Implement nacl_irt_clock for non-sfi mode.

components/nacl/loader/nonsfi/irt_clock.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <errno.h>
+#include <time.h>
+
+#include "components/nacl/loader/nonsfi/abi_conversion.h"
+#include "components/nacl/loader/nonsfi/irt_interfaces.h"
+#include "native_client/src/trusted/service_runtime/include/sys/time.h"
+
+namespace nacl {
+namespace nonsfi {
+namespace {
+
+bool NaClAbiClockIdToClockId(int nacl_clk_id, clockid_t* host_clk_id) {
+  switch (nacl_clk_id) {
+    case NACL_ABI_CLOCK_REALTIME:
+      *host_clk_id = CLOCK_REALTIME;
+      break;
+    case NACL_ABI_CLOCK_MONOTONIC:
+      *host_clk_id = CLOCK_MONOTONIC;
+      break;
+    case NACL_ABI_CLOCK_PROCESS_CPUTIME_ID:
+      *host_clk_id = CLOCK_PROCESS_CPUTIME_ID;
+      break;
+    case NACL_ABI_CLOCK_THREAD_CPUTIME_ID:
+      *host_clk_id = CLOCK_THREAD_CPUTIME_ID;
+      break;
+    default:
+      // Unknown clock id.
+      return false;
+  }
+  return true;
+}
+
+int IrtClockGetRes(int clk_id, struct nacl_abi_timespec* rem) {

[Mark Seaborn, 2014/01/15 19:49:28]

Should be "res", not "rem"

[hidehiko, 2014/01/16 05:30:12]

Oops, done.

+  clockid_t host_clk_id;
+  if (!NaClAbiClockIdToClockId(clk_id, &host_clk_id))
+    return EINVAL;
+
+  struct timespec host_rem;
+  if (clock_getres(host_clk_id, &host_rem))
+    return errno;
+
+  if (rem)

[Mark Seaborn, 2014/01/15 19:49:28]

Hmm, interesting that clock_getres() checks for NULL but clock_gettime()
doesn't.

I see that this is required by the standard:
http://pubs.opengroup.org/onlinepubs/009695399/functions/clock_getres.html

Can you add a comment here: "clock_getres() requires a NULL check but
clock_gettime() doesn't"

I think this means there is a NaCl bug.  Under NaCl, I think clock_getres(X,
NULL) will give an EFAULT error.  Could you check and file a NaCl bug, so that
we can make sure that NaCl and non-SFI modes give a consistent result in this
case?

[hidehiko, 2014/01/16 05:30:12]

Done to add the comment.

What I found are:
https://code.google.com/p/chromium/codesearch#chromium/src/native_client/src/...
https://code.google.com/p/chromium/codesearch#chromium/src/native_client/pnac...

The first one seems to return EFAULT, and the latter one seems to be crashed?
I'll file a bug later.

+    TimeSpecToNaClAbiTimeSpec(host_rem, rem);
+  return 0;
+}
+
+int IrtClockGetTime(int clk_id, struct nacl_abi_timespec* tp) {
+  clockid_t host_clk_id;
+  if (!NaClAbiClockIdToClockId(clk_id, &host_clk_id))
+    return EINVAL;
+
+  struct timespec host_tp;
+  if (clock_gettime(host_clk_id, &host_tp))
+    return errno;
+
+  TimeSpecToNaClAbiTimeSpec(host_tp, tp);
+  return 0;
+}
+
+}  // namespace
+
+// Both clock_getres and clock_gettime should use nacl's ABI, nacl_clockid_t

[Mark Seaborn, 2014/01/15 19:49:28]

You probably don't need to comment about the casting for all of these
interfaces, or you could just make the comment a little shorter, e.g. "cast away
distinction between foo* and nacl_abi_foo*".

[hidehiko, 2014/01/16 05:30:12]

Done. I'll send a follow up CL for other files, which are already landed.

[Mark Seaborn, 2014/01/16 19:14:13]

You don't have to change the existing ones unless you particularly want to.  I
was just suggesting that a boilerplate comment would make things easier for you.
:-)

+// and struct nacl_abi_timespec. However, the definition of nacl_irt_clock
+// uses host type, clockid_t and timespec, so here we need to cast them.
+const nacl_irt_clock kIrtClock = {
+  reinterpret_cast<int(*)(clockid_t, struct timespec*)>(IrtClockGetRes),
+  reinterpret_cast<int(*)(clockid_t, struct timespec*)>(IrtClockGetTime),
+};
+
+}  // namespace nonsfi
+}  // namespace nacl