Re: Old timestamps in the future?

[Paul Smith]

On Fri, 2022-12-09 at 14:59 +0100, Gisle Vanem wrote:
> A file dated '1. Jan. 1970, 00:20' is wrongly claimed to be in the
> future.  Some wrap going on here or something wrong with the logic in
> 'remake.c'? But a file dated '1. Jan. 1970, 01:00' is
> accepted fine.
> 
> Looking at e.g.'is_ordinary_mtime()' it seems a 'st_mtime' must
> be larger than some X-value to qualify as a valid timestamp.
> So the above 20 min on Windows is not enough to be accepted
> as "ordinary" (?)

I don't know how things work on Windows, plus you seem to be using
POSIX tools here so you must be using some Windows-based POSIX
facilities that you don't specify (Cygwin?  MinGW?  WSL?)

I cannot reproduce this behavior on my GNU/Linux system.

But, note that touch writes timestamps in the current timezone by
default.  It could be that your timezone (which you also didn't
specify) makes a difference, when you are talking about timestamps
right at the edge of the epoch.

If you force UTC, for example:

  $ TZ=UTC make

does it make a difference in behavior?

I recommend you choose 1970-01-02 instead of 1970-01-01, just to be
safe regardless of local time.