chiark / gitweb /
shared: add formats-util.h
[elogind.git] / src / shared / time-util.c
index 860be61..1c36c57 100644 (file)
 
 #include <time.h>
 #include <string.h>
 
 #include <time.h>
 #include <string.h>
+#include <sys/timex.h>
+#include <sys/timerfd.h>
 
 #include "util.h"
 #include "time-util.h"
 
 #include "util.h"
 #include "time-util.h"
+#include "strv.h"
 
 usec_t now(clockid_t clock_id) {
         struct timespec ts;
 
 usec_t now(clockid_t clock_id) {
         struct timespec ts;
@@ -46,25 +49,20 @@ dual_timestamp* dual_timestamp_from_realtime(dual_timestamp *ts, usec_t u) {
         int64_t delta;
         assert(ts);
 
         int64_t delta;
         assert(ts);
 
-        if (u == (usec_t) -1) {
-                ts->realtime = ts->monotonic = (usec_t) -1;
+        if (u == USEC_INFINITY || u <= 0) {
+                ts->realtime = ts->monotonic = u;
                 return ts;
         }
 
         ts->realtime = u;
 
                 return ts;
         }
 
         ts->realtime = u;
 
-        if (u == 0)
-                ts->monotonic = 0;
-        else {
-                delta = (int64_t) now(CLOCK_REALTIME) - (int64_t) u;
-
-                ts->monotonic = now(CLOCK_MONOTONIC);
+        delta = (int64_t) now(CLOCK_REALTIME) - (int64_t) u;
+        ts->monotonic = now(CLOCK_MONOTONIC);
 
 
-                if ((int64_t) ts->monotonic > delta)
-                        ts->monotonic -= delta;
-                else
-                        ts->monotonic = 0;
-        }
+        if ((int64_t) ts->monotonic > delta)
+                ts->monotonic -= delta;
+        else
+                ts->monotonic = 0;
 
         return ts;
 }
 
         return ts;
 }
@@ -73,8 +71,8 @@ dual_timestamp* dual_timestamp_from_monotonic(dual_timestamp *ts, usec_t u) {
         int64_t delta;
         assert(ts);
 
         int64_t delta;
         assert(ts);
 
-        if (u == (usec_t) -1) {
-                ts->realtime = ts->monotonic = (usec_t) -1;
+        if (u == USEC_INFINITY) {
+                ts->realtime = ts->monotonic = USEC_INFINITY;
                 return ts;
         }
 
                 return ts;
         }
 
@@ -95,10 +93,10 @@ usec_t timespec_load(const struct timespec *ts) {
 
         if (ts->tv_sec == (time_t) -1 &&
             ts->tv_nsec == (long) -1)
 
         if (ts->tv_sec == (time_t) -1 &&
             ts->tv_nsec == (long) -1)
-                return (usec_t) -1;
+                return USEC_INFINITY;
 
         if ((usec_t) ts->tv_sec > (UINT64_MAX - (ts->tv_nsec / NSEC_PER_USEC)) / USEC_PER_SEC)
 
         if ((usec_t) ts->tv_sec > (UINT64_MAX - (ts->tv_nsec / NSEC_PER_USEC)) / USEC_PER_SEC)
-                return (usec_t) -1;
+                return USEC_INFINITY;
 
         return
                 (usec_t) ts->tv_sec * USEC_PER_SEC +
 
         return
                 (usec_t) ts->tv_sec * USEC_PER_SEC +
@@ -108,7 +106,7 @@ usec_t timespec_load(const struct timespec *ts) {
 struct timespec *timespec_store(struct timespec *ts, usec_t u)  {
         assert(ts);
 
 struct timespec *timespec_store(struct timespec *ts, usec_t u)  {
         assert(ts);
 
-        if (u == (usec_t) -1) {
+        if (u == USEC_INFINITY) {
                 ts->tv_sec = (time_t) -1;
                 ts->tv_nsec = (long) -1;
                 return ts;
                 ts->tv_sec = (time_t) -1;
                 ts->tv_nsec = (long) -1;
                 return ts;
@@ -125,10 +123,10 @@ usec_t timeval_load(const struct timeval *tv) {
 
         if (tv->tv_sec == (time_t) -1 &&
             tv->tv_usec == (suseconds_t) -1)
 
         if (tv->tv_sec == (time_t) -1 &&
             tv->tv_usec == (suseconds_t) -1)
-                return (usec_t) -1;
+                return USEC_INFINITY;
 
