]> git.lizzy.rs Git - dragonfireclient.git/blobdiff - src/porting.cpp
Don't ignore server disconnects in client code
[dragonfireclient.git] / src / porting.cpp
index f0337b6102f2cbb3d90fb22a1627f1f8ce497ac4..09627431c7e8bd501498d9ef147b92c93da787a4 100644 (file)
@@ -25,29 +25,40 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "porting.h"
 
-#if defined(__FreeBSD__)
+#if defined(__FreeBSD__)  || defined(__NetBSD__) || defined(__DragonFly__) || defined(__OpenBSD__)
        #include <sys/types.h>
        #include <sys/sysctl.h>
+       extern char **environ;
 #elif defined(_WIN32)
        #include <windows.h>
        #include <wincrypt.h>
        #include <algorithm>
+       #include <shlwapi.h>
+       #include <shellapi.h>
+       #include <mmsystem.h>
 #endif
 #if !defined(_WIN32)
        #include <unistd.h>
        #include <sys/utsname.h>
+       #if !defined(__ANDROID__)
+               #include <spawn.h>
+       #endif
 #endif
 #if defined(__hpux)
        #define _PSTAT64
        #include <sys/pstat.h>
 #endif
-#if !defined(_WIN32) && !defined(__APPLE__) && \
-       !defined(__ANDROID__) && !defined(SERVER)
-       #define XORG_USED
+#if defined(__ANDROID__)
+       #include "porting_android.h"
+#endif
+#if defined(__APPLE__)
+       // For _NSGetEnviron()
+       // Related: https://gitlab.haskell.org/ghc/ghc/issues/2458
+       #include <crt_externs.h>
 #endif
-#ifdef XORG_USED
-       #include <X11/Xlib.h>
-       #include <X11/Xutil.h>
+
+#if defined(__HAIKU__)
+        #include <FindDirectory.h>
 #endif
 
 #include "config.h"
@@ -55,8 +66,18 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "filesys.h"
 #include "log.h"
 #include "util/string.h"
-#include "settings.h"
 #include <list>
+#include <cstdarg>
+#include <cstdio>
+
+#if !defined(SERVER) && defined(_WIN32)
+// On Windows export some driver-specific variables to encourage Minetest to be
+// executed on the discrete GPU in case of systems with two. Portability is fun.
+extern "C" {
+       __declspec(dllexport) DWORD NvOptimusEnablement = 1;
+       __declspec(dllexport) DWORD AmdPowerXpressRequestHighPerformance = 1;
+}
+#endif
 
 namespace porting
 {
@@ -67,7 +88,7 @@ namespace porting
 
 bool g_killed = false;
 
-bool * signal_handler_killstatus(void)
+bool *signal_handler_killstatus()
 {
        return &g_killed;
 }
@@ -175,26 +196,32 @@ bool detectMSVCBuildDir(const std::string &path)
                "bin\\Build",
                NULL
        };
-       return (removeStringEnd(path, ends) != "");
+       return (!removeStringEnd(path, ends).empty());
 }
 
 std::string get_sysinfo()
 {
 #ifdef _WIN32
-       OSVERSIONINFO osvi;
+
        std::ostringstream oss;
-       std::string tmp;
-       ZeroMemory(&osvi, sizeof(OSVERSIONINFO));
-       osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
-       GetVersionEx(&osvi);
-       tmp = osvi.szCSDVersion;
-       std::replace(tmp.begin(), tmp.end(), ' ', '_');
-
-       oss << "Windows/" << osvi.dwMajorVersion << "."
-               << osvi.dwMinorVersion;
-       if (osvi.szCSDVersion[0])
-               oss << "-" << tmp;
-       oss << " ";
+       LPSTR filePath = new char[MAX_PATH];
+       UINT blockSize;
+       VS_FIXEDFILEINFO *fixedFileInfo;
+
+       GetSystemDirectoryA(filePath, MAX_PATH);
+       PathAppendA(filePath, "kernel32.dll");
+
+       DWORD dwVersionSize = GetFileVersionInfoSizeA(filePath, NULL);
+       LPBYTE lpVersionInfo = new BYTE[dwVersionSize];
+
+       GetFileVersionInfoA(filePath, 0, dwVersionSize, lpVersionInfo);
+       VerQueryValueA(lpVersionInfo, "\\", (LPVOID *)&fixedFileInfo, &blockSize);
+
+       oss << "Windows/"
+               << HIWORD(fixedFileInfo->dwProductVersionMS) << '.' // Major
+               << LOWORD(fixedFileInfo->dwProductVersionMS) << '.' // Minor
+               << HIWORD(fixedFileInfo->dwProductVersionLS) << ' '; // Build
+
        #ifdef _WIN64
        oss << "x86_64";
        #else
@@ -205,6 +232,9 @@ std::string get_sysinfo()
                oss << "x86";
        #endif
 
