Fixing crash on windows when uFormat() is to long

utilite/src/UConversion.cpp

@@ -338,7 +338,8 @@ std::string uFormatv (const char *fmt, va_list args)
 
         // Try to vsnprintf into our buffer.
 #ifdef _MSC_VER
-    	int needed = vsnprintf_s(buf, size, size, fmt, argsTmp);
+    	// _TRUNCATE: return -1 if it doesn't fit (count=size would call the invalid parameter handler and abort)
+    	int needed = vsnprintf_s(buf, size, _TRUNCATE, fmt, argsTmp);
 #else
     	int needed = vsnprintf (buf, size, fmt, argsTmp);
 #endif

utilite/test/test_uconversion.cpp

@@ -201,3 +201,14 @@ TEST(UConversionTest, UFormat)
     EXPECT_NE(result.find("42"), std::string::npos);
 }
 
+TEST(UConversionTest, UFormatLongerThanItsFirstBuffer)
+{
+    // Over the 1024 bytes uFormat first tries: formatted whole, not truncated (MSVC's
+    // checked vsnprintf_s used to abort the process instead).
+    const std::string longText(3000, 'a');
+    std::string result = uFormat("%s %d", longText.c_str(), 42);
+    EXPECT_EQ(result, longText + " 42");
+    result = uFormat("%s", std::string(1023, 'b').c_str());
+    EXPECT_EQ(result, std::string(1023, 'b'));
+}
+