Fix handling of special chars in ACL LOAD.

Now it is also possible for ACL SETUSER to accept empty strings
as valid operations (doing nothing), so for instance

    ACL SETUSER myuser ""

Will have just the effect of creating a user in the default state.

This should fix redis#7329.

src/acl.c

@@ -732,10 +732,11 @@ void ACLAddAllowedSubcommand(user *u, unsigned long id, const char *sub) {
  * EEXIST: You are adding a key pattern after "*" was already added. This is
  *         almost surely an error on the user side.
  * ENODEV: The password you are trying to remove from the user does not exist.
- * EBADMSG: The hash you are trying to add is not a valid hash. 
+ * EBADMSG: The hash you are trying to add is not a valid hash.
  */
 int ACLSetUser(user *u, const char *op, ssize_t oplen) {
     if (oplen == -1) oplen = strlen(op);
+    if (oplen == 0) return C_OK; /* Empty string is a no-operation. */
     if (!strcasecmp(op,"on")) {
         u->flags |= USER_FLAG_ENABLED;
         u->flags &= ~USER_FLAG_DISABLED;
@@ -1297,7 +1298,7 @@ sds ACLLoadFromFile(const char *filename) {
         if (lines[i][0] == '\0') continue;
 
         /* Split into arguments */
-        argv = sdssplitargs(lines[i],&argc);
+        argv = sdssplitlen(lines[i],sdslen(lines[i])," ",1,&argc);
         if (argv == NULL) {
             errors = sdscatprintf(errors,
                      "%s:%d: unbalanced quotes in acl line. ",
@@ -1329,11 +1330,14 @@ sds ACLLoadFromFile(const char *filename) {
             continue;
         }
 
-        /* Try to process the line using the fake user to validate iif
-         * the rules are able to apply cleanly. */
+        /* Try to process the line using the fake user to validate if
+         * the rules are able to apply cleanly. At this stage we also
+         * trim trailing spaces, so that we don't have to handle that
+         * in ACLSetUser(). */
         ACLSetUser(fakeuser,"reset",-1);
         int j;
         for (j = 2; j < argc; j++) {
+            argv[j] = sdstrim(argv[j],"\t\r\n");
             if (ACLSetUser(fakeuser,argv[j],sdslen(argv[j])) != C_OK) {
                 char *errmsg = ACLSetUserStringError();
                 errors = sdscatprintf(errors,