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\\Debug",
 167                 "bin\\Build",
 168                 NULL
 169         };
 170         return (removeStringEnd(path, ends) != "");
 171 }
 172
 173 std::string get_sysinfo()
 174 {
 175 #ifdef _WIN32
 176         OSVERSIONINFO osvi;
 177         std::ostringstream oss;
 178         std::string tmp;
 179         ZeroMemory(&osvi, sizeof(OSVERSIONINFO));
 180         osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
 181         GetVersionEx(&osvi);
 182         tmp = osvi.szCSDVersion;
 183         std::replace(tmp.begin(), tmp.end(), ' ', '_');
 184
 185         oss << "Windows/" << osvi.dwMajorVersion << "."
 186                 << osvi.dwMinorVersion;
 187         if (osvi.szCSDVersion[0])
 188                 oss << "-" << tmp;
 189         oss << " ";
 190         #ifdef _WIN64
 191         oss << "x86_64";
 192         #else
 193         BOOL is64 = FALSE;
 194         if (IsWow64Process(GetCurrentProcess(), &is64) && is64)
 195                 oss << "x86_64"; // 32-bit app on 64-bit OS
 196         else
 197                 oss << "x86";
 198         #endif
 199
 200         return oss.str();
 201 #else
 202         struct utsname osinfo;
 203         uname(&osinfo);
 204         return std::string(osinfo.sysname) + "/"
 205                 + osinfo.release + " " + osinfo.machine;
 206 #endif
 207 }
 208
 209
 210 bool getCurrentWorkingDir(char *buf, size_t len)
 211 {
 212 #ifdef _WIN32
 213         DWORD ret = GetCurrentDirectory(len, buf);
 214         return (ret != 0) && (ret <= len);
 215 #else
 216         return getcwd(buf, len);
 217 #endif
 218 }
 219
 220
 221 bool getExecPathFromProcfs(char *buf, size_t buflen)
 222 {
 223 #ifndef _WIN32
 224         buflen--;
 225
 226         ssize_t len;
 227         if ((len = readlink("/proc/self/exe",     buf, buflen)) == -1 &&
 228                 (len = readlink("/proc/curproc/file", buf, buflen)) == -1 &&
 229                 (len = readlink("/proc/curproc/exe",  buf, buflen)) == -1)
 230                 return false;
 231
 232         buf[len] = '\0';
 233         return true;
 234 #else
 235         return false;
 236 #endif
 237 }
 238
 239 //// Windows
 240 #if defined(_WIN32)
 241
 242 bool getCurrentExecPath(char *buf, size_t len)
 243 {
 244         DWORD written = GetModuleFileNameA(NULL, buf, len);
 245         if (written == 0 || written == len)
 246                 return false;
 247
 248         return true;
 249 }
 250
 251
 252 //// Linux
 253 #elif defined(linux) || defined(__linux) || defined(__linux__)
 254
 255 bool getCurrentExecPath(char *buf, size_t len)
 256 {
 257         if (!getExecPathFromProcfs(buf, len))
 258                 return false;
 259
 260         return true;
 261 }
 262
 263
 264 //// Mac OS X, Darwin
 265 #elif defined(__APPLE__)
 266
 267 bool getCurrentExecPath(char *buf, size_t len)
 268 {
 269         uint32_t lenb = (uint32_t)len;
 270         if (_NSGetExecutablePath(buf, &lenb) == -1)
 271                 return false;
 272
 273         return true;
 274 }
 275
 276
 277 //// FreeBSD, NetBSD, DragonFlyBSD
 278 #elif defined(__FreeBSD__) || defined(__NetBSD__) || defined(__DragonFly__)
 279
 280 bool getCurrentExecPath(char *buf, size_t len)
 281 {
 282         // Try getting path from procfs first, since valgrind
 283         // doesn't work with the latter
 284         if (getExecPathFromProcfs(buf, len))
 285                 return true;
 286
 287         int mib[4];
 288
 289         mib[0] = CTL_KERN;
 290         mib[1] = KERN_PROC;
 291         mib[2] = KERN_PROC_PATHNAME;
 292         mib[3] = -1;
 293
 294         if (sysctl(mib, 4, buf, &len, NULL, 0) == -1)
 295                 return false;
 296
 297         return true;
 298 }
 299
 300
 301 //// Solaris
 302 #elif defined(__sun) || defined(sun)
