[U-Boot] [PATCH v2 1/3] env: unify logic to check and apply changes

Marek Vasut
2012-03-29T20:19:01Z

Dear Gerlando Falauto,

WD prodded me too long to review this patchset ;-D

> The logic of checking special parameters (e.g. baudrate, stdin, stdout,
> for a valid value and/or whether can be overwritten) and applying the
> new value to the running system is now all within a single function
> env_check_apply() which can be called whenever changes are made
> to the environment, no matter if by set, default or import.
>
> With this patch env_check_apply() is only called by "env set",
> retaining previous behavior.
>
> Also allow for selectively importing/resetting variables.
>
> So add 3 new arguments to himport_r():
> o "nvars", "vars":, number and list of variables to take into account
> (0 means ALL)
>
> o "apply" callback function to check whether a variable can be
> overwritten, and possibly immediately apply the changes;
> when NULL, no check is performed.
>
> Signed-off-by: Gerlando Falauto <gerlando.falauto@keymile.com>

[...]

> + }
> +#if defined(CONFIG_CMD_NET)
> + else if (strcmp(name, "bootfile") == 0) {
> + copy_filename(BootFile, newval, sizeof(BootFile));

Can you remove the camel-case here please?

> + return 0;
> + }
> +#endif
> + return 0;
> +}
> +
> +/*
> + * Set a new environment variable,
> + * or replace or delete an existing one.
> +*/
> +int _do_env_set(int flag, int argc, char * const argv[])
> +{
> + int i, len;
> + char *name, *value, *s;
> + ENTRY e, *ep;
> +
> + name = argv[1];
> + value = argv[2];
> +
> + if (strchr(name, '=')) {
> + printf("## Error: illegal character '='"
> + "in variable name \"%s\"\n", name);
> + return 1;
> + }
> +
> + env_id++;
> + /*
> + * search if variable with this name already exists
> + */
> + e.key = name;
> + e.data = NULL;
> + hsearch_r(e, FIND, &ep, &env_htab);
> +
> + /*
> + * Perform requested checks. Notice how since we are overwriting
> + * a single variable, we need to set H_NOCLEAR
> + */
> + if (env_check_apply(name, ep ? ep->data : NULL, value, H_NOCLEAR)) {
> + debug("check function did not approve, refusing\n");
> + return 1;
> + }
> +
> /* Delete only ? */
> if (argc < 3 || argv[2] == NULL) {
> int rc = hdelete_r(name, &env_htab);
> @@ -337,34 +412,6 @@ int _do_env_set(int flag, int argc, char * const
> argv[]) return 1;
> }
>
> - /*
> - * Some variables should be updated when the corresponding
> - * entry in the environment is changed
> - */
> - if (strcmp(name, "ipaddr") == 0) {
> - char *s = argv[2]; /* always use only one arg */
> - char *e;
> - unsigned long addr;
> - bd->bi_ip_addr = 0;
> - for (addr = 0, i = 0; i < 4; ++i) {
> - ulong val = s ? simple_strtoul(s, &e, 10) : 0;
> - addr <<= 8;
> - addr |= val & 0xFF;
> - if (s)
> - s = *e ? e + 1 : e;
> - }
> - bd->bi_ip_addr = htonl(addr);
> - return 0;
> - } else if (strcmp(argv[1], "loadaddr") == 0) {
> - load_addr = simple_strtoul(argv[2], NULL, 16);
> - return 0;
> - }
> -#if defined(CONFIG_CMD_NET)
> - else if (strcmp(argv[1], "bootfile") == 0) {
> - copy_filename(BootFile, argv[2], sizeof(BootFile));
> - return 0;
> - }
> -#endif
> return 0;
> }
>
> @@ -886,7 +933,8 @@ static int do_env_import(cmd_tbl_t *cmdtp, int flag,
> addr = (char *)ep->data;
> }
>
> - if (himport_r(&env_htab, addr, size, sep, del ? 0 : H_NOCLEAR) == 0) {
> + if (himport_r(&env_htab, addr, size, sep, del ? 0 : H_NOCLEAR,
> + 0, NULL, NULL) == 0) {
> error("Environment import failed: errno = %d\n", errno);
> return 1;
> }
> diff --git a/common/env_common.c b/common/env_common.c
> index 8a71096..7e2bb2f 100644
> --- a/common/env_common.c
> +++ b/common/env_common.c
> @@ -175,7 +175,8 @@ void set_default_env(const char *s)
> }
>
> if (himport_r(&env_htab, (char *)default_environment,
> - sizeof(default_environment), '\0', 0) == 0)
> + sizeof(default_environment), '\0', 0,
> + 0, NULL, NULL) == 0)
> error("Environment import failed: errno = %d\n", errno);
>
> gd->flags |= GD_FLG_ENV_READY;
> @@ -200,7 +201,8 @@ int env_import(const char *buf, int check)
> }
> }
>
> - if (himport_r(&env_htab, (char *)ep->data, ENV_SIZE, '\0', 0)) {
> + if (himport_r(&env_htab, (char *)ep->data, ENV_SIZE, '\0', 0,
> + 0, NULL, NULL)) {
> gd->flags |= GD_FLG_ENV_READY;
> return 1;
> }
> diff --git a/include/environment.h b/include/environment.h
> index 3c145af..3a3e6b8 100644
> --- a/include/environment.h
> +++ b/include/environment.h
> @@ -193,6 +193,13 @@ 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)
> + */
> +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 ef53edb..2a59e03 100644
> --- a/include/search.h
> +++ b/include/search.h
> @@ -47,6 +47,13 @@ typedef struct entry {
> struct _ENTRY;
>
> /*
> + * Callback function to be called for checking whether the given change
> may + * be applied or not. Must return 0 for approval, 1 for denial.
> + */
> +typedef int (*apply_cb)(const char *name, const char *oldval,
> + const char *newval, int flag);

