Function mi_out_stderr

3rd/mimalloc-2.0.9/src/options.c:175–209

static void mi_cdecl mi_out_stderr(const char* msg, void* arg) {
  MI_UNUSED(arg);
  if (msg == NULL) return;
  #ifdef _WIN32
  // on windows with redirection, the C runtime cannot handle locale dependent output
  // after the main thread closes so we use direct console output.
  if (!_mi_preloading()) {
    // _cputs(msg);  // _cputs cannot be used at is aborts if it fails to lock the console
    static HANDLE hcon = INVALID_HANDLE_VALUE;
    static bool hconIsConsole;
    if (hcon == INVALID_HANDLE_VALUE) {
      CONSOLE_SCREEN_BUFFER_INFO sbi;
      hcon = GetStdHandle(STD_ERROR_HANDLE);
      hconIsConsole = ((hcon != INVALID_HANDLE_VALUE) && GetConsoleScreenBufferInfo(hcon, &sbi));
    }
    const size_t len = strlen(msg);
    if (len > 0 && len < UINT32_MAX) {
      DWORD written = 0;
      if (hconIsConsole) {
        WriteConsoleA(hcon, msg, (DWORD)len, &written, NULL);
      }
      else if (hcon != INVALID_HANDLE_VALUE) {
        // use direct write if stderr was redirected
        WriteFile(hcon, msg, (DWORD)len, &written, NULL);
      }
      else {
        // finally fall back to fputs after all
        fputs(msg, stderr);
      }
    }
  }
  #else
  fputs(msg, stderr);
  #endif
}

// Since an output function can be registered earliest in the `main`
// function we also buffer output that happens earlier. When