[RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host

[RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host

[Pierre Muller]

  Here is an alternate proposal to get rid of that double \r 
problem encountered when running the testsuite with mingw host GDB.

  maint set testsuite-mode on
force stdout and stderr to use binary mode.

  maint set testsuite-mode off
restores stdout and stderr "normal" text mode behavior.

  Comments welcome,

Pierre Muller
GDB pascal language maintainer


2013-09-18  Pierre Muller  <muller@sourceware.org>

	* mingw-hdep.c (set_output_binary_mode): New function.
	(set_output_normal_mode, set_maint_testsuite_mode): New functions.
	(show_maint_testsuite_mode): New function.
	(_initialize_mingw_hdep): Add new command,
	"maintenance set testsuite-mode on/off".

testsuite/ChangeLog:

	* testsuite/lib/gdb.exp (*-*-mingw* hosts): Add
	"maint set testsuite-mode" and "set interacitve-mode on"
	startup command.


Index: src/gdb/mingw-hdep.c
===================================================================
RCS file: /cvs/src/src/gdb/mingw-hdep.c,v
retrieving revision 1.16
diff -u -p -r1.16 mingw-hdep.c
--- src/gdb/mingw-hdep.c	6 Apr 2013 06:52:06 -0000	1.16
+++ src/gdb/mingw-hdep.c	17 Sep 2013 23:00:49 -0000
@@ -21,6 +21,8 @@
 #include "main.h"
 #include "serial.h"
 #include "event-loop.h"
+#include "command.h"
+#include "gdbcmd.h"
 
 #include "gdb_assert.h"
 #include "gdb_select.h"
@@ -265,6 +267,50 @@ gdb_call_async_signal_handler (struct as
   SetEvent (sigint_event);
 }
 
+/* Set stdout and stderr handles to binary unbuffered mode.  */
+
+static void
+set_output_binary_mode (void)
+{
+  /* In textmode, a '\n' is automatically expanded into "\r\n".  This
+     results in expect seeing "\r\r\n".  The tests aren't prepared
+     currently for other forms of eol.  As a workaround, we force the
+     output to binary mode.  */
+  setmode (fileno (stdout), O_BINARY);
+  setmode (fileno (stderr), O_BINARY);
+}
+
+/* Restore stdout and stderr handles to "normal" mode.  */
+
+static void
+set_output_normal_mode (void)
+{
+  setmode (fileno (stdout), O_TEXT);
+  setmode (fileno (stderr), O_TEXT);
+}
+
+static int maint_testsuite_mode = 0;
+
+/* Sets the maintenance testsuite mode using the static global
+   testuite_mode.  */
+
+static void
+set_maint_testsuite_mode (char *args, int from_tty,
+			       struct cmd_list_element *c)
+{
+  if (maint_testsuite_mode)
+    set_output_binary_mode ();
+  else
+    set_output_normal_mode ();
+}
+
+static void
+show_maint_testsuite_mode (struct ui_file *file, int from_tty,
+		struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file, _("Testsuite mode is %s.\n"), value);
+}
+
 /* -Wmissing-prototypes */
 extern initialize_file_ftype _initialize_mingw_hdep;
 
@@ -272,4 +318,16 @@ void
 _initialize_mingw_hdep (void)
 {
   sigint_event = CreateEvent (0, FALSE, FALSE, 0);
+  add_setshow_boolean_cmd ("testsuite-mode", class_maintenance,
+			   &maint_testsuite_mode, _("\
+Set to adapt to dejagnu testsuite runs."), _("\
+Show whether GDB is adapted to run testsuite."), _("\
+Use \"on\" to enable, \"off\" to disable.\n\
+If enabled, stdout and stderr are set to binary mode,\n\
+to allow better testing."),
+			   set_maint_testsuite_mode,
+			   show_maint_testsuite_mode,
+			   &maintenance_set_cmdlist,
+			   &maintenance_show_cmdlist);
+
 }
Index: src/gdb/testsuite/lib/gdb.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/lib/gdb.exp,v
retrieving revision 1.245
diff -u -p -r1.245 gdb.exp
--- src/gdb/testsuite/lib/gdb.exp	16 Sep 2013 23:59:02 -0000
1.245
+++ src/gdb/testsuite/lib/gdb.exp	17 Sep 2013 23:01:48 -0000
@@ -61,6 +61,10 @@ global INTERNAL_GDBFLAGS
 if ![info exists INTERNAL_GDBFLAGS] {
     set INTERNAL_GDBFLAGS "-nw -nx -data-directory $BUILD_DATA_DIRECTORY"
 }
+if [ishost "*-*-mingw*"] {
+    verbose "mingw host, needs testsuite-mode"
+#    append INTERNAL_GDBFLAGS " -iex {maint set testsuite-mode on} -iex
{set interactive-mode on}"
+}
 
