util: add a helper function to convert wide strings (Windows)

CMakeLists.txt

@@ -449,6 +449,7 @@ elseif(WIN32)
         src/util/windows/getline.c
         src/util/windows/pwd.c
         src/util/windows/register.c
+        src/util/windows/unicode.c
         src/util/windows/utsname.c
         src/util/windows/wmi.cpp
     )
@@ -546,6 +547,7 @@ elseif(WIN32)
         PRIVATE "ws2_32"
         PRIVATE "ntdll"
         PRIVATE "version"
+        PRIVATE "setupapi"
     )
     if(USE_WIN_NTAPI)
         target_compile_definitions(libfastfetch PRIVATE FF_USE_WIN_NTAPI)

src/detection/os/os_windows.cpp

@@ -1,5 +1,6 @@
 extern "C" {
 #include "os.h"
+#include "util/windows/unicode.h"
 }
 #include "util/windows/wmi.hpp"
 
@@ -36,11 +37,7 @@ static const char* getOsNameByWinbrand(FFstrbuf* osName)
             return "GetProcAddress(BrandingFormatString) failed";
 
         const wchar_t* rawName = BrandingFormatString(L"%WINDOWS_LONG%");
-        int size_needed = WideCharToMultiByte(CP_UTF8, 0, rawName, -1, nullptr, 0, nullptr, nullptr);
-        ffStrbufEnsureFree(osName, (uint32_t)size_needed);
-        WideCharToMultiByte(CP_UTF8, 0, rawName, -1, osName->chars, size_needed, nullptr, nullptr);
-        osName->length = (uint32_t)size_needed;
-        osName->chars[size_needed] = '\0';
+        ffWcharToUtf8(rawName, osName);
         GlobalFree((HGLOBAL)rawName);
         return NULL;
     }

src/util/windows/unicode.c

@@ -0,0 +1,17 @@
+#include "unicode.h"
+
+void ffWcharToUtf8(const wchar_t* input, FFstrbuf* result)
+{
+    int len = (int)wcslen(input);
+    if(len <= 0)
+    {
+        ffStrbufClear(result);
+        return;
+    }
+
+    int size_needed = WideCharToMultiByte(CP_UTF8, 0, input, len, NULL, 0, NULL, NULL);
+    ffStrbufEnsureFree(result, (uint32_t)size_needed);
+    WideCharToMultiByte(CP_UTF8, 0, input, len, result->chars, size_needed, NULL, NULL);
+    result->length = (uint32_t)size_needed;
+    result->chars[size_needed] = '\0';
+}

src/util/windows/unicode.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#ifndef FASTFETCH_INCLUDED_UNICODE_H
+#define FASTFETCH_INCLUDED_UNICODE_H
+
+#include "fastfetch.h"
+
+void ffWcharToUtf8(const wchar_t* input, FFstrbuf* result);
+
+#endif