[PATCH] Fix PR win32/24284: tcp_auto_retry doesn't work in MinGW
Sergio Durigan Junior
sergiodj@redhat.com
Thu Aug 29 16:36:00 GMT 2019
On Thursday, August 29 2019, Pedro Alves wrote:
> On 8/27/19 4:50 PM, Sergio Durigan Junior wrote:
>> This was reported by Bernhard Wodok, along with a patch to fix the
>> issue. I adjusted the patch a bit, and I'm submitting the patch on
>> his behalf.
>>
>> According to Bernhard, the issue can be reproduced by doing:
>>
>> 1. start gdb
>> 2. enter 'target remote :2345'
>> 3. observe that it throws a "connection refused" error immediately
>> instead of waiting and throwing a timeout error
>>
>> I.e., I believe it can be reproduced by our current tests, which is
>> why I'm not proposing any extra tests here (well, I don't use nor have
>> any Windows system to test this, so...).
>>
>> The problem happens because we call 'gdb_select' passing 0 as its
>> first argument,
Thanks for the review, Pedro.
> I assume this is from wait_for_connect? Please mention that above.
Yes. I'll do that.
> Must be, because I just now noticed that gdb_usleep is now dead code.
>
> The comment in wait_for_connect is quite curious, kind of implies that
> this worked on Windows at some point:
>
> /* Use gdb_select here, since we have no file descriptors, and on
> Windows, plain select doesn't work in that case. */
> n = gdb_select (0, NULL, NULL, NULL, &t);
Indeed. This comment was added by:
commit 84603566b73e9ad18d094da3b7510ab480db8170
Author: Sandra Loosemore <sandra@codesourcery.com>
Date: Tue Jan 6 17:07:08 2009 +0000
It's not entirely clear that calling gdb_select on Windows will actually
call WaitForMultipleObjects. There is a 'select'c call in the Windows
API:
https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-select
So maybe it was assumed that the code would call this function
instead...
>> --- a/gdb/mingw-hdep.c
>> +++ b/gdb/mingw-hdep.c
>> @@ -64,6 +64,17 @@ gdb_select (int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
>> int num_ready;
>> size_t indx;
>>
>> + if (n == 0)
>> + {
>> + /* The MS API says that the first argument to
>> + WaitForMultipleObjects cannot be zero. That's we just use
>> + a regular Sleep here. */
>
> The sentence:
>
> "That's we just use a regular Sleep here."
>
> is non-grammatical. Missing a "why" in "That's why" ?
Yes, fixed.
> OK with that fixed.
Thanks, pushed: 16d01f9cd49f553a958a69ad3c9f781ebd402da8
--
Sergio
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