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 #ifdef _WIN32
  45 #define _WIN32_WINNT 0x0500
  46 #include <windows.h>
  47 #define UUID MYUUID
  48 #endif
  49 #include <stdio.h>
  50 #ifdef HAVE_UNISTD_H
  51 #include <unistd.h>
  52 #endif
  53 #ifdef HAVE_STDLIB_H
  54 #include <stdlib.h>
  55 #endif
  56 #include <string.h>
  57 #include <fcntl.h>
  58 #include <errno.h>
  59 #include <sys/types.h>
  60 #ifdef HAVE_SYS_TIME_H
  61 #include <sys/time.h>
  62 #endif
  63 #ifdef HAVE_SYS_WAIT_H
  64 #include <sys/wait.h>
  65 #endif
  66 #include <sys/stat.h>
  67 #ifdef HAVE_SYS_FILE_H
  68 #include <sys/file.h>
  69 #endif
  70 #ifdef HAVE_SYS_IOCTL_H
  71 #include <sys/ioctl.h>
  72 #endif
  73 #ifdef HAVE_SYS_RANDOM_H
  74 #include <sys/random.h>
  75 #endif
  76 #ifdef HAVE_SYS_SOCKET_H
  77 #include <sys/socket.h>
  78 #endif
  79 #ifdef HAVE_SYS_UN_H
  80 #include <sys/un.h>
  81 #endif
  82 #ifdef HAVE_SYS_SOCKIO_H
  83 #include <sys/sockio.h>
  84 #endif
  85 #ifdef HAVE_NET_IF_H
  86 #include <net/if.h>
  87 #endif
  88 #ifdef HAVE_NETINET_IN_H
  89 #include <netinet/in.h>
  90 #endif
  91 #ifdef HAVE_NET_IF_DL_H
  92 #include <net/if_dl.h>
  93 #endif
  94 #if defined(__linux__) && defined(HAVE_SYS_SYSCALL_H)
  95 #include <sys/syscall.h>
  96 #endif
  97 #ifdef HAVE_SYS_RESOURCE_H
  98 #include <sys/resource.h>
  99 #endif
 100
 101 #include "uuidP.h"
 102 #include "uuidd.h"
 103
 104 #ifdef HAVE_SRANDOM
 105 #define srand(x)        srandom(x)
 106 #define rand()          random()
 107 #endif
 108
 109 #ifdef TLS
 110 #define THREAD_LOCAL static TLS
 111 #else
 112 #define THREAD_LOCAL static
 113 #endif
 114
 115 #if defined(__linux__) && defined(__NR_gettid) && defined(HAVE_JRAND48)
 116 #define DO_JRAND_MIX
 117 THREAD_LOCAL unsigned short jrand_seed[3];
 118 #endif
 119
 120 static int get_random_fd(void)
 121 {
 122         struct timeval  tv;
 123         static int      fd = -2;
 124         int             i;
 125
 126         if (fd == -2) {
 127                 gettimeofday(&tv, 0);
 128 #ifndef _WIN32
 129                 fd = open("/dev/urandom", O_RDONLY);
 130                 if (fd == -1)
 131                         fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
 132                 if (fd >= 0) {
 133                         i = fcntl(fd, F_GETFD);
 134                         if (i >= 0)
 135                                 fcntl(fd, F_SETFD, i | FD_CLOEXEC);
 136                 }
 137 #endif
 138                 srand(((unsigned)getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
 139 #ifdef DO_JRAND_MIX
 140                 jrand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
 141                 jrand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
 142                 jrand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
 143 #endif
 144         }
 145         /* Crank the random number generator a few times */
 146         gettimeofday(&tv, 0);
 147         for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
 148                 rand();
 149         return fd;
 150 }
 151
 152
 153 /*
 154  * Generate a series of random bytes.  Use /dev/urandom if possible,
 155  * and if not, use srandom/random.
 156  */
 157 static void get_random_bytes(void *buf, int nbytes)
 158 {
 159         int i, n = nbytes, fd;
 160         int lose_counter = 0;
 161         unsigned char *cp = buf;
 162
 163 #ifdef HAVE_GETRANDOM
 164         i = getrandom(buf, nbytes, 0);
 165         if (i == nbytes)
 166                 return;
 167 #endif
 168 #ifdef HAVE_GETENTROPY
 169         if (getentropy(buf, nbytes) == 0)
 170                 return;
 171 #endif
 172
 173         fd = get_random_fd();
 174         if (fd >= 0) {
 175                 while (n > 0) {
 176                         i = read(fd, cp, n);
 177                         if (i <= 0) {
 178                                 if (lose_counter++ > 16)
 179                                         break;
 180                                 continue;
 181                         }
 182                         n -= i;
 183                         cp += i;
 184                         lose_counter = 0;
 185                 }
 186         }
 187
 188         /*
 189          * We do this all the time, but this is the only source of
 190          * randomness if /dev/random/urandom is out to lunch.
