Networking (Windows): print readable error message

src/util/debug.h

@@ -24,3 +24,5 @@ static inline const char* ffFindFileName(const char* file)
 #endif
 
 #define FF_DEBUG(format, ...) FF_DEBUG_PRINT(__FILE__, __LINE__, format, ##__VA_ARGS__)
+
+const char* ffDebugWin32Error(unsigned long errorCode);

src/util/debug_windows.c

@@ -0,0 +1,28 @@
+#include "debug.h"
+
+#include <windows.h>
+
+const char* ffDebugWin32Error(DWORD errorCode)
+{
+    static char buffer[256];
+
+    DWORD len = FormatMessageA(
+        FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+        NULL,
+        (DWORD) errorCode,
+        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+        buffer,
+        sizeof(buffer),
+        NULL);
+
+    if (len == 0) {
+        snprintf(buffer, sizeof(buffer), "Unknown error code (%lu)", errorCode);
+    } else {
+        // Remove trailing newline
+        if (buffer[len - 1] == '\n') buffer[len - 1] = '\0';
+        if (buffer[len - 2] == '\r') buffer[len - 2] = '\0';
+        snprintf(buffer + len - 2, sizeof(buffer) - len + 2, " (%lu)", errorCode);
+    }
+
+    return buffer;
+}