Add unsigned to streambuffer

luprex/core/cpp/streambuffer.cpp

@@ -19,11 +19,12 @@ StreamBuffer::StreamBuffer() {
 }
 
 StreamBuffer::StreamBuffer(int64_t size, bool fixed) {
-    assert(size > 0);
+    assert(size >= 0);
     init(fixed, true, (char*)malloc(size), size);
 }
 
 StreamBuffer::StreamBuffer(const char *s, int64_t size) {
+    assert(size >= 0);
     init(true, false, const_cast<char *>(s), size);
 }
 
@@ -150,11 +151,11 @@ void StreamBuffer::write_ztbytes(const char *s) {
 
 void StreamBuffer::write_string(const std::string &s) {
     if (s.size() >= 255) {
-        write_int8(0xFF);
-        write_int64(s.size());
+        write_uint8(0xFF);
+        write_uint64(s.size());
         write_bytes(s.c_str(), s.size());
     } else {
-        write_int8(s.size());
+        write_uint8(s.size());
         write_bytes(s.c_str(), s.size());
     }
 }
@@ -219,10 +220,11 @@ const char *StreamBuffer::read_bytes(int64_t bytes) {
 }
 
 std::string StreamBuffer::read_string(int64_t max_allowed) {
-    int64_t len = read_int8();
+    int64_t len = read_uint8();
     if (len == 255) {
         len = read_int64();
     }
+    if (len < 0) throw StreamCorruption();
     if (len > max_allowed) throw StreamCorruption();
     const char *bytes = read_bytes(len);
     return std::string(bytes, len);