[PATCH] server/console: ensure conhost has created the TTY input stream before waiting

[Eric Pouech]

some PE executables (like mingw's gdb port) just do something like:
- WaitForSingleObject(GetStdHandle(STD_INPUT_HANDLE), INFINITE) and hang
  for ever (the read operations are done *after* the wait operation
  succeeds)
(of course, the real wait operation is more complex, but the problematic
part boils down to that)

this hangs for ever because conhost's main input thread hasn't been started
yet

this patch sends once a peek IOCTL before waiting, hence ensuring conhost's
main input stream has been started

this lets i686 and x64_86 mingw's gdb port to accept user's input

(this is second attempt to fix this bug, based on Jacek's feedback on
first try)

A+
Signed-off-by: Eric Pouech

---
 server/console.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/server/console.c b/server/console.c
index 977c428cf9f..b4ef1d21874 100644
--- a/server/console.c
+++ b/server/console.c
@@ -136,6 +136,7 @@ struct console_server
     struct list           read_queue;  /* blocking read queue */
     int                   busy;        /* flag if server processing an ioctl */
     int                   term_fd;     /* UNIX terminal fd */
+    int                   once_input;  /* flag if input thread has already been requested */
     struct termios        termios;     /* original termios */
 };

@@ -892,6 +893,7 @@ static struct object *create_console_server( void )
     server->console = NULL;
     server->busy    = 0;
     server->term_fd = -1;
+    server->once_input = 0;
     list_init( &server->queue );
     list_init( &server->read_queue );
     server->fd = alloc_pseudo_fd( &console_server_fd_ops, &server->obj, FILE_SYNCHRONOUS_IO_NONALERT );
@@ -1310,11 +1312,19 @@ static void console_input_dump( struct object *obj, int verbose )

static int console_input_add_queue( struct object *obj, struct wait_queue_entry *entry )
 {
+    struct console_server* server;
     if (!current->process->console)
     {
         set_error( STATUS_ACCESS_DENIED );
         return 0;
     }
+    server = current->process->console->server;
+    /* before waiting, ensure conhost's input thread has been started */
+    if ( server && !server->once_input )
+    {
+        queue_host_ioctl( server, IOCTL_CONDRV_PEEK, 0, NULL, NULL);
+        server->once_input = 1;
+    }
     return add_queue( &current->process->console->obj, entry );
 }