>> +	if (!element_node->name) {
>> +		pr_err("%s: strdup failed\n", __func__);
>> +		goto out_free;
>> +	}
>> +	if (value)
>> +		element_node->value = (char *)value;
>> +	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)
>> {
>> @@ -39,10 +386,193 @@ static int show_config(const char *key, const char *value,
>> 	return 0;
>> }
>> 
>> +static void find_config(struct config_section **section_node,
>> +			struct config_element **element_node,
>> +			const char *section_name, const char *name)
>> +{
>> +	*section_node = find_section(section_name);
>> +
>> +	if (*section_node != NULL)
>> +		*element_node = find_element(name, *section_node);
>> +	else
>> +		*element_node = NULL;
>> +}
>> +
>> +static int show_spec_config(const char *section_name, const char *name,
>> +			    char *value __maybe_unused)
>> +{
>> +	int i;
>> +	struct config_section *section_node = NULL;
>> +	struct config_element *element_node = NULL;
>> +	char key[BUFSIZ];
>> +
>> +	find_config(&section_node, &element_node, section_name, name);
>> +
>> +	if (section_node && element_node) {
>> +		scnprintf(key, sizeof(key), "%s.%s",
>> +			  section_node->name, element_node->name);
>> +		return show_config(key, element_node->value, NULL);
>> +	}
>> +
>> +	for (i = 0; default_configsets[i].section_name != NULL; i++) {
>> +		if (!strcmp(default_configsets[i].section_name, section_name)
>> +		    && !strcmp(default_configsets[i].name, name)) {
>> +			printf("%s.%s=%s\n", default_configsets[i].section_name,
>> +			       default_configsets[i].name, default_configsets[i].value);
>> +			return 0;
>> +		}
>> +	}
>> +
>> +	pr_err("Error: Failed to find the variable.\n");
>> +
>> +	return 0;
>> +}
>> +
>> +static char *normalize_value(const char *section_name, const char *name, const char *value)
>> +{
>> +	int i;
>> +	char key[BUFSIZ];
>> +	char *normalized;
>> +
>> +	scnprintf(key, sizeof(key), "%s.%s", section_name, name);
>> +	for (i = 0; default_configsets[i].section_name != NULL; i++) {
>> +		if (!strcmp(default_configsets[i].section_name, section_name)
>> +		    && !strcmp(default_configsets[i].name, name)) {
>> +			normalized = zalloc(BUFSIZ);
>> +			if (!default_configsets[i].type)
>> +				scnprintf(normalized, BUFSIZ, "%s", value);
>> +			else if (!strcmp(default_configsets[i].type, TYPE_BOOL))
>> +				scnprintf(normalized, BUFSIZ, "%s",
>> +					  perf_config_bool(key, value) ? "true" : "false");
>> +			else if (!strcmp(default_configsets[i].type, TYPE_ON_OFF))
>> +				scnprintf(normalized, BUFSIZ, "%s",
>> +					  perf_config_bool(key, value) ? "on" : "off");
>> +			else if (!strcmp(default_configsets[i].type, TYPE_INT))
>> +				scnprintf(normalized, BUFSIZ, "%d",
>> +					  perf_config_int(key, value));
>> +			else if (!strcmp(default_configsets[i].type, TYPE_LONG))
>> +				scnprintf(normalized, BUFSIZ, "%"PRId64,
>> +					  perf_config_u64(key, value));
>> +			else if (!strcmp(default_configsets[i].type, TYPE_DIRNAME))
>> +				scnprintf(normalized, BUFSIZ, "%s",
>> +					  perf_config_dirname(key, value));
>> +			return normalized;
>> +		}
>> +	}
>> +
>> +	normalized = strdup(value);
>> +	if (!normalized) {
>> +		pr_err("%s: strdup failed\n", __func__);
>> +		return NULL;
>> +	}
>> +
>> +	return normalized;
>> +}
>> +
>> +static int set_config(const char *section_name, const char *name, char *value)
>> +{
>> +	struct config_section *section_node = NULL;
>> +	struct config_element *element_node = NULL;
>> +
>> +	find_config(&section_node, &element_node, section_name, name);
>> +	if (value != NULL) {
>> +		value = normalize_value(section_name, name, value);
>> +
>> +		/* if there isn't existent section, add a new section */
>> +		if (!section_node) {
