Date:	Mon, 13 Apr 2015 15:55:29 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Taeung Song <treeze.taeung@...il.com>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	linux-kernel@...r.kernel.org, jolsa@...hat.com
Subject: Re: [PATCH 2/2] perf tools: Add a option 'remove' to perf-config and
 features which get or set a config variable.

On Sun, Apr 12, 2015 at 11:44:49PM +0900, Taeung Song wrote:
> This patch consists of adding functions
> which get, set or remove a specific config variable.
> For the syntax examples,
> 
>    perf config [options] [section.subkey[=value]]
> 
>    display a specific key(section.subkey) and value
>    # perf config report.queue
> 
>    set a specific key and value
>    # perf config report.queue=100M
> 
>    remove a specific key
>    # perf config -r | --remove report.queue
> 
> Signed-off-by: Taeung Song <treeze.taeung@...il.com>
> ---
>  tools/perf/Documentation/perf-config.txt |   8 ++
>  tools/perf/builtin-config.c              | 224 ++++++++++++++++++++++++++++++-
>  tools/perf/util/cache.h                  |  17 +++
>  tools/perf/util/config.c                 |  35 ++++-
>  4 files changed, 278 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt
> index b251702..7354b18 100644
> --- a/tools/perf/Documentation/perf-config.txt
> +++ b/tools/perf/Documentation/perf-config.txt
> @@ -8,7 +8,11 @@ perf-config - Get and set variables in configuration file.
>  SYNOPSIS
>  --------
>  [verse]
> +'perf config' section.subkey[=value]
> +or
>  'perf config' -a | --all
> +or
> +'perf config' -r | --remove section.subkey

I'd like to suggest to split -r option handling into a separate patch.


>  
>  DESCRIPTION
>  -----------
> @@ -21,6 +25,10 @@ OPTIONS
>  --all::
>  	Show all variables with key and value into each sections.
>  
> +-r::
> +--remove::
> +	Remove a specific variable.
> +
>  CONFIGURATION FILE
>  ------------------
>  
> diff --git a/tools/perf/builtin-config.c b/tools/perf/builtin-config.c
> index 7cf6d03..205e053 100644
> --- a/tools/perf/builtin-config.c
> +++ b/tools/perf/builtin-config.c
> @@ -15,15 +15,24 @@
>  
>  static struct {
>  	bool all_action;
> +	bool get_action;
> +	bool set_action;
> +	bool remove_action;
>  } params;
>  
> +LIST_HEAD(sections);
> +static char *given_section_name;
> +static char *given_subkey;
> +static char *given_value;

Why this given_* variables are needed?  I think they can be passed
simply via function arguments?


> +
>  static const char * const config_usage[] = {
> -	"perf config [options]",
> +	"perf config [options] [section.subkey[=value]]",
>  	NULL
>  };
>  static const struct option config_options[] = {
>  	OPT_GROUP("Action"),
>  	OPT_BOOLEAN('a', "all", &params.all_action, "print all configurations"),
> +	OPT_BOOLEAN('r', "remove", &params.remove_action, "remove a variable: section.subkey"),
>  	OPT_END()
>  };
>  
> @@ -35,6 +44,72 @@ static void check_argc(int argc, int limit)
>  	usage_with_options(config_usage, config_options);
>  }
>  
> +static struct config_section *find_config_section(const char *section_name)
> +{
> +	struct config_section *section_node;

It'd be better to split declaration and function body with a blank line.


> +	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;
> +	LIST_HEAD(element_head);
> +
> +	section_node = zalloc(sizeof(*section_node));
> +	if (!section_node)
> +		return NULL;
> +
> +	INIT_LIST_HEAD(&section_node->element_head);
> +	list_splice(&element_head, &section_node->element_head);

I don't see why this additional element_head is needed?


> +	section_node->name = strdup(section_name);
> +	if (!section_node->name) {
> +		pr_err("%s: strdup failed\n", __func__);
> +		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) {

You need to free all previously allocated memory (i.e. the element_node).


> +		pr_err("%s: strdup failed\n", __func__);
> +		return -1;
> +	}
> +	if (value) {
> +		element_node->value = strdup(value);
> +		if (!element_node->value) {

Ditto.


> +			pr_err("%s: strdup failed\n", __func__);
> +			return -1;
> +		}
> +	} else
> +		element_node->value = NULL;
> +
> +	list_add_tail(&element_node->list, head);
> +
> +	return 0;
> +}
> +
>  static int show_config(const char *key, const char *value,
>  			   void *cb __maybe_unused)
>  {
> @@ -46,22 +121,165 @@ static int show_config(const char *key, const char *value,
>  	return 0;
>  }
>  
> +static int show_spec_config(struct config_section *section_node
> +			    , struct config_element *element_node)
> +{
> +	char key[BUFSIZ];
> +
> +	if (section_node && element_node) {
> +		sprintf(key, "%s.%s", section_node->name, element_node->subkey);

Please use scnprintf() instead of sprintf().


