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

[Marek Vasut <marex@denx.de>]

Dear Gerlando Falauto,

> 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.

Not really, I don't really care ;-)

> 
> >>>   		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",