 191          */
 192         for (cp = buf, i = 0; i < nbytes; i++)
 193                 *cp++ ^= (rand() >> 7) & 0xFF;
 194 #ifdef DO_JRAND_MIX
 195         {
 196                 unsigned short tmp_seed[3];
 197
 198                 memcpy(tmp_seed, jrand_seed, sizeof(tmp_seed));
 199                 jrand_seed[2] = jrand_seed[2] ^ syscall(__NR_gettid);
 200                 for (cp = buf, i = 0; i < nbytes; i++)
 201                         *cp++ ^= (jrand48(tmp_seed) >> 7) & 0xFF;
 202                 memcpy(jrand_seed, tmp_seed,
 203                        sizeof(jrand_seed) - sizeof(unsigned short));
 204         }
 205 #endif
 206
 207         return;
 208 }
 209
 210 /*
 211  * Get the ethernet hardware address, if we can find it...
 212  *
 213  * XXX for a windows version, probably should use GetAdaptersInfo:
 214  * http://www.codeguru.com/cpp/i-n/network/networkinformation/article.php/c5451
 215  * commenting out get_node_id just to get gen_uuid to compile under windows
 216  * is not the right way to go!
 217  */
 218 static int get_node_id(unsigned char *node_id)
 219 {
 220 #ifdef HAVE_NET_IF_H
 221         int             sd;
 222         struct ifreq    ifr, *ifrp;
 223         struct ifconf   ifc;
 224         char buf[1024];
 225         int             n, i;
 226         unsigned char   *a;
 227 #ifdef HAVE_NET_IF_DL_H
 228         struct sockaddr_dl *sdlp;
 229 #endif
 230
 231 /*
 232  * BSD 4.4 defines the size of an ifreq to be
 233  * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
 234  * However, under earlier systems, sa_len isn't present, so the size is
 235  * just sizeof(struct ifreq)
 236  */
 237 #ifdef HAVE_SA_LEN
 238 #ifndef max
 239 #define max(a,b) ((a) > (b) ? (a) : (b))
 240 #endif
 241 #define ifreq_size(i) max(sizeof(struct ifreq),\
 242      sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
 243 #else
 244 #define ifreq_size(i) sizeof(struct ifreq)
 245 #endif /* HAVE_SA_LEN*/
 246
 247         sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 248         if (sd < 0) {
 249                 return -1;
 250         }
 251         memset(buf, 0, sizeof(buf));
 252         ifc.ifc_len = sizeof(buf);
 253         ifc.ifc_buf = buf;
 254         if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
 255                 close(sd);
 256                 return -1;
 257         }
 258         n = ifc.ifc_len;
 259         for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
 260                 ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
 261                 strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
 262 #ifdef SIOCGIFHWADDR
 263                 if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
 264                         continue;
 265                 a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
 266 #else
 267 #ifdef SIOCGENADDR
 268                 if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
 269                         continue;
 270                 a = (unsigned char *) ifr.ifr_enaddr;
 271 #else
 272 #ifdef HAVE_NET_IF_DL_H
 273                 sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
 274                 if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
 275                         continue;
 276                 a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
 277 #else
 278                 /*
 279                  * XXX we don't have a way of getting the hardware
 280                  * address
 281                  */
 282                 close(sd);
 283                 return 0;
 284 #endif /* HAVE_NET_IF_DL_H */
 285 #endif /* SIOCGENADDR */
 286 #endif /* SIOCGIFHWADDR */
 287                 if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
 288                         continue;
 289                 if (node_id) {
 290                         memcpy(node_id, a, 6);
 291                         close(sd);
 292                         return 1;
 293                 }
 294         }
 295         close(sd);
 296 #endif
 297         return 0;
 298 }
 299
 300 /* Assume that the gettimeofday() has microsecond granularity */
 301 #define MAX_ADJUSTMENT 10
 302
 303 static int get_clock(uint32_t *clock_high, uint32_t *clock_low,
 304                      uint16_t *ret_clock_seq, int *num)
 305 {
 306         THREAD_LOCAL int                adjustment = 0;
 307         THREAD_LOCAL struct timeval     last = {0, 0};
 308         THREAD_LOCAL int                state_fd = -2;
