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 #define _DEFAULT_SOURCE   /* since glibc 2.20 _SVID_SOURCE is deprecated */
  41
  42 #include "config.h"
  43
  44 #include <stdio.h>
  45 #ifdef HAVE_UNISTD_H
  46 #include <unistd.h>
  47 #endif
  48 #ifdef HAVE_STDLIB_H
  49 #include <stdlib.h>
  50 #endif
  51 #include <string.h>
  52 #include <fcntl.h>
  53 #include <errno.h>
  54 #include <sys/types.h>
  55 #ifdef HAVE_SYS_TIME_H
  56 #include <sys/time.h>
  57 #endif
  58 #ifdef HAVE_SYS_WAIT_H
  59 #include <sys/wait.h>
  60 #endif
  61 #include <sys/stat.h>
  62 #ifdef HAVE_SYS_FILE_H
  63 #include <sys/file.h>
  64 #endif
  65 #ifdef HAVE_SYS_IOCTL_H
  66 #include <sys/ioctl.h>
  67 #endif
  68 #ifdef HAVE_SYS_RANDOM_H
  69 #include <sys/random.h>
  70 #endif
  71 #ifdef HAVE_SYS_SOCKET_H
  72 #include <sys/socket.h>
  73 #endif
  74 #ifdef HAVE_SYS_UN_H
  75 #include <sys/un.h>
  76 #endif
  77 #ifdef HAVE_SYS_SOCKIO_H
  78 #include <sys/sockio.h>
  79 #endif
  80 #ifdef HAVE_NET_IF_H
  81 #include <net/if.h>
  82 #endif
  83 #ifdef HAVE_NETINET_IN_H
  84 #include <netinet/in.h>
  85 #endif
  86 #ifdef HAVE_NET_IF_DL_H
  87 #include <net/if_dl.h>
  88 #endif
  89 #if defined(__linux__) && defined(HAVE_SYS_SYSCALL_H)
  90 #include <sys/syscall.h>
  91 #endif
  92 #ifdef HAVE_SYS_RESOURCE_H
  93 #include <sys/resource.h>
  94 #endif
  95
  96 #include "uuidP.h"
  97 #include "uuidd.h"
  98
  99 #ifdef HAVE_SRANDOM
 100 #define srand(x)        srandom(x)
 101 #define rand()          random()
 102 #endif
 103
 104 #ifdef TLS
 105 #define THREAD_LOCAL static TLS
 106 #else
 107 #define THREAD_LOCAL static
 108 #endif
 109
 110 #if defined(__linux__) && defined(__NR_gettid) && defined(HAVE_JRAND48)
 111 #define DO_JRAND_MIX
 112 THREAD_LOCAL unsigned short jrand_seed[3];
 113 #endif
 114
 115 static int get_random_fd(void)
 116 {
 117         struct timeval  tv;
 118         static int      fd = -2;
 119         int             i;
 120
 121         if (fd == -2) {
 122                 gettimeofday(&tv, 0);
 123 #ifndef _WIN32
 124                 fd = open("/dev/urandom", O_RDONLY);
 125                 if (fd == -1)
 126                         fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
 127                 if (fd >= 0) {
 128                         i = fcntl(fd, F_GETFD);
 129                         if (i >= 0)
 130                                 fcntl(fd, F_SETFD, i | FD_CLOEXEC);
 131                 }
 132 #endif
 133                 srand(((unsigned)getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
 134 #ifdef DO_JRAND_MIX
 135                 jrand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
 136                 jrand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
 137                 jrand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
 138 #endif
 139         }
 140         /* Crank the random number generator a few times */
 141         gettimeofday(&tv, 0);
 142         for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
 143                 rand();
 144         return fd;
 145 }
 146
 147
 148 /*
 149  * Generate a series of random bytes.  Use /dev/urandom if possible,
 150  * and if not, use srandom/random.
