Re: CYGWIN file input redirection

[Pedro Alves <palves@redhat.com>]

On 10/24/2016 02:24 PM, Eli Zaretskii wrote:

> I'm not sure I see the problem.  If you debug GDB's redirection code,
> you will probably not redirect that GDB's standard streams, right?
> IOW, you would
> 
>   > gdb ./gdb.exe
>   (top-gdb) run foo.exe
>   (gdb) run < bar > baz
> 
> Right?  Or did you mean something else?

OK.  I guess I was confused.  So let's just forget my comment.

> 
>> It'd be nice to add comments mentioning what syntax works and doesn't
>> work.  Is there something users should know about syntax, that
>> should be added to the manual?
> 
> The code is supposed to support everything cmd.exe supports, and
> nothing else.  Ah, I see I didn't implement the likes of "2>&1".  Will
> do.
> 
> The only thing beyond what cmd.exe supports is that one can use
> Unix-style forward slashes in redirected file names, which comes in
> handy because GDB's file-name completion helps.  Not sure if this
> should be in the manual.  WDYT?

Seems fine not to mention that, since gdb supports forward slashes
throughout, anyway.  If it didn't support them here probably someone 
would call it a bug.

> 
>> Ideally some test would "prove" this all works, which would
>> also make it possible to more confidently change the implementation
>> later on if we find it necessary.  It's been years since I'd tried to
>> run the testsuite for mingw gdb (under cygwin/msys/msys2 of course)
>> and I have no idea whether people are doing that nowadays.  I have
>> the impression that maybe no one is..  And then, I can't seem to
>> find any existing test that exercises redirection, even
>> on Unix...  :-/  Oh well.
> 
> Right.  I don't have a setup for running the test suite.  I did, of
> course, test the code manually.
> 
>>>> +  if (inferior_io_terminal
>>>> +      && !(inf_stdin != INVALID_HANDLE_VALUE
>>>> +	   && inf_stdout != INVALID_HANDLE_VALUE
>>>> +	   && inf_stderr != INVALID_HANDLE_VALUE))
>>
>> I find these double-negatives hard to read.  I'd suggest:
>>
>>   if (inferior_io_terminal
>>       && (inf_stdin == INVALID_HANDLE_VALUE
>> 	  || inf_stdout == INVALID_HANDLE_VALUE
>> 	  || inf_stderr == INVALID_HANDLE_VALUE))
> 
> Interesting, I actually find the latter harder to grasp.  The former
> says "if not all of the handles are valid".  I can add a macro
> VALID_HANDLE, if that would help.

Leave it be as you had it then.  It was just a minor suggestion.

> 
> Thanks for the review, I will add the missing bits and fixes and
> resubmit.

Thanks,
Pedro Alves