src/porting.cpp

   1 /*
   2 Minetest
   3 Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU Lesser General Public License as published by
   7 the Free Software Foundation; either version 2.1 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU Lesser General Public License for more details.
  14
  15 You should have received a copy of the GNU Lesser General Public License along
  16 with this program; if not, write to the Free Software Foundation, Inc.,
  17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 /*
  21         Random portability stuff
  22
  23         See comments in porting.h
  24 */
  25
  26 #include "porting.h"
  27
  28 #if defined(__FreeBSD__)
  29         #include <sys/types.h>
  30         #include <sys/sysctl.h>
  31 #elif defined(_WIN32)
  32         #include <windows.h>
  33         #include <wincrypt.h>
  34         #include <algorithm>
  35 #endif
  36 #if !defined(_WIN32)
  37         #include <unistd.h>
  38         #include <sys/utsname.h>
  39 #endif
  40 #if defined(__hpux)
  41         #define _PSTAT64
  42         #include <sys/pstat.h>
  43 #endif
  44 #if !defined(_WIN32) && !defined(__APPLE__) && \
  45         !defined(__ANDROID__) && !defined(SERVER)
  46         #define XORG_USED
  47 #endif
  48 #ifdef XORG_USED
  49         #include <X11/Xlib.h>
  50         #include <X11/Xutil.h>
  51 #endif
  52
  53 #include "config.h"
  54 #include "debug.h"
  55 #include "filesys.h"
  56 #include "log.h"
  57 #include "util/string.h"
  58 #include "settings.h"
  59 #include <list>
  60
  61 namespace porting
  62 {
  63
  64 /*
  65         Signal handler (grabs Ctrl-C on POSIX systems)
  66 */
  67
  68 bool g_killed = false;
  69
  70 bool * signal_handler_killstatus(void)
  71 {
  72         return &g_killed;
  73 }
  74
  75 #if !defined(_WIN32) // POSIX
  76         #include <signal.h>
  77
  78 void sigint_handler(int sig)
  79 {
  80         if (!g_killed) {
  81                 dstream << "INFO: sigint_handler(): "
  82                         << "Ctrl-C pressed, shutting down." << std::endl;
  83
  84                 // Comment out for less clutter when testing scripts
  85                 /*dstream << "INFO: sigint_handler(): "
  86                                 << "Printing debug stacks" << std::endl;
  87                 debug_stacks_print();*/
  88
  89                 g_killed = true;
  90         } else {
  91                 (void)signal(SIGINT, SIG_DFL);
  92         }
  93 }
  94
  95 void signal_handler_init(void)
  96 {
  97         (void)signal(SIGINT, sigint_handler);
  98 }
  99
 100 #else // _WIN32
 101         #include <signal.h>
 102
 103 BOOL WINAPI event_handler(DWORD sig)
 104 {
 105         switch (sig) {
 106         case CTRL_C_EVENT:
 107         case CTRL_CLOSE_EVENT:
 108         case CTRL_LOGOFF_EVENT:
 109         case CTRL_SHUTDOWN_EVENT:
 110                 if (!g_killed) {
 111                         dstream << "INFO: event_handler(): "
 112                                 << "Ctrl+C, Close Event, Logoff Event or Shutdown Event,"
 113                                 " shutting down." << std::endl;
 114                         g_killed = true;
 115                 } else {
 116                         (void)signal(SIGINT, SIG_DFL);
 117                 }
 118                 break;
 119         case CTRL_BREAK_EVENT:
 120                 break;
 121         }
 122
 123         return TRUE;
 124 }
 125
 126 void signal_handler_init(void)
 127 {
 128         SetConsoleCtrlHandler((PHANDLER_ROUTINE)event_handler, TRUE);
 129 }
 130
 131 #endif
 132
 133
 134 /*
 135         Path mangler
 136 */
 137
 138 // Default to RUN_IN_PLACE style relative paths
 139 std::string path_share = "..";
 140 std::string path_user = "..";
 141 std::string path_locale = path_share + DIR_DELIM + "locale";
 142 std::string path_cache = path_user + DIR_DELIM + "cache";
 143
 144
 145 std::string getDataPath(const char *subpath)
 146 {
 147         return path_share + DIR_DELIM + subpath;
 148 }
 149
 150 void pathRemoveFile(char *path, char delim)
 151 {
 152         // Remove filename and path delimiter
 153         int i;
 154         for(i = strlen(path)-1; i>=0; i--)
 155         {
 156                 if(path[i] == delim)
 157                         break;
 158         }
 159         path[i] = 0;
 160 }
 161
 162 bool detectMSVCBuildDir(const std::string &path)
 163 {
 164         const char *ends[] = {
 165                 "bin\\Release",
 166                 "bin\\MinSizeRel",
 167                 "bin\\RelWithDebInfo",
 168                 "bin\\Debug",
 169                 "bin\\Build",
 170                 NULL
 171         };
 172         return (removeStringEnd(path, ends) != "");
 173 }
 174
 175 std::string get_sysinfo()
 176 {
 177 #ifdef _WIN32
 178         OSVERSIONINFO osvi;
 179         std::ostringstream oss;
 180         std::string tmp;
 181         ZeroMemory(&osvi, sizeof(OSVERSIONINFO));
 182         osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
 183         GetVersionEx(&osvi);
 184         tmp = osvi.szCSDVersion;
 185         std::replace(tmp.begin(), tmp.end(), ' ', '_');
 186
 187         oss << "Windows/" << osvi.dwMajorVersion << "."