+       delete[] lpVersionInfo;
+       delete[] filePath;
+
        return oss.str();
 #else
        struct utsname osinfo;
@@ -305,6 +335,12 @@ bool getCurrentExecPath(char *buf, size_t len)
        return true;
 }
 
+#elif defined(__HAIKU__)
+
+bool getCurrentExecPath(char *buf, size_t len)
+{
+       return find_path(B_APP_IMAGE_SYMBOL, B_FIND_PATH_IMAGE_PATH, NULL, buf, len) == B_OK;
+}
 
 //// Solaris
 #elif defined(__sun) || defined(sun)
@@ -349,6 +385,21 @@ bool getCurrentExecPath(char *buf, size_t len)
 #endif
 
 
+//// Non-Windows
+#if !defined(_WIN32)
+
+const char *getHomeOrFail()
+{
+       const char *home = getenv("HOME");
+       // In rare cases the HOME environment variable may be unset
+       FATAL_ERROR_IF(!home,
+               "Required environment variable HOME is not set");
+       return home;
+}
+
+#endif
+
+
 //// Windows
 #if defined(_WIN32)
 
@@ -361,20 +412,27 @@ bool setSystemPaths()
                "Failed to get current executable path");
        pathRemoveFile(buf, '\\');
 
+       std::string exepath(buf);
+
        // Use ".\bin\.."
-       path_share = std::string(buf) + "\\..";
+       path_share = exepath + "\\..";
+       if (detectMSVCBuildDir(exepath)) {
+               // The msvc build dir schould normaly not be present if properly installed,
+               // but its usefull for debugging.
+               path_share += DIR_DELIM "..";
+       }
 
-       // Use "C:\Documents and Settings\user\Application Data\<PROJECT_NAME>"
+       // Use "C:\Users\<user>\AppData\Roaming\<PROJECT_NAME_C>"
        DWORD len = GetEnvironmentVariable("APPDATA", buf, sizeof(buf));
        FATAL_ERROR_IF(len == 0 || len > sizeof(buf), "Failed to get APPDATA");
 
-       path_user = std::string(buf) + DIR_DELIM + PROJECT_NAME;
+       path_user = std::string(buf) + DIR_DELIM + PROJECT_NAME_C;
        return true;
 }
 
 
 //// Linux
-#elif defined(__linux__)
+#elif defined(__linux__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__DragonFly__)
 
 bool setSystemPaths()
 {
@@ -396,7 +454,7 @@ bool setSystemPaths()
        // It is identified by containing the subdirectory "builtin".
        std::list<std::string> trylist;
        std::string static_sharedir = STATIC_SHAREDIR;
-       if (static_sharedir != "" && static_sharedir != ".")
+       if (!static_sharedir.empty() && static_sharedir != ".")
                trylist.push_back(static_sharedir);
 
        trylist.push_back(bindir + DIR_DELIM ".." DIR_DELIM "share"
@@ -408,7 +466,7 @@ bool setSystemPaths()
 #endif
 
        for (std::list<std::string>::const_iterator
-                       i = trylist.begin(); i != trylist.end(); i++) {
+                       i = trylist.begin(); i != trylist.end(); ++i) {
                const std::string &trypath = *i;
                if (!fs::PathExists(trypath) ||
                        !fs::PathExists(trypath + DIR_DELIM + "builtin")) {
@@ -428,7 +486,7 @@ bool setSystemPaths()
        }
 
 #ifndef __ANDROID__
-       path_user = std::string(getenv("HOME")) + DIR_DELIM "."
+       path_user = std::string(getHomeOrFail()) + DIR_DELIM "."
                + PROJECT_NAME;
 #endif
 
@@ -452,7 +510,7 @@ bool setSystemPaths()
        }
        CFRelease(resources_url);
 