 # The variable gdb_prompt is a regexp which matches the gdb prompt.
 # Set it if it is not already set.

Re: [RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host

[Joel Brobecker]

>   Here is an alternate proposal to get rid of that double \r 
> problem encountered when running the testsuite with mingw host GDB.
> 
>   maint set testsuite-mode on
> force stdout and stderr to use binary mode.
> 
>   maint set testsuite-mode off
> restores stdout and stderr "normal" text mode behavior.

FWIW, I tend to think that it's better to test the debugger in
an environment that is as close as possible to reality. For
those reasons, I tend to favor Yao's approach.  But it's not
a strong opinion.

-- 
Joel

Re: [RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host

[Doug Evans]

On Tue, Sep 17, 2013 at 7:11 PM, Joel Brobecker <brobecker@adacore.com> wrote:
>>   Here is an alternate proposal to get rid of that double \r
>> problem encountered when running the testsuite with mingw host GDB.
>>
>>   maint set testsuite-mode on
>> force stdout and stderr to use binary mode.
>>
>>   maint set testsuite-mode off
>> restores stdout and stderr "normal" text mode behavior.
>
> FWIW, I tend to think that it's better to test the debugger in
> an environment that is as close as possible to reality. For
> those reasons, I tend to favor Yao's approach.  But it's not
> a strong opinion.

Can someone explain how \r\r\n occurs?
Presumably two difference pieces of software are doing the \n -> \r\n
translation.
What are they?

[hacking the testsuite may be preferable in some way, but I'm worried
that road will be long and painful]

RE: [RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host

[Pierre Muller]

> -----Message d'origine-----
> De : gdb-patches-owner@sourceware.org [mailto:gdb-patches-
> owner@sourceware.org] De la part de Doug Evans
> Envoyé : mercredi 18 septembre 2013 09:20
> À : Joel Brobecker
> Cc : Pierre Muller; gdb-patches
> Objet : Re: [RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host
> 
> On Tue, Sep 17, 2013 at 7:11 PM, Joel Brobecker <brobecker@adacore.com>
> wrote:
> >>   Here is an alternate proposal to get rid of that double \r
> >> problem encountered when running the testsuite with mingw host GDB.
> >>
> >>   maint set testsuite-mode on
> >> force stdout and stderr to use binary mode.
> >>
> >>   maint set testsuite-mode off
> >> restores stdout and stderr "normal" text mode behavior.
> >
> > FWIW, I tend to think that it's better to test the debugger in
> > an environment that is as close as possible to reality. For
> > those reasons, I tend to favor Yao's approach.  But it's not
> > a strong opinion.
> 
> Can someone explain how \r\r\n occurs?

  As I finally analyzed the problem,
it all comes from the fact that mingw compiled GDB executables
open stdout and stderr in text mode and this generates a \n -> \r\n
translation inside GDB.

> Presumably two difference pieces of software are doing the \n -> \r\n
> translation.
  There is also some \r-> \r\n translation appearing
in normal testsuite on any system.

> What are they?
> 
> [hacking the testsuite may be preferable in some way, but I'm worried
> that road will be long and painful]

  I tried for a while to achieve something reliable...
Here is my last version... Quite ugly and still far from perfect...
This is one of the reasons why I doubt that Yao's patch will work
flawlessly...