         if ((usec_t) tv->tv_sec > (UINT64_MAX - tv->tv_usec) / USEC_PER_SEC)
 
         if ((usec_t) tv->tv_sec > (UINT64_MAX - tv->tv_usec) / USEC_PER_SEC)
-                return (usec_t) -1;
+                return USEC_INFINITY;
 
         return
                 (usec_t) tv->tv_sec * USEC_PER_SEC +
 
         return
                 (usec_t) tv->tv_sec * USEC_PER_SEC +
@@ -138,108 +136,136 @@ usec_t timeval_load(const struct timeval *tv) {
 struct timeval *timeval_store(struct timeval *tv, usec_t u) {
         assert(tv);
 
 struct timeval *timeval_store(struct timeval *tv, usec_t u) {
         assert(tv);
 
-        if (u == (usec_t) -1) {
+        if (u == USEC_INFINITY) {
                 tv->tv_sec = (time_t) -1;
                 tv->tv_usec = (suseconds_t) -1;
                 tv->tv_sec = (time_t) -1;
                 tv->tv_usec = (suseconds_t) -1;
-                return tv;
+        } else {
+                tv->tv_sec = (time_t) (u / USEC_PER_SEC);
+                tv->tv_usec = (suseconds_t) (u % USEC_PER_SEC);
         }
 
         }
 
-        tv->tv_sec = (time_t) (u / USEC_PER_SEC);
-        tv->tv_usec = (suseconds_t) (u % USEC_PER_SEC);
-
         return tv;
 }
 
         return tv;
 }
 
-char *format_timestamp(char *buf, size_t l, usec_t t) {
+static char *format_timestamp_internal(char *buf, size_t l, usec_t t, bool utc) {
         struct tm tm;
         time_t sec;
 
         assert(buf);
         assert(l > 0);
 
         struct tm tm;
         time_t sec;
 
         assert(buf);
         assert(l > 0);
 
-        if (t <= 0)
+        if (t <= 0 || t == USEC_INFINITY)
                 return NULL;
 
         sec = (time_t) (t / USEC_PER_SEC);
 
                 return NULL;
 
         sec = (time_t) (t / USEC_PER_SEC);
 
-        if (strftime(buf, l, "%a %Y-%m-%d %H:%M:%S %Z", localtime_r(&sec, &tm)) <= 0)
+        if (utc)
+                gmtime_r(&sec, &tm);
+        else
+                localtime_r(&sec, &tm);
+        if (strftime(buf, l, "%a %Y-%m-%d %H:%M:%S %Z", &tm) <= 0)
                 return NULL;
 
         return buf;
 }
 
                 return NULL;
 
         return buf;
 }
 
-char *format_timestamp_us(char *buf, size_t l, usec_t t) {
+char *format_timestamp(char *buf, size_t l, usec_t t) {
+        return format_timestamp_internal(buf, l, t, false);
+}
+
+char *format_timestamp_utc(char *buf, size_t l, usec_t t) {
+        return format_timestamp_internal(buf, l, t, true);
+}
+
+static char *format_timestamp_internal_us(char *buf, size_t l, usec_t t, bool utc) {
         struct tm tm;
         time_t sec;
 
         assert(buf);
         assert(l > 0);
 
         struct tm tm;
         time_t sec;
 
         assert(buf);
         assert(l > 0);
 
-        if (t <= 0)
+        if (t <= 0 || t == USEC_INFINITY)
                 return NULL;
 
         sec = (time_t) (t / USEC_PER_SEC);
                 return NULL;
 
         sec = (time_t) (t / USEC_PER_SEC);
-        localtime_r(&sec, &tm);
+        if (utc)
+                gmtime_r(&sec, &tm);
+        else
+                localtime_r(&sec, &tm);
 
         if (strftime(buf, l, "%a %Y-%m-%d %H:%M:%S", &tm) <= 0)
                 return NULL;
 
         if (strftime(buf, l, "%a %Y-%m-%d %H:%M:%S", &tm) <= 0)
                 return NULL;
-        snprintf(buf + strlen(buf), l - strlen(buf), ".%06llu", t % USEC_PER_SEC);
+        snprintf(buf + strlen(buf), l - strlen(buf), ".%06llu", (unsigned long long) (t % USEC_PER_SEC));
         if (strftime(buf + strlen(buf), l - strlen(buf), " %Z", &tm) <= 0)
                 return NULL;
 
         return buf;
 }
 
         if (strftime(buf + strlen(buf), l - strlen(buf), " %Z", &tm) <= 0)
                 return NULL;
 
         return buf;
 }
 
+char *format_timestamp_us(char *buf, size_t l, usec_t t) {
+        return format_timestamp_internal_us(buf, l, t, false);
+}
+
+char *format_timestamp_us_utc(char *buf, size_t l, usec_t t) {
+        return format_timestamp_internal_us(buf, l, t, true);
+}
+
 char *format_timestamp_relative(char *buf, size_t l, usec_t t) {
 char *format_timestamp_relative(char *buf, size_t l, usec_t t) {
+        const char *s;
         usec_t n, d;
 
         usec_t n, d;
 
