On 2015-03-24 20:53, Corinna Vinschen wrote:
>
> On Mar 24 19:59, Denis Excoffier wrote:
>> On 2015-02-28 16:30, Corinna Vinschen wrote:
>>> I can not reproduce this in mintty, nor in a Cygwin xterm started on a
>>> remote X server running under Linux. I can reproduce this with a local
>>> xterm started via startxwin. But, and that's the problem, I can
>>> reproduce it with the current 1.7.35-0.5 test release, with 1.7.34, and
>>> last but not least also with a debug version of the Cygwin DLL in which I
>>> backed out all PTY-related changes since last November.
>>>
>>> I'm not sure this is a giveaway, but from that it seems this problem
>>> is not directly related to a Cygwin change in the last months.
>>>
>>> So, jturney and I are wondering when exactly you encountered this problem
>>> for the first time. Did it coincide with a certain Cygwin release,
>>> or a certain X server? Or new X libs, perhaps?
>>>
>>> Anything you can provide to narrow down the potential culprit would be
>>> helpful.
>>>
>> Well. Here is some more inputs.
>>
>> This is connected with the "min" option of stty. When this occurs,
>> 'stty -a' says '4' for min. If i change into 'stty min 5' the characters
>> come by chunks of 5.
>>
>> I had a look into the sources of xterm, xinit, coreutils, tcsh and cygwin and
>> i definitely don't understand where the 4 comes from. In any case, 4 should
>> not be
>> the problem, because 'stty min 4' is perfectly legitimate.
>>
>> The doc of stty says that 'min' (and 'time') are used in case of '-icanon'.
>> However, i found in fhandler_tty.cc that it seems not to be always the case.
>> After i applied the following patch:
>>
>> diff -uNr cygwin-snapshot-20150317-1.original/winsup/cygwin/fhandler_tty.cc
>> cygwin-snapshot-20150317-1.patched/winsup/cygwin/fhandler_tty.cc
>> --- cygwin-snapshot-20150317-1.original/winsup/cygwin/fhandler_tty.cc
>> 2015-03-17 11:42:16.000000000 +0100
>> +++ cygwin-snapshot-20150317-1.patched/winsup/cygwin/fhandler_tty.cc
>> 2015-03-24 19:32:42.000000000 +0100
>> @@ -715,7 +715,7 @@
>>
>> if (is_nonblocking () || !ptr) /* Indicating tcflush(). */
>> time_to_wait = 0;
>> - else if ((get_ttyp ()->ti.c_lflag & ICANON))
>> + else if (!(get_ttyp ()->ti.c_lflag & ICANON))
>
> No, this is wrong. You're switching the code for icanon with the
> code for -icanon. -icanon in stty means ICANON is switched off.
>
> I just gave it another try and the behaviour is perfectly valid.
>
> The real problem is that "something" is setting VMIN to 4. And that's
> somehow inside the X server, if I'm not completely wrong:
>
> - If you start an xterm from mintty like this:
>
> xterm -display :0
>
> and then call `stty -a' in it, you'll see that min is 1, and then
> script will behave as desired.
>
> - However, if you start xterm from the X server tray icon and then
> call `stty -a' in it, min is set to 4 and script will misbehave.
> If you call `stty min 1' before calling script, script will work
> as expected again.
>
> So, why does the X server (or whatever controls starting applications
> from the X server tray icon) set VMIN to 4?
>
It seems that this has something to do with tcsh (and not with XWin).
If you arrange your environment in order that the xterm launches /bin/bash
(instead of tcsh), you get min=0 under 'stty -a' and /bin/script behaves
as expected. If afterwards, in such an xterm, you run '/bin/csh -f', you get
min=4.
Consider the following:
diff -uNr tcsh-6.18.01-original/ed.init.c tcsh-6.18.01-patched/ed.init.c
--- tcsh-6.18.01-original/ed.init.c 2006-08-24 22:56:08.000000000 +0200
+++ tcsh-6.18.01-patched/ed.init.c 2015-03-25 15:56:33.000000000 +0100
@@ -65,7 +65,7 @@
(uc)CDSWTCH, (uc)CERASE2, (uc)CSTART, (uc)CSTOP,
(uc)CWERASE, (uc)CSUSP, (uc)CDSUSP, (uc)CREPRINT,
(uc)CDISCARD, (uc)CLNEXT, (uc)CSTATUS, (uc)CPAGE,
- (uc)CPGOFF, (uc)CKILL2, (uc)CBRK, (uc)CMIN,
+ (uc)CPGOFF, (uc)CKILL2, (uc)CBRK, (uc)1,
(uc)CTIME
},
{
In the original code, CMIN is set to CEOF and CEOF is set to Control-D, hence
min=4. With the patch above, all seems to go well. But this does not
explain why the min=4 is not permanent.
Regards,
Denis Excoffier.
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