> +		show_config(key, element_node->value, NULL);
> +	} else
> +		pr_err("Error: Failed to find the variable.\n");
> +
> +	return 0;
> +}
> +
> +static int set_config(struct config_section *section_node, struct config_element *element_node)
> +{
> +	if (!given_value) {
> +		/* value == NULL means remove the variable */
> +		if (section_node && element_node)
> +			element_node->value = NULL;
> +		else /* do nothing */
> +			return 0;
> +	} else {
> +		/* if there isn't existent section, add a new section */
> +		if (!section_node) {
> +			section_node = init_config_section(given_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_config_element(&section_node->element_head, given_subkey, given_value);
> +		else
> +			element_node->value = given_value;
> +	}
> +
> +	perf_configset_write_in_full();
> +
> +	return 0;
> +}
> +
> +static int collect_config(const char *var, const char *value
> +			  , void *cb __maybe_unused)
> +{
> +	struct config_section *section_node;
> +	char *section_name, *subkey;
> +	char *key = strdup(var);
> +
> +	if (!key) {
> +		pr_err("%s: strdup failed\n", __func__);
> +		return -1;
> +	}
> +	section_name = strsep(&key, ".");
> +	subkey = strsep(&key, ".");
> +	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);
> +	}
> +
> +	add_config_element(&section_node->element_head, subkey, value);
> +
> +	return 0;
> +}
> +
> +static int perf_configset_with_option(configset_fn_t fn, const char *var)
> +{
> +	struct config_section *section_node = NULL;
> +	struct config_element *element_node = NULL;
> +	char *key = strdup(var);

Need to check return value here.


> +	const char *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;
> +	}
> +
> +	given_value = strrchr(key, '=');

I think it should be strchr so that it can find first '=' character
instead of the last one in case the given_value contains the '=' like
env variables.


> +	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 (strsep(&key, ".") != NULL)
> +		return -1;
> +	if (given_value)
> +		given_subkey = strsep(&given_subkey, "=");
> +
> +	perf_config(collect_config, NULL);
> +
> +	section_node = find_config_section(given_section_name);
> +
> +	if (section_node != NULL)
> +		element_node = find_config_element(given_subkey, section_node);
> +
> +	fn(section_node, element_node);

Here, given_section, subkey and value can be passed.


> +
> +	return 0;
> +}
> +
>  int cmd_config(int argc, const char **argv, const char *prefix __maybe_unused)
>  {
>  	int 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 (argc > 0) {
> +	if (origin_argc > argc)
> +		is_option = true;
> +	else
> +		is_option = false;
> +
> +	if (!is_option && argc > 0) {
>  		if (strcmp(argv[0], "-") == 0) {
>  			pr_warning("  Error: '-' is not supported.\n");
>  			usage_with_options(config_usage, config_options);
>  		}
> +
> +		switch (argc) {
> +		case 1:
> +			value = strrchr(argv[0], '=');
> +			if (value == NULL || value == argv[0])
> +				params.get_action = true;
> +			else
> +				params.set_action = true;
> +			break;
> +		default:
> +			break;
> +		}
>  	}
>  
> -	if (argc == 0 || params.all_action) {
> +	if ((!is_option && argc == 0) || params.all_action) {
>  		check_argc(argc, 0);
>  		ret = perf_config(show_config, NULL);
> +	} else if (params.get_action) {
> +		check_argc(argc, 1);
> +		ret = perf_configset_with_option(show_spec_config, argv[0]);
> +	} else if (params.set_action || params.remove_action) {
> +		check_argc(argc, 1);
> +		ret = perf_configset_with_option(set_config, argv[0]);
>  	} else {
>  		pr_warning("Error: Unknown argument.\n");
>  		usage_with_options(config_usage, config_options);
> diff --git a/tools/perf/util/cache.h b/tools/perf/util/cache.h
> index fbcca21..17b271f 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)(struct config_section *, struct config_element *);
> +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..ffcbe96 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 +501,36 @@ out:
>  	return ret;
>  }
>  
> +int perf_configset_write_in_full(void)
> +{
> +	struct config_section *section_node;
> +	struct config_element *element_node;
> +	char section[BUFSIZ];
> +	char key_value_pair[BUFSIZ];
> +	const char *first_line = "# this file is auto-generated.\n";
> +	FILE *f = fopen(config_file_name, "w");
> +
> +	if (!f)
> +		return -1;
> +
> +	fwrite(first_line, strlen(first_line), 1, f);
> +	/* overwrite configvariables */
> +	list_for_each_entry(section_node, &sections, list) {
> +		sprintf(section, "[%s]\n", section_node->name);
> +		fwrite(section, strlen(section), 1, f);

Why not calling fprintf() directly?


> +		list_for_each_entry(element_node, &section_node->element_head, list) {
> +			if (element_node->value) {
> +				sprintf(key_value_pair, "\t%s = %s\n"
> +					, element_node->subkey, element_node->value);
> +				fwrite(key_value_pair, strlen(key_value_pair), 1, f);

Ditto..

Thanks,
Namhyung


> +			}
> +		}
> +	}
> +	fclose(f);
> +
> +	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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