[U-Boot] [PATCH v3 3/6] env: add check/apply logic to himport_r()

[Gerlando Falauto <gerlando.falauto@keymile.com>]

On 04/02/2012 09:01 PM, Marek Vasut wrote:
> Dear Marek Vasut,
>
>> Dear Gerlando Falauto,
>>
>>> Change hashtable so that a callback function will decide whether a
>>> variable can be overwritten, and possibly apply the changes.
>>>
>>> So add a new field to struct hsearch_data:
>>>   o "apply" callback function to check whether a variable can be
>>>
>>>      overwritten, and possibly immediately apply the changes;
>>>      when NULL, no check is performed.
>>>
>>> And a new argument to himport_r():
>>>   o "do_apply": whether to call the apply callback function
>>>
>>> NOTE: This patch does not change the current behavior.
>>>
>>> Signed-off-by: Gerlando Falauto<gerlando.falauto@keymile.com>
>>> ---
>>>
>>>   common/cmd_nvedit.c   |    3 ++-
>>>   common/env_common.c   |    8 +++++---
>>>   include/environment.h |    9 +++++++++
>>>   include/search.h      |   14 +++++++++++++-
>>>   lib/hashtable.c       |   20 +++++++++++++++++++-
>>>   5 files changed, 48 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/common/cmd_nvedit.c b/common/cmd_nvedit.c
>>> index 59668a6..fc6165f 100644
>>> --- a/common/cmd_nvedit.c
>>> +++ b/common/cmd_nvedit.c
>>> @@ -201,6 +201,7 @@ static int do_env_grep(cmd_tbl_t *cmdtp, int flag,
>>>
>>>    * environment variable, then (if successful) apply the changes to
>>>
>>> internals so * to make them effective.  Code for this function was taken
>>> out of * _do_env_set(), which now calls it instead.
>>> + * Also called as a callback function by himport_r().
>>>
>>>    * Returns 0 in case of success, 1 in case of failure.
>>>    * When (flag&  H_FORCE) is set, do not print out any error message and
>>>
>>> force * overwriting of write-once variables.
>>> @@ -931,7 +932,7 @@ static int do_env_import(cmd_tbl_t *cmdtp, int flag,
>>>
>>>   	}
>>>   	
>>>   	if (himport_r(&env_htab, addr, size, sep, del ? 0 : H_NOCLEAR,
>>>
>>> -			0, NULL) == 0) {
>>> +			0, NULL, 0 /* do_apply */) == 0) {
>>>
>>>   		error("Environment import failed: errno = %d\n", errno);
>>>   		return 1;
>>>   	
>>>   	}
>>>
>>> diff --git a/common/env_common.c b/common/env_common.c
>>> index a93c062..5558c1c 100644
>>> --- a/common/env_common.c
>>> +++ b/common/env_common.c
>>> @@ -122,7 +122,9 @@ const uchar default_environment[] = {
>>>
>>>   	"\0"
>>>
>>>   };
>>>
>>> -struct hsearch_data env_htab;
>>> +struct hsearch_data env_htab = {
>>> +	.apply = env_check_apply,
>>> +};
>>>
>>>   static uchar __env_get_char_spec(int index)
>>>   {
>>>
>>> @@ -183,7 +185,7 @@ void set_default_env(const char *s)
>>>
>>>   	if (himport_r(&env_htab, (char *)default_environment,
>>>   	
>>>   			sizeof(default_environment), '\0', 0,
>>>
>>> -			0, NULL) == 0)
>>> +			0, NULL, 0 /* do_apply */) == 0)
>>
>> Please replace that 0 /*...*/ stuff with simple NULL
>
> Oh, it's integer ... so just remove the comment, sorry.

The comment would have been a way to shed some light on one of the 8 
arguments the function takes.
But if it's against some coding style guideline, I'll simply remove it.