 303
 304 bool getCurrentExecPath(char *buf, size_t len)
 305 {
 306         const char *exec = getexecname();
 307         if (exec == NULL)
 308                 return false;
 309
 310         if (strlcpy(buf, exec, len) >= len)
 311                 return false;
 312
 313         return true;
 314 }
 315
 316
 317 // HP-UX
 318 #elif defined(__hpux)
 319
 320 bool getCurrentExecPath(char *buf, size_t len)
 321 {
 322         struct pst_status psts;
 323
 324         if (pstat_getproc(&psts, sizeof(psts), 0, getpid()) == -1)
 325                 return false;
 326
 327         if (pstat_getpathname(buf, len, &psts.pst_fid_text) == -1)
 328                 return false;
 329
 330         return true;
 331 }
 332
 333
 334 #else
 335
 336 bool getCurrentExecPath(char *buf, size_t len)
 337 {
 338         return false;
 339 }
 340
 341 #endif
 342
 343
 344 //// Windows
 345 #if defined(_WIN32)
 346
 347 bool setSystemPaths()
 348 {
 349         char buf[BUFSIZ];
 350
 351         // Find path of executable and set path_share relative to it
 352         FATAL_ERROR_IF(!getCurrentExecPath(buf, sizeof(buf)),
 353                 "Failed to get current executable path");
 354         pathRemoveFile(buf, '\\');
 355
 356         // Use ".\bin\.."
 357         path_share = std::string(buf) + "\\..";
 358
 359         // Use "C:\Documents and Settings\user\Application Data\<PROJECT_NAME>"
 360         DWORD len = GetEnvironmentVariable("APPDATA", buf, sizeof(buf));
 361         FATAL_ERROR_IF(len == 0 || len > sizeof(buf), "Failed to get APPDATA");
 362
 363         path_user = std::string(buf) + DIR_DELIM + PROJECT_NAME;
 364         return true;
 365 }
 366
 367
 368 //// Linux
 369 #elif defined(linux) || defined(__linux)
 370
 371 bool setSystemPaths()
 372 {
 373         char buf[BUFSIZ];
 374
 375         if (!getCurrentExecPath(buf, sizeof(buf))) {
 376 #ifdef __ANDROID__
 377                 errorstream << "Unable to read bindir "<< std::endl;
 378 #else
 379                 FATAL_ERROR("Unable to read bindir");
 380 #endif
 381                 return false;
 382         }
 383
 384         pathRemoveFile(buf, '/');
 385         std::string bindir(buf);
 386
 387         // Find share directory from these.
 388         // It is identified by containing the subdirectory "builtin".
 389         std::list<std::string> trylist;
 390         std::string static_sharedir = STATIC_SHAREDIR;
 391         if (static_sharedir != "" && static_sharedir != ".")
 392                 trylist.push_back(static_sharedir);
 393
 394         trylist.push_back(bindir + DIR_DELIM ".." DIR_DELIM "share"
 395                 DIR_DELIM + PROJECT_NAME);
 396         trylist.push_back(bindir + DIR_DELIM "..");
 397
 398 #ifdef __ANDROID__
 399         trylist.push_back(path_user);
 400 #endif
 401
 402         for (std::list<std::string>::const_iterator
 403                         i = trylist.begin(); i != trylist.end(); i++) {
 404                 const std::string &trypath = *i;
 405                 if (!fs::PathExists(trypath) ||
 406                         !fs::PathExists(trypath + DIR_DELIM + "builtin")) {
 407                         warningstream << "system-wide share not found at \""
 408                                         << trypath << "\""<< std::endl;
 409                         continue;
 410                 }
 411
 412                 // Warn if was not the first alternative
 413                 if (i != trylist.begin()) {
 414                         warningstream << "system-wide share found at \""
 415                                         << trypath << "\"" << std::endl;
 416                 }
 417
 418                 path_share = trypath;
 419                 break;
 420         }
 421
 422 #ifndef __ANDROID__
 423         path_user = std::string(getenv("HOME")) + DIR_DELIM "."
