Make clock_gettime() and clock_getres() work for CloudABI programs.

Though the standard C library uses a 'struct timespec' using a 64-bit
'time_t', there is no need to use such a type at the system call level.
CloudABI uses a simple 64-bit unsigned timestamp in nanoseconds. This is
sufficient to express any time value from 1970 to 2554.

The CloudABI low-level interface also supports fetching timestamp values
with a lower precision. Instead of overloading the clock ID argument for
this purpose, the system call provides a precision argument that may be
used to specify the maximum slack. The current system call
implementation does not use this information, but it's good to already
have this available.

Expose cloudabi_convert_timespec(), as we're going to need this for
fstat() as well.

Obtained from:	https://github.com/NuxiNL/freebsd

2 files changed, 87 insertions, 4 deletions

diff --git a/sys/compat/cloudabi/cloudabi_clock.c b/sys/compat/cloudabi/cloudabi_clock.c
index a6b783c..8462f23 100644
--- a/sys/compat/cloudabi/cloudabi_clock.c
+++ b/sys/compat/cloudabi/cloudabi_clock.c
@@ -26,22 +26,100 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include <sys/param.h>
+#include <sys/proc.h>
+#include <sys/stdint.h>
+#include <sys/syscallsubr.h>
+
 #include <compat/cloudabi/cloudabi_proto.h>
+#include <compat/cloudabi/cloudabi_syscalldefs.h>
+#include <compat/cloudabi/cloudabi_util.h>
+
+/* Converts a CloudABI clock ID to a FreeBSD clock ID. */
+static int
+cloudabi_convert_clockid(cloudabi_clockid_t in, clockid_t *out)
+{
+	switch (in) {
+	case CLOUDABI_CLOCK_MONOTONIC:
+		*out = CLOCK_MONOTONIC;
+		return (0);
+	case CLOUDABI_CLOCK_PROCESS_CPUTIME_ID:
+		*out = CLOCK_PROCESS_CPUTIME_ID;
+		return (0);
+	case CLOUDABI_CLOCK_REALTIME:
+		*out = CLOCK_REALTIME;
+		return (0);
+	case CLOUDABI_CLOCK_THREAD_CPUTIME_ID:
+		*out = CLOCK_THREAD_CPUTIME_ID;
+		return (0);
+	default:
+		return (EINVAL);
+	}
+}
+
+/* Converts a struct timespec to a CloudABI timestamp. */
+int
+cloudabi_convert_timespec(const struct timespec *in, cloudabi_timestamp_t *out)
+{
+	cloudabi_timestamp_t s, ns;
+
+	if (in->tv_sec < 0) {
+		/* Timestamps from before the Epoch cannot be expressed. */
+		*out = 0;
+		return (EOVERFLOW);
+	}
+	s = in->tv_sec;
+	ns = in->tv_nsec;
+	if (s > UINT64_MAX / 1000000000 ||
+	    (s == UINT64_MAX / 1000000000 && ns > UINT64_MAX % 1000000000)) {
+		/* Addition of seconds and nanoseconds would overflow. */
+		*out = UINT64_MAX;
+		return (EOVERFLOW);
+	}
+	*out = s * 1000000000 + ns;
+	return (0);
+}
 
 int
 cloudabi_sys_clock_res_get(struct thread *td,
     struct cloudabi_sys_clock_res_get_args *uap)
 {
+	struct timespec ts;
+	cloudabi_timestamp_t cts;
+	int error;
+	clockid_t clockid;
 
-	/* Not implemented. */
-	return (ENOSYS);
+	error = cloudabi_convert_clockid(uap->clock_id, &clockid);
+	if (error != 0)
+		return (error);
+	error = kern_clock_getres(td, clockid, &ts);
+	if (error != 0)
+		return (error);
+	error = cloudabi_convert_timespec(&ts, &cts);
+	if (error != 0)
+		return (error);
+	td->td_retval[0] = cts;
+	return (0);
 }
 
 int
 cloudabi_sys_clock_time_get(struct thread *td,
     struct cloudabi_sys_clock_time_get_args *uap)
 {
+	struct timespec ts;
+	cloudabi_timestamp_t cts;
+	int error;
+	clockid_t clockid;
 
-	/* Not implemented. */
-	return (ENOSYS);
+	error = cloudabi_convert_clockid(uap->clock_id, &clockid);
+	if (error != 0)
+		return (error);
+	error = kern_clock_gettime(td, clockid, &ts);
+	if (error != 0)
+		return (error);
+	error = cloudabi_convert_timespec(&ts, &cts);
+	if (error != 0)
+		return (error);
+	td->td_retval[0] = cts;
+	return (0);
 }
diff --git a/sys/compat/cloudabi/cloudabi_util.h b/sys/compat/cloudabi/cloudabi_util.h
index 4389e3d..d9e6f12 100644
--- a/sys/compat/cloudabi/cloudabi_util.h
+++ b/sys/compat/cloudabi/cloudabi_util.h
@@ -30,7 +30,12 @@
 
 #include <compat/cloudabi/cloudabi_syscalldefs.h>
 
+struct timespec;
+
 /* Converts a FreeBSD errno to a CloudABI errno. */
 cloudabi_errno_t cloudabi_convert_errno(int);
 
+/* Converts a struct timespec to a CloudABI timestamp. */
+int cloudabi_convert_timespec(const struct timespec *, cloudabi_timestamp_t *);
+
 #endif