win32: try to recover from strange console mode

Execute a remote command on a Windows server using ssh:

   ~$ ssh localhost 'echo hello'
   rmy@localhost's password:
   hello

If such a command is run from a busybox-w32 shell the console enters
a strange mode when the command completes.

Attempt to recover by setting the console back to a default mode.

- This doesn't work in a legacy console.

- The new mode may not be _exactly_ correct, but it's better than how
  ssh leaves it.

Costs 80-96 bytes.

(GitHub issue #288)

1 files changed, 14 insertions, 4 deletions

diff --git a/win32/winansi.c b/win32/winansi.c
index 15f443f4b..ef566684e 100644
--- a/win32/winansi.c
+++ b/win32/winansi.c
@@ -76,7 +76,10 @@ int skip_ansi_emulation(int reset)
         static int skip = -1;
 
         if (skip < 0 || reset) {
+                HANDLE h;
+                DWORD oldmode, newmode;
                 const char *var = getenv(BB_SKIP_ANSI_EMULATION);
+
                 if (var) {
                         skip = atoi(var);
                         if (skip < 0 || skip > 2)
@@ -87,11 +90,10 @@ int skip_ansi_emulation(int reset)
                 }
 
                 if (is_console(STDOUT_FILENO)) {
-                        HANDLE h = get_console();
-                        DWORD oldmode, newmode;
-
+                        h = get_console();
                         if (GetConsoleMode(h, &oldmode)) {
-                                newmode = oldmode;
+                                // Try to recover from mode 0 induced by SSH.
+                                newmode = oldmode == 0 ? 3 : oldmode;
                                 if (skip)
                                         newmode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING;
                                 else
@@ -103,6 +105,14 @@ int skip_ansi_emulation(int reset)
                                 }
                         }
                 }
+
+                // Try to recover from mode 0 induced by SSH.
+                if (reset && is_console_in(STDIN_FILENO)) {
+                        h = GetStdHandle(STD_INPUT_HANDLE);
+                        if (GetConsoleMode(h, &oldmode) && oldmode == 0) {
+                                SetConsoleMode(h, 0x1f7);
+                        }
+                }
         }
 
         return skip;