Merge pull request #6176 from poettering/timer-boottime-monotonic

WakeSystem= and other timer fixes.

src/basic/time-util.c

@@ -107,7 +107,7 @@ dual_timestamp* dual_timestamp_from_realtime(dual_timestamp *ts, usec_t u) {
         ts->realtime = u;
 
         delta = (int64_t) now(CLOCK_REALTIME) - (int64_t) u;
-        ts->monotonic = usec_sub(now(CLOCK_MONOTONIC), delta);
+        ts->monotonic = usec_sub_signed(now(CLOCK_MONOTONIC), delta);
 
         return ts;
 }
@@ -124,8 +124,8 @@ triple_timestamp* triple_timestamp_from_realtime(triple_timestamp *ts, usec_t u)
 
         ts->realtime = u;
         delta = (int64_t) now(CLOCK_REALTIME) - (int64_t) u;
-        ts->monotonic = usec_sub(now(CLOCK_MONOTONIC), delta);
-        ts->boottime = clock_boottime_supported() ? usec_sub(now(CLOCK_BOOTTIME), delta) : USEC_INFINITY;
+        ts->monotonic = usec_sub_signed(now(CLOCK_MONOTONIC), delta);
+        ts->boottime = clock_boottime_supported() ? usec_sub_signed(now(CLOCK_BOOTTIME), delta) : USEC_INFINITY;
 
         return ts;
 }
@@ -141,7 +141,7 @@ dual_timestamp* dual_timestamp_from_monotonic(dual_timestamp *ts, usec_t u) {
 
         ts->monotonic = u;
         delta = (int64_t) now(CLOCK_MONOTONIC) - (int64_t) u;
-        ts->realtime = usec_sub(now(CLOCK_REALTIME), delta);
+        ts->realtime = usec_sub_signed(now(CLOCK_REALTIME), delta);
 
         return ts;
 }
@@ -156,8 +156,8 @@ dual_timestamp* dual_timestamp_from_boottime_or_monotonic(dual_timestamp *ts, us
 
         dual_timestamp_get(ts);
         delta = (int64_t) now(clock_boottime_or_monotonic()) - (int64_t) u;
-        ts->realtime = usec_sub(ts->realtime, delta);
-        ts->monotonic = usec_sub(ts->monotonic, delta);
+        ts->realtime = usec_sub_signed(ts->realtime, delta);
+        ts->monotonic = usec_sub_signed(ts->monotonic, delta);
 
         return ts;
 }
@@ -1351,3 +1351,22 @@ unsigned long usec_to_jiffies(usec_t u) {
 
         return DIV_ROUND_UP(u , USEC_PER_SEC / hz);
 }
+
+usec_t usec_shift_clock(usec_t x, clockid_t from, clockid_t to) {
+        usec_t a, b;
+
+        if (x == USEC_INFINITY)
+                return USEC_INFINITY;
+        if (map_clock_id(from) == map_clock_id(to))
+                return x;
+
+        a = now(from);
+        b = now(to);
+
+        if (x > a)
+                /* x lies in the future */
+                return usec_add(b, usec_sub_unsigned(x, a));
+        else
+                /* x lies in the past */
+                return usec_sub_unsigned(b, usec_sub_unsigned(a, x));
+}

src/basic/time-util.h

@@ -145,6 +145,8 @@ bool clock_boottime_supported(void);
 bool clock_supported(clockid_t clock);
 clockid_t clock_boottime_or_monotonic(void);
 
+usec_t usec_shift_clock(usec_t, clockid_t from, clockid_t to);
+
 #define xstrftime(buf, fmt, tm) \
         assert_message_se(strftime(buf, ELEMENTSOF(buf), fmt, tm) > 0, \
                           "xstrftime: " #buf "[] must be big enough")
@@ -169,19 +171,23 @@ static inline usec_t usec_add(usec_t a, usec_t b) {
         return c;
 }
 
-static inline usec_t usec_sub(usec_t timestamp, int64_t delta) {
-        if (delta < 0)
-                return usec_add(timestamp, (usec_t) (-delta));
+static inline usec_t usec_sub_unsigned(usec_t timestamp, usec_t delta) {
 
         if (timestamp == USEC_INFINITY) /* Make sure infinity doesn't degrade */
                 return USEC_INFINITY;
-
-        if (timestamp < (usec_t) delta)
+        if (timestamp < delta)
                 return 0;
 
         return timestamp - delta;
 }
 
+static inline usec_t usec_sub_signed(usec_t timestamp, int64_t delta) {
+        if (delta < 0)
+                return usec_add(timestamp, (usec_t) (-delta));
+        else
+                return usec_sub_unsigned(timestamp, (usec_t) delta);
+}
+
 #if SIZEOF_TIME_T == 8
 /* The last second we can format is 31. Dec 9999, 1s before midnight, because otherwise we'd enter 5 digit year
  * territory. However, since we want to stay away from this in all timezones we take one day off. */