 188                 << osvi.dwMinorVersion;
 189         if (osvi.szCSDVersion[0])
 190                 oss << "-" << tmp;
 191         oss << " ";
 192         #ifdef _WIN64
 193         oss << "x86_64";
 194         #else
 195         BOOL is64 = FALSE;
 196         if (IsWow64Process(GetCurrentProcess(), &is64) && is64)
 197                 oss << "x86_64"; // 32-bit app on 64-bit OS
 198         else
 199                 oss << "x86";
 200         #endif
 201
 202         return oss.str();
 203 #else
 204         struct utsname osinfo;
 205         uname(&osinfo);
 206         return std::string(osinfo.sysname) + "/"
 207                 + osinfo.release + " " + osinfo.machine;
 208 #endif
 209 }
 210
 211
 212 bool getCurrentWorkingDir(char *buf, size_t len)
 213 {
 214 #ifdef _WIN32
 215         DWORD ret = GetCurrentDirectory(len, buf);
 216         return (ret != 0) && (ret <= len);
 217 #else
 218         return getcwd(buf, len);
 219 #endif
 220 }
 221
 222
 223 bool getExecPathFromProcfs(char *buf, size_t buflen)
 224 {
 225 #ifndef _WIN32
 226         buflen--;
 227
 228         ssize_t len;
 229         if ((len = readlink("/proc/self/exe",     buf, buflen)) == -1 &&
 230                 (len = readlink("/proc/curproc/file", buf, buflen)) == -1 &&
 231                 (len = readlink("/proc/curproc/exe",  buf, buflen)) == -1)
 232                 return false;
 233
 234         buf[len] = '\0';
 235         return true;
 236 #else
 237         return false;
 238 #endif
 239 }
 240
 241 //// Windows
 242 #if defined(_WIN32)
 243
 244 bool getCurrentExecPath(char *buf, size_t len)
 245 {
 246         DWORD written = GetModuleFileNameA(NULL, buf, len);
 247         if (written == 0 || written == len)
 248                 return false;
 249
 250         return true;
 251 }
 252
 253
 254 //// Linux
 255 #elif defined(linux) || defined(__linux) || defined(__linux__)
 256
 257 bool getCurrentExecPath(char *buf, size_t len)
 258 {
 259         if (!getExecPathFromProcfs(buf, len))
 260                 return false;
 261
 262         return true;
 263 }
 264
 265
 266 //// Mac OS X, Darwin
 267 #elif defined(__APPLE__)
 268
 269 bool getCurrentExecPath(char *buf, size_t len)
 270 {
 271         uint32_t lenb = (uint32_t)len;
 272         if (_NSGetExecutablePath(buf, &lenb) == -1)
 273                 return false;
 274
 275         return true;
 276 }
 277
 278
 279 //// FreeBSD, NetBSD, DragonFlyBSD
 280 #elif defined(__FreeBSD__) || defined(__NetBSD__) || defined(__DragonFly__)
 281
 282 bool getCurrentExecPath(char *buf, size_t len)
 283 {
 284         // Try getting path from procfs first, since valgrind
 285         // doesn't work with the latter
 286         if (getExecPathFromProcfs(buf, len))
 287                 return true;
 288
 289         int mib[4];
 290
 291         mib[0] = CTL_KERN;
 292         mib[1] = KERN_PROC;
 293         mib[2] = KERN_PROC_PATHNAME;
 294         mib[3] = -1;
 295
 296         if (sysctl(mib, 4, buf, &len, NULL, 0) == -1)
 297                 return false;
 298
 299         return true;
 300 }
 301
 302
 303 //// Solaris
 304 #elif defined(__sun) || defined(sun)
 305
 306 bool getCurrentExecPath(char *buf, size_t len)
 307 {
 308         const char *exec = getexecname();
 309         if (exec == NULL)
 310                 return false;
 311
 312         if (strlcpy(buf, exec, len) >= len)
 313                 return false;
 314
 315         return true;
 316 }
 317
 318
 319 // HP-UX
