Signed-off-by: Gerlando Falauto <gerlando.fala...@keymile.com>
---
 common/cmd_nvedit.c   |  152 +++++++++++++++++++++++++++++++------------------
 common/env_common.c   |   15 ++++-
 include/environment.h |    7 ++
 include/search.h      |   13 ++++
 lib/hashtable.c       |   50 ++++++++++++++++
 5 files changed, 179 insertions(+), 58 deletions(-)

diff --git a/common/cmd_nvedit.c b/common/cmd_nvedit.c
index fa99c44..10b9552 100644
--- a/common/cmd_nvedit.c
+++ b/common/cmd_nvedit.c
@@ -194,32 +194,23 @@ static int do_env_grep (cmd_tbl_t *cmdtp, int flag, int 
argc, char * const argv[
 #endif
 
 /*
- * Set a new environment variable,
- * or replace or delete an existing one.
+ * Performs consistency checking before setting, replacing,
+ * or deleting an 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.
+ * Also called as a callback function by himport_ex().
+ * Returns 0 in case of success, 1 in case of failure.
+ * When (flag & H_FORCE) is set, force overwriting of
+ * write-once variables.
  */
 
-int _do_env_set (int flag, int argc, char * const argv[])
+int env_check_apply(const char *name, const char *oldval,
+                   const char *newval, int flag)
 {
        bd_t  *bd = gd->bd;
-       int   i, len;
+       int   i;
        int   console = -1;
-       char  *name, *value, *s;
-       ENTRY e, *ep;
-
-       name = argv[1];
-
-       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);
 
        /* Check for console redirection */
        if (strcmp(name, "stdin") == 0)
@@ -230,22 +221,23 @@ int _do_env_set (int flag, int argc, char * const argv[])
                console = stderr;
 
        if (console != -1) {
-               if (argc < 3) {         /* Cannot delete it! */
+               if ((newval == NULL) || (*newval == '\0')) {
+                       /* We cannot delete stdin/stdout/stderr */
                        printf("Can't delete \"%s\"\n", name);
                        return 1;
                }
 
 #ifdef CONFIG_CONSOLE_MUX
-               i = iomux_doenv(console, argv[2]);
+               i = iomux_doenv(console, newval);
                if (i)
                        return i;
 #else
                /* Try assigning specified device */
-               if (console_assign(console, argv[2]) < 0)
+               if (console_assign(console, newval) < 0)
                        return 1;
 
 #ifdef CONFIG_SERIAL_MULTI
-               if (serial_assign(argv[2]) < 0)
+               if (serial_assign(newval) < 0)
                        return 1;
 #endif
 #endif /* CONFIG_CONSOLE_MUX */
@@ -255,23 +247,29 @@ int _do_env_set (int flag, int argc, char * const argv[])
         * Some variables like "ethaddr" and "serial#" can be set only
         * once and cannot be deleted; also, "ver" is readonly.
         */
-       if (ep) {               /* variable exists */
+       if ((oldval != NULL) /* variable exists */
+        && ((flag & H_FORCE) == 0)) { /* and we are not forced */
 #ifndef CONFIG_ENV_OVERWRITE
                if ((strcmp(name, "serial#") == 0) ||
                    ((strcmp(name, "ethaddr") == 0)
 #if defined(CONFIG_OVERWRITE_ETHADDR_ONCE) && defined(CONFIG_ETHADDR)
-                    && (strcmp(ep->data, MK_STR(CONFIG_ETHADDR)) != 0)
+                    && (strcmp(oldval, MK_STR(CONFIG_ETHADDR)) != 0)
 #endif /* CONFIG_OVERWRITE_ETHADDR_ONCE && CONFIG_ETHADDR */
                    ) ) {
                        printf("Can't overwrite \"%s\"\n", name);
                        return 1;
                }
 #endif
+       }
+       /* if variable exists... */
+       if ((oldval != NULL)
+       /* or we are in a scratched-out environment */
+       || ((flag & H_NOCLEAR) == 0)) {
                /*
                 * Switch to new baudrate if new baudrate is supported
                 */
                if (strcmp(name, "baudrate") == 0) {
-                       int baudrate = simple_strtoul(argv[2], NULL, 10);
+                       int baudrate = simple_strtoul(newval, NULL, 10);
                        int i;
                        for (i = 0; i < N_BAUDRATES; ++i) {
                                if (baudrate == baudrate_table[i])
@@ -282,6 +280,10 @@ int _do_env_set (int flag, int argc, char * const argv[])
                                        baudrate);
                                return 1;
                        }
+                       if (gd->baudrate == baudrate) {
+                               /* If unchanged, we just say it's OK */
+                               return 0;
+                       }
                        printf ("## Switch baudrate to %d bps and press ENTER 
...\n",
                                baudrate);
                        udelay(50000);
@@ -299,6 +301,72 @@ int _do_env_set (int flag, int argc, char * const argv[])
                }
        }
 
