lib/uuid/gen_uuid.c

   1 /*
   2  * gen_uuid.c --- generate a DCE-compatible uuid
   3  *
   4  * Copyright (C) 1996, 1997, 1998, 1999 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, and the entire permission notice in its entirety,
  12  *    including the disclaimer of warranties.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. The name of the author may not be used to endorse or promote
  17  *    products derived from this software without specific prior
  18  *    written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  21  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  22  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
  23  * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
  24  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  26  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  27  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  28  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
  30  * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
  31  * DAMAGE.
  32  * %End-Header%
  33  */
  34
  35 /*
  36  * Force inclusion of SVID stuff since we need it if we're compiling in
  37  * gcc-wall wall mode
  38  */
  39 #define _SVID_SOURCE
  40
  41 #include "config.h"
  42
  43 #ifdef _WIN32
  44 #define _WIN32_WINNT 0x0500
  45 #include <windows.h>
  46 #define UUID MYUUID
  47 #endif
  48 #include <stdio.h>
  49 #ifdef HAVE_UNISTD_H
  50 #include <unistd.h>
  51 #endif
  52 #ifdef HAVE_STDLIB_H
  53 #include <stdlib.h>
  54 #endif
  55 #include <string.h>
  56 #include <fcntl.h>
  57 #include <errno.h>
  58 #include <sys/types.h>
  59 #ifdef HAVE_SYS_TIME_H
  60 #include <sys/time.h>
  61 #endif
  62 #include <sys/wait.h>
  63 #include <sys/stat.h>
  64 #ifdef HAVE_SYS_FILE_H
  65 #include <sys/file.h>
  66 #endif
  67 #ifdef HAVE_SYS_IOCTL_H
  68 #include <sys/ioctl.h>
  69 #endif
  70 #ifdef HAVE_SYS_SOCKET_H
  71 #include <sys/socket.h>
  72 #endif
  73 #ifdef HAVE_SYS_UN_H
  74 #include <sys/un.h>
  75 #endif
  76 #ifdef HAVE_SYS_SOCKIO_H
  77 #include <sys/sockio.h>
  78 #endif
  79 #ifdef HAVE_NET_IF_H
  80 #include <net/if.h>
  81 #endif
  82 #ifdef HAVE_NETINET_IN_H
  83 #include <netinet/in.h>
  84 #endif
  85 #ifdef HAVE_NET_IF_DL_H
  86 #include <net/if_dl.h>
  87 #endif
  88 #if defined(__linux__) && defined(HAVE_SYS_SYSCALL_H)
  89 #include <sys/syscall.h>
  90 #endif
  91 #ifdef HAVE_SYS_RESOURCE_H
  92 #include <sys/resource.h>
  93 #endif
  94
  95 #include "uuidP.h"
  96 #include "uuidd.h"
  97
  98 #ifdef HAVE_SRANDOM
  99 #define srand(x)        srandom(x)
 100 #define rand()          random()
 101 #endif
 102
 103 #ifdef TLS
 104 #define THREAD_LOCAL static TLS
 105 #else
 106 #define THREAD_LOCAL static
 107 #endif
 108
 109 #if defined(__linux__) && defined(__NR_gettid) && defined(HAVE_JRAND48)
 110 #define DO_JRAND_MIX
 111 THREAD_LOCAL unsigned short jrand_seed[3];
 112 #endif
 113
 114 #ifdef _WIN32
 115 static void gettimeofday (struct timeval *tv, void *dummy)
 116 {
 117         FILETIME        ftime;
 118         uint64_t        n;
 119
 120         GetSystemTimeAsFileTime (&ftime);
 121         n = (((uint64_t) ftime.dwHighDateTime << 32)
 122              + (uint64_t) ftime.dwLowDateTime);
 123         if (n) {
 124                 n /= 10;
 125                 n -= ((369 * 365 + 89) * (uint64_t) 86400) * 1000000;
 126         }
 127
 128         tv->tv_sec = n / 1000000;
 129         tv->tv_usec = n % 1000000;
 130 }
 131
 132 static int getuid (void)
 133 {
 134         return 1;
 135 }
 136 #endif
 137
 138 static int get_random_fd(void)
 139 {
 140         struct timeval  tv;
 141         static int      fd = -2;
 142         int             i;
 143
 144         if (fd == -2) {
 145                 gettimeofday(&tv, 0);
 146 #ifndef _WIN32
 147                 fd = open("/dev/urandom", O_RDONLY);
 148                 if (fd == -1)
 149                         fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
 150                 if (fd >= 0) {
 151                         i = fcntl(fd, F_GETFD);
 152                         if (i >= 0)
 153                                 fcntl(fd, F_SETFD, i | FD_CLOEXEC);
 154                 }
 155 #endif
 156                 srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
 157 #ifdef DO_JRAND_MIX
 158                 jrand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
 159                 jrand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
 160                 jrand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
 161 #endif
 162         }
 163         /* Crank the random number generator a few times */
 164         gettimeofday(&tv, 0);
 165         for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
 166                 rand();
 167         return fd;
 168 }
 169
 170
 171 /*
 172  * Generate a series of random bytes.  Use /dev/urandom if possible,
 173  * and if not, use srandom/random.
