Re: [ptxdist] year 2038 Toolchain

[Ian Abbott <abbotti@mev.co.uk>]

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.

-- 
-=( Ian Abbott <abbotti@mev.co.uk> || MEV Ltd. is a company  )=-
-=( registered in England & Wales.  Regd. number: 02862268.  )=-
-=( Regd. addr.: S11 & 12 Building 67, Europa Business Park, )=-
-=( Bird Hall Lane, STOCKPORT, SK3 0XA, UK. || www.mev.co.uk )=-