 151  */
 152 static void get_random_bytes(void *buf, int nbytes)
 153 {
 154         int i, n = nbytes, fd;
 155         int lose_counter = 0;
 156         unsigned char *cp = buf;
 157
 158 #ifdef HAVE_GETRANDOM
 159         i = getrandom(buf, nbytes, 0);
 160         if (i == nbytes)
 161                 return;
 162 #endif
 163 #ifdef HAVE_GETENTROPY
 164         if (getentropy(buf, nbytes) == 0)
 165                 return;
 166 #endif
 167
 168         fd = get_random_fd();
 169         if (fd >= 0) {
 170                 while (n > 0) {
 171                         i = read(fd, cp, n);
 172                         if (i <= 0) {
 173                                 if (lose_counter++ > 16)
 174                                         break;
 175                                 continue;
 176                         }
 177                         n -= i;
 178                         cp += i;
 179                         lose_counter = 0;
 180                 }
 181         }
 182
 183         /*
 184          * We do this all the time, but this is the only source of
 185          * randomness if /dev/random/urandom is out to lunch.
 186          */
 187         for (cp = buf, i = 0; i < nbytes; i++)
 188                 *cp++ ^= (rand() >> 7) & 0xFF;
 189 #ifdef DO_JRAND_MIX
 190         {
 191                 unsigned short tmp_seed[3];
 192
 193                 memcpy(tmp_seed, jrand_seed, sizeof(tmp_seed));
 194                 jrand_seed[2] = jrand_seed[2] ^ syscall(__NR_gettid);
 195                 for (cp = buf, i = 0; i < nbytes; i++)
 196                         *cp++ ^= (jrand48(tmp_seed) >> 7) & 0xFF;
 197                 memcpy(jrand_seed, tmp_seed,
 198                        sizeof(jrand_seed) - sizeof(unsigned short));
 199         }
 200 #endif
 201
 202         return;
 203 }
 204
 205 /*
 206  * Get the ethernet hardware address, if we can find it...
 207  *
 208  * XXX for a windows version, probably should use GetAdaptersInfo:
 209  * http://www.codeguru.com/cpp/i-n/network/networkinformation/article.php/c5451
 210  * commenting out get_node_id just to get gen_uuid to compile under windows
 211  * is not the right way to go!
 212  */
 213 static int get_node_id(unsigned char *node_id)
 214 {
 215 #ifdef HAVE_NET_IF_H
 216         int             sd;
 217         struct ifreq    ifr, *ifrp;
 218         struct ifconf   ifc;
 219         char buf[1024];
 220         int             n, i;
 221         unsigned char   *a;
 222 #ifdef HAVE_NET_IF_DL_H
 223         struct sockaddr_dl *sdlp;
 224 #endif
 225
 226 /*
 227  * BSD 4.4 defines the size of an ifreq to be
 228  * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
 229  * However, under earlier systems, sa_len isn't present, so the size is
 230  * just sizeof(struct ifreq)
 231  */
 232 #ifdef HAVE_SA_LEN
 233 #ifndef max
 234 #define max(a,b) ((a) > (b) ? (a) : (b))
 235 #endif
 236 #define ifreq_size(i) max(sizeof(struct ifreq),\
 237      sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
 238 #else
 239 #define ifreq_size(i) sizeof(struct ifreq)
 240 #endif /* HAVE_SA_LEN*/
 241
 242         sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 243         if (sd < 0) {
 244                 return -1;
 245         }
 246         memset(buf, 0, sizeof(buf));
 247         ifc.ifc_len = sizeof(buf);
 248         ifc.ifc_buf = buf;
 249         if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
 250                 close(sd);
 251                 return -1;
 252         }
 253         n = ifc.ifc_len;
 254         for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
 255                 ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
 256                 strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
 257 #ifdef SIOCGIFHWADDR
 258                 if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
 259                         continue;
 260                 a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
 261 #else
 262 #ifdef SIOCGENADDR