 174  */
 175 static void get_random_bytes(void *buf, int nbytes)
 176 {
 177         int i, n = nbytes, fd = get_random_fd();
 178         int lose_counter = 0;
 179         unsigned char *cp = buf;
 180
 181         if (fd >= 0) {
 182                 while (n > 0) {
 183                         i = read(fd, cp, n);
 184                         if (i <= 0) {
 185                                 if (lose_counter++ > 16)
 186                                         break;
 187                                 continue;
 188                         }
 189                         n -= i;
 190                         cp += i;
 191                         lose_counter = 0;
 192                 }
 193         }
 194
 195         /*
 196          * We do this all the time, but this is the only source of
 197          * randomness if /dev/random/urandom is out to lunch.
 198          */
 199         for (cp = buf, i = 0; i < nbytes; i++)
 200                 *cp++ ^= (rand() >> 7) & 0xFF;
 201 #ifdef DO_JRAND_MIX
 202         {
 203                 unsigned short tmp_seed[3];
 204
 205                 memcpy(tmp_seed, jrand_seed, sizeof(tmp_seed));
 206                 jrand_seed[2] = jrand_seed[2] ^ syscall(__NR_gettid);
 207                 for (cp = buf, i = 0; i < nbytes; i++)
 208                         *cp++ ^= (jrand48(tmp_seed) >> 7) & 0xFF;
 209                 memcpy(jrand_seed, tmp_seed,
 210                        sizeof(jrand_seed) - sizeof(unsigned short));
 211         }
 212 #endif
 213
 214         return;
 215 }
 216
 217 /*
 218  * Get the ethernet hardware address, if we can find it...
 219  *
 220  * XXX for a windows version, probably should use GetAdaptersInfo:
 221  * http://www.codeguru.com/cpp/i-n/network/networkinformation/article.php/c5451
 222  * commenting out get_node_id just to get gen_uuid to compile under windows
 223  * is not the right way to go!
 224  */
 225 static int get_node_id(unsigned char *node_id)
 226 {
 227 #ifdef HAVE_NET_IF_H
 228         int             sd;
 229         struct ifreq    ifr, *ifrp;
 230         struct ifconf   ifc;
 231         char buf[1024];
 232         int             n, i;
 233         unsigned char   *a;
 234 #ifdef HAVE_NET_IF_DL_H
 235         struct sockaddr_dl *sdlp;
 236 #endif
 237
 238 /*
 239  * BSD 4.4 defines the size of an ifreq to be
 240  * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
 241  * However, under earlier systems, sa_len isn't present, so the size is
 242  * just sizeof(struct ifreq)
 243  */
 244 #ifdef HAVE_SA_LEN
 245 #ifndef max
 246 #define max(a,b) ((a) > (b) ? (a) : (b))
 247 #endif
 248 #define ifreq_size(i) max(sizeof(struct ifreq),\
 249      sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
 250 #else
 251 #define ifreq_size(i) sizeof(struct ifreq)
 252 #endif /* HAVE_SA_LEN*/
 253
 254         sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 255         if (sd < 0) {
 256                 return -1;
 257         }
 258         memset(buf, 0, sizeof(buf));
 259         ifc.ifc_len = sizeof(buf);
 260         ifc.ifc_buf = buf;
 261         if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
 262                 close(sd);
 263                 return -1;
 264         }
 265         n = ifc.ifc_len;
 266         for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
 267                 ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
 268                 strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
 269 #ifdef SIOCGIFHWADDR
 270                 if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
 271                         continue;
 272                 a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
 273 #else
 274 #ifdef SIOCGENADDR
 275                 if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
 276                         continue;
 277                 a = (unsigned char *) ifr.ifr_enaddr;
 278 #else
 279 #ifdef HAVE_NET_IF_DL_H
 280                 sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
 281                 if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
 282                         continue;
 283                 a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
 284 #else
 285                 /*
 286                  * XXX we don't have a way of getting the hardware
 287                  * address
 288                  */
 289                 close(sd);
 290                 return 0;
 291 #endif /* HAVE_NET_IF_DL_H */
 292 #endif /* SIOCGENADDR */
 293 #endif /* SIOCGIFHWADDR */
 294                 if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
