Re: [PATCH v3 09/49] semihosting: Adjust error checking in common_semi_cb

[Richard Henderson]

On 5/23/22 08:35, Richard Henderson wrote:
> > That implies that our current code is right, in that the
> > way to check for "did the call fail" is to look at the
> > retcode, not the errno (in the same way that if you make a
> > native syscall or library call you look first at its return
> > value, not at errno). There's nothing in the protocol text
> > that makes a guarantee that the errno value is non-0 if and
> > only if the call failed.
>
> I admit that I didn't check the gdb code.  I looked at our side and saw that when the 
> second result is missing that we'd supply 0, and interpreted "can be omitted" as "will be 
> omitted" on success.

Checking, can->will is actually correct, and gdb will omit the errno parameter 
on success.

https://sourceware.org/git?p=binutils-gdb.git;a=blob;f=gdb/remote-fileio.c;h=fe191fb6069a53a3844656a81e77069afa781946;hb=HEAD#l328

So I think checking err != 0 is a good change.


r~