Is the typedef really necessary ?

> +
> +/*
> * Family of hash table handling functions. The functions also
> * have reentrant counterparts ending with _r. The non-reentrant
> * functions all work on a signle internal hashing table.
> @@ -94,11 +101,19 @@ extern ssize_t hexport_r(struct hsearch_data *__htab,
> const char __sep, char **__resp, size_t __size,
> int argc, char * const argv[]);
>
> +/*
> + * nvars, vars: variables to import (nvars == 0 means all)
> + * apply_cb: callback function to check validity of the new argument,
> + * and possibly apply changes (NULL means accept everything)
> + */
> extern int himport_r(struct hsearch_data *__htab,
> const char *__env, size_t __size, const char __sep,
> - int __flag);
> + int __flag,
> + int nvars, char * const vars[],
> + apply_cb apply);
>
> /* Flags for himport_r() */
> #define H_NOCLEAR 1 /* do not clear hash table before
importing */
> +#define H_FORCE 2 /* overwrite read-only/write-once
variables */

Make this 1 << x please.

>
> #endif /* search.h */
> diff --git a/lib/hashtable.c b/lib/hashtable.c
> index abd61c8..75b9b07 100644
> --- a/lib/hashtable.c
> +++ b/lib/hashtable.c
> @@ -603,6 +603,22 @@ ssize_t hexport_r(struct hsearch_data *htab, const
> char sep, * himport()
> */
>
> +/* Check whether variable name is amongst vars[] */
> +static int process_var(const char *name, int nvars, char * const vars[])

You mean check_var()?

> +{
> + int i = 0;
> + /* No variables specified means process all of them */
> + if (nvars == 0)
> + return 1;
> +
> + for (i = 0; i < nvars; i++) {
> + if (!strcmp(name, vars[i]))
> + return 1;
> + }
> + debug("Skipping non-listed variable %s\n", name);
> + return 0;
> +}
> +
> /*
> * Import linearized data into hash table.
> *
> @@ -639,7 +655,9 @@ ssize_t hexport_r(struct hsearch_data *htab, const char
> sep, */
>
> int himport_r(struct hsearch_data *htab,
> - const char *env, size_t size, const char sep, int flag)
> + const char *env, size_t size, const char sep, int flag,
> + int nvars, char * const vars[],
> + apply_cb apply)
> {
> char *data, *sp, *dp, *name, *value;
>
> @@ -726,6 +744,8 @@ int himport_r(struct hsearch_data *htab,
> *dp++ = '\0'; /* terminate name */
>
> debug("DELETE CANDIDATE: \"%s\"\n", name);
> + if (!process_var(name, nvars, vars))
> + continue;
>
> if (hdelete_r(name, htab) == 0)
> debug("DELETE ERROR
##############################\n");
> @@ -743,10 +763,31 @@ int himport_r(struct hsearch_data *htab,
> *sp++ = '\0'; /* terminate value */
> ++dp;
>
> + /* Skip variables which are not supposed to be treated */
> + if (!process_var(name, nvars, vars))
> + continue;
> +
> /* enter into hash table */
> e.key = name;
> e.data = value;

Do you need to do this if you eventually later figure out you have no apply()
callback and you did this for no reason?

>
> + /* if there is an apply function, check what it has to say */
> + if (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 (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",