-       path_user = std::string(getenv("HOME"))
+       path_user = std::string(getHomeOrFail())
                + "/Library/Application Support/"
                + PROJECT_NAME;
        return true;
@@ -464,7 +522,7 @@ bool setSystemPaths()
 bool setSystemPaths()
 {
        path_share = STATIC_SHAREDIR;
-       path_user  = std::string(getenv("HOME")) + DIR_DELIM "."
+       path_user  = std::string(getHomeOrFail()) + DIR_DELIM "."
                + lowercase(PROJECT_NAME);
        return true;
 }
@@ -542,11 +600,15 @@ void initializePaths()
        if (!setSystemPaths())
                errorstream << "Failed to get one or more system-wide path" << std::endl;
 
+
+#  ifdef _WIN32
+       path_cache = path_user + DIR_DELIM + "cache";
+#  else
        // Initialize path_cache
        // First try $XDG_CACHE_HOME/PROJECT_NAME
        const char *cache_dir = getenv("XDG_CACHE_HOME");
        const char *home_dir = getenv("HOME");
-       if (cache_dir) {
+       if (cache_dir && cache_dir[0] != '\0') {
                path_cache = std::string(cache_dir) + DIR_DELIM + PROJECT_NAME;
        } else if (home_dir) {
                // Then try $HOME/.cache/PROJECT_NAME
@@ -558,27 +620,28 @@ void initializePaths()
        }
        // Migrate cache folder to new location if possible
        migrateCachePath();
-#endif
+#  endif // _WIN32
+#endif // RUN_IN_PLACE
 
        infostream << "Detected share path: " << path_share << std::endl;
        infostream << "Detected user path: " << path_user << std::endl;
        infostream << "Detected cache path: " << path_cache << std::endl;
 
-#ifdef USE_GETTEXT
+#if USE_GETTEXT
        bool found_localedir = false;
 #  ifdef STATIC_LOCALEDIR
-       if (STATIC_LOCALEDIR[0] && fs::PathExists(STATIC_LOCALEDIR)) {
+       /* STATIC_LOCALEDIR may be a generalized path such as /usr/share/locale that
+        * doesn't necessarily contain our locale files, so check data path first. */
+       path_locale = getDataPath("locale");
+       if (fs::PathExists(path_locale)) {
+               found_localedir = true;
+               infostream << "Using in-place locale directory " << path_locale
+                       << " even though a static one was provided." << std::endl;
+       } else if (STATIC_LOCALEDIR[0] && fs::PathExists(STATIC_LOCALEDIR)) {
                found_localedir = true;
                path_locale = STATIC_LOCALEDIR;
-               infostream << "Using locale directory " << STATIC_LOCALEDIR << std::endl;
-       } else {
-               path_locale = getDataPath("locale");
-               if (fs::PathExists(path_locale)) {
-                       found_localedir = true;
-                       infostream << "Using in-place locale directory " << path_locale
-                               << " even though a static one was provided "
-                               << "(RUN_IN_PLACE or CUSTOM_LOCALEDIR)." << std::endl;
-               }
+               infostream << "Using static locale directory " << STATIC_LOCALEDIR
+                       << std::endl;
        }
 #  else
        path_locale = getDataPath("locale");
@@ -592,310 +655,137 @@ void initializePaths()
 #endif  // USE_GETTEXT
 }
 