 320 #elif defined(__hpux)
 321
 322 bool getCurrentExecPath(char *buf, size_t len)
 323 {
 324         struct pst_status psts;
 325
 326         if (pstat_getproc(&psts, sizeof(psts), 0, getpid()) == -1)
 327                 return false;
 328
 329         if (pstat_getpathname(buf, len, &psts.pst_fid_text) == -1)
 330                 return false;
 331
 332         return true;
 333 }
 334
 335
 336 #else
 337
 338 bool getCurrentExecPath(char *buf, size_t len)
 339 {
 340         return false;
 341 }
 342
 343 #endif
 344
 345
 346 //// Windows
 347 #if defined(_WIN32)
 348
 349 bool setSystemPaths()
 350 {
 351         char buf[BUFSIZ];
 352
 353         // Find path of executable and set path_share relative to it
 354         FATAL_ERROR_IF(!getCurrentExecPath(buf, sizeof(buf)),
 355                 "Failed to get current executable path");
 356         pathRemoveFile(buf, '\\');
 357
 358         // Use ".\bin\.."
 359         path_share = std::string(buf) + "\\..";
 360
 361         // Use "C:\Documents and Settings\user\Application Data\<PROJECT_NAME>"
 362         DWORD len = GetEnvironmentVariable("APPDATA", buf, sizeof(buf));
 363         FATAL_ERROR_IF(len == 0 || len > sizeof(buf), "Failed to get APPDATA");
 364
 365         path_user = std::string(buf) + DIR_DELIM + PROJECT_NAME;
 366         return true;
 367 }
 368
 369
 370 //// Linux
 371 #elif defined(linux) || defined(__linux)
 372
 373 bool setSystemPaths()
 374 {
 375         char buf[BUFSIZ];
 376
 377         if (!getCurrentExecPath(buf, sizeof(buf))) {
 378 #ifdef __ANDROID__
 379                 errorstream << "Unable to read bindir "<< std::endl;
 380 #else
 381                 FATAL_ERROR("Unable to read bindir");
 382 #endif
 383                 return false;
 384         }
 385
 386         pathRemoveFile(buf, '/');
 387         std::string bindir(buf);
 388
 389         // Find share directory from these.
 390         // It is identified by containing the subdirectory "builtin".
 391         std::list<std::string> trylist;
 392         std::string static_sharedir = STATIC_SHAREDIR;
 393         if (static_sharedir != "" && static_sharedir != ".")
 394                 trylist.push_back(static_sharedir);
 395
 396         trylist.push_back(bindir + DIR_DELIM ".." DIR_DELIM "share"
 397                 DIR_DELIM + PROJECT_NAME);
 398         trylist.push_back(bindir + DIR_DELIM "..");
 399
 400 #ifdef __ANDROID__
 401         trylist.push_back(path_user);
 402 #endif
 403
 404         for (std::list<std::string>::const_iterator
 405                         i = trylist.begin(); i != trylist.end(); i++) {
 406                 const std::string &trypath = *i;
 407                 if (!fs::PathExists(trypath) ||
 408                         !fs::PathExists(trypath + DIR_DELIM + "builtin")) {
 409                         warningstream << "system-wide share not found at \""
 410                                         << trypath << "\""<< std::endl;
 411                         continue;
 412                 }
 413
 414                 // Warn if was not the first alternative
 415                 if (i != trylist.begin()) {
 416                         warningstream << "system-wide share found at \""
 417                                         << trypath << "\"" << std::endl;
 418                 }
 419
 420                 path_share = trypath;
 421                 break;
 422         }
 423
 424 #ifndef __ANDROID__
 425         path_user = std::string(getenv("HOME")) + DIR_DELIM "."
