[PATCH v2 5/8] makedumpfile: Read and process filter commands from config file.

[Ken'ichi Ohmichi]

Hi Mahesh,

On Wed, 18 May 2011 01:34:15 +0530
Mahesh J Salgaonkar <mahesh at linux.vnet.ibm.com> wrote:
> 
> This patch enables to makedumpfile to read and process filter commands from
> specified config file. It builds a list of filter info consisting of memory
> address (paddr) and size to be filtered out. This list is used during
> read_pfn() function to filter out user specified kernel data from vmcore
> before writing it to compressed DUMPFILE. The filtered memory locations are
> filled with 'X' (0x58) character.
> 
> The filter command syntax is:
> 	erase <Symbol>[.member[...]] [size <SizeValue>[K|M]]
> 	erase <Symbol>[.member[...]] [size <SizeSymbol>]
> 	erase <Symbol>[.member[...]] [nullify]
> 
> Below are the examples how filter commands in config file look like:
> 
> 	erase modules
> 	erase cred_jar.name size 10
> 	erase vmlist.addr nullify

Thank you for the work.
I tested this feature by the above example, and confirmed the feature
works fine. Nice work :-)

There are some comments in the below lines.
Can you check them ?

> +/*
> + * Read the non-terminal's which are in the form of <Symbol>[.member[...]]
> + */
> +struct config_entry *
> +create_config_entry(const char *token, unsigned short flag, int line)
> +{
> +	struct config_entry *ce = NULL, *ptr, *prev_ce;
> +	char *str, *cur, *next;
> +	long len;
> +	int depth = 0;
> +
> +	if (!token)
> +		return NULL;
> +
> +	cur = str = strdup(token);
> +	prev_ce = ptr = NULL;
> +	while (cur != NULL) {
> +		if ((next = strchr(cur, '.')) != NULL) {
> +			*next++ = '\0';
> +		}
> +		if (!strlen(cur)) {
> +			cur = next;
> +			continue;
> +		}
> +
> +		if ((ptr = calloc(1, sizeof(struct config_entry))) == NULL) {
> +			ERRMSG("Can't allocate memory for config_entry\n");
> +			goto err_out;
> +		}
> +		ptr->line = line;
> +		ptr->flag |= flag;
> +		if (depth == 0) {
> +			/* First node is always a symbol name */
> +			ptr->flag |= SYMBOL_ENTRY;
> +		}
> +		if (flag & FILTER_ENTRY) {
> +			ptr->name = strdup(cur);
> +		}
> +		if (flag & SIZE_ENTRY) {
> +			char ch = '\0';
> +			int n = 0;
> +			/* See if absolute length is provided */
> +			if ((depth == 0) &&
> +				((n = sscanf(cur, "%zd%c", &len, &ch)) > 0)) {
> +				if (len < 0) {
> +					ERRMSG("Config error at %d: size "
> +						"value must be positive.\n",
> +						line);
> +					goto err_out;
> +				}
> +				ptr->size = len;
> +				ptr->flag |= ENTRY_RESOLVED;
> +				if (n == 2) {
> +					/* Handle suffix.
> +					 * K = Kilobytes
> +					 * M = Megabytes
> +					 */
> +					switch (ch) {
> +					case 'M':
> +					case 'm':
> +						ptr->size *= 1024;
> +					case 'K':
> +					case 'k':
> +						ptr->size *= 1024;
> +						break;
> +					}
> +				}
> +			}
> +			else
> +				ptr->name = strdup(cur);
> +		}
> +		if (prev_ce) {
> +			prev_ce->next = ptr;
> +			prev_ce = ptr;
> +		}
> +		else
> +			ce = prev_ce = ptr;
> +		cur = next;
> +		depth++;
> +		ptr = NULL;
> +	}
> +	free(str);
> +	return ce;
> +
> +err_out:
> +	if (ce)
> +		free_config_entry(ce);
> +	if (ptr)
> +		free_config_entry(ptr);

"free(str);" is necessary.

> +	return NULL;
> +}

[..]

> +/*
> + * read filter config file and return each string token. If the parameter
> + * expected_token is non-NULL, then return the current token if it matches
> + * with expected_token otherwise save the current token and return NULL.
> + * At start of every module section filter_config.new_section is set to 1 and
> + * subsequent function invocations return NULL untill filter_config.new_section
> + * is reset to 0 by passing @flag = CONFIG_NEW_CMD (0x02).
> + *
> + * Parameters:
> + * @expected_token	INPUT
> + *	Token string to match with currnet token.
> + *	=NULL - return the current available token.
> + *
> + * @flag		INPUT
> + *	=0x01 - Skip to next module section.
> + *	=0x02 - Treat the next token as next filter command and reset.
> + *
> + * @line		OUTPUT
> + *	Line number of current token in filter config file.
> + *
> + * @cur_mod		OUTPUT
> + *	Points to current module section name on non-NULL return value.
> + *
> + * @eof			OUTPUT
> + *	set to -1 when end of file is reached.
> + *	set to -2 when end of section is reached.
> + */
> +static char *
> +get_config_token(char *expected_token, unsigned char flag, int *line,
> +			char **cur_mod, int *eof)
> +{
> +	char *p;
> +	struct filter_config *fc = &filter_config;
> +	int skip = flag & CONFIG_SKIP_SECTION;

CONFIG_SKIP_SECTION is used only here, and we need to fix get_config()
for the readability. Please check my comment in get_config().

[..]

> +/*
> + * Configuration file 'makedumpfile.conf' contains filter commands.
> + * Every individual filter command is considered as a config entry. A config
> + * entry can be provided on a single line or multiple lines.
> + */
> +struct config *
> +get_config(int skip)
> +{
> +	struct config *config;
> +	char *token = NULL;
> +	static int line_count = 0;
> +	char *cur_module = NULL;
> +	int eof = 0;
> +	unsigned char flag = CONFIG_NEW_CMD | skip;

We need to change the above:

	unsigned char flag = CONFIG_NEW_CMD;
	if (skip)
		flag |= CONFIG_SKIP_SECTION;

> +
> +	if ((config = calloc(1, sizeof(struct config))) == NULL)
> +		return NULL;
> +
> +	if (get_config_token("erase", flag, &line_count, &cur_module, &eof)) {
> +		if (cur_module)
> +			config->module_name = strdup(cur_module);
> +
> +		if (!read_filter_entry(config, line_count))
> +			goto err_out;
> +	}
> +	else {
> +		if (!eof) {
> +			token = get_config_token(NULL, 0, &line_count,
> +								NULL, NULL);
> +			ERRMSG("Config error at %d: Invalid token '%s'.\n",
> +							line_count, token);
> +		}
> +		goto err_out;
> +	}
> +	return config;
> +err_out:
> +	if (config)
> +		free_config(config);
> +	return NULL;
> +}

BTW makedumpfile.c has become a large file which is bigger than 10KLine,
and I will separate it to some files for the maintenance.


Thanks
Ken'ichi Ohmichi