+////
+//// OS-specific Secure Random
+////
 
+#ifdef WIN32
 
-void setXorgClassHint(const video::SExposedVideoData &video_data,
-       const std::string &name)
-{
-#ifdef XORG_USED
-       if (video_data.OpenGLLinux.X11Display == NULL)
-               return;
-
-       XClassHint *classhint = XAllocClassHint();
-       classhint->res_name  = (char *)name.c_str();
-       classhint->res_class = (char *)name.c_str();
-
-       XSetClassHint((Display *)video_data.OpenGLLinux.X11Display,
-               video_data.OpenGLLinux.X11Window, classhint);
-       XFree(classhint);
-#endif
-}
-
-bool setXorgWindowIcon(IrrlichtDevice *device)
-{
-#ifdef XORG_USED
-#      if RUN_IN_PLACE
-       return setXorgWindowIconFromPath(device,
-                       path_share + "/misc/" PROJECT_NAME "-xorg-icon-128.png");
-#      else
-       // We have semi-support for reading in-place data if we are
-       // compiled with RUN_IN_PLACE. Don't break with this and
-       // also try the path_share location.
-       return
-               setXorgWindowIconFromPath(device,
-                       ICON_DIR "/hicolor/128x128/apps/" PROJECT_NAME ".png") ||
-               setXorgWindowIconFromPath(device,
-                       path_share + "/misc/" PROJECT_NAME "-xorg-icon-128.png");
-#      endif
-       return false;
-#endif
-}
-
-bool setXorgWindowIconFromPath(IrrlichtDevice *device,
-       const std::string &icon_file)
+bool secure_rand_fill_buf(void *buf, size_t len)
 {
-#ifdef XORG_USED
-
-       video::IVideoDriver *v_driver = device->getVideoDriver();
-
-       video::IImageLoader *image_loader = NULL;
-       u32 cnt = v_driver->getImageLoaderCount();
-       for (u32 i = 0; i < cnt; i++) {
-               if (v_driver->getImageLoader(i)->isALoadableFileExtension(icon_file.c_str())) {
-                       image_loader = v_driver->getImageLoader(i);
-                       break;
-               }
-       }
-
-       if (!image_loader) {
-               warningstream << "Could not find image loader for file '"
-                       << icon_file << "'" << std::endl;
-               return false;
-       }
-
-       io::IReadFile *icon_f = device->getFileSystem()->createAndOpenFile(icon_file.c_str());
-
-       if (!icon_f) {
-               warningstream << "Could not load icon file '"
-                       << icon_file << "'" << std::endl;
-               return false;
-       }
-
-       video::IImage *img = image_loader->loadImage(icon_f);
-
-       if (!img) {
-               warningstream << "Could not load icon file '"
-                       << icon_file << "'" << std::endl;
-               icon_f->drop();
-               return false;
-       }
-
-       u32 height = img->getDimension().Height;
-       u32 width = img->getDimension().Width;
-
-       size_t icon_buffer_len = 2 + height * width;
-       long *icon_buffer = new long[icon_buffer_len];
-
-       icon_buffer[0] = width;
-       icon_buffer[1] = height;
-
-       for (u32 x = 0; x < width; x++) {
-               for (u32 y = 0; y < height; y++) {
-                       video::SColor col = img->getPixel(x, y);
-                       long pixel_val = 0;
-                       pixel_val |= (u8)col.getAlpha() << 24;
-                       pixel_val |= (u8)col.getRed() << 16;
-                       pixel_val |= (u8)col.getGreen() << 8;
-                       pixel_val |= (u8)col.getBlue();
-                       icon_buffer[2 + x + y * width] = pixel_val;
-               }
-       }
-
-       img->drop();
-       icon_f->drop();
-
-       const video::SExposedVideoData &video_data = v_driver->getExposedVideoData();
-
-       Display *x11_dpl = (Display *)video_data.OpenGLLinux.X11Display;
+       HCRYPTPROV wctx;
 
-       if (x11_dpl == NULL) {
-               warningstream << "Could not find x11 display for setting its icon."
-                       << std::endl;
-               delete [] icon_buffer;
+       if (!CryptAcquireContext(&wctx, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
                return false;
-       }
-
-       Window x11_win = (Window)video_data.OpenGLLinux.X11Window;
-
-       Atom net_wm_icon = XInternAtom(x11_dpl, "_NET_WM_ICON", False);
-       Atom cardinal = XInternAtom(x11_dpl, "CARDINAL", False);
-       XChangeProperty(x11_dpl, x11_win,
-               net_wm_icon, cardinal, 32,
-               PropModeReplace, (const unsigned char *)icon_buffer,
-               icon_buffer_len);
 
-       delete [] icon_buffer;
-
-#endif
+       CryptGenRandom(wctx, len, (BYTE *)buf);
+       CryptReleaseContext(wctx, 0);
        return true;
 }
 
-////
-//// Video/Display Information (Client-only)
-////
-
-#ifndef SERVER
-
-static irr::IrrlichtDevice *device;
+#else
 
-void initIrrlicht(irr::IrrlichtDevice *device_)
+bool secure_rand_fill_buf(void *buf, size_t len)
 {
-       device = device_;
-}
+       // N.B.  This function checks *only* for /dev/urandom, because on most
+       // common OSes it is non-blocking, whereas /dev/random is blocking, and it
+       // is exceptionally uncommon for there to be a situation where /dev/random
+       // exists but /dev/urandom does not.  This guesswork is necessary since
+       // random devices are not covered by any POSIX standard...
+       FILE *fp = fopen("/dev/urandom", "rb");
+       if (!fp)
+               return false;
 