+       /*
+        * Some variables should be updated when the corresponding
+        * entry in the environment is changed
+        */
+
+       if (strcmp(name, "ipaddr") == 0) {
+               const char *s = newval; /* 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(newval, "loadaddr") == 0) {
+               load_addr = simple_strtoul(newval, NULL, 16);
+               return 0;
+       }
+#if defined(CONFIG_CMD_NET)
+       else if (strcmp(newval, "bootfile") == 0) {
+               copy_filename(BootFile, newval, sizeof(BootFile));
+               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);
@@ -336,34 +404,6 @@ 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;
 }
 
diff --git a/common/env_common.c b/common/env_common.c
index c7e9bea..db607e1 100644
--- a/common/env_common.c
+++ b/common/env_common.c
@@ -172,6 +172,9 @@ const uchar *env_get_addr (int index)
 
 void set_default_env(const char *s)
 {
+       /* By default, do not apply changes as they will eventually
+        * be applied by someone else */
+       apply_cb apply_function = NULL;
        if (sizeof(default_environment) > ENV_SIZE) {
                puts("*** Error - default environment is too large\n\n");
                return;
@@ -183,14 +186,22 @@ void set_default_env(const char *s)
                                "using default environment\n\n",
                                s+1);
                } else {
+                       /* This set_to_default was explicitly asked for
+                        * by the user, as opposed to being a recovery
+                        * mechanism. Therefore we chack every single
+                        * variable and apply changes to the system
+                        * right away (e.g. baudrate, console).
+                        */
+                       apply_function = env_check_apply;
                        puts(s);
                }
        } else {
                puts("Using default environment\n\n");
        }
 
-       if (himport_r(&env_htab, (char *)default_environment,
-                   sizeof(default_environment), '\0', 0) == 0) {
+       if (himport_ex(&env_htab, (char *)default_environment,
+                   sizeof(default_environment), '\0', 0,
+                     0, NULL, apply_function) == 0) {
                error("Environment import failed: errno = %d\n", errno);
        }
        gd->flags |= GD_FLG_ENV_READY;
diff --git a/include/environment.h b/include/environment.h
index 6394a96..cd98f91 100644
--- a/include/environment.h
+++ b/include/environment.h
@@ -174,6 +174,13 @@ 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
 
 #endif /* _ENVIRONMENT_H_ */
diff --git a/include/search.h b/include/search.h
index b4edd43..4ac7171 100644
--- a/include/search.h
+++ b/include/search.h
@@ -46,6 +46,11 @@ typedef struct entry {
 /* Opaque type for internal use.  */
 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);
+
 /*
  * Family of hash table handling functions.  The functions also
  * have reentrant counterparts ending with _r.  The non-reentrant
@@ -97,7 +102,15 @@ extern int himport_r(struct hsearch_data *__htab,
                     const char *__env, size_t __size, const char __sep,
                     int __flag);
 
+extern int himport_ex(struct hsearch_data *__htab,
+                    const char *__env, size_t __size, const char __sep,
+                    int __flag,
+                    int __argc, char * const __argv[],
+                    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 */
 
 #endif /* search.h */
diff --git a/lib/hashtable.c b/lib/hashtable.c
index 6895550..a2c268f 100644
--- a/lib/hashtable.c
+++ b/lib/hashtable.c
@@ -630,6 +630,33 @@ 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)
 {
+       return himport_ex(htab, env, size, sep, flag, 0, NULL, NULL);
+}
+
+/* Check whether variable name is amongst vars[] */
+static int process_var(const char *name, int nvars, char * const vars[])
+{
+       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;
+}
+
+
+
+int himport_ex(struct hsearch_data *htab,
+             const char *env, size_t size, const char sep, int flag,
+             int nvars, char * const vars[],
+             int(*apply)(const char *, const char *, const char *, int)
+             )
+{
        char *data, *sp, *dp, *name, *value;
 
        /* Test for correct arguments.  */
@@ -715,6 +742,8 @@ 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");
@@ -732,10 +761,31 @@ 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;
 
+               /* 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",
-- 
1.7.1

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