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 493aecc..983e747 100644 --- a/common/cmd_nvedit.c +++ b/common/cmd_nvedit.c @@ -202,6 +202,7 @@ 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. @@ -915,7 +916,7 @@ 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 8f142ed..c6e7c4c 100644 --- a/common/env_common.c +++ b/common/env_common.c @@ -133,7 +133,9 @@ 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) { @@ -194,7 +196,7 @@ 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) error("Environment import failed: errno = %d\n", errno);
gd->flags |= GD_FLG_ENV_READY; @@ -220,7 +222,7 @@ 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 */)) { gd->flags |= GD_FLG_ENV_READY; return 1; } diff --git a/include/environment.h b/include/environment.h index ae3f7b6..90fb130 100644 --- a/include/environment.h +++ b/include/environment.h @@ -184,6 +184,15 @@ 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",