[PATCH v2] Cygwin: pty: Introduce disable_pcon in environment CYGWIN.

[Takashi Yano]

- For programs which does not work properly with pseudo console,
  disable_pcon in environment CYGWIN is introduced. If disable_pcon
  is set, pseudo console support is disabled.
---
 winsup/cygwin/environ.cc      | 1 +
 winsup/cygwin/fhandler_tty.cc | 2 ++
 winsup/cygwin/globals.cc      | 1 +
 winsup/doc/cygwinenv.xml      | 6 ++++++
 4 files changed, 10 insertions(+)

diff --git a/winsup/cygwin/environ.cc b/winsup/cygwin/environ.cc
index 8c5ce64e1..7eb4780a8 100644
--- a/winsup/cygwin/environ.cc
+++ b/winsup/cygwin/environ.cc
@@ -120,6 +120,7 @@ static struct parse_thing
   {"reset_com", {&reset_com}, setbool, NULL, {{false}, {true}}},
   {"wincmdln", {&wincmdln}, setbool, NULL, {{false}, {true}}},
   {"winsymlinks", {func: set_winsymlinks}, isfunc, NULL, {{0}, {0}}},
+  {"disable_pcon", {&disable_pcon}, setbool, NULL, {{false}, {true}}},
   {NULL, {0}, setdword, 0, {{0}, {0}}}
 };
 
diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index fff5bebe3..a5db0967b 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -3132,6 +3132,8 @@ is_running_as_service (void)
 bool
 fhandler_pty_master::setup_pseudoconsole ()
 {
+  if (disable_pcon)
+    return false;
   /* If the legacy console mode is enabled, pseudo console seems
      not to work as expected. To determine console mode, registry
      key ForceV2 in HKEY_CURRENT_USER\Console is checked. */
diff --git a/winsup/cygwin/globals.cc b/winsup/cygwin/globals.cc
index ebe8b569f..a9648fe6a 100644
--- a/winsup/cygwin/globals.cc
+++ b/winsup/cygwin/globals.cc
@@ -71,6 +71,7 @@ bool pipe_byte;
 bool reset_com;
 bool wincmdln;
 winsym_t allow_winsymlinks = WSYM_sysfile;
+bool disable_pcon;
 
 bool NO_COPY in_forkee;
 
diff --git a/winsup/doc/cygwinenv.xml b/winsup/doc/cygwinenv.xml
index 6f67cb95d..1bc02f986 100644
--- a/winsup/doc/cygwinenv.xml
+++ b/winsup/doc/cygwinenv.xml
@@ -99,6 +99,12 @@ system call will immediately fail.</para>
 <xref linkend="pathnames-symlinks"></xref>.</para>
 </listitem>
 
+<listitem>
+<para><envar>disable_pcon</envar> - if set, pseudo console support in
+pty will be disabled. This is for programs which does not work properly
+under pty with pseudo console enabled. Defaults to not set.
+</listitem>
+
 </itemizedlist>
 
 </sect2>
-- 
2.21.0