 295                         continue;
 296                 if (node_id) {
 297                         memcpy(node_id, a, 6);
 298                         close(sd);
 299                         return 1;
 300                 }
 301         }
 302         close(sd);
 303 #endif
 304         return 0;
 305 }
 306
 307 /* Assume that the gettimeofday() has microsecond granularity */
 308 #define MAX_ADJUSTMENT 10
 309
 310 static int get_clock(uint32_t *clock_high, uint32_t *clock_low,
 311                      uint16_t *ret_clock_seq, int *num)
 312 {
 313         THREAD_LOCAL int                adjustment = 0;
 314         THREAD_LOCAL struct timeval     last = {0, 0};
 315         THREAD_LOCAL int                state_fd = -2;
 316         THREAD_LOCAL FILE               *state_f;
 317         THREAD_LOCAL uint16_t           clock_seq;
 318         struct timeval                  tv;
 319         struct flock                    fl;
 320         uint64_t                        clock_reg;
 321         mode_t                          save_umask;
 322         int                             len;
 323
 324         if (state_fd == -2) {
 325                 save_umask = umask(0);
 326                 state_fd = open("/var/lib/libuuid/clock.txt",
 327                                 O_RDWR|O_CREAT, 0660);
 328                 (void) umask(save_umask);
 329                 if (state_fd >= 0) {
 330                         state_f = fdopen(state_fd, "r+");
 331                         if (!state_f) {
 332                                 close(state_fd);
 333                                 state_fd = -1;
 334                         }
 335                 }
 336         }
 337         fl.l_type = F_WRLCK;
 338         fl.l_whence = SEEK_SET;
 339         fl.l_start = 0;
 340         fl.l_len = 0;
 341         fl.l_pid = 0;
 342         if (state_fd >= 0) {
 343                 rewind(state_f);
 344                 while (fcntl(state_fd, F_SETLKW, &fl) < 0) {
 345                         if ((errno == EAGAIN) || (errno == EINTR))
 346                                 continue;
 347                         fclose(state_f);
 348                         state_fd = -1;
 349                         break;
 350                 }
 351         }
 352         if (state_fd >= 0) {
 353                 unsigned int cl;
 354                 unsigned long tv1, tv2;
 355                 int a;
 356
 357                 if (fscanf(state_f, "clock: %04x tv: %lu %lu adj: %d\n",
 358                            &cl, &tv1, &tv2, &a) == 4) {
 359                         clock_seq = cl & 0x3FFF;
 360                         last.tv_sec = tv1;
 361                         last.tv_usec = tv2;
 362                         adjustment = a;
 363                 }
 364         }
 365
 366         if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
 367                 get_random_bytes(&clock_seq, sizeof(clock_seq));
 368                 clock_seq &= 0x3FFF;
 369                 gettimeofday(&last, 0);
 370                 last.tv_sec--;
 371         }
 372
 373 try_again:
 374         gettimeofday(&tv, 0);
 375         if ((tv.tv_sec < last.tv_sec) ||
 376             ((tv.tv_sec == last.tv_sec) &&
 377              (tv.tv_usec < last.tv_usec))) {
 378                 clock_seq = (clock_seq+1) & 0x3FFF;
 379                 adjustment = 0;
 380                 last = tv;
 381         } else if ((tv.tv_sec == last.tv_sec) &&
 382             (tv.tv_usec == last.tv_usec)) {
 383                 if (adjustment >= MAX_ADJUSTMENT)
 384                         goto try_again;
 385                 adjustment++;
 386         } else {
 387                 adjustment = 0;
 388                 last = tv;
 389         }
 390
 391         clock_reg = tv.tv_usec*10 + adjustment;
 392         clock_reg += ((uint64_t) tv.tv_sec)*10000000;
 393         clock_reg += (((uint64_t) 0x01B21DD2) << 32) + 0x13814000;
 394
 395         if (num && (*num > 1)) {
 396                 adjustment += *num - 1;
 397                 last.tv_usec += adjustment / 10;
 398                 adjustment = adjustment % 10;
 399                 last.tv_sec += last.tv_usec / 1000000;
 400                 last.tv_usec = last.tv_usec % 1000000;
 401         }
 402
 403         if (state_fd > 0) {
 404                 rewind(state_f);
 405                 len = fprintf(state_f,
 406                               "clock: %04x tv: %016lu %08lu adj: %08d\n",
 407                               clock_seq, last.tv_sec, (long)last.tv_usec,
 408                               adjustment);