 426                 + PROJECT_NAME;
 427 #endif
 428
 429         return true;
 430 }
 431
 432
 433 //// Mac OS X
 434 #elif defined(__APPLE__)
 435
 436 bool setSystemPaths()
 437 {
 438         CFBundleRef main_bundle = CFBundleGetMainBundle();
 439         CFURLRef resources_url = CFBundleCopyResourcesDirectoryURL(main_bundle);
 440         char path[PATH_MAX];
 441         if (CFURLGetFileSystemRepresentation(resources_url,
 442                         TRUE, (UInt8 *)path, PATH_MAX)) {
 443                 path_share = std::string(path);
 444         } else {
 445                 warningstream << "Could not determine bundle resource path" << std::endl;
 446         }
 447         CFRelease(resources_url);
 448
 449         path_user = std::string(getenv("HOME"))
 450                 + "/Library/Application Support/"
 451                 + PROJECT_NAME;
 452         return true;
 453 }
 454
 455
 456 #else
 457
 458 bool setSystemPaths()
 459 {
 460         path_share = STATIC_SHAREDIR;
 461         path_user  = std::string(getenv("HOME")) + DIR_DELIM "."
 462                 + lowercase(PROJECT_NAME);
 463         return true;
 464 }
 465
 466
 467 #endif
 468
 469 void migrateCachePath()
 470 {
 471         const std::string local_cache_path = path_user + DIR_DELIM + "cache";
 472
 473         // Delete tmp folder if it exists (it only ever contained
 474         // a temporary ogg file, which is no longer used).
 475         if (fs::PathExists(local_cache_path + DIR_DELIM + "tmp"))
 476                 fs::RecursiveDelete(local_cache_path + DIR_DELIM + "tmp");
 477
 478         // Bail if migration impossible
 479         if (path_cache == local_cache_path || !fs::PathExists(local_cache_path)
 480                         || fs::PathExists(path_cache)) {
 481                 return;
 482         }
 483         if (!fs::Rename(local_cache_path, path_cache)) {
 484                 errorstream << "Failed to migrate local cache path "
 485                         "to system path!" << std::endl;
 486         }
 487 }
 488
 489 void initializePaths()
 490 {
 491 #if RUN_IN_PLACE
 492         char buf[BUFSIZ];
 493
 494         infostream << "Using relative paths (RUN_IN_PLACE)" << std::endl;
 495
 496         bool success =
 497                 getCurrentExecPath(buf, sizeof(buf)) ||
 498                 getExecPathFromProcfs(buf, sizeof(buf));
 499
 500         if (success) {
 501                 pathRemoveFile(buf, DIR_DELIM_CHAR);
 502                 std::string execpath(buf);
 503
 504                 path_share = execpath + DIR_DELIM "..";
 505                 path_user  = execpath + DIR_DELIM "..";
 506
 507                 if (detectMSVCBuildDir(execpath)) {
 508                         path_share += DIR_DELIM "..";
 509                         path_user  += DIR_DELIM "..";
 510                 }
 511         } else {
 512                 errorstream << "Failed to get paths by executable location, "
 513                         "trying cwd" << std::endl;
 514
 515                 if (!getCurrentWorkingDir(buf, sizeof(buf)))
 516                         FATAL_ERROR("Ran out of methods to get paths");
 517
 518                 size_t cwdlen = strlen(buf);
 519                 if (cwdlen >= 1 && buf[cwdlen - 1] == DIR_DELIM_CHAR) {
 520                         cwdlen--;
 521                         buf[cwdlen] = '\0';
 522                 }
 523
 524                 if (cwdlen >= 4 && !strcmp(buf + cwdlen - 4, DIR_DELIM "bin"))
 525                         pathRemoveFile(buf, DIR_DELIM_CHAR);
 526
 527                 std::string execpath(buf);
 528
 529                 path_share = execpath;
 530                 path_user  = execpath;
 531         }
 532         path_cache = path_user + DIR_DELIM + "cache";
 533 #else
 534         infostream << "Using system-wide paths (NOT RUN_IN_PLACE)" << std::endl;
 535
 536         if (!setSystemPaths())
 537                 errorstream << "Failed to get one or more system-wide path" << std::endl;
 538
 539         // Initialize path_cache
 540         // First try $XDG_CACHE_HOME/PROJECT_NAME
 541         const char *cache_dir = getenv("XDG_CACHE_HOME");
