1 files changed, 8 insertions, 4 deletions

diff --git a/qobject/qstring.c b/qobject/qstring.c
index afca54b47a..0f1510e792 100644
--- a/qobject/qstring.c
+++ b/qobject/qstring.c
@@ -37,21 +37,23 @@ size_t qstring_get_length(const QString *qstring)
  *
  * Return string reference
  */
-QString *qstring_from_substr(const char *str, int start, int end)
+QString *qstring_from_substr(const char *str, size_t start, size_t end)
 {
     QString *qstring;
 
+    assert(start <= end);
+
     qstring = g_malloc(sizeof(*qstring));
     qobject_init(QOBJECT(qstring), QTYPE_QSTRING);
 
-    qstring->length = end - start + 1;
+    qstring->length = end - start;
     qstring->capacity = qstring->length;
 
+    assert(qstring->capacity < SIZE_MAX);
     qstring->string = g_malloc(qstring->capacity + 1);
     memcpy(qstring->string, str + start, qstring->length);
     qstring->string[qstring->length] = 0;
 
-
     return qstring;
 }
 
@@ -62,13 +64,15 @@ QString *qstring_from_substr(const char *str, int start, int end)
  */
 QString *qstring_from_str(const char *str)
 {
-    return qstring_from_substr(str, 0, strlen(str) - 1);
+    return qstring_from_substr(str, 0, strlen(str));
 }
 
 static void capacity_increase(QString *qstring, size_t len)
 {
     if (qstring->capacity < (qstring->length + len)) {
+        assert(len <= SIZE_MAX - qstring->capacity);
         qstring->capacity += len;
+        assert(qstring->capacity <= SIZE_MAX / 2);
         qstring->capacity *= 2; /* use exponential growth */
 
         qstring->string = g_realloc(qstring->string, qstring->capacity + 1);