  Please do not consider this as a RFC, I only send it here
to show that I tried hard for a while to
do a replacement of \r\n to \r+\n only a the correct locations
in the testuite....





2011-05-24  Pierre Muller  <muller@ics.u-strasbg.fr>

	* testsuite/lib/gdb-textmode.exp: New file.
	* testsuite/lib/gdb.exp (transform_gdb_expect_code): New variable,
	set to adapt_expcode_to_text_mode.
	(gdb_expect): Call $transform_gdb_expect_code if not empty.



Index: src/gdb/testsuite/lib/gdb-textmode.exp
===================================================================
RCS file: testsuite/lib/gdb-textmode.exp
diff -N testsuite/lib/gdb-textmode.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ src/gdb/testsuite/lib/gdb-textmode.exp	24 May 2011 13:19:32 -0000
@@ -0,0 +1,286 @@
+# Copyright 2011
+# Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file was written by Pierre Muller. (muller@ics.u-strasbg.fr)
+
+# The main purpose of this file is to implement procedure
+# adapt_expcode_to_text_mode
+# which transforms gdb_expect regular expressions
+# in order to accept two carriage return instead of one.
+
+# This is enabled by default in gdb.exp for mingw djgpp and solaris
+# targets that generate two carriage return instead of one.
+
+global transform_gdb_expect_code
+
+# This variable can be set to zero in site.exp
+# to disable use of text_mode substitution
+
+if { ![info exists use_gdb_textmode] } {
+    global use_gdb_textmode
+    set use_gdb_textmode 1
+}
+
+# Patterns used to delimit regular expressions with expcode
+# These patterns must not appear inside any regular expression used
+# but can be changed here if needed.
+# Change needs an according change to testpattern below.
+set open1 "#A#"
+set open2 "#a#"
+set close1 "#Z#"
+set close2 "#z#"
+# Paranoia check before anything else
+# Needs to be updated if any of the four variables above are changed.
+set testpattern "#\[azAZ\]#"
+
+
+# Several testing procedures and variables.
+trace add variable transform_gdb_expect_code write log_verbose
+
+proc stacktrace {} {
+    set stack "Stack trace:\n"
+    for {set i 1} {$i < [info level]} {incr i} {
+	set lvl [info level -$i]
+	set pname [lindex $lvl 0]
+	append stack [string repeat " " $i]$pname
+	foreach value [lrange $lvl 1 end] arg [info args $pname] {
+	    if {$value eq ""} {
+                info default $pname $arg value
+	    }
+	    append stack " $arg='$value'"
+	}
+	append stack \n
+    }
+    return $stack
+}
+
+global should_debug
+
+if { ! [info exists should_debug] } {
+    set should_debug 0
+}
+
+set store_verbose 0
+
+proc maybe_debug { arg } {
+    global should_debug
+    global verbose
+    global store_verbose
+    if { $should_debug } {
+	exp_internal $arg
+	if { $arg > 0 } {
+	    set store_verbose $verbose
+	    set verbose [expr $verbose + 1]
+	} else {
+	    set verbose $store_verbose
+	}
+    }
+}
+
+
+proc log_verbose { var args } {
+  set name "$var"
+  global $name
+  verbose -log "DEBUG name is $name"
+
+  set value [subst $$name];
+
+  verbose -log "DEBUG transform expect code: $var {$value} $args"
+  set bt [stacktrace]
+  verbose -log "$bt"
+}
+
+# Special code used to transform regular expressions inside
