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

[Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com>]

Hi Ken'ichi,

On 08/11/2011 07:37 AM, Ken'ichi Ohmichi wrote:
> 
> Hi Mahesh,
> 
> On Wed, 18 May 2011 01:34:15 +0530
> Mahesh J Salgaonkar <mahesh@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 :-)

Thanks :-)

> 
> 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.
> 

Nice catch. Agree.

>> +	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;
>

Agree.

Thanks,
-Mahesh.

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