 542         const char *home_dir = getenv("HOME");
 543         if (cache_dir) {
 544                 path_cache = std::string(cache_dir) + DIR_DELIM + PROJECT_NAME;
 545         } else if (home_dir) {
 546                 // Then try $HOME/.cache/PROJECT_NAME
 547                 path_cache = std::string(home_dir) + DIR_DELIM + ".cache"
 548                         + DIR_DELIM + PROJECT_NAME;
 549         } else {
 550                 // If neither works, use $PATH_USER/cache
 551                 path_cache = path_user + DIR_DELIM + "cache";
 552         }
 553         // Migrate cache folder to new location if possible
 554         migrateCachePath();
 555 #endif
 556
 557         infostream << "Detected share path: " << path_share << std::endl;
 558         infostream << "Detected user path: " << path_user << std::endl;
 559         infostream << "Detected cache path: " << path_cache << std::endl;
 560
 561         bool found_localedir = false;
 562 #ifdef STATIC_LOCALEDIR
 563         if (STATIC_LOCALEDIR[0] && fs::PathExists(STATIC_LOCALEDIR)) {
 564                 found_localedir = true;
 565                 path_locale = STATIC_LOCALEDIR;
 566                 infostream << "Using locale directory " << STATIC_LOCALEDIR << std::endl;
 567         } else {
 568                 path_locale = getDataPath("locale");
 569                 if (fs::PathExists(path_locale)) {
 570                         found_localedir = true;
 571                         infostream << "Using in-place locale directory " << path_locale
 572                                 << " even though a static one was provided "
 573                                 << "(RUN_IN_PLACE or CUSTOM_LOCALEDIR)." << std::endl;
 574                 }
 575         }
 576 #else
 577         path_locale = getDataPath("locale");
 578         if (fs::PathExists(path_locale)) {
 579                 found_localedir = true;
 580         }
 581 #endif
 582         if (!found_localedir) {
 583                 errorstream << "Couldn't find a locale directory!" << std::endl;
 584         }
 585 }
 586
 587
 588
 589 void setXorgClassHint(const video::SExposedVideoData &video_data,
 590         const std::string &name)
 591 {
 592 #ifdef XORG_USED
 593         if (video_data.OpenGLLinux.X11Display == NULL)
 594                 return;
 595
 596         XClassHint *classhint = XAllocClassHint();
 597         classhint->res_name  = (char *)name.c_str();
 598         classhint->res_class = (char *)name.c_str();
 599
 600         XSetClassHint((Display *)video_data.OpenGLLinux.X11Display,
 601                 video_data.OpenGLLinux.X11Window, classhint);
 602         XFree(classhint);
 603 #endif
 604 }
 605
 606
 607 ////
 608 //// Video/Display Information (Client-only)
 609 ////
 610
 611 #ifndef SERVER
 612
 613 static irr::IrrlichtDevice *device;
 614
 615 void initIrrlicht(irr::IrrlichtDevice *device_)
 616 {
 617         device = device_;
 618 }
 619
 620 v2u32 getWindowSize()
 621 {
 622         return device->getVideoDriver()->getScreenSize();
 623 }
 624
 625
 626 std::vector<core::vector3d<u32> > getSupportedVideoModes()
 627 {
 628         IrrlichtDevice *nulldevice = createDevice(video::EDT_NULL);
 629         sanity_check(nulldevice != NULL);
 630
 631         std::vector<core::vector3d<u32> > mlist;
 632         video::IVideoModeList *modelist = nulldevice->getVideoModeList();
 633
 634         u32 num_modes = modelist->getVideoModeCount();
 635         for (u32 i = 0; i != num_modes; i++) {
 636                 core::dimension2d<u32> mode_res = modelist->getVideoModeResolution(i);
 637                 s32 mode_depth = modelist->getVideoModeDepth(i);
 638                 mlist.push_back(core::vector3d<u32>(mode_res.Width, mode_res.Height, mode_depth));
 639         }
 640
 641         nulldevice->drop();
 642
 643         return mlist;
 644 }
 645
 646 std::vector<irr::video::E_DRIVER_TYPE> getSupportedVideoDrivers()
 647 {
 648         std::vector<irr::video::E_DRIVER_TYPE> drivers;
 649
 650         for (int i = 0; i != irr::video::EDT_COUNT; i++) {
 651                 if (irr::IrrlichtDevice::isDriverSupported((irr::video::E_DRIVER_TYPE)i))