+# gdb_expect to be able to cope with the two \r appearing if
+# stdout is open in text mode.
+# This simply replaces all \r\n by \r+\n, expect if the pattern is within
+# square brackets.
+# FIXME: if expcode contains variables that themselves contain \r\n
+# patterns, those patterns are not correctly converted.
+
+proc adapt_re_expcode_to_text_mode { expcode } {
+    # Phase 1: Protect \\r\\n or \r\n inside squiare brackets
+    # Protect all '\r\n' inside square brackets by
+    # replacing those '\\r\\n' by '\\rzz\\n'
+    verbose "adapt_re_expcode_to_text_mode \"$expcode\"" 2
+ 
+    set subst1a [regsub -all {\[([^]]*)(\\?\\r)(\\?\\n)([^]]*)\]}
"$expcode" \
+		{[\1\2zz\3\4]} expcode1a]
+    if { $subst1a > 0 } {
+	verbose "subst1a $subst1a" 2
+	verbose "before \"$expcode\"" 2
+	verbose "after \"$expcode1a\"" 2
+    }
+    # replacing those '\r\n' by '\rZZ\n'
+    set subst1b [regsub -all {\[([^]]*)\r\n([^]]*)\]} $expcode1a \
+		{[\1\rZZ\n\2]} expcode1]
+    if { $subst1b > 0 } {
+	verbose "subst1b $subst1b" 2
+	verbose "before \"$expcode1a\"" 2
+	verbose "after \"$expcode1\"" 2
+    }
+
+    set subst1 [expr $subst1a + $subst1b];
+    if { $subst1 > 0 } {
+	verbose "expcode1 is \"$expcode1\"" 2
+    }
+
+    # Phase 2a: Replace other \\r\\n by \\r+\\n
+    #exp_internal 1
+    set subst2a [regsub -all {(\\?\\r)(\\?\\n)} $expcode1 {\1+\2}
expcode2a]
+    if { $subst2a > 0 } {
+	verbose "subst2a $subst2a" 2
+	verbose "before \"$expcode1\"" 2
+	verbose "after \"$expcode2a\"" 2
+    }
+    # Phase 2b: Replace other \r\n by \r+\n
+    set subst2b [regsub -all {\r\n} $expcode2a "\r+\n" expcode2]
+    if { $subst2b > 0 } {
+	verbose "subst2b $subst2b" 2
+	verbose "before \"$expcode2a\"" 2
+	verbose "after \"$expcode2\"" 2
+    }
+
+    set subst2 [expr $subst2a + $subst2b];
+
+    # Phase 3a: Convert back \\rzz\\n into \\r\\n inside square brackets
+    set subst3a [regsub -all {\[([^]]*)(\\?\\r)zz(\\?\\n)([^]]*)\]}
$expcode2 \
+		{[\1\2\3\4]} expcode3a]
+    if { $subst3a > 0 } {
+	verbose "subst3a $subst3a" 2
+	verbose "before \"$expcode2\"" 2
+	verbose "after \"$expcode3a\"" 2
+    }
+
+    # Phase 3b: Convert back \rZZ\n into \r\n inside square brackets
+    set subst3b [regsub -all {\[([^]]*)\\rZZ\\n([^]]*)\]} $expcode3a \
+		"\[\\1\r\n\\2\]" expcode3]
+    if { $subst3b > 0 } {
+	verbose "subst3b $subst3b" 2
+	verbose "before \"$expcode3a\"" 2
+	verbose "after \"$expcode3\"" 2
+    }
+
+    set subst3 [expr $subst3a + $subst3b];
+
+    set subst [expr $subst1 + $subst2 + $subst3];
+    if { ($subst1a != $subst3a) || ($subst1b != $subst3b) } {
+	verbose "Problem with substitution expcode3=\"$expcode3\""
+    }
+    if { $subst2 != 0 } {
+	verbose "Special replacement gdb_expect $subst substitutions"
+	verbose "Special replacement in gdb_expect returned
expcode=\"$expcode\""
+    }
+    if { $subst != 0 } {
+	verbose "subst1=$subst1 subst2=$subst2 subst3=$subst3" 3
+    }
+    return $expcode3
+}
+
+proc adapt_expcode_to_text_mode { expcode } {
+    global gdb_prompt
+    global use_gdb_textmode
+    global testpattern
+    global open1 open2
+    global close1 close2
+
+    verbose "Special replacement in gdb_expect entry expcode=\"$expcode\""
4
+    if { $use_gdb_textmode == 0 } {