 424                 + PROJECT_NAME;
 425 #endif
 426
 427         return true;
 428 }
 429
 430
 431 //// Mac OS X
 432 #elif defined(__APPLE__)
 433
 434 bool setSystemPaths()
 435 {
 436         CFBundleRef main_bundle = CFBundleGetMainBundle();
 437         CFURLRef resources_url = CFBundleCopyResourcesDirectoryURL(main_bundle);
 438         char path[PATH_MAX];
 439         if (CFURLGetFileSystemRepresentation(resources_url,
 440                         TRUE, (UInt8 *)path, PATH_MAX)) {
 441                 path_share = std::string(path);
 442         } else {
 443                 warningstream << "Could not determine bundle resource path" << std::endl;
 444         }
 445         CFRelease(resources_url);
 446
 447         path_user = std::string(getenv("HOME"))
 448                 + "/Library/Application Support/"
 449                 + PROJECT_NAME;
 450         return true;
 451 }
 452
 453
 454 #else
 455
 456 bool setSystemPaths()
 457 {
 458         path_share = STATIC_SHAREDIR;
 459         path_user  = std::string(getenv("HOME")) + DIR_DELIM "."
 460                 + lowercase(PROJECT_NAME);
 461         return true;
 462 }
 463
 464
 465 #endif
 466
 467 void migrateCachePath()
 468 {
 469         const std::string local_cache_path = path_user + DIR_DELIM + "cache";
 470
 471         // Delete tmp folder if it exists (it only ever contained
 472         // a temporary ogg file, which is no longer used).
 473         if (fs::PathExists(local_cache_path + DIR_DELIM + "tmp"))
 474                 fs::RecursiveDelete(local_cache_path + DIR_DELIM + "tmp");
 475
 476         // Bail if migration impossible
 477         if (path_cache == local_cache_path || !fs::PathExists(local_cache_path)
 478                         || fs::PathExists(path_cache)) {
 479                 return;
 480         }
 481         if (!fs::Rename(local_cache_path, path_cache)) {
 482                 errorstream << "Failed to migrate local cache path "
 483                         "to system path!" << std::endl;
 484         }
 485 }
 486
 487 void initializePaths()
 488 {
 489 #if RUN_IN_PLACE
 490         char buf[BUFSIZ];
 491
 492         infostream << "Using relative paths (RUN_IN_PLACE)" << std::endl;
 493
 494         bool success =
 495                 getCurrentExecPath(buf, sizeof(buf)) ||
 496                 getExecPathFromProcfs(buf, sizeof(buf));
 497
 498         if (success) {
 499                 pathRemoveFile(buf, DIR_DELIM_CHAR);
 500                 std::string execpath(buf);
 501
 502                 path_share = execpath + DIR_DELIM "..";
 503                 path_user  = execpath + DIR_DELIM "..";
 504
 505                 if (detectMSVCBuildDir(execpath)) {
 506                         path_share += DIR_DELIM "..";
 507                         path_user  += DIR_DELIM "..";
 508                 }
 509         } else {
 510                 errorstream << "Failed to get paths by executable location, "
 511                         "trying cwd" << std::endl;
 512
 513                 if (!getCurrentWorkingDir(buf, sizeof(buf)))
 514                         FATAL_ERROR("Ran out of methods to get paths");
 515
 516                 size_t cwdlen = strlen(buf);
 517                 if (cwdlen >= 1 && buf[cwdlen - 1] == DIR_DELIM_CHAR) {
 518                         cwdlen--;
 519                         buf[cwdlen] = '\0';
 520                 }
 521
 522                 if (cwdlen >= 4 && !strcmp(buf + cwdlen - 4, DIR_DELIM "bin"))
 523                         pathRemoveFile(buf, DIR_DELIM_CHAR);
 524
 525                 std::string execpath(buf);
 526
 527                 path_share = execpath;
 528                 path_user  = execpath;
 529         }
 530 #else
 531         infostream << "Using system-wide paths (NOT RUN_IN_PLACE)" << std::endl;
 532
 533         if (!setSystemPaths())
 534                 errorstream << "Failed to get one or more system-wide path" << std::endl;
 535
 536         // Initialize path_cache
 537         // First try $XDG_CACHE_HOME/PROJECT_NAME
 538         const char *cache_dir = getenv("XDG_CACHE_HOME");
 539         if (cache_dir) {
