Re: compat_sys_times() bogus until jiffies >= 0.

[Andreas Schwab]

David Miller <davem@xxxxxxxxxxxxx> writes:

> I agree with this analysis.
>
> The Linux man page for times() explicitly lists (clock_t) -1 as a
> return value meaning error.
>
> So even if we did make some effort to return errors "properly" (via
> force_successful_syscall_return() et al.) userspace would still be
> screwed because (clock_t) -1 would be interpreted as an error.
>
> Actually I think this basically proves we cannot return (clock_t) -1
> ever because all existing userland (I'm not talking about inside
> glibc, I'm talking about inside of applications) will see this as an
> error.
>
> User applications have no other way to check for error.
>
> This API is definitely very poorly designed, no matter which way we
> "fix" this some case will remain broken.

A possible remedy is to return the ticks since process start time, which
delays the wrap around much further.  POSIX only demands consistency
within the same process.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@xxxxxxx
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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