+	return "$expcode"
+    }
+
+    set paranoia_check [regexp "$testpattern" $expcode" sub0]
+    if {$paranoia_check > 0 } {
+	verbose -log "PROBLEM: pattern $testpattern found in expcode " \
+	    "inside adapt_expcode_to_text_mode"
+    }
+
+    set before1 0
+    set before2 0
+    set substcode "$expcode"
+    set found_match 1
+    while {$found_match > 0} {
+	set sub0 ""
+	set sub1 ""
+	set sub2 ""
+	set sub3 ""
+	set found_match [regexp {^(.*-re *)( \"(?:\\"|[^"])*\" )(.*)$}
$substcode sub0 sub1 sub2 sub3]
+	if { $found_match } {
+	    set sub2s [adapt_re_expcode_to_text_mode $sub2]
+	    set substcodea "$sub1$open1$sub2s$close1$sub3"
+	    verbose  "found_match result=$found_match, sub2=\"$sub2\"" 4
+	    verbose  "sub1=\"$sub1\" sub3=\"$sub3\"" 4
+	    if { ! [string equal "$sub2" "$sub2s" ] } {
+		verbose "sub2 is changed to \"$sub2s\"" 3
+	    }
+	    incr before1 $found_match
+	    set substcode "$substcodea"
+	    verbose "new substcode=\"$substcode\"" 4
+	}
+    }
+    set found_match 1
+    while {$found_match > 0} {
+	set sub0 ""
+	set sub1 ""
+	set sub2 ""
+	set sub3 ""
+	set found_match [regexp {^(.*-re *)( \{(?:[^{}]|\{.*\})*\} )(.*)$}
$substcode sub0 sub1 sub2 sub3]
+	if { $found_match } {
+	    set sub2s [adapt_re_expcode_to_text_mode $sub2]
+	    set substcodea "$sub1$open2$sub2s$close2$sub3"
+	    verbose "found_match result=$found_match, sub2=\"$sub2\"" 4
+	    verbose "sub1=\"$sub1\" sub3=\"$sub3\"" 4
+	    if { ! [string equal "$sub2" "$sub2s" ] } {
+		verbose "sub2 is changed to \"$sub2s\"" 3
+	    }
+	    incr before2 $found_match
+	    set substcode "$substcodea"
+	    verbose "new substcode=\"$substcode\"" 4
+	}
+    }
+    if {$before1 > 0 || $before2 > 0 } {
+      set count [expr $before1 + $before2]
+      verbose "Found $count matches \"$substcode\"" 3
+    } else {
+	verbose -log "No matches found in \"$substcode\"" 4
+    }
+
+    # Remove all delimiters
+    # Use non greedy pattern version with .*?
+    # But add a final call without the question mark, otherwise
+    # one pattern could be missed.
+
+    set after1 [regsub -all "${open1}(.*?)$close1" $substcode {\1}
substcodea]
+    set after2 [regsub -all "${open2}(.*?)$close2" $substcodea {\1}
substcode]
+    set after1b [regsub -all "${open1}(.*)$close1" $substcode {\1}
substcodea]
+    set after2b [regsub -all "${open2}(.*)$close2" $substcodea {\1}
substcode]
+
+    if { $before1 != $after1 + $after1b
+         || $before2 != $after2 + $after2b } {
+	verbose -log "PROBLEM: substitution mismatch"
+	verbose -log "before1=$before1"
+	verbose -log "after1=$after1"
+	verbose -log "after1b=$after1b"
+	verbose -log "before2=$before2"
+	verbose -log "after2=$after2"
+	verbose -log "after2b=$after2b"
+	verbose -log "expcode=\"$substcode\""
+    } else {
+	verbose "expcode=\"$substcode\"" 4
+    }
+    return $substcode
+}
+
Index: src/gdb/testsuite/lib/gdb.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/lib/gdb.exp,v
retrieving revision 1.177
diff -u -p -r1.177 gdb.exp
--- src/gdb/testsuite/lib/gdb.exp	24 May 2011 12:01:22 -0000
1.177
+++ src/gdb/testsuite/lib/gdb.exp	24 May 2011 13:19:33 -0000
@@ -97,6 +97,26 @@ if ![info exists env(EXEEXT)] {
     set EXEEXT $env(EXEEXT)
 }
 
