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

Marek Vasut
2012-04-02T19:00:05Z

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

> 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",