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Re: CYGWIN file input redirection
> Cc: email@example.com
> From: Pedro Alves <firstname.lastname@example.org>
> Date: Mon, 24 Oct 2016 13:36:34 +0100
> On 10/22/2016 10:30 AM, Eli Zaretskii wrote:
> > Ping! Is this OK to push to master, please?
> I think this should have a NEWS entry.
Yes, I thought about this myself. Will do.
> Since on Windows, programs are expected to handle redirection
??? No, they don't (I believe you thought about wildcard expansion?).
Redirection on Windows shell command line works like on Unix: the
shell invokes the program with standard streams redirected according
to the redirection symbols. Which is exactly what this code emulates
> isn't there a chance that this will make it a bit
> harder to debug such redirection code in inferiors that
> do it themselves? E.g., imagine if you're debugging cmd.exe's
> redirection code. Or maybe even debugging this new code
> in gdb itself? Do we need a knob to be able to disable
> this feature?
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?
> 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
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?
> 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.
Thanks for the review, I will add the missing bits and fixes and