 309         THREAD_LOCAL FILE               *state_f;
 310         THREAD_LOCAL uint16_t           clock_seq;
 311         struct timeval                  tv;
 312 #ifndef _WIN32
 313         struct flock                    fl;
 314 #endif
 315         uint64_t                        clock_reg;
 316         mode_t                          save_umask;
 317         int                             len;
 318
 319         if (state_fd == -2) {
 320                 save_umask = umask(0);
 321                 state_fd = open("/var/lib/libuuid/clock.txt",
 322                                 O_RDWR|O_CREAT, 0660);
 323                 (void) umask(save_umask);
 324                 if (state_fd >= 0) {
 325                         state_f = fdopen(state_fd, "r+");
 326                         if (!state_f) {
 327                                 close(state_fd);
 328                                 state_fd = -1;
 329                         }
 330                 }
 331         }
 332 #ifndef _WIN32
 333         fl.l_type = F_WRLCK;
 334         fl.l_whence = SEEK_SET;
 335         fl.l_start = 0;
 336         fl.l_len = 0;
 337         fl.l_pid = 0;
 338         if (state_fd >= 0) {
 339                 rewind(state_f);
 340                 while (fcntl(state_fd, F_SETLKW, &fl) < 0) {
 341                         if ((errno == EAGAIN) || (errno == EINTR))
 342                                 continue;
 343                         fclose(state_f);
 344                         state_fd = -1;
 345                         break;
 346                 }
 347         }
 348 #endif
 349         if (state_fd >= 0) {
 350                 unsigned int cl;
 351                 unsigned long tv1, tv2;
 352                 int a;
 353
 354                 if (fscanf(state_f, "clock: %04x tv: %lu %lu adj: %d\n",
 355                            &cl, &tv1, &tv2, &a) == 4) {
 356                         clock_seq = cl & 0x3FFF;
 357                         last.tv_sec = tv1;
 358                         last.tv_usec = tv2;
 359                         adjustment = a;
 360                 }
 361         }
 362
 363         if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
 364                 get_random_bytes(&clock_seq, sizeof(clock_seq));
 365                 clock_seq &= 0x3FFF;
 366                 gettimeofday(&last, 0);
 367                 last.tv_sec--;
 368         }
 369
 370 try_again:
 371         gettimeofday(&tv, 0);
 372         if ((tv.tv_sec < last.tv_sec) ||
 373             ((tv.tv_sec == last.tv_sec) &&
 374              (tv.tv_usec < last.tv_usec))) {
 375                 clock_seq = (clock_seq+1) & 0x3FFF;
 376                 adjustment = 0;
 377                 last = tv;
 378         } else if ((tv.tv_sec == last.tv_sec) &&
 379             (tv.tv_usec == last.tv_usec)) {
 380                 if (adjustment >= MAX_ADJUSTMENT)
 381                         goto try_again;
 382                 adjustment++;
 383         } else {
 384                 adjustment = 0;
 385                 last = tv;
 386         }
 387
 388         clock_reg = tv.tv_usec*10 + adjustment;
 389         clock_reg += ((uint64_t) tv.tv_sec)*10000000;
 390         clock_reg += (((uint64_t) 0x01B21DD2) << 32) + 0x13814000;
 391
 392         if (num && (*num > 1)) {
 393                 adjustment += *num - 1;
 394                 last.tv_usec += adjustment / 10;
 395                 adjustment = adjustment % 10;
 396                 last.tv_sec += last.tv_usec / 1000000;
 397                 last.tv_usec = last.tv_usec % 1000000;
 398         }
 399
 400         if (state_fd > 0) {
 401                 rewind(state_f);
 402                 len = fprintf(state_f,
 403                               "clock: %04x tv: %016lu %08lu adj: %08d\n",
 404                               clock_seq, (unsigned long)last.tv_sec,
 405                               (unsigned long)last.tv_usec, adjustment);
 406                 fflush(state_f);
 407                 if (ftruncate(state_fd, len) < 0) {
 408                         fprintf(state_f, "                   \n");
 409                         fflush(state_f);
 410                 }
 411                 rewind(state_f);
 412 #ifndef _WIN32
 413                 fl.l_type = F_UNLCK;
 414                 if (fcntl(state_fd, F_SETLK, &fl) < 0) {
 415                         fclose(state_f);
 416                         state_fd = -1;
 417                 }
 418 #endif
 419         }
 420
