Re: [gforth] errno weirdness

[Rene Hartmann]

Reepca Russelstein wrote:
> errno stubbornly refuses to change from 0 no matter what kind of
> ridiculous shenanigans I get up to, (-12938 -12932 kill, for example).
> Considering C libraries' annoying tendency to communicate all useful
> debugging information through that one point, that's pretty
> frustrating. The C functions themselves return -1 as is expected, but
> errno refuses to change, even when I erroneously use functions from
> libc.fs itself (example: s" /argle" s" /blargle" link).
>
> So now I'm stuck trying to figure out why my ptraces are randomly
> failing despite using the exact same arguments without knowing what
> the error even is. I'm on the latest git checkout presently.
>
> Any ideas? My first guess would be that something in gforth itself is
> overwriting errno routinely...
>
> Oh. Well then, turns out the problem only occurs when interactively
> checking errno - when it's in a compiled definition it works fine. I
> suppose that makes sense, but it's definitely not what I expected. I
> don't suppose something could be done about that, even if it's just
> adding a note to the manual?

Are you taking into account that errno is a macro on some systems so the 
errno variable may not be used at all? Under Linux, I call 
__errno_location() which is what errno expands to (plus a *).

Under GForth it seems to be possible to expand macros but I'm trying to 
stay portable to other Forths as much as possible.

--
René Hartmann