Re: [ptxdist] year 2038 Toolchain

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

On 23/05/2024 07:41, Erwin Rol wrote:
> Hey all,
> 
> I am working on arm32 (imx6ul) and need to support dates beyond 2038. 
> With the new ptxdist 2038 support it seems to work in C, but I ran into 
> problems with C++.
> 
> 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.
> 
> Conversion functions on the other hand seem to work;
> 
> auto t = std::chrono::system_clock::from_time_t(time(nullptr));
> 
> does a correct conversion of dates > 2038.
> 
> The defines like _TIME_BITS=64 are set correctly, and time_t is 64bit. 
> Also calls like gettimeofday() works correctly.
> 
> Since the C++ std lib is part of the Toolchain, can it be that the 
> Toolchain is not build correctly ?
> 
> Anybody any experience with y2038 in C++ on ptxdist ?
> 
> best regards,
> 
> Erwin
> 

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.

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