+# Use special procedure adapt_expcode_to_text_mode
+# on targets that tend to emit two '\r' instead of one one
+# as expected in many regular expressions used in gdb_expect calls.
+# The global variable transform_gdb_expect_code
+# has a default empty value, but gets set to
+# the procedure that handles the transformation to support the two '\r'
+# for targets that are in textmode by default or emit two '\r' for
+# other reasons.
+global transform_gdb_expect_code
+set transform_gdb_expect_code ""
+
+# targets that use adapt_expcode_to_text_mode procedure
+# load lib/gdb-textmode.exp file that contains the procedure
implementation.
+if { [istarget "*-*-mingw*"] || [istarget "*djgpp"]
+     || [istarget "*-*-solaris*"] } {
+    load_lib gdb-textmode.exp
+    set transform_gdb_expect_code "adapt_expcode_to_text_mode";
+    verbose "Using adapt_expcode_to_text_mode proc for target"
+}
+
 set octal "\[0-7\]+"
 
 set inferior_exited_re "(\\\[Inferior \[0-9\]+ \\(.*\\) exited)"
@@ -2431,6 +2451,10 @@ proc gdb_expect { args } {
 
     global suppress_flag;
     global remote_suppress_flag;
+    global transform_gdb_expect_code;
+    if { "$transform_gdb_expect_code" != "" } {
+	set expcode [$transform_gdb_expect_code $expcode];
+    }
     if [info exists remote_suppress_flag] {
 	set old_val $remote_suppress_flag;
     }

Re: [RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host

[Joel Brobecker]

> > Presumably two difference pieces of software are doing the \n -> \r\n
> > translation.
>   There is also some \r-> \r\n translation appearing
> in normal testsuite on any system.

I am wondering if there would be a way to disable that testsuite
translation in that case...

-- 
Joel

RE: [RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host

[Pierre Muller]

> -----Message d'origine-----
> De : gdb-patches-owner@sourceware.org [mailto:gdb-patches-
> owner@sourceware.org] De la part de Joel Brobecker
> Envoyé : mercredi 18 septembre 2013 15:44
> À : Pierre Muller
> Cc : 'Doug Evans'; 'gdb-patches'
> Objet : Re: [RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host
> 
> > > Presumably two difference pieces of software are doing the \n -> \r\n
> > > translation.
> >   There is also some \r-> \r\n translation appearing
> > in normal testsuite on any system.
> 
> I am wondering if there would be a way to disable that testsuite
> translation in that case...
  Maybe we could use this
http://www.tcl.tk/man/tcl8.0/TclCmd/fconfigure.htm

  But I still did not understand how it really works,
nor did I really find to which channel I should apply
this so that mingw host GDB's output is handled correctly.

  Maybe someone else on the list knows more about this
tcl command and how it could be used for our problem!

Pierre Muller

Re: [RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host

[Doug Evans]

On Wed, Sep 18, 2013 at 8:59 AM, Pierre Muller
<pierre.muller@ics-cnrs.unistra.fr> wrote:
>
>
>> -----Message d'origine-----
>> De : gdb-patches-owner@sourceware.org [mailto:gdb-patches-
>> owner@sourceware.org] De la part de Joel Brobecker
>> Envoyé : mercredi 18 septembre 2013 15:44
>> À : Pierre Muller
>> Cc : 'Doug Evans'; 'gdb-patches'
>> Objet : Re: [RFC] Testsuite: Avoid \r\r\n problem of *-*-mingw* host
>>
>> > > Presumably two difference pieces of software are doing the \n -> \r\n
>> > > translation.
>> >   There is also some \r-> \r\n translation appearing
>> > in normal testsuite on any system.
>>
>> I am wondering if there would be a way to disable that testsuite
>> translation in that case...
>   Maybe we could use this
> http://www.tcl.tk/man/tcl8.0/TclCmd/fconfigure.htm
>
>   But I still did not understand how it really works,
> nor did I really find to which channel I should apply
> this so that mingw host GDB's output is handled correctly.
>
>   Maybe someone else on the list knows more about this
> tcl command and how it could be used for our problem!
>
> Pierre Muller

If it is Tcl that's doing the other \n -> \r\n translation this looks promising.