 409                 fflush(state_f);
 410                 if (ftruncate(state_fd, len) < 0) {
 411                         fprintf(state_f, "                   \n");
 412                         fflush(state_f);
 413                 }
 414                 rewind(state_f);
 415                 fl.l_type = F_UNLCK;
 416                 if (fcntl(state_fd, F_SETLK, &fl) < 0) {
 417                         fclose(state_f);
 418                         state_fd = -1;
 419                 }
 420         }
 421
 422         *clock_high = clock_reg >> 32;
 423         *clock_low = clock_reg;
 424         *ret_clock_seq = clock_seq;
 425         return 0;
 426 }
 427
 428 #if defined(USE_UUIDD) && defined(HAVE_SYS_UN_H)
 429 static ssize_t read_all(int fd, char *buf, size_t count)
 430 {
 431         ssize_t ret;
 432         ssize_t c = 0;
 433         int tries = 0;
 434
 435         memset(buf, 0, count);
 436         while (count > 0) {
 437                 ret = read(fd, buf, count);
 438                 if (ret <= 0) {
 439                         if ((errno == EAGAIN || errno == EINTR || ret == 0) &&
 440                             (tries++ < 5))
 441                                 continue;
 442                         return c ? c : -1;
 443                 }
 444                 if (ret > 0)
 445                         tries = 0;
 446                 count -= ret;
 447                 buf += ret;
 448                 c += ret;
 449         }
 450         return c;
 451 }
 452
 453 /*
 454  * Close all file descriptors
 455  */
 456 static void close_all_fds(void)
 457 {
 458         int i, max;
 459
 460 #if defined(HAVE_SYSCONF) && defined(_SC_OPEN_MAX)
 461         max = sysconf(_SC_OPEN_MAX);
 462 #elif defined(HAVE_GETDTABLESIZE)
 463         max = getdtablesize();
 464 #elif defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
 465         struct rlimit rl;
 466
 467         getrlimit(RLIMIT_NOFILE, &rl);
 468         max = rl.rlim_cur;
 469 #else
 470         max = OPEN_MAX;
 471 #endif
 472
 473         for (i=0; i < max; i++) {
 474                 close(i);
 475                 if (i <= 2)
 476                         open("/dev/null", O_RDWR);
 477         }
 478 }
 479 #endif /* defined(USE_UUIDD) && defined(HAVE_SYS_UN_H) */
 480
 481 /*
 482  * Try using the uuidd daemon to generate the UUID
 483  *
 484  * Returns 0 on success, non-zero on failure.
 485  */
 486 static int get_uuid_via_daemon(int op, uuid_t out, int *num)
 487 {
 488 #if defined(USE_UUIDD) && defined(HAVE_SYS_UN_H)
 489         char op_buf[64];
 490         int op_len;
 491         int s;
 492         ssize_t ret;
 493         int32_t reply_len = 0, expected = 16;
 494         struct sockaddr_un srv_addr;
 495         struct stat st;
 496         pid_t pid;
 497         static const char *uuidd_path = UUIDD_PATH;
 498         static int access_ret = -2;
 499         static int start_attempts = 0;
 500
 501         if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
 502                 return -1;
 503
 504         srv_addr.sun_family = AF_UNIX;
 505         strcpy(srv_addr.sun_path, UUIDD_SOCKET_PATH);
 506
 507         if (connect(s, (const struct sockaddr *) &srv_addr,
 508                     sizeof(struct sockaddr_un)) < 0) {
 509                 if (access_ret == -2)
 510                         access_ret = access(uuidd_path, X_OK);
 511                 if (access_ret == 0)
 512                         access_ret = stat(uuidd_path, &st);
 513                 if (access_ret == 0 && (st.st_mode & (S_ISUID | S_ISGID)) == 0)
 514                         access_ret = access(UUIDD_DIR, W_OK);
 515                 if (access_ret == 0 && start_attempts++ < 5) {
 516                         if ((pid = fork()) == 0) {
 517                                 close_all_fds();
 518                                 execl(uuidd_path, "uuidd", "-qT", "300",
 519                                       (char *) NULL);
 520                                 exit(1);
 521                         }
 522                         (void) waitpid(pid, 0, 0);
 523                         if (connect(s, (const struct sockaddr *) &srv_addr,
 524                                     sizeof(struct sockaddr_un)) < 0)
 525                                 goto fail;
 526                 } else
 527                         goto fail;
 528         }
 529         op_buf[0] = op;
 530         op_len = 1;
 531         if (op == UUIDD_OP_BULK_TIME_UUID) {
 532                 memcpy(op_buf+1, num, sizeof(*num));
 533                 op_len += sizeof(*num);
 534                 expected += sizeof(*num);