 263                 if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
 264                         continue;
 265                 a = (unsigned char *) ifr.ifr_enaddr;
 266 #else
 267 #ifdef HAVE_NET_IF_DL_H
 268                 sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
 269                 if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
 270                         continue;
 271                 a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
 272 #else
 273                 /*
 274                  * XXX we don't have a way of getting the hardware
 275                  * address
 276                  */
 277                 close(sd);
 278                 return 0;
 279 #endif /* HAVE_NET_IF_DL_H */
 280 #endif /* SIOCGENADDR */
 281 #endif /* SIOCGIFHWADDR */
 282                 if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
 283                         continue;
 284                 if (node_id) {
 285                         memcpy(node_id, a, 6);
 286                         close(sd);
 287                         return 1;
 288                 }
 289         }
 290         close(sd);
 291 #endif
 292         return 0;
 293 }
 294
 295 /* Assume that the gettimeofday() has microsecond granularity */
 296 #define MAX_ADJUSTMENT 10
 297
 298 static int get_clock(uint32_t *clock_high, uint32_t *clock_low,
 299                      uint16_t *ret_clock_seq, int *num)
 300 {
 301         THREAD_LOCAL int                adjustment = 0;
 302         THREAD_LOCAL struct timeval     last = {0, 0};
 303         THREAD_LOCAL int                state_fd = -2;
 304         THREAD_LOCAL FILE               *state_f;
 305         THREAD_LOCAL uint16_t           clock_seq;
 306         struct timeval                  tv;
 307 #ifndef _WIN32
 308         struct flock                    fl;
 309 #endif
 310         uint64_t                        clock_reg;
 311         mode_t                          save_umask;
 312         int                             len;
 313
 314         if (state_fd == -2) {
 315                 save_umask = umask(0);
 316                 state_fd = open("/var/lib/libuuid/clock.txt",
 317                                 O_RDWR|O_CREAT, 0660);
 318                 (void) umask(save_umask);
 319                 if (state_fd >= 0) {
 320                         state_f = fdopen(state_fd, "r+");
 321                         if (!state_f) {
 322                                 close(state_fd);
 323                                 state_fd = -1;
 324                         }
 325                 }
 326         }
 327 #ifndef _WIN32
 328         fl.l_type = F_WRLCK;
 329         fl.l_whence = SEEK_SET;
 330         fl.l_start = 0;
 331         fl.l_len = 0;
 332         fl.l_pid = 0;
 333         if (state_fd >= 0) {
 334                 rewind(state_f);
 335                 while (fcntl(state_fd, F_SETLKW, &fl) < 0) {
 336                         if ((errno == EAGAIN) || (errno == EINTR))
 337                                 continue;
 338                         fclose(state_f);
 339                         state_fd = -1;
 340                         break;
 341                 }
 342         }
 343 #endif
 344         if (state_fd >= 0) {
 345                 unsigned int cl;
 346                 unsigned long tv1, tv2;
 347                 int a;
 348
 349                 if (fscanf(state_f, "clock: %04x tv: %lu %lu adj: %d\n",
 350                            &cl, &tv1, &tv2, &a) == 4) {
 351                         clock_seq = cl & 0x3FFF;
 352                         last.tv_sec = tv1;
 353                         last.tv_usec = tv2;
 354                         adjustment = a;
 355                 }
 356         }
 357
 358         if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
 359                 get_random_bytes(&clock_seq, sizeof(clock_seq));
 360                 clock_seq &= 0x3FFF;
 361                 gettimeofday(&last, 0);
 362                 last.tv_sec--;
 363         }
 364
 365 try_again:
 366         gettimeofday(&tv, 0);
 367         if ((tv.tv_sec < last.tv_sec) ||
 368             ((tv.tv_sec == last.tv_sec) &&
 369              (tv.tv_usec < last.tv_usec))) {
 370                 clock_seq = (clock_seq+1) & 0x3FFF;
 371                 adjustment = 0;
 372                 last = tv;
 373         } else if ((tv.tv_sec == last.tv_sec) &&
 374             (tv.tv_usec == last.tv_usec)) {
 375                 if (adjustment >= MAX_ADJUSTMENT)
 376                         goto try_again;
 377                 adjustment++;
 378         } else {
 379                 adjustment = 0;
 380                 last = tv;
 381         }
 382
 383         clock_reg = tv.tv_usec*10 + adjustment;
 384         clock_reg += ((uint64_t) tv.tv_sec)*10000000;
 385         clock_reg += (((uint64_t) 0x01B21DD2) << 32) + 0x13814000;
 386
 387         if (num && (*num > 1)) {
 388                 adjustment += *num - 1;
 389                 last.tv_usec += adjustment / 10;
 390                 adjustment = adjustment % 10;
 391                 last.tv_sec += last.tv_usec / 1000000;
 392                 last.tv_usec = last.tv_usec % 1000000;
 393         }
 394
 395         if (state_fd > 0) {
 396                 rewind(state_f);
 397                 len = fprintf(state_f,
 398                               "clock: %04x tv: %016lu %08lu adj: %08d\n",
 399                               clock_seq, (unsigned long)last.tv_sec,
 400                               (unsigned long)last.tv_usec, adjustment);
 401                 fflush(state_f);
 402                 if (ftruncate(state_fd, len) < 0) {
 403                         fprintf(state_f, "                   \n");
 404                         fflush(state_f);
 405                 }
 406                 rewind(state_f);
 407 #ifndef _WIN32
 408                 fl.l_type = F_UNLCK;
 409                 if (fcntl(state_fd, F_SETLK, &fl) < 0) {
 410                         fclose(state_f);
 411                         state_fd = -1;
 412                 }
 413 #endif
 414         }
 415
 416         *clock_high = clock_reg >> 32;
 417         *clock_low = clock_reg;
 418         *ret_clock_seq = clock_seq;
 419         return 0;
 420 }
 421
 422 #if defined(USE_UUIDD) && defined(HAVE_SYS_UN_H)
 423 static ssize_t read_all(int fd, char *buf, size_t count)
 424 {
 425         ssize_t ret;
 426         ssize_t c = 0;
 427         int tries = 0;
 428
 429         memset(buf, 0, count);
 430         while (count > 0) {
 431                 ret = read(fd, buf, count);
 432                 if (ret <= 0) {
 433                         if ((errno == EAGAIN || errno == EINTR || ret == 0) &&
 434                             (tries++ < 5))
 435                                 continue;
 436                         return c ? c : -1;
 437                 }
 438                 if (ret > 0)
 439                         tries = 0;
 440                 count -= ret;
 441                 buf += ret;
 442                 c += ret;
 443         }
 444         return c;
 445 }
 446
 447 /*
 448  * Close all file descriptors
 449  */
 450 static void close_all_fds(void)
 451 {
 452         int i, max;
 453
 454 #if defined(HAVE_SYSCONF) && defined(_SC_OPEN_MAX)
 455         max = sysconf(_SC_OPEN_MAX);
 456 #elif defined(HAVE_GETDTABLESIZE)
 457         max = getdtablesize();
 458 #elif defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
 459         struct rlimit rl;
 460
 461         getrlimit(RLIMIT_NOFILE, &rl);
 462         max = rl.rlim_cur;
 463 #else
 464         max = OPEN_MAX;
 465 #endif
 466
 467         for (i=0; i < max; i++) {
 468                 close(i);
 469                 if (i <= 2)
 470                         open("/dev/null", O_RDWR);
 471         }
 472 }
 473 #endif /* defined(USE_UUIDD) && defined(HAVE_SYS_UN_H) */
 474
 475 #if __GNUC_PREREQ (4, 6)
 476 #pragma GCC diagnostic push
 477 #if !defined(USE_UUIDD) || !defined(HAVE_SYS_UN_H)
 478 #pragma GCC diagnostic ignored "-Wunused-parameter"
 479 #endif
 480 #endif