-        n = now(CLOCK_REALTIME);
-
-        if (t <= 0 || t > n || t + USEC_PER_DAY*7 <= t)
+        if (t <= 0 || t == USEC_INFINITY)
                 return NULL;
 
                 return NULL;
 
-        d = n - t;
+        n = now(CLOCK_REALTIME);
+        if (n > t) {
+                d = n - t;
+                s = "ago";
+        } else {
+                d = t - n;
+                s = "left";
+        }
 
         if (d >= USEC_PER_YEAR)
 
         if (d >= USEC_PER_YEAR)
-                snprintf(buf, l, "%llu years %llu months ago",
-                         (unsigned long long) (d / USEC_PER_YEAR),
-                         (unsigned long long) ((d % USEC_PER_YEAR) / USEC_PER_MONTH));
+                snprintf(buf, l, USEC_FMT " years " USEC_FMT " months %s",
+                         d / USEC_PER_YEAR,
+                         (d % USEC_PER_YEAR) / USEC_PER_MONTH, s);
         else if (d >= USEC_PER_MONTH)
         else if (d >= USEC_PER_MONTH)
-                snprintf(buf, l, "%llu months %llu days ago",
-                         (unsigned long long) (d / USEC_PER_MONTH),
-                         (unsigned long long) ((d % USEC_PER_MONTH) / USEC_PER_DAY));
+                snprintf(buf, l, USEC_FMT " months " USEC_FMT " days %s",
+                         d / USEC_PER_MONTH,
+                         (d % USEC_PER_MONTH) / USEC_PER_DAY, s);
         else if (d >= USEC_PER_WEEK)
         else if (d >= USEC_PER_WEEK)
-                snprintf(buf, l, "%llu weeks %llu days ago",
-                         (unsigned long long) (d / USEC_PER_WEEK),
-                         (unsigned long long) ((d % USEC_PER_WEEK) / USEC_PER_DAY));
+                snprintf(buf, l, USEC_FMT " weeks " USEC_FMT " days %s",
+                         d / USEC_PER_WEEK,
+                         (d % USEC_PER_WEEK) / USEC_PER_DAY, s);
         else if (d >= 2*USEC_PER_DAY)
         else if (d >= 2*USEC_PER_DAY)
-                snprintf(buf, l, "%llu days ago", (unsigned long long) (d / USEC_PER_DAY));
+                snprintf(buf, l, USEC_FMT " days %s", d / USEC_PER_DAY, s);
         else if (d >= 25*USEC_PER_HOUR)
         else if (d >= 25*USEC_PER_HOUR)
-                snprintf(buf, l, "1 day %lluh ago",
-                         (unsigned long long) ((d - USEC_PER_DAY) / USEC_PER_HOUR));
+                snprintf(buf, l, "1 day " USEC_FMT "h %s",
+                         (d - USEC_PER_DAY) / USEC_PER_HOUR, s);
         else if (d >= 6*USEC_PER_HOUR)
         else if (d >= 6*USEC_PER_HOUR)
-                snprintf(buf, l, "%lluh ago",
-                         (unsigned long long) (d / USEC_PER_HOUR));
+                snprintf(buf, l, USEC_FMT "h %s",
+                         d / USEC_PER_HOUR, s);
         else if (d >= USEC_PER_HOUR)
         else if (d >= USEC_PER_HOUR)
-                snprintf(buf, l, "%lluh %llumin ago",
-                         (unsigned long long) (d / USEC_PER_HOUR),
-                         (unsigned long long) ((d % USEC_PER_HOUR) / USEC_PER_MINUTE));
+                snprintf(buf, l, USEC_FMT "h " USEC_FMT "min %s",
+                         d / USEC_PER_HOUR,
+                         (d % USEC_PER_HOUR) / USEC_PER_MINUTE, s);
         else if (d >= 5*USEC_PER_MINUTE)
         else if (d >= 5*USEC_PER_MINUTE)
-                snprintf(buf, l, "%llumin ago",
-                         (unsigned long long) (d / USEC_PER_MINUTE));
+                snprintf(buf, l, USEC_FMT "min %s",
+                         d / USEC_PER_MINUTE, s);
         else if (d >= USEC_PER_MINUTE)
         else if (d >= USEC_PER_MINUTE)
-                snprintf(buf, l, "%llumin %llus ago",
-                         (unsigned long long) (d / USEC_PER_MINUTE),
-                         (unsigned long long) ((d % USEC_PER_MINUTE) / USEC_PER_SEC));
+                snprintf(buf, l, USEC_FMT "min " USEC_FMT "s %s",
+                         d / USEC_PER_MINUTE,
+                         (d % USEC_PER_MINUTE) / USEC_PER_SEC, s);
         else if (d >= USEC_PER_SEC)
         else if (d >= USEC_PER_SEC)
-                snprintf(buf, l, "%llus ago",
-                         (unsigned long long) (d / USEC_PER_SEC));
+                snprintf(buf, l, USEC_FMT "s %s",
+                         d / USEC_PER_SEC, s);
         else if (d >= USEC_PER_MSEC)
         else if (d >= USEC_PER_MSEC)
-                snprintf(buf, l, "%llums ago",
-                         (unsigned long long) (d / USEC_PER_MSEC));
+                snprintf(buf, l, USEC_FMT "ms %s",
+                         d / USEC_PER_MSEC, s);
         else if (d > 0)
         else if (d > 0)
-                snprintf(buf, l, "%lluus ago",
-                         (unsigned long long) d);
+                snprintf(buf, l, USEC_FMT"us %s",
+                         d, s);
         else
                 snprintf(buf, l, "now");
 