 652                         drivers.push_back((irr::video::E_DRIVER_TYPE)i);
 653         }
 654
 655         return drivers;
 656 }
 657
 658 const char *getVideoDriverName(irr::video::E_DRIVER_TYPE type)
 659 {
 660         static const char *driver_ids[] = {
 661                 "null",
 662                 "software",
 663                 "burningsvideo",
 664                 "direct3d8",
 665                 "direct3d9",
 666                 "opengl",
 667                 "ogles1",
 668                 "ogles2",
 669         };
 670
 671         return driver_ids[type];
 672 }
 673
 674
 675 const char *getVideoDriverFriendlyName(irr::video::E_DRIVER_TYPE type)
 676 {
 677         static const char *driver_names[] = {
 678                 "NULL Driver",
 679                 "Software Renderer",
 680                 "Burning's Video",
 681                 "Direct3D 8",
 682                 "Direct3D 9",
 683                 "OpenGL",
 684                 "OpenGL ES1",
 685                 "OpenGL ES2",
 686         };
 687
 688         return driver_names[type];
 689 }
 690
 691 #       ifndef __ANDROID__
 692 #               ifdef XORG_USED
 693
 694 static float calcDisplayDensity()
 695 {
 696         const char *current_display = getenv("DISPLAY");
 697
 698         if (current_display != NULL) {
 699                 Display *x11display = XOpenDisplay(current_display);
 700
 701                 if (x11display != NULL) {
 702                         /* try x direct */
 703                         float dpi_height = floor(DisplayHeight(x11display, 0) /
 704                                                         (DisplayHeightMM(x11display, 0) * 0.039370) + 0.5);
 705                         float dpi_width = floor(DisplayWidth(x11display, 0) /
 706                                                         (DisplayWidthMM(x11display, 0) * 0.039370) + 0.5);
 707
 708                         XCloseDisplay(x11display);
 709
 710                         return std::max(dpi_height,dpi_width) / 96.0;
 711                 }
 712         }
 713
 714         /* return manually specified dpi */
 715         return g_settings->getFloat("screen_dpi")/96.0;
 716 }
 717
 718
 719 float getDisplayDensity()
 720 {
 721         static float cached_display_density = calcDisplayDensity();
 722         return cached_display_density;
 723 }
 724
 725
 726 #               else // XORG_USED
 727 float getDisplayDensity()
 728 {
 729         return g_settings->getFloat("screen_dpi")/96.0;
 730 }
 731 #               endif // XORG_USED
 732
 733 v2u32 getDisplaySize()
 734 {
 735         IrrlichtDevice *nulldevice = createDevice(video::EDT_NULL);
 736
 737         core::dimension2d<u32> deskres = nulldevice->getVideoModeList()->getDesktopResolution();
 738         nulldevice -> drop();
 739
 740         return deskres;
 741 }
 742 #       endif // __ANDROID__
 743 #endif // SERVER
 744
 745
 746 ////
 747 //// OS-specific Secure Random
 748 ////
 749
 750 #ifdef WIN32
 751
 752 bool secure_rand_fill_buf(void *buf, size_t len)
 753 {
 754         HCRYPTPROV wctx;
 755
 756         if (!CryptAcquireContext(&wctx, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
 757                 return false;
 758
 759         CryptGenRandom(wctx, len, (BYTE *)buf);
 760         CryptReleaseContext(wctx, 0);
 761         return true;
 762 }
 763
 764 #else
 765
 766 bool secure_rand_fill_buf(void *buf, size_t len)
 767 {
 768         // N.B.  This function checks *only* for /dev/urandom, because on most
 769         // common OSes it is non-blocking, whereas /dev/random is blocking, and it
 770         // is exceptionally uncommon for there to be a situation where /dev/random
 771         // exists but /dev/urandom does not.  This guesswork is necessary since
 772         // random devices are not covered by any POSIX standard...
 773         FILE *fp = fopen("/dev/urandom", "rb");
 774         if (!fp)
 775                 return false;
 776
 777         bool success = fread(buf, len, 1, fp) == 1;
 778
 779         fclose(fp);
 780         return success;
 781 }
 782
 783 #endif
 784
 785 } //namespace porting