-v2u32 getWindowSize()
-{
-       return device->getVideoDriver()->getScreenSize();
+       bool success = fread(buf, len, 1, fp) == 1;
+
+       fclose(fp);
+       return success;
 }
 
+#endif
 
-std::vector<core::vector3d<u32> > getSupportedVideoModes()
+void attachOrCreateConsole()
 {
-       IrrlichtDevice *nulldevice = createDevice(video::EDT_NULL);
-       sanity_check(nulldevice != NULL);
-
-       std::vector<core::vector3d<u32> > mlist;
-       video::IVideoModeList *modelist = nulldevice->getVideoModeList();
-
-       u32 num_modes = modelist->getVideoModeCount();
-       for (u32 i = 0; i != num_modes; i++) {
-               core::dimension2d<u32> mode_res = modelist->getVideoModeResolution(i);
-               s32 mode_depth = modelist->getVideoModeDepth(i);
-               mlist.push_back(core::vector3d<u32>(mode_res.Width, mode_res.Height, mode_depth));
+#ifdef _WIN32
+       static bool consoleAllocated = false;
+       const bool redirected = (_fileno(stdout) == -2 || _fileno(stdout) == -1); // If output is redirected to e.g a file
+       if (!consoleAllocated && redirected && (AttachConsole(ATTACH_PARENT_PROCESS) || AllocConsole())) {
+               freopen("CONOUT$", "w", stdout);
+               freopen("CONOUT$", "w", stderr);
+               consoleAllocated = true;
        }
-
-       nulldevice->drop();
-
-       return mlist;
+#endif
 }
 
-std::vector<irr::video::E_DRIVER_TYPE> getSupportedVideoDrivers()
-{
-       std::vector<irr::video::E_DRIVER_TYPE> drivers;
-
-       for (int i = 0; i != irr::video::EDT_COUNT; i++) {
-               if (irr::IrrlichtDevice::isDriverSupported((irr::video::E_DRIVER_TYPE)i))
-                       drivers.push_back((irr::video::E_DRIVER_TYPE)i);
+int mt_snprintf(char *buf, const size_t buf_size, const char *fmt, ...)
+{
+       // https://msdn.microsoft.com/en-us/library/bt7tawza.aspx
+       //  Many of the MSVC / Windows printf-style functions do not support positional
+       //  arguments (eg. "%1$s"). We just forward the call to vsnprintf for sane
+       //  platforms, but defer to _vsprintf_p on MSVC / Windows.
+       // https://github.com/FFmpeg/FFmpeg/blob/5ae9fa13f5ac640bec113120d540f70971aa635d/compat/msvcrt/snprintf.c#L46
+       //  _vsprintf_p has to be shimmed with _vscprintf_p on -1 (for an example see
+       //  above FFmpeg link).
+       va_list args;
+       va_start(args, fmt);
+#ifndef _MSC_VER
+       int c = vsnprintf(buf, buf_size, fmt, args);
+#else  // _MSC_VER
+       int c = _vsprintf_p(buf, buf_size, fmt, args);
+       if (c == -1)
+               c = _vscprintf_p(fmt, args);
+#endif // _MSC_VER
+       va_end(args);
+       return c;
+}
+
+static bool open_uri(const std::string &uri)
+{
+       if (uri.find_first_of("\r\n") != std::string::npos) {
+               errorstream << "Unable to open URI as it is invalid, contains new line: " << uri << std::endl;
+               return false;
        }
 