>> +			section_node = init_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) {
>> +			add_element(&section_node->element_head, name, value);
>> +		} else {
>> +			if (!element_node->value)
>> +				free(element_node->value);
>> +			element_node->value = value;
>> +		}
>> +	}
>> +	return perf_configset_write_in_full();
>> +}
>> +
>> +static int collect_current_config(const char *var, const char *value,
>> +			  void *cb __maybe_unused)
>> +{
>> +	struct config_section *section_node;
>> +	char *key = strdup(var);
>> +	char *section_name, *name;
>> +
>> +	if (!key) {
>> +		pr_err("%s: strdup failed\n", __func__);
>> +		return -1;
>> +	}
>> +	section_name = strsep(&key, ".");
>> +	name = strsep(&key, ".");
>> +
>> +	section_node = find_section(section_name);
>> +	if (!section_node) {
>> +		section_node = init_section(section_name);
>> +		if (!section_node)
>> +			return -1;
>> +		list_add_tail(&section_node->list, &sections);
>> +	}
>> +
>> +	return add_element(&section_node->element_head, name,
>> +			   normalize_value(section_name, name, value));
>> +}
>> +
>> +static int perf_configset_with_option(configset_fn_t fn, const char *var, char *value)
>> +{
>> +	char *section_name;
>> +	char *name;
>> +	const char *last_dot;
>> +	char *key = strdup(var);
>> +
>> +	if (!key) {
>> +		pr_err("%s: strdup failed\n", __func__);
>> +		return -1;
>> +	}
>> +	last_dot = strchr(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;
>> +	}
>> +
>> +	section_name = strsep(&key, ".");
>> +	name = strsep(&key, ".");
>> +
>> +	if (!value) {
>> +		/* do nothing */
>> +	} else if (!strcmp(value, "=")) {
>> +		pr_err("The config variable does not contain a value: %s.%s\n",
>> +		       section_name, name);
>> +		return -1;
>> +	} else {
>> +		value++;
>> +		name = strsep(&name, "=");
>> +	}
>> +
>> +	return fn(section_name, name, value);
>> +
>> +	pr_err("invalid key: %s\n", var);
>> +	return -1;
>> +}
>> +
>> int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
>> {
>> -	int ret = 0;
>> +	int i, ret = 0;
>> 	int origin_argc = argc - 1;
>> +	char *value;
>> 	bool has_option;
>> 
>> 	argc = parse_options(argc, argv, config_options, config_usage,
>> @@ -52,6 +582,9 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
>> 	else
>> 		has_option = false;
>> 
>> +	INIT_LIST_HEAD(&sections);
>> +	perf_config(collect_current_config, NULL);
>> +
>> 	switch (actions) {
>> 	case ACTION_LIST:
>> 		if (argc == 0)
>> @@ -63,6 +596,19 @@ int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
>> 		if (!has_option && argc == 0) {
>> 			ret = perf_config(show_config, NULL);
>> 			goto out;
>> +		} else if (argc > 0) {
>> +			for (i = 0; argv[i]; i++) {
>> +				value = strchr(argv[i], '=');
>> +				if (value == NULL)
>> +					ret = perf_configset_with_option(show_spec_config,
>> +									 argv[i], value);
>> +				else
>> +					ret = perf_configset_with_option(set_config,
>> +									 argv[i], value);
>> +				if (ret < 0)
>> +					break;
>> +			}
>> +			goto out;
>> 		} else
>> 			goto out_err;
>> 	}
>> diff --git a/tools/perf/util/cache.h b/tools/perf/util/cache.h
>> index c861373..36d7839 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 *name;
>> +	char *value;
>> +	struct list_head list;
>> +};
>> +
>> +struct config_section {
>> +	char *name;
>> +	struct list_head element_head;
>> +	struct list_head list;
>> +};
>> +
>> +struct list_head sections;
>> +
>> +typedef int (*configset_fn_t)(const char *, const char *, 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..b6c0d2c 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->name, 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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