 540                 path_cache = std::string(cache_dir) + DIR_DELIM + PROJECT_NAME;
 541         } else {
 542                 // Then try $HOME/.cache/PROJECT_NAME
 543                 const char *home_dir = getenv("HOME");
 544                 if (home_dir) {
 545                         path_cache = std::string(home_dir) + DIR_DELIM + ".cache"
 546                                 + DIR_DELIM + PROJECT_NAME;
 547                 }
 548                 // If neither works, leave it at $PATH_USER/cache
 549         }
 550         // Migrate cache folder to new location if possible
 551         migrateCachePath();
 552 #endif
 553
 554         infostream << "Detected share path: " << path_share << std::endl;
 555         infostream << "Detected user path: " << path_user << std::endl;
 556         infostream << "Detected cache path: " << path_cache << std::endl;
 557
 558         bool found_localedir = false;
 559 #ifdef STATIC_LOCALEDIR
 560         if (STATIC_LOCALEDIR[0] && fs::PathExists(STATIC_LOCALEDIR)) {
 561                 found_localedir = true;
 562                 path_locale = STATIC_LOCALEDIR;
 563                 infostream << "Using locale directory " << STATIC_LOCALEDIR << std::endl;
 564         } else {
 565                 path_locale = getDataPath("locale");
 566                 if (fs::PathExists(path_locale)) {
 567                         found_localedir = true;
 568                         infostream << "Using in-place locale directory " << path_locale
 569                                 << " even though a static one was provided "
 570                                 << "(RUN_IN_PLACE or CUSTOM_LOCALEDIR)." << std::endl;
 571                 }
 572         }
 573 #else
 574         path_locale = getDataPath("locale");
 575         if (fs::PathExists(path_locale)) {
 576                 found_localedir = true;
 577         }
 578 #endif
 579         if (!found_localedir) {
 580                 errorstream << "Couldn't find a locale directory!" << std::endl;
 581         }
 582 }
 583
 584
 585
 586 void setXorgClassHint(const video::SExposedVideoData &video_data,
 587         const std::string &name)
 588 {
 589 #ifdef XORG_USED
 590         if (video_data.OpenGLLinux.X11Display == NULL)
 591                 return;
 592
 593         XClassHint *classhint = XAllocClassHint();
 594         classhint->res_name  = (char *)name.c_str();
 595         classhint->res_class = (char *)name.c_str();
 596
 597         XSetClassHint((Display *)video_data.OpenGLLinux.X11Display,
 598                 video_data.OpenGLLinux.X11Window, classhint);
 599         XFree(classhint);
 600 #endif
 601 }
 602
 603
 604 ////
 605 //// Video/Display Information (Client-only)
 606 ////
 607
 608 #ifndef SERVER
 609
 610 static irr::IrrlichtDevice *device;
 611
 612 void initIrrlicht(irr::IrrlichtDevice *device_)
 613 {
 614         device = device_;
 615 }
 616
 617 v2u32 getWindowSize()
 618 {
 619         return device->getVideoDriver()->getScreenSize();
 620 }
 621
 622
 623 std::vector<core::vector3d<u32> > getSupportedVideoModes()
 624 {
 625         IrrlichtDevice *nulldevice = createDevice(video::EDT_NULL);
 626         sanity_check(nulldevice != NULL);
 627
 628         std::vector<core::vector3d<u32> > mlist;
 629         video::IVideoModeList *modelist = nulldevice->getVideoModeList();
 630
 631         u32 num_modes = modelist->getVideoModeCount();
 632         for (u32 i = 0; i != num_modes; i++) {
 633                 core::dimension2d<u32> mode_res = modelist->getVideoModeResolution(i);
 634                 s32 mode_depth = modelist->getVideoModeDepth(i);
 635                 mlist.push_back(core::vector3d<u32>(mode_res.Width, mode_res.Height, mode_depth));
 636         }
 637
 638         nulldevice->drop();
 639
 640         return mlist;
 641 }
 642
 643 std::vector<irr::video::E_DRIVER_TYPE> getSupportedVideoDrivers()
 644 {
 645         std::vector<irr::video::E_DRIVER_TYPE> drivers;
 646
 647         for (int i = 0; i != irr::video::EDT_COUNT; i++) {
 648                 if (irr::IrrlichtDevice::isDriverSupported((irr::video::E_DRIVER_TYPE)i))
