diff options
Diffstat (limited to 'libuuid/src/gen_uuid.c')
| -rw-r--r-- | libuuid/src/gen_uuid.c | 120 |
1 files changed, 89 insertions, 31 deletions
diff --git a/libuuid/src/gen_uuid.c b/libuuid/src/gen_uuid.c index 826cd22..59e8c23 100644 --- a/libuuid/src/gen_uuid.c +++ b/libuuid/src/gen_uuid.c @@ -207,6 +207,28 @@ static int get_node_id(unsigned char *node_id) return 0; } +enum { STATE_FD_ERROR = -1, STATE_FD_INIT = -2 }; + +static int state_fd_init(const char *clock_file, FILE **fp) +{ + mode_t save_umask; + int state_fd; + FILE *state_f; + + save_umask = umask(0); + state_fd = open(clock_file, O_RDWR|O_CREAT|O_CLOEXEC, 0660); + (void) umask(save_umask); + if (state_fd != -1) { + state_f = fdopen(state_fd, "r+" UL_CLOEXECSTR); + if (!state_f) { + close(state_fd); + state_fd = STATE_FD_ERROR; + } else + *fp = state_f; + } + return state_fd; +} + /* Assume that the gettimeofday() has microsecond granularity */ #define MAX_ADJUSTMENT 10 /* Reserve a clock_seq value for the 'continuous clock' implementation */ @@ -223,32 +245,16 @@ static int get_clock(uint32_t *clock_high, uint32_t *clock_low, { THREAD_LOCAL int adjustment = 0; THREAD_LOCAL struct timeval last = {0, 0}; - THREAD_LOCAL int state_fd = -2; + THREAD_LOCAL int state_fd = STATE_FD_INIT; THREAD_LOCAL FILE *state_f; THREAD_LOCAL uint16_t clock_seq; struct timeval tv; uint64_t clock_reg; - mode_t save_umask; int ret = 0; - if (state_fd == -1) - ret = -1; + if (state_fd == STATE_FD_INIT) + state_fd = state_fd_init(LIBUUID_CLOCK_FILE, &state_f); - if (state_fd == -2) { - save_umask = umask(0); - state_fd = open(LIBUUID_CLOCK_FILE, O_RDWR|O_CREAT|O_CLOEXEC, 0660); - (void) umask(save_umask); - if (state_fd != -1) { - state_f = fdopen(state_fd, "r+" UL_CLOEXECSTR); - if (!state_f) { - close(state_fd); - state_fd = -1; - ret = -1; - } - } - else - ret = -1; - } if (state_fd >= 0) { rewind(state_f); while (flock(state_fd, LOCK_EX) < 0) { @@ -256,11 +262,13 @@ static int get_clock(uint32_t *clock_high, uint32_t *clock_low, continue; fclose(state_f); close(state_fd); - state_fd = -1; + state_fd = STATE_FD_ERROR; ret = -1; break; } - } + } else + ret = -1; + if (state_fd >= 0) { unsigned int cl; unsigned long tv1, tv2; @@ -355,44 +363,94 @@ static uint64_t get_clock_counter(void) /* * Get continuous clock value. * - * Return -1 if there is no further clock counter available, + * Return -1 if there is no valid clock counter available, * otherwise return 0. * * This implementation doesn't deliver clock counters based on * the current time because last_clock_reg is only incremented * by the number of requested UUIDs. * max_clock_offset is used to limit the offset of last_clock_reg. + * used/reserved UUIDs are written to LIBUUID_CLOCK_CONT_FILE. */ static int get_clock_cont(uint32_t *clock_high, uint32_t *clock_low, int num, uint32_t max_clock_offset) { - /* 100ns based time offset according to RFC 4122. 4.1.4. */ + /* all 64bit clock_reg values in this function represent '100ns ticks' + * due to the combination of tv_usec + MAX_ADJUSTMENT */ + + /* time offset according to RFC 4122. 4.1.4. */ const uint64_t reg_offset = (((uint64_t) 0x01B21DD2) << 32) + 0x13814000; static uint64_t last_clock_reg = 0; - uint64_t clock_reg; + static uint64_t saved_clock_reg = 0; + static int state_fd = STATE_FD_INIT; + static FILE *state_f = NULL; + uint64_t clock_reg, next_clock_reg; - if (last_clock_reg == 0) - last_clock_reg = get_clock_counter(); + if (state_fd == STATE_FD_ERROR) + return -1; clock_reg = get_clock_counter(); + + if (state_fd == STATE_FD_INIT) { + struct stat st; + + state_fd = state_fd_init(LIBUUID_CLOCK_CONT_FILE, &state_f); + if (state_fd == STATE_FD_ERROR) + return -1; + + if (fstat(state_fd, &st)) + goto error; + + if (st.st_size) { + rewind(state_f); + if (fscanf(state_f, "cont: %"SCNu64"\n", &last_clock_reg) != 1) + goto error; + } else + last_clock_reg = clock_reg; + + saved_clock_reg = last_clock_reg; + } + if (max_clock_offset) { - uint64_t clock_offset = max_clock_offset * 10000000ULL; - if (last_clock_reg < (clock_reg - clock_offset)) - last_clock_reg = clock_reg - clock_offset; + uint64_t co = 10000000ULL * (uint64_t)max_clock_offset; // clock_offset in [100ns] + + if ((last_clock_reg + co) < clock_reg) + last_clock_reg = clock_reg - co; } clock_reg += MAX_ADJUSTMENT; - if ((last_clock_reg + num) >= clock_reg) + next_clock_reg = last_clock_reg + (uint64_t)num; + if (next_clock_reg >= clock_reg) return -1; + if (next_clock_reg >= saved_clock_reg) { + uint64_t cl = next_clock_reg + 100000000ULL; // 10s interval in [100ns] + int l; + + rewind(state_f); + l = fprintf(state_f, "cont: %020"PRIu64" \n", cl); + if (l < 30 || fflush(state_f)) + goto error; + saved_clock_reg = cl; + } + *clock_high = (last_clock_reg + reg_offset) >> 32; *clock_low = last_clock_reg + reg_offset; - last_clock_reg += num; + last_clock_reg = next_clock_reg; return 0; + +error: + if (state_fd >= 0) + close(state_fd); + if (state_f) + fclose(state_f); + state_fd = STATE_FD_ERROR; + state_f = NULL; + return -1; } #if defined(HAVE_UUIDD) && defined(HAVE_SYS_UN_H) |