 535         }
 536
 537         ret = write(s, op_buf, op_len);
 538         if (ret < 1)
 539                 goto fail;
 540
 541         ret = read_all(s, (char *) &reply_len, sizeof(reply_len));
 542         if (ret < 0)
 543                 goto fail;
 544
 545         if (reply_len != expected)
 546                 goto fail;
 547
 548         ret = read_all(s, op_buf, reply_len);
 549
 550         if (op == UUIDD_OP_BULK_TIME_UUID)
 551                 memcpy(op_buf+16, num, sizeof(int));
 552
 553         memcpy(out, op_buf, 16);
 554
 555         close(s);
 556         return ((ret == expected) ? 0 : -1);
 557
 558 fail:
 559         close(s);
 560 #endif
 561         return -1;
 562 }
 563
 564 void uuid__generate_time(uuid_t out, int *num)
 565 {
 566         static unsigned char node_id[6];
 567         static int has_init = 0;
 568         struct uuid uu;
 569         uint32_t        clock_mid;
 570
 571         if (!has_init) {
 572                 if (get_node_id(node_id) <= 0) {
 573                         get_random_bytes(node_id, 6);
 574                         /*
 575                          * Set multicast bit, to prevent conflicts
 576                          * with IEEE 802 addresses obtained from
 577                          * network cards
 578                          */
 579                         node_id[0] |= 0x01;
 580                 }
 581                 has_init = 1;
 582         }
 583         get_clock(&clock_mid, &uu.time_low, &uu.clock_seq, num);
 584         uu.clock_seq |= 0x8000;
 585         uu.time_mid = (uint16_t) clock_mid;
 586         uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
 587         memcpy(uu.node, node_id, 6);
 588         uuid_pack(&uu, out);
 589 }
 590
 591 void uuid_generate_time(uuid_t out)
 592 {
 593 #ifdef TLS
 594         THREAD_LOCAL int                num = 0;
 595         THREAD_LOCAL struct uuid        uu;
 596         THREAD_LOCAL time_t             last_time = 0;
 597         time_t                          now;
 598
 599         if (num > 0) {
 600                 now = time(0);
 601                 if (now > last_time+1)
 602                         num = 0;
 603         }
 604         if (num <= 0) {
 605                 num = 1000;
 606                 if (get_uuid_via_daemon(UUIDD_OP_BULK_TIME_UUID,
 607                                         out, &num) == 0) {
 608                         last_time = time(0);
 609                         uuid_unpack(out, &uu);
 610                         num--;
 611                         return;
 612                 }
 613                 num = 0;
 614         }
 615         if (num > 0) {
 616                 uu.time_low++;
 617                 if (uu.time_low == 0) {
 618                         uu.time_mid++;
 619                         if (uu.time_mid == 0)
 620                                 uu.time_hi_and_version++;
 621                 }
 622                 num--;
 623                 uuid_pack(&uu, out);
 624                 return;
 625         }
 626 #else
 627         if (get_uuid_via_daemon(UUIDD_OP_TIME_UUID, out, 0) == 0)
 628                 return;
 629 #endif
 630
 631         uuid__generate_time(out, 0);
 632 }
 633
 634
 635 void uuid__generate_random(uuid_t out, int *num)
 636 {
 637         uuid_t  buf;
 638         struct uuid uu;
 639         int i, n;
 640
 641         if (!num || !*num)
 642                 n = 1;
 643         else
 644                 n = *num;
 645
 646         for (i = 0; i < n; i++) {
 647                 get_random_bytes(buf, sizeof(buf));
 648                 uuid_unpack(buf, &uu);
 649
 650                 uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
 651                 uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF)
 652                         | 0x4000;
 653                 uuid_pack(&uu, out);
 654                 out += sizeof(uuid_t);
 655         }
 656 }
 657
 658 void uuid_generate_random(uuid_t out)
 659 {
 660         int     num = 1;
 661         /* No real reason to use the daemon for random uuid's -- yet */
 662
 663         uuid__generate_random(out, &num);
 664 }
 665
 666
 667 /*
 668  * This is the generic front-end to uuid_generate_random and
 669  * uuid_generate_time.  It uses uuid_generate_random only if
 670  * /dev/urandom is available, since otherwise we won't have
 671  * high-quality randomness.
 672  */
 673 void uuid_generate(uuid_t out)
 674 {
 675         if (get_random_fd() >= 0)
 676                 uuid_generate_random(out);
 677         else
 678                 uuid_generate_time(out);
 679 }