Add clock_getres syscall

src/Enclave.edl

@@ -97,6 +97,7 @@ enclave {
 
         void occlum_ocall_gettimeofday([out] struct timeval* tv);
         void occlum_ocall_clock_gettime(clockid_t clockid, [out] struct timespec* ts);
+        void occlum_ocall_clock_getres(clockid_t clockid, [out] struct timespec* res);
         void occlum_ocall_rdtsc([out] uint32_t* low, [out] uint32_t* high);
 
         void occlum_ocall_nanosleep([in] const struct timespec* req);

src/libos/src/syscall/mod.rs

@@ -306,7 +306,7 @@ macro_rules! process_syscall_table_with_callback {
             (TimerDelete = 226) => handle_unsupported(),
             (ClockSettime = 227) => handle_unsupported(),
             (ClockGettime = 228) => do_clock_gettime(clockid: clockid_t, ts_u: *mut timespec_t),
-            (ClockGetres = 229) => handle_unsupported(),
+            (ClockGetres = 229) => do_clock_getres(clockid: clockid_t, res_u: *mut timespec_t),
             (ClockNanosleep = 230) => handle_unsupported(),
             (ExitGroup = 231) => do_exit_group(exit_status: i32),
             (EpollWait = 232) => do_epoll_wait(epfd: c_int, events: *mut libc::epoll_event, maxevents: c_int, timeout: c_int),
@@ -775,6 +775,19 @@ fn do_clock_gettime(clockid: clockid_t, ts_u: *mut timespec_t) -> Result<isize>
     Ok(0)
 }
 
+fn do_clock_getres(clockid: clockid_t, res_u: *mut timespec_t) -> Result<isize> {
+    if res_u.is_null() {
+        return Ok(0);
+    }
+    check_mut_ptr(res_u)?;
+    let clockid = time::ClockID::from_raw(clockid)?;
+    let res = time::do_clock_getres(clockid)?;
+    unsafe {
+        *res_u = res;
+    }
+    Ok(0)
+}
+
 // TODO: handle remainder
 fn do_nanosleep(req_u: *const timespec_t, rem_u: *mut timespec_t) -> Result<isize> {
     check_ptr(req_u)?;

src/libos/src/time/mod.rs

@@ -137,6 +137,28 @@ pub fn do_clock_gettime(clockid: ClockID) -> Result<timespec_t> {
     Ok(tv)
 }
 
+pub fn do_clock_getres(clockid: ClockID) -> Result<timespec_t> {
+    extern "C" {
+        fn occlum_ocall_clock_getres(clockid: clockid_t, res: *mut timespec_t) -> sgx_status_t;
+    }
+
+    let mut res: timespec_t = Default::default();
+    unsafe {
+        occlum_ocall_clock_getres(clockid as clockid_t, &mut res as *mut timespec_t);
+    }
+    let validate_resolution = |res: &timespec_t| -> Result<()> {
+        // The resolution can be ranged from 1 nanosecond to a few milliseconds
+        if res.sec == 0 && res.nsec > 0 && res.nsec < 1_000_000_000 {
+            Ok(())
+        } else {
+            return_errno!(EINVAL, "invalid value for resolution");
+        }
+    };
+    // do sanity check
+    validate_resolution(&res).expect("ocall returned invalid resolution");
+    Ok(res)
+}
+
 pub fn do_nanosleep(req: &timespec_t) -> Result<()> {
     extern "C" {
         fn occlum_ocall_nanosleep(req: *const timespec_t) -> sgx_status_t;

src/pal/src/ocalls/time.c

@@ -10,6 +10,10 @@ void occlum_ocall_clock_gettime(int clockid, struct timespec *tp) {
     clock_gettime(clockid, tp);
 }
 
+void occlum_ocall_clock_getres(int clockid, struct timespec *res) {
+    clock_getres(clockid, res);
+}
+
 void occlum_ocall_nanosleep(const struct timespec *req) {
     nanosleep(req, NULL);
 }

test/time/main.c

@@ -29,6 +29,27 @@ int test_clock_gettime() {
     return 0;
 }
 
+// ============================================================================
+// Test cases for clock_getres
+// ============================================================================
+
+int test_clock_getres() {
+    struct timespec res;
+    if (clock_getres(CLOCK_REALTIME, &res)) {
+        THROW_ERROR("clock_getres(CLOCK_REALTIME, ...) failed");
+    }
+    if (clock_getres(CLOCK_MONOTONIC, &res)) {
+        THROW_ERROR("clock_getres(CLOCK_MONOTONIC, ...) failed");
+    }
+    if (clock_getres(CLOCK_MONOTONIC_COARSE, &res)) {
+        THROW_ERROR("clock_getres(CLOCK_MONOTONIC_COARSE, ...) failed");
+    }
+    if (clock_getres(CLOCK_REALTIME, NULL)) {
+        THROW_ERROR("clock_getres(CLOCK_REALTIME, NULL) failed");
+    }
+    return 0;
+}
+
 // ============================================================================
 // Test suite
 // ============================================================================
@@ -36,6 +57,7 @@ int test_clock_gettime() {
 static test_case_t test_cases[] = {
     TEST_CASE(test_gettimeofday),
     TEST_CASE(test_clock_gettime),
+    TEST_CASE(test_clock_getres),
 };
 
 int main() {