Correct comment about stat truncating st_mtimespec to seconds

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@338000 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Fiselier
2018-07-26 03:42:25 +00:00
parent 94d2ed559a
commit cff3d7b202

View File

@@ -208,15 +208,11 @@ static const bool SupportsMinTime = [] {
static const bool SupportsNanosecondRoundTrip = [] {
NanoSec ns(3);
// Test if the file_time_type period is less than that of nanoseconds.
auto ft_dur = duration_cast<file_time_type::duration>(ns);
if (duration_cast<NanoSec>(ft_dur) != ns)
return false;
static_assert(std::is_same<file_time_type::period, std::nano>::value, "");
// Test that the system call we use to set the times also supports nanosecond
// resolution. (utimes does not)
file_time_type ft(ft_dur);
file_time_type ft(ns);
{
scoped_test_env env;
const path p = env.create_file("file", 42);
@@ -225,13 +221,14 @@ static const bool SupportsNanosecondRoundTrip = [] {
}
}();
// The HFS+ filesystem (used by default before macOS 10.13) stores timestamps at
// a 1-second granularity, and APFS (now the default) at a 1 nanosecond granularity.
// 1-second granularity is also the norm on many of the supported filesystems
// on Linux as well.
static const bool WorkaroundStatTruncatesToSeconds = [] {
MicroSec micros(3);
static_assert(std::is_same<file_time_type::period, std::nano>::value, "");
// Test for the behavior of OS X 10.11 and older, which truncates the result
// of st_mtimespec to seconds.
file_time_type ft(micros);
{
scoped_test_env env;
@@ -594,14 +591,4 @@ TEST_CASE(test_exists_fails)
TEST_CHECK_THROW_RESULT(filesystem_error, Checker, last_write_time(file));
}
// Just for sanity ensure that WorkaroundStatTruncatesToSeconds is only
// ever true on Apple platforms.
TEST_CASE(apple_truncates_to_seconds_check) {
#ifndef __APPLE__
TEST_CHECK(!WorkaroundStatTruncatesToSeconds);
#else
TEST_CHECK(SupportsNanosecondRoundTrip != WorkaroundStatTruncatesToSeconds);
#endif
}
TEST_SUITE_END()