[newlib-cygwin/cygwin-3_4-branch] Cygwin: console: Fix hangup of less on quit after the window is resized.

Takashi Yano tyan0@sourceware.org
Thu Dec 22 11:51:13 GMT 2022


https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=76e1edeb27a573a955ebf3ae5a7a7fd1a75b290f

commit 76e1edeb27a573a955ebf3ae5a7a7fd1a75b290f
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Thu Dec 22 20:25:22 2022 +0900

    Cygwin: console: Fix hangup of less on quit after the window is resized.
    
    https://cygwin.com/pipermail/cygwin/2022-December/252737.html
    
    If the less is started from non-cygwin shell and window size is
    changed, it will hang-up when quitting. The cause of the proglem is
    that less uses longjump() in signal handler. If the signal handler
    is called while cygwin is acquiring the mutex, cygwin loses the
    chance to release mutex. With this patch, the mutex is released
    just before calling kill_pgrp() and re-acquired when kill_pgrp()
    returns.
    
    Reported-by: Gregory Mason <grmason@epic.com>
    Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>

Diff:
---
 winsup/cygwin/fhandler/console.cc | 4 ++++
 winsup/cygwin/release/3.4.4       | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/winsup/cygwin/fhandler/console.cc b/winsup/cygwin/fhandler/console.cc
index a4a367005..bfcdb84b3 100644
--- a/winsup/cygwin/fhandler/console.cc
+++ b/winsup/cygwin/fhandler/console.cc
@@ -939,7 +939,11 @@ fhandler_console::send_winch_maybe ()
       if (wincap.has_con_24bit_colors () && !con_is_legacy
 	  && wincap.has_con_broken_tabs ())
 	fix_tab_position (get_output_handle ());
+      /* longjmp() may be called in the signal handler like less,
+	 so release input_mutex temporarily before kill_pgrp(). */
+      release_input_mutex ();
       get_ttyp ()->kill_pgrp (SIGWINCH);
+      acquire_input_mutex (mutex_timeout);
       return true;
     }
   return false;
diff --git a/winsup/cygwin/release/3.4.4 b/winsup/cygwin/release/3.4.4
index 6ac702375..3331b3166 100644
--- a/winsup/cygwin/release/3.4.4
+++ b/winsup/cygwin/release/3.4.4
@@ -3,3 +3,7 @@ Bug Fixes
 
 - Fix an uninitialized variable having weird side-effects in path handling.
   Addresses: https://cygwin.com/pipermail/cygwin/2022-December/252734.html
+
+- Fix hang-up of less on quit which occurs when it is started from non-cygwin
+  shell and window is resized.
+  Addresses: https://cygwin.com/pipermail/cygwin/2022-December/252737.html


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