On 23/05/2024 12:52, Erwin Rol wrote:
On 5/23/24 12:38, Ian Abbott wrote:
On 23/05/2024 07:41, Erwin Rol wrote:
The following code;
auto t = std::chrono::system_clock::now();
does not seem to work correctly. When the system date is less than
2038 it works and gives back the correct time, but for dates > 2038
it seems to return some 1970 date.
I guess that libstdc++ in the toolchain would need to be rebuilt with
64-bit time_t support. Although <chrono> uses a 64-bit integer type
internally, some of the functions such as
std::chrono::system_clock::now() use compiled in code that picks up
the C system time ABI at the time libstdc++ was built. So now() will
read the system time using the 32-bit system time ABI (so will suffer
from Y2038 problems) and convert it to its own internal 64-bit integer
type. Other functions such as
std::chrono::system_clock::from_time_t(std::time_t) are not compiled
in so will use whatever C system time ABI was selected when <chrono>
was included.
I believe libstd++ uses gettimeofday internally, which should use time_t
for the seconds field, which should be 64bit if _TIME_BITS=64 is
defined. I just hacked the Toolchain to try it, but it is a slow
process, build toolchain -> build project -> test :-)
If I figure it out I'll let you guys know (so it can be added to the
official Toolchain)
Rememember to define _FILE_OFFSET_BITS=64 too if it is not already
defined. _TIME_BITS=64 is ineffective when _FILE_OFFSET_BITS=32 for
Glibc policy reasons.
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