         else
                 snprintf(buf, l, "now");
 
@@ -270,11 +296,14 @@ char *format_timespan(char *buf, size_t l, usec_t t, usec_t accuracy) {
         assert(buf);
         assert(l > 0);
 
         assert(buf);
         assert(l > 0);
 
-        if (t == (usec_t) -1)
-                return NULL;
+        if (t == USEC_INFINITY) {
+                strncpy(p, "infinity", l-1);
+                p[l-1] = 0;
+                return p;
+        }
 
         if (t <= 0) {
 
         if (t <= 0) {
-                snprintf(p, l, "0");
+                strncpy(p, "0", l-1);
                 p[l-1] = 0;
                 return p;
         }
                 p[l-1] = 0;
                 return p;
         }
@@ -282,7 +311,7 @@ char *format_timespan(char *buf, size_t l, usec_t t, usec_t accuracy) {
         /* The result of this function can be parsed with parse_sec */
 
         for (i = 0; i < ELEMENTSOF(table); i++) {
         /* The result of this function can be parsed with parse_sec */
 
         for (i = 0; i < ELEMENTSOF(table); i++) {
-                int k;
+                int k = 0;
                 size_t n;
                 bool done = false;
                 usec_t a, b;
                 size_t n;
                 bool done = false;
                 usec_t a, b;
@@ -318,9 +347,9 @@ char *format_timespan(char *buf, size_t l, usec_t t, usec_t accuracy) {
 
                         if (j > 0) {
                                 k = snprintf(p, l,
 
                         if (j > 0) {
                                 k = snprintf(p, l,
-                                             "%s%llu.%0*llu%s",
+                                             "%s"USEC_FMT".%0*llu%s",
                                              p > buf ? " " : "",
                                              p > buf ? " " : "",
-                                             (unsigned long long) a,
+                                             a,
                                              j,
                                              (unsigned long long) b,
                                              table[i].suffix);
                                              j,
                                              (unsigned long long) b,
                                              table[i].suffix);
@@ -333,9 +362,9 @@ char *format_timespan(char *buf, size_t l, usec_t t, usec_t accuracy) {
                 /* No? Then let's show it normally */
                 if (!done) {
                         k = snprintf(p, l,
                 /* No? Then let's show it normally */
                 if (!done) {
                         k = snprintf(p, l,
-                                     "%s%llu%s",
+                                     "%s"USEC_FMT"%s",
                                      p > buf ? " " : "",
                                      p > buf ? " " : "",
-                                     (unsigned long long) a,
+                                     a,
                                      table[i].suffix);
 
                         t = b;
                                      table[i].suffix);
 
                         t = b;
@@ -363,10 +392,10 @@ void dual_timestamp_serialize(FILE *f, const char *name, dual_timestamp *t) {
         if (!dual_timestamp_is_set(t))
                 return;
 
         if (!dual_timestamp_is_set(t))
                 return;
 