-       return drivers;
-}
-
-const char *getVideoDriverName(irr::video::E_DRIVER_TYPE type)
-{
-       static const char *driver_ids[] = {
-               "null",
-               "software",
-               "burningsvideo",
-               "direct3d8",
-               "direct3d9",
-               "opengl",
-               "ogles1",
-               "ogles2",
-       };
-
-       return driver_ids[type];
-}
-
-
-const char *getVideoDriverFriendlyName(irr::video::E_DRIVER_TYPE type)
-{
-       static const char *driver_names[] = {
-               "NULL Driver",
-               "Software Renderer",
-               "Burning's Video",
-               "Direct3D 8",
-               "Direct3D 9",
-               "OpenGL",
-               "OpenGL ES1",
-               "OpenGL ES2",
-       };
-
-       return driver_names[type];
+#if defined(_WIN32)
+       return (intptr_t)ShellExecuteA(NULL, NULL, uri.c_str(), NULL, NULL, SW_SHOWNORMAL) > 32;
+#elif defined(__ANDROID__)
+       openURIAndroid(uri);
+       return true;
+#elif defined(__APPLE__)
+       const char *argv[] = {"open", uri.c_str(), NULL};
+       return posix_spawnp(NULL, "open", NULL, NULL, (char**)argv,
+               (*_NSGetEnviron())) == 0;
+#else
+       const char *argv[] = {"xdg-open", uri.c_str(), NULL};
+       return posix_spawnp(NULL, "xdg-open", NULL, NULL, (char**)argv, environ) == 0;
+#endif
 }
 
-#      ifndef __ANDROID__
-#              ifdef XORG_USED
-
-static float calcDisplayDensity()
+bool open_url(const std::string &url)
 {
-       const char *current_display = getenv("DISPLAY");
-
-       if (current_display != NULL) {
-               Display *x11display = XOpenDisplay(current_display);
-
-               if (x11display != NULL) {
-                       /* try x direct */
-                       float dpi_height = floor(DisplayHeight(x11display, 0) /
-                                                       (DisplayHeightMM(x11display, 0) * 0.039370) + 0.5);
-                       float dpi_width = floor(DisplayWidth(x11display, 0) /
-                                                       (DisplayWidthMM(x11display, 0) * 0.039370) + 0.5);
-
-                       XCloseDisplay(x11display);
-
-                       return std::max(dpi_height,dpi_width) / 96.0;
-               }
+       if (url.substr(0, 7) != "http://" && url.substr(0, 8) != "https://") {
+               errorstream << "Unable to open browser as URL is missing schema: " << url << std::endl;
+               return false;
        }
 
-       /* return manually specified dpi */
-       return g_settings->getFloat("screen_dpi")/96.0;
-}
-
-
-float getDisplayDensity()
-{
-       static float cached_display_density = calcDisplayDensity();
-       return cached_display_density;
-}
-
-
-#              else // XORG_USED
-float getDisplayDensity()
-{
-       return g_settings->getFloat("screen_dpi")/96.0;
+       return open_uri(url);
 }
-#              endif // XORG_USED
-
-v2u32 getDisplaySize()
-{
-       IrrlichtDevice *nulldevice = createDevice(video::EDT_NULL);
 
-       core::dimension2d<u32> deskres = nulldevice->getVideoModeList()->getDesktopResolution();
-       nulldevice -> drop();
-
-       return deskres;
-}
-#      endif // __ANDROID__
-#endif // SERVER
-
-
-////
-//// OS-specific Secure Random
-////
-
-#ifdef WIN32
-
-bool secure_rand_fill_buf(void *buf, size_t len)
+bool open_directory(const std::string &path)
 {
-       HCRYPTPROV wctx;
-
-       if (!CryptAcquireContext(&wctx, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
+       if (!fs::IsDir(path)) {
+               errorstream << "Unable to open directory as it does not exist: " << path << std::endl;
                return false;
+       }
 
-       CryptGenRandom(wctx, len, (BYTE *)buf);
-       CryptReleaseContext(wctx, 0);
-       return true;
+       return open_uri(path);
 }
 
-#else
+// Load performance counter frequency only once at startup
+#ifdef _WIN32
 
-bool secure_rand_fill_buf(void *buf, size_t len)
+inline double get_perf_freq()
 {
-       // N.B.  This function checks *only* for /dev/urandom, because on most
-       // common OSes it is non-blocking, whereas /dev/random is blocking, and it
-       // is exceptionally uncommon for there to be a situation where /dev/random
-       // exists but /dev/urandom does not.  This guesswork is necessary since
-       // random devices are not covered by any POSIX standard...
-       FILE *fp = fopen("/dev/urandom", "rb");
-       if (!fp)
-               return false;
+       // Also use this opportunity to enable high-res timers
+       timeBeginPeriod(1);
 
-       bool success = fread(buf, len, 1, fp) == 1;
-
-       fclose(fp);
-       return success;
+       LARGE_INTEGER freq;
+       QueryPerformanceFrequency(&freq);
+       return freq.QuadPart;
 }
 
+double perf_freq = get_perf_freq();
+
 #endif
 
 } //namespace porting