patch 7.4.876

Problem:    Windows7: when using vim.exe with msys or msys2, conhost.exe
            (console window provider on Windows7) will freeze or crash.
Solution:   Make original screen buffer active, before executing external
            program.  And when the program is finished, revert to vim's one.
            (Taro Muraoka)

src/os_win32.c

@@ -234,6 +234,7 @@ static int suppress_winsize = 1;	/* don't fiddle with console */
 
 static char_u *exe_path = NULL;
 
+static BOOL is_win7 = FALSE;
 static BOOL win8_or_later = FALSE;
 
 /*
@@ -680,6 +681,9 @@ PlatformId(void)
 
 	g_PlatformId = ovi.dwPlatformId;
 
+	if ((ovi.dwMajorVersion == 6 && ovi.dwMinorVersion == 1))
+	    is_win7 = TRUE;
+
 	if ((ovi.dwMajorVersion == 6 && ovi.dwMinorVersion >= 2)
 		|| ovi.dwMajorVersion > 6)
 	    win8_or_later = TRUE;
@@ -4581,11 +4585,12 @@ mch_system(char *cmd, int options)
     else
 	return mch_system_classic(cmd, options);
 }
+
 #else
 
 # ifdef FEAT_MBYTE
     static int
-mch_system(char *cmd, int options)
+mch_system1(char *cmd, int options)
 {
     if (enc_codepage >= 0 && (int)GetACP() != enc_codepage)
     {
@@ -4600,9 +4605,31 @@ mch_system(char *cmd, int options)
     return system(cmd);
 }
 # else
-#  define mch_system(c, o) system(c)
+#  define mch_system1(c, o) system(c)
 # endif
 
+    static int
+mch_system(char *cmd, int options)
+{
+    int ret;
+
+    /*
+     * Restore non-termcap screen buffer before execute external program, and
+     * revert it after.  Because msys and msys2's programs will cause freeze
+     * or crash conhost.exe (Windows's console window provider) and vim.exe,
+     * if active screen buffer is vim's one on Windows7.
+     */
+    if (is_win7 && g_fTermcapMode)
+	SetConsoleActiveScreenBuffer(g_cbNonTermcap.handle);
+
+    ret = mch_system1(cmd, options);
+
+    if (is_win7 && g_fTermcapMode)
+	SetConsoleActiveScreenBuffer(g_cbTermcap.handle);
+
+    return ret;
+}
+
 #endif
 
 /*

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    876,
 /**/
     875,
 /**/