-        fprintf(f, "%s=%llu %llu\n",
+        fprintf(f, "%s="USEC_FMT" "USEC_FMT"\n",
                 name,
                 name,
-                (unsigned long long) t->realtime,
-                (unsigned long long) t->monotonic);
+                t->realtime,
+                t->monotonic);
 }
 
 void dual_timestamp_deserialize(const char *value, dual_timestamp *t) {
 }
 
 void dual_timestamp_deserialize(const char *value, dual_timestamp *t) {
@@ -375,7 +404,7 @@ void dual_timestamp_deserialize(const char *value, dual_timestamp *t) {
         assert(value);
         assert(t);
 
         assert(value);
         assert(t);
 
-        if (sscanf(value, "%lli %llu", &a, &b) != 2)
+        if (sscanf(value, "%llu %llu", &a, &b) != 2)
                 log_debug("Failed to parse finish timestamp value %s", value);
         else {
                 t->realtime = a;
                 log_debug("Failed to parse finish timestamp value %s", value);
         else {
                 t->realtime = a;
@@ -425,6 +454,7 @@ int parse_timestamp(const char *t, usec_t *usec) {
          *   tomorrow             (time is set to 00:00:00)
          *   +5min
          *   -5days
          *   tomorrow             (time is set to 00:00:00)
          *   +5min
          *   -5days
+         *   @2147483647          (seconds since epoch)
          *
          */
 
          *
          */
 
@@ -453,21 +483,23 @@ int parse_timestamp(const char *t, usec_t *usec) {
                 goto finish;
 
         } else if (t[0] == '+') {
                 goto finish;
 
         } else if (t[0] == '+') {
-
                 r = parse_sec(t+1, &plus);
                 if (r < 0)
                         return r;
 
                 goto finish;
                 r = parse_sec(t+1, &plus);
                 if (r < 0)
                         return r;
 
                 goto finish;
-        } else if (t[0] == '-') {
 
 
+        } else if (t[0] == '-') {
                 r = parse_sec(t+1, &minus);
                 if (r < 0)
                         return r;
 
                 goto finish;
 
                 r = parse_sec(t+1, &minus);
                 if (r < 0)
                         return r;
 
                 goto finish;
 
-        } else if (endswith(t, " ago")) {
+        } else if (t[0] == '@')
+                return parse_sec(t + 1, usec);
+
+        else if (endswith(t, " ago")) {
                 _cleanup_free_ char *z;
 
                 z = strndup(t, strlen(t) - 4);
                 _cleanup_free_ char *z;
 
                 z = strndup(t, strlen(t) - 4);
@@ -479,6 +511,18 @@ int parse_timestamp(const char *t, usec_t *usec) {
                         return r;
 
                 goto finish;
                         return r;
 
                 goto finish;
+        } else if (endswith(t, " left")) {
+                _cleanup_free_ char *z;
+
+                z = strndup(t, strlen(t) - 4);
+                if (!z)
+                        return -ENOMEM;
+
+                r = parse_sec(z, &plus);
+                if (r < 0)
+                        return r;
+
+                goto finish;
         }
 
         for (i = 0; i < ELEMENTSOF(day_nr); i++) {
         }
 
         for (i = 0; i < ELEMENTSOF(day_nr); i++) {
@@ -604,7 +648,7 @@ int parse_sec(const char *t, usec_t *usec) {
                 { "", USEC_PER_SEC }, /* default is sec */
         };
 
                 { "", USEC_PER_SEC }, /* default is sec */
         };
 
-        const char *p;
+        const char *p, *s;
         usec_t r = 0;
         bool something = false;
 
         usec_t r = 0;
         bool something = false;
 
@@ -612,6 +656,18 @@ int parse_sec(const char *t, usec_t *usec) {
         assert(usec);
 
         p = t;
         assert(usec);
 
         p = t;
+
+        p += strspn(p, WHITESPACE);
+        s = startswith(p, "infinity");
+        if (s) {
+                s += strspn(s, WHITESPACE);
+                if (*s != 0)
+                        return -EINVAL;
+
+                *usec = USEC_INFINITY;
+                return 0;
+        }
+
         for (;;) {
                 long long l, z = 0;
                 char *e;
         for (;;) {
                 long long l, z = 0;
                 char *e;
@@ -717,7 +773,7 @@ int parse_nsec(const char *t, nsec_t *nsec) {
                 { "", 1ULL }, /* default is nsec */
         };
 
