patch 9.1.0264: libgpm may delete some signal handlersv9.1.0264

Problem:  libgpm may delete some signal handlers
Solution: restore these signal handlers after calling gpm
          (Julio B)

When 'mouse' is set, vim is trying to detect mouse support on startup.
Eventually, vim resorts to using libgpm as the final method of
mouse detection. This library may delete some signals handlers that were
initially set up by vim.

This is how:
- mch_setmouse() calls gpm_open()
- Gpm_Open is executed, which returns early on line 210 [1]
- Keep in mind that lines 353-373 [2] are skipped, so
  gpm_saved_suspend_hook and gpm_saved_winch_hook are empty
- Finally, Gpm_Close is called, which will reset [3] SIGWINCH and
  SIGTSTP to an empty sigaction.

[1] https://github.com/telmich/gpm/blob/e82d1a653ca94aa4ed12441424da6ce780b1e530/src/lib/liblow.c#L210
[2] https://github.com/telmich/gpm/blob/e82d1a653ca94aa4ed12441424da6ce780b1e530/src/lib/liblow.c#L353-L373
[3] https://github.com/telmich/gpm/blob/e82d1a653ca94aa4ed12441424da6ce780b1e530/src/lib/liblow.c#L419-L424

fixes: #12154
closes: #14401

Signed-off-by: Julio B <julio.bacel@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

2 files changed, 14 insertions, 0 deletions

diff --git a/src/os_unix.c b/src/os_unix.c
index e98911e0f8..da7f56a675 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -7494,7 +7494,19 @@ gpm_open(void)
 	return 1; // succeed
     }
     if (gpm_fd == -2)
+    {
 	Gpm_Close(); // We don't want to talk to xterm via gpm
+
+        // Gpm_Close fails to properly restore the WINCH and TSTP handlers,
+        // leading to Vim ignoring resize signals. We have to re-initialize
+        // these handlers again here.
+# ifdef SIGWINCH
+	mch_signal(SIGWINCH, sig_winch);
+# endif
+# ifdef SIGTSTP
+	mch_signal(SIGTSTP, restricted ? SIG_IGN : sig_tstp);
+# endif
+    }
     return 0;
 }
 
diff --git a/src/version.c b/src/version.c
index 1a82d9b3ab..861adf1bd8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    264,
+/**/
     263,
 /**/
     262,