 649                         drivers.push_back((irr::video::E_DRIVER_TYPE)i);
 650         }
 651
 652         return drivers;
 653 }
 654
 655 const char *getVideoDriverName(irr::video::E_DRIVER_TYPE type)
 656 {
 657         static const char *driver_ids[] = {
 658                 "null",
 659                 "software",
 660                 "burningsvideo",
 661                 "direct3d8",
 662                 "direct3d9",
 663                 "opengl",
 664                 "ogles1",
 665                 "ogles2",
 666         };
 667
 668         return driver_ids[type];
 669 }
 670
 671
 672 const char *getVideoDriverFriendlyName(irr::video::E_DRIVER_TYPE type)
 673 {
 674         static const char *driver_names[] = {
 675                 "NULL Driver",
 676                 "Software Renderer",
 677                 "Burning's Video",
 678                 "Direct3D 8",
 679                 "Direct3D 9",
 680                 "OpenGL",
 681                 "OpenGL ES1",
 682                 "OpenGL ES2",
 683         };
 684
 685         return driver_names[type];
 686 }
 687
 688 #       ifndef __ANDROID__
 689 #               ifdef XORG_USED
 690
 691 static float calcDisplayDensity()
 692 {
 693         const char *current_display = getenv("DISPLAY");
 694
 695         if (current_display != NULL) {
 696                 Display *x11display = XOpenDisplay(current_display);
 697
 698                 if (x11display != NULL) {
 699                         /* try x direct */
 700                         float dpi_height = floor(DisplayHeight(x11display, 0) /
 701                                                         (DisplayHeightMM(x11display, 0) * 0.039370) + 0.5);
 702                         float dpi_width = floor(DisplayWidth(x11display, 0) /
 703                                                         (DisplayWidthMM(x11display, 0) * 0.039370) + 0.5);
 704
 705                         XCloseDisplay(x11display);
 706
 707                         return std::max(dpi_height,dpi_width) / 96.0;
 708                 }
 709         }
 710
 711         /* return manually specified dpi */
 712         return g_settings->getFloat("screen_dpi")/96.0;
 713 }
 714
 715
 716 float getDisplayDensity()
 717 {
 718         static float cached_display_density = calcDisplayDensity();
 719         return cached_display_density;
 720 }
 721
 722
 723 #               else // XORG_USED
 724 float getDisplayDensity()
 725 {
 726         return g_settings->getFloat("screen_dpi")/96.0;
 727 }
 728 #               endif // XORG_USED
 729
 730 v2u32 getDisplaySize()
 731 {
 732         IrrlichtDevice *nulldevice = createDevice(video::EDT_NULL);
 733
 734         core::dimension2d<u32> deskres = nulldevice->getVideoModeList()->getDesktopResolution();
 735         nulldevice -> drop();
 736
 737         return deskres;
 738 }
 739 #       endif // __ANDROID__
 740 #endif // SERVER
 741
 742
 743 ////
 744 //// OS-specific Secure Random
 745 ////
 746
 747 #ifdef WIN32
 748
 749 bool secure_rand_fill_buf(void *buf, size_t len)
 750 {
 751         HCRYPTPROV wctx;
 752
 753         if (!CryptAcquireContext(&wctx, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
 754                 return false;
 755
 756         CryptGenRandom(wctx, len, (BYTE *)buf);
 757         CryptReleaseContext(wctx, 0);
 758         return true;
 759 }
 760
 761 #else
 762
 763 bool secure_rand_fill_buf(void *buf, size_t len)
 764 {
 765         // N.B.  This function checks *only* for /dev/urandom, because on most
 766         // common OSes it is non-blocking, whereas /dev/random is blocking, and it
 767         // is exceptionally uncommon for there to be a situation where /dev/random
 768         // exists but /dev/urandom does not.  This guesswork is necessary since
 769         // random devices are not covered by any POSIX standard...
 770         FILE *fp = fopen("/dev/urandom", "rb");
 771         if (!fp)
 772                 return false;
 773
 774         bool success = fread(buf, len, 1, fp) == 1;
 775
 776         fclose(fp);
 777         return success;
 778 }
 779
 780 #endif
 781
 782 } //namespace porting