 421         *clock_high = clock_reg >> 32;
 422         *clock_low = clock_reg;
 423         *ret_clock_seq = clock_seq;
 424         return 0;
 425 }
 426
 427 #if defined(USE_UUIDD) && defined(HAVE_SYS_UN_H)
 428 static ssize_t read_all(int fd, char *buf, size_t count)
 429 {
 430         ssize_t ret;
 431         ssize_t c = 0;
 432         int tries = 0;
 433
 434         memset(buf, 0, count);
 435         while (count > 0) {
 436                 ret = read(fd, buf, count);
 437                 if (ret <= 0) {
 438                         if ((errno == EAGAIN || errno == EINTR || ret == 0) &&
 439                             (tries++ < 5))
 440                                 continue;
 441                         return c ? c : -1;
 442                 }
 443                 if (ret > 0)
 444                         tries = 0;
 445                 count -= ret;
 446                 buf += ret;
 447                 c += ret;
 448         }
 449         return c;
 450 }
 451
 452 /*
 453  * Close all file descriptors
 454  */
 455 static void close_all_fds(void)
 456 {
 457         int i, max;
 458
 459 #if defined(HAVE_SYSCONF) && defined(_SC_OPEN_MAX)
 460         max = sysconf(_SC_OPEN_MAX);
 461 #elif defined(HAVE_GETDTABLESIZE)
 462         max = getdtablesize();
 463 #elif defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
 464         struct rlimit rl;
 465
 466         getrlimit(RLIMIT_NOFILE, &rl);
 467         max = rl.rlim_cur;
 468 #else
 469         max = OPEN_MAX;
 470 #endif
 471
 472         for (i=0; i < max; i++) {
 473                 close(i);
 474                 if (i <= 2)
 475                         open("/dev/null", O_RDWR);
 476         }
 477 }
 478 #endif /* defined(USE_UUIDD) && defined(HAVE_SYS_UN_H) */
 479
 480 #if __GNUC_PREREQ (4, 6)
 481 #pragma GCC diagnostic push
 482 #if !defined(USE_UUIDD) || !defined(HAVE_SYS_UN_H)
 483 #pragma GCC diagnostic ignored "-Wunused-parameter"
 484 #endif
 485 #endif
 486 /*
 487  * Try using the uuidd daemon to generate the UUID
 488  *
 489  * Returns 0 on success, non-zero on failure.
 490  */
 491 static int get_uuid_via_daemon(int op, uuid_t out, int *num)
 492 {
 493 #if defined(USE_UUIDD) && defined(HAVE_SYS_UN_H)
 494         char op_buf[64];
 495         int op_len;
 496         int s;
 497         ssize_t ret;
 498         int32_t reply_len = 0, expected = 16;
 499         struct sockaddr_un srv_addr;
 500         struct stat st;
 501         pid_t pid;
 502         static const char *uuidd_path = UUIDD_PATH;
 503         static int access_ret = -2;
 504         static int start_attempts = 0;
 505
 506         if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
 507                 return -1;
 508
 509         srv_addr.sun_family = AF_UNIX;
 510         strcpy(srv_addr.sun_path, UUIDD_SOCKET_PATH);
 511
 512         if (connect(s, (const struct sockaddr *) &srv_addr,
 513                     sizeof(struct sockaddr_un)) < 0) {
 514                 if (access_ret == -2)
 515                         access_ret = access(uuidd_path, X_OK);
 516                 if (access_ret == 0)
 517                         access_ret = stat(uuidd_path, &st);
 518                 if (access_ret == 0 && (st.st_mode & (S_ISUID | S_ISGID)) == 0)
 519                         access_ret = access(UUIDD_DIR, W_OK);
 520                 if (access_ret == 0 && start_attempts++ < 5) {
 521                         if ((pid = fork()) == 0) {
 522                                 close_all_fds();
 523                                 execl(uuidd_path, "uuidd", "-qT", "300",
 524                                       (char *) NULL);
 525                                 exit(1);
 526                         }
 527                         (void) waitpid(pid, 0, 0);
 528                         if (connect(s, (const struct sockaddr *) &srv_addr,
 529                                     sizeof(struct sockaddr_un)) < 0)
 530                                 goto fail;
 531                 } else
 532                         goto fail;
 533         }
 534         op_buf[0] = op;
 535         op_len = 1;
 536         if (op == UUIDD_OP_BULK_TIME_UUID) {
 537                 memcpy(op_buf+1, num, sizeof(*num));
 538                 op_len += sizeof(*num);
 539                 expected += sizeof(*num);
 540         }
 541
 542         ret = write(s, op_buf, op_len);
 543         if (ret < 1)
 544                 goto fail;
 545
 546         ret = read_all(s, (char *) &reply_len, sizeof(reply_len));