                 { "", 1ULL }, /* default is nsec */
         };
 
-        const char *p;
+        const char *p, *s;
         nsec_t r = 0;
         bool something = false;
 
         nsec_t r = 0;
         bool something = false;
 
@@ -725,6 +781,18 @@ int parse_nsec(const char *t, nsec_t *nsec) {
         assert(nsec);
 
         p = t;
         assert(nsec);
 
         p = t;
+
+        p += strspn(p, WHITESPACE);
+        s = startswith(p, "infinity");
+        if (s) {
+                s += strspn(s, WHITESPACE);
+                if (*s != 0)
+                        return -EINVAL;
+
+                *nsec = NSEC_INFINITY;
+                return 0;
+        }
+
         for (;;) {
                 long long l, z = 0;
                 char *e;
         for (;;) {
                 long long l, z = 0;
                 char *e;
@@ -792,3 +860,135 @@ int parse_nsec(const char *t, nsec_t *nsec) {
 
         return 0;
 }
 
         return 0;
 }
+
+bool ntp_synced(void) {
+        struct timex txc = {};
+
+        if (adjtimex(&txc) < 0)
+                return false;
+
+        if (txc.status & STA_UNSYNC)
+                return false;
+
+        return true;
+}
+
+int get_timezones(char ***ret) {
+        _cleanup_fclose_ FILE *f = NULL;
+        _cleanup_strv_free_ char **zones = NULL;
+        size_t n_zones = 0, n_allocated = 0;
+
+        assert(ret);
+
+        zones = strv_new("UTC", NULL);
+        if (!zones)
+                return -ENOMEM;
+
+        n_allocated = 2;
+        n_zones = 1;
+
+        f = fopen("/usr/share/zoneinfo/zone.tab", "re");
+        if (f) {
+                char l[LINE_MAX];
+
+                FOREACH_LINE(l, f, return -errno) {
+                        char *p, *w;
+                        size_t k;
+
+                        p = strstrip(l);
+
+                        if (isempty(p) || *p == '#')
+                                continue;
+
+                        /* Skip over country code */
+                        p += strcspn(p, WHITESPACE);
+                        p += strspn(p, WHITESPACE);
+
+                        /* Skip over coordinates */
+                        p += strcspn(p, WHITESPACE);
+                        p += strspn(p, WHITESPACE);
+
+                        /* Found timezone name */
+                        k = strcspn(p, WHITESPACE);
+                        if (k <= 0)
+                                continue;
+
+                        w = strndup(p, k);
+                        if (!w)
+                                return -ENOMEM;
+
+                        if (!GREEDY_REALLOC(zones, n_allocated, n_zones + 2)) {
+                                free(w);
+                                return -ENOMEM;
+                        }
+
+                        zones[n_zones++] = w;
+                        zones[n_zones] = NULL;
+                }
+
+                strv_sort(zones);
+
+        } else if (errno != ENOENT)
+                return -errno;
+
+        *ret = zones;
+        zones = NULL;
+
+        return 0;
+}
+
+bool timezone_is_valid(const char *name) {
+        bool slash = false;
+        const char *p, *t;
+        struct stat st;
+
+        if (!name || *name == 0 || *name == '/')
+                return false;
+
+        for (p = name; *p; p++) {
+                if (!(*p >= '0' && *p <= '9') &&
+                    !(*p >= 'a' && *p <= 'z') &&
+                    !(*p >= 'A' && *p <= 'Z') &&
+                    !(*p == '-' || *p == '_' || *p == '+' || *p == '/'))
+                        return false;
+
+                if (*p == '/') {
+
+                        if (slash)
+                                return false;
+
+                        slash = true;
+                } else
+                        slash = false;
+        }
+
+        if (slash)
+                return false;
+
+        t = strjoina("/usr/share/zoneinfo/", name);
+        if (stat(t, &st) < 0)
+                return false;
+
+        if (!S_ISREG(st.st_mode))
+                return false;
+
+        return true;
+}
+
+clockid_t clock_boottime_or_monotonic(void) {
+        static clockid_t clock = -1;
+        int fd;
+
+        if (clock != -1)
+                return clock;
+
+        fd = timerfd_create(CLOCK_BOOTTIME, TFD_NONBLOCK|TFD_CLOEXEC);
+        if (fd < 0)
+                clock = CLOCK_MONOTONIC;
+        else {
+                safe_close(fd);
+                clock = CLOCK_BOOTTIME;
+        }
+
+        return clock;
+}