Publish ITWorx Pulse source

internal/hostcollect/clock_linux.go

@@ -0,0 +1,46 @@
+//go:build linux
+
+package hostcollect
+
+import (
+	"math"
+	"syscall"
+
+	"github.com/itworx/pulse/internal/host"
+)
+
+// Bits of the adjtimex status word, defined here because the standard syscall package
+// does not export them on every architecture.
+const (
+	staUnsync = 0x0040 // clock is not synchronised to a reference
+	staNano   = 0x2000 // offset and precision are in nanoseconds, not microseconds
+	timeError = 5      // adjtimex state: the clock is not synchronised
+)
+
+// readClockSync asks the kernel about clock discipline with adjtimex(2) in read mode.
+//
+// A zeroed Timex has Modes == 0, which makes the call a pure read: it adjusts nothing.
+// Docker's default seccomp profile still gates adjtimex behind CAP_SYS_TIME, which the
+// agent drops, so the expected in-container result is EPERM. The caller turns that into
+// a warning; see Collector.clock.
+func readClockSync() (host.RawTime, error) {
+	timex := syscall.Timex{}
+	state, err := syscall.Adjtimex(&timex)
+	if err != nil {
+		return host.RawTime{}, err
+	}
+	divisor := 1e6
+	if timex.Status&staNano != 0 {
+		divisor = 1e9
+	}
+	offset := math.Abs(float64(timex.Offset)) / divisor
+	if math.IsNaN(offset) || math.IsInf(offset, 0) {
+		offset = 0
+	}
+	return host.RawTime{
+		Synchronized: timex.Status&staUnsync == 0 && state != timeError,
+		// The kernel exposes no stratum; that belongs to the NTP daemon, which the
+		// agent deliberately does not talk to.
+		OffsetSeconds: offset,
+	}, nil
+}