>
>>
>>>   		error("Environment import failed: errno = %d\n", errno);
>>>   	
>>>   	gd->flags |= GD_FLG_ENV_READY;
>>>
>>> @@ -209,7 +211,7 @@ int env_import(const char *buf, int check)
>>>
>>>   	}
>>>   	
>>>   	if (himport_r(&env_htab, (char *)ep->data, ENV_SIZE, '\0', 0,
>>>
>>> -			0, NULL)) {
>>> +			0, NULL, 0 /* do_apply */)) {
>>
>> DTTO, otherwise looks fine.
>>
>>>   		gd->flags |= GD_FLG_ENV_READY;
>>>   		return 1;
>>>   	
>>>   	}
>>>
>>> diff --git a/include/environment.h b/include/environment.h
>>> index 1ef44f3..236e179 100644
>>> --- a/include/environment.h
>>> +++ b/include/environment.h
>>> @@ -193,6 +193,15 @@ void set_default_env(const char *s);
>>>
>>>   /* Import from binary representation into hash table */
>>>   int env_import(const char *buf, int check);
>>>
>>> +/*
>>> + * Check if variable "name" can be changed from oldval to newval,
>>> + * and if so, apply the changes (e.g. baudrate).
>>> + * When (flag&  H_FORCE) is set, it does not print out any error
>>> + * message and forces overwriting of write-once variables.
>>> + */
>>> +int env_check_apply(const char *name, const char *oldval,
>>> +			const char *newval, int flag);
>>> +
>>>
>>>   #endif /* DO_DEPS_ONLY */
>>>
>>>   #endif /* _ENVIRONMENT_H_ */
>>>
>>> diff --git a/include/search.h b/include/search.h
>>> index 94d75fc..721c8ac 100644
>>> --- a/include/search.h
>>> +++ b/include/search.h
>>> @@ -57,6 +57,16 @@ struct hsearch_data {
>>>
>>>   	struct _ENTRY *table;
>>>   	unsigned int size;
>>>   	unsigned int filled;
>>>
>>> +/*
>>> + * Callback function which will check whether the given change for
>>> variable + * "name" from "oldval" to "newval" may be applied or not, and
>>> possibly apply + * such change.
>>> + * When (flag&  H_FORCE) is set, it shall not print out any error
>>> message and + * shall force overwriting of write-once variables.
>>> +.* Must return 0 for approval, 1 for denial.
>>> + */
>>> +	int (*apply)(const char *name, const char *oldval,
>>> +			const char *newval, int flag);
>>>
>>>   };
>>>
>>>   /* Create a new hashing table which will at most contain NEL elements.
>>>   */
>>>
>>> @@ -97,10 +107,12 @@ extern ssize_t hexport_r(struct hsearch_data
>>> *__htab,
>>>
>>>   /*
>>>
>>>    * nvars: length of vars array
>>>    * vars: array of strings (variable names) to import (nvars == 0 means
>>>
>>> all) + * do_apply: whether to call callback function to check the new
>>> argument, + * and possibly apply changes (false means accept everything)
>>>
>>>    */
>>>
>>>   extern int himport_r(struct hsearch_data *__htab,
>>>
>>>   		     const char *__env, size_t __size, const char __sep,
>>>
>>> -		     int __flag, int nvars, char * const vars[]);
>>> +		     int __flag, int nvars, char * const vars[], int do_apply);
>>>
>>>   /* Flags for himport_r() */
>>>   #define	H_NOCLEAR	(1<<  0) /* do not clear hash table before
>>
>> importing */
>>
>>> diff --git a/lib/hashtable.c b/lib/hashtable.c
>>> index 0610e86..6cfba56 100644
>>> --- a/lib/hashtable.c
>>> +++ b/lib/hashtable.c
>>> @@ -658,7 +658,7 @@ static int is_var_in_set(const char *name, int nvars,
>>> char * const vars[])
>>>
>>>   int himport_r(struct hsearch_data *htab,
>>>
>>>   		const char *env, size_t size, const char sep, int flag,
>>>
>>> -		int nvars, char * const vars[])
>>> +		int nvars, char * const vars[], int do_apply)
>>>
>>>   {
>>>
>>>   	char *data, *sp, *dp, *name, *value;
>>>
>>> @@ -772,6 +772,24 @@ int himport_r(struct hsearch_data *htab,
>>>
>>>   		e.key = name;
>>>   		e.data = value;
>>>
>>> +		/* if there is an apply function, check what it has to say */
>>> +		if (do_apply&&  htab->apply != NULL) {
>>> +			debug("searching before calling cb function"
>>> +				" for  %s\n", name);
>>> +			/*
>>> +			 * Search for variable in existing env, so to pass
>>> +			 * its previous value to the apply callback
>>> +			 */
>>> +			hsearch_r(e, FIND,&rv, htab);
>>> +			debug("previous value was %s\n", rv ? rv->data : "");
>>> +			if (htab->apply(name, rv ? rv->data : NULL,
>>> +				value, flag)) {
>>> +				debug("callback function refused to set"
>>> +					" variable %s, skipping it!\n", name);
>>> +				continue;
>>> +			}
>>> +		}
>>> +
>>>
>>>   		hsearch_r(e, ENTER,&rv, htab);
>>>   		if (rv == NULL) {
>>>   		
>>>   			printf("himport_r: can't insert \"%s=%s\" into hash
>>
>> table\n",