 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 #if __GNUC_PREREQ (4, 6)
 564 #pragma GCC diagnostic pop
 565 #endif
 566
 567 void uuid__generate_time(uuid_t out, int *num)
 568 {
 569         static unsigned char node_id[6];
 570         static int has_init = 0;
 571         struct uuid uu;
 572         uint32_t        clock_mid;
 573
 574         if (!has_init) {
 575                 if (get_node_id(node_id) <= 0) {
 576                         get_random_bytes(node_id, 6);
 577                         /*
 578                          * Set multicast bit, to prevent conflicts
 579                          * with IEEE 802 addresses obtained from
 580                          * network cards
 581                          */
 582                         node_id[0] |= 0x01;
 583                 }
 584                 has_init = 1;
 585         }
 586         get_clock(&clock_mid, &uu.time_low, &uu.clock_seq, num);
 587         uu.clock_seq |= 0x8000;
 588         uu.time_mid = (uint16_t) clock_mid;
 589         uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
 590         memcpy(uu.node, node_id, 6);
 591         uuid_pack(&uu, out);
 592 }
 593
 594 void uuid_generate_time(uuid_t out)
 595 {
 596 #ifdef TLS
 597         THREAD_LOCAL int                num = 0;
 598         THREAD_LOCAL struct uuid        uu;
 599         THREAD_LOCAL time_t             last_time = 0;
 600         time_t                          now;
 601
 602         if (num > 0) {
 603                 now = time(0);
 604                 if (now > last_time+1)
 605                         num = 0;
 606         }
 607         if (num <= 0) {
 608                 num = 1000;
 609                 if (get_uuid_via_daemon(UUIDD_OP_BULK_TIME_UUID,
 610                                         out, &num) == 0) {
 611                         last_time = time(0);
 612                         uuid_unpack(out, &uu);
 613                         num--;
 614                         return;
 615                 }
 616                 num = 0;
 617         }
 618         if (num > 0) {
 619                 uu.time_low++;
 620                 if (uu.time_low == 0) {
 621                         uu.time_mid++;
 622                         if (uu.time_mid == 0)
 623                                 uu.time_hi_and_version++;
 624                 }
 625                 num--;
 626                 uuid_pack(&uu, out);
 627                 return;
 628         }
 629 #else
 630         if (get_uuid_via_daemon(UUIDD_OP_TIME_UUID, out, 0) == 0)
 631                 return;
 632 #endif
 633
 634         uuid__generate_time(out, 0);
 635 }
 636
 637
 638 void uuid__generate_random(uuid_t out, int *num)
 639 {
 640         uuid_t  buf;
 641         struct uuid uu;
 642         int i, n;
 643
 644         if (!num || !*num)
 645                 n = 1;
 646         else
 647                 n = *num;
 648
 649         for (i = 0; i < n; i++) {
 650                 get_random_bytes(buf, sizeof(buf));
 651                 uuid_unpack(buf, &uu);
 652
 653                 uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
 654                 uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF)
 655                         | 0x4000;
 656                 uuid_pack(&uu, out);
 657                 out += sizeof(uuid_t);
 658         }
 659 }
 660
 661 void uuid_generate_random(uuid_t out)
 662 {
 663         int     num = 1;
 664         /* No real reason to use the daemon for random uuid's -- yet */
 665
 666         uuid__generate_random(out, &num);
 667 }
 668
 669
 670 /*
 671  * This is the generic front-end to uuid_generate_random and
 672  * uuid_generate_time.  It uses uuid_generate_random only if
 673  * /dev/urandom is available, since otherwise we won't have
 674  * high-quality randomness.
 675  */
 676 void uuid_generate(uuid_t out)
 677 {
 678         if (get_random_fd() >= 0)
 679                 uuid_generate_random(out);
 680         else
 681                 uuid_generate_time(out);
 682 }