Move monotonic_time to BPF class, use CLOCK_MONOTONIC
This allows all the tools (currently: trace and memleak) to use the
`monotonic_time` facility, with the fix to use `CLOCK_MONOTONIC`
instead of `CLOCK_MONOTONIC_RAW`. Resolves
@@ -115,6 +115,30 @@ class BPF(object):
"linux/netdevice.h": ["sk_buff", "net_device"]
}
+ # BPF timestamps come from the monotonic clock. To be able to filter
+ # and compare them from Python, we need to invoke clock_gettime.
+ # Adapted from http://stackoverflow.com/a/1205762
+ CLOCK_MONOTONIC = 1 # see <linux/time.h>
+
+ class timespec(ct.Structure):
+ _fields_ = [('tv_sec', ct.c_long), ('tv_nsec', ct.c_long)]
+
+ _librt = ct.CDLL('librt.so.1', use_errno=True)
+ _clock_gettime = _librt.clock_gettime
+ _clock_gettime.argtypes = [ct.c_int, ct.POINTER(timespec)]
+
+ @classmethod
+ def monotonic_time(cls):
+ """monotonic_time()
+ Returns the system monotonic time from clock_gettime, using the
+ CLOCK_MONOTONIC constant. The time returned is in nanoseconds.
+ """
+ t = cls.timespec()
+ if cls._clock_gettime(cls.CLOCK_MONOTONIC, ct.pointer(t)) != 0:
+ errno = ct.get_errno()
+ raise OSError(errno, os.strerror(errno))
+ return t.tv_sec * 1e9 + t.tv_nsec
+
@classmethod
def generate_auto_includes(cls, program_words):
"""
