Control lib: Fix string handling corner cases

strncpy() does not enforce NUL-termination, but snprintf() does. So we need to ensure all strings are terminated. Another issue was the use of the wrong length parameter for these functions, resulting in the limiting arguments not being applied to the right length.

src/lib/controllib/block/Block.cpp

@@ -66,16 +66,20 @@ void Block::getName(char *buf, size_t n)
 {
 	if (getParent() == NULL) {
 		strncpy(buf, _name, n);
+		// ensure string is terminated
+		buf[n - 1] = '\0';
 
 	} else {
 		char parentName[blockNameLengthMax];
 		getParent()->getName(parentName, n);
 
 		if (!strcmp(_name, "")) {
-			strncpy(buf, parentName, blockNameLengthMax);
+			strncpy(buf, parentName, n);
+			// ensure string is terminated
+			buf[n - 1] = '\0';
 
 		} else {
-			snprintf(buf, blockNameLengthMax, "%s_%s", parentName, _name);
+			snprintf(buf, n, "%s_%s", parentName, _name);
 		}
 	}
 }

src/lib/controllib/block/BlockParam.cpp

@@ -62,12 +62,16 @@ BlockParamBase::BlockParamBase(Block *parent, const char *name, bool parent_pref
 
 		if (!strcmp(name, "")) {
 			strncpy(fullname, parentName, blockNameLengthMax);
+			// ensure string is terminated
+			fullname[sizeof(fullname) - 1] = '\0';
 
 		} else if (parent_prefix) {
 			snprintf(fullname, blockNameLengthMax, "%s_%s", parentName, name);
 
 		} else {
 			strncpy(fullname, name, blockNameLengthMax);
+			// ensure string is terminated
+			fullname[sizeof(fullname) - 1] = '\0';
 		}
 
 		parent->getParams().add(this);