 547         if (ret < 0)
 548                 goto fail;
 549
 550         if (reply_len != expected)
 551                 goto fail;
 552
 553         ret = read_all(s, op_buf, reply_len);
 554
 555         if (op == UUIDD_OP_BULK_TIME_UUID)
 556                 memcpy(op_buf+16, num, sizeof(int));
 557
 558         memcpy(out, op_buf, 16);
 559
 560         close(s);
 561         return ((ret == expected) ? 0 : -1);
 562
 563 fail:
 564         close(s);
 565 #endif
 566         return -1;
 567 }
 568 #if __GNUC_PREREQ (4, 6)
 569 #pragma GCC diagnostic pop
 570 #endif
 571
 572 void uuid__generate_time(uuid_t out, int *num)
 573 {
 574         static unsigned char node_id[6];
 575         static int has_init = 0;
 576         struct uuid uu;
 577         uint32_t        clock_mid;
 578
 579         if (!has_init) {
 580                 if (get_node_id(node_id) <= 0) {
 581                         get_random_bytes(node_id, 6);
 582                         /*
 583                          * Set multicast bit, to prevent conflicts
 584                          * with IEEE 802 addresses obtained from
 585                          * network cards
 586                          */
 587                         node_id[0] |= 0x01;
 588                 }
 589                 has_init = 1;
 590         }
 591         get_clock(&clock_mid, &uu.time_low, &uu.clock_seq, num);
 592         uu.clock_seq |= 0x8000;
 593         uu.time_mid = (uint16_t) clock_mid;
 594         uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
 595         memcpy(uu.node, node_id, 6);
 596         uuid_pack(&uu, out);
 597 }
 598
 599 void uuid_generate_time(uuid_t out)
 600 {
 601 #ifdef TLS
 602         THREAD_LOCAL int                num = 0;
 603         THREAD_LOCAL struct uuid        uu;
 604         THREAD_LOCAL time_t             last_time = 0;
 605         time_t                          now;
 606
 607         if (num > 0) {
 608                 now = time(0);
 609                 if (now > last_time+1)
 610                         num = 0;
 611         }
 612         if (num <= 0) {
 613                 num = 1000;
 614                 if (get_uuid_via_daemon(UUIDD_OP_BULK_TIME_UUID,
 615                                         out, &num) == 0) {
 616                         last_time = time(0);
 617                         uuid_unpack(out, &uu);
 618                         num--;
 619                         return;
 620                 }
 621                 num = 0;
 622         }
 623         if (num > 0) {
 624                 uu.time_low++;
 625                 if (uu.time_low == 0) {
 626                         uu.time_mid++;
 627                         if (uu.time_mid == 0)
 628                                 uu.time_hi_and_version++;
 629                 }
 630                 num--;
 631                 uuid_pack(&uu, out);
 632                 return;
 633         }
 634 #else
 635         if (get_uuid_via_daemon(UUIDD_OP_TIME_UUID, out, 0) == 0)
 636                 return;
 637 #endif
 638
 639         uuid__generate_time(out, 0);
 640 }
 641
 642
 643 void uuid__generate_random(uuid_t out, int *num)
 644 {
 645         uuid_t  buf;
 646         struct uuid uu;
 647         int i, n;
 648
 649         if (!num || !*num)
 650                 n = 1;
 651         else
 652                 n = *num;
 653
 654         for (i = 0; i < n; i++) {
 655                 get_random_bytes(buf, sizeof(buf));
 656                 uuid_unpack(buf, &uu);
 657
 658                 uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
 659                 uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF)
 660                         | 0x4000;
 661                 uuid_pack(&uu, out);
 662                 out += sizeof(uuid_t);
 663         }
 664 }
 665
 666 void uuid_generate_random(uuid_t out)
 667 {
 668         int     num = 1;
 669         /* No real reason to use the daemon for random uuid's -- yet */
 670
 671         uuid__generate_random(out, &num);
 672 }
 673
 674
 675 /*
 676  * This is the generic front-end to uuid_generate_random and
 677  * uuid_generate_time.  It uses uuid_generate_random only if
 678  * /dev/urandom is available, since otherwise we won't have
 679  * high-quality randomness.
 680  */
 681 void uuid_generate(uuid_t out)
 682 {
 683         if (get_random_fd() >= 0)
 684                 uuid_generate_random(out);
 685         else
 686                 uuid_generate_time(out);
 687 }