[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 on console input objects,
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.

V2 => V3 (including Jacek's comments)
- space style conventions
- move once_input flag setting into CONDRV_SETUP_INPUT handling
- applied same change to console objects' add_queue as to console_input objects
  (and let the later call into the former)
- made console_server flags' storage a bit field

A+
Signed-off-by: Eric Pouech <eric.pouech at gmail.com>

---
 server/console.c |   43 ++++++++++++++++++++++++++++++-------------
 1 file changed, 30 insertions(+), 13 deletions(-)

diff --git a/server/console.c b/server/console.c
index 977c428cf9f..5224324c7f6 100644
--- a/server/console.c
+++ b/server/console.c
@@ -71,13 +71,14 @@ static struct object *console_lookup_name( struct object *obj, struct unicode_st
                                            unsigned int attr, struct object *root );
 static struct object *console_open_file( struct object *obj, unsigned int access,
                                          unsigned int sharing, unsigned int options );
+static int console_add_queue( struct object *obj, struct wait_queue_entry *entry );
 
 static const struct object_ops console_ops =
 {
     sizeof(struct console),           /* size */
     &file_type,                       /* type */
     console_dump,                     /* dump */
-    add_queue,                        /* add_queue */
+    console_add_queue,                /* add_queue */
     remove_queue,                     /* remove_queue */
     console_signaled,                 /* signaled */
     no_satisfied,                     /* satisfied */
@@ -129,14 +130,15 @@ struct console_host_ioctl
 
 struct console_server
 {
-    struct object         obj;         /* object header */
-    struct fd            *fd;          /* pseudo-fd for ioctls */
-    struct console       *console;     /* attached console */
-    struct list           queue;       /* ioctl queue */
-    struct list           read_queue;  /* blocking read queue */
-    int                   busy;        /* flag if server processing an ioctl */
-    int                   term_fd;     /* UNIX terminal fd */
-    struct termios        termios;     /* original termios */
+    struct object         obj;            /* object header */
+    struct fd            *fd;             /* pseudo-fd for ioctls */
+    struct console       *console;        /* attached console */
+    struct list           queue;          /* ioctl queue */
+    struct list           read_queue;     /* blocking read queue */
+    unsigned int          busy : 1;       /* flag if server processing an ioctl */
+    unsigned int          once_input : 1; /* flag if input thread has already been requested */
+    int                   term_fd;        /* UNIX terminal fd */
+    struct termios        termios;        /* original termios */
 };
 
 static void console_server_dump( struct object *obj, int verbose );
@@ -462,6 +464,19 @@ static const struct fd_ops console_connection_fd_ops =
 
 static struct list screen_buffer_list = LIST_INIT(screen_buffer_list);
 
+static int queue_host_ioctl( struct console_server *server, unsigned int code, unsigned int output,
+                             struct async *async, struct async_queue *queue );
+
+static int console_add_queue( struct object *obj, struct wait_queue_entry *entry )
+{
+    struct console *console = (struct console*)obj;
+    assert( obj->ops == &console_ops );
+    /* before waiting, ensure conhost's input thread has been started */
+    if (console->server && !console->server->once_input)
+        queue_host_ioctl( console->server, IOCTL_CONDRV_PEEK, 0, NULL, NULL );
+    return add_queue( &console->obj, entry );
+}
+
 static int console_signaled( struct object *obj, struct wait_queue_entry *entry )
 {
     struct console *console = (struct console*)obj;
@@ -889,9 +904,10 @@ static struct object *create_console_server( void )
     struct console_server *server;
 
     if (!(server = alloc_object( &console_server_ops ))) return NULL;
-    server->console = NULL;
-    server->busy    = 0;
-    server->term_fd = -1;
+    server->console    = NULL;
+    server->busy       = 0;
+    server->once_input = 0;
+    server->term_fd    = -1;
     list_init( &server->queue );
     list_init( &server->read_queue );
     server->fd = alloc_pseudo_fd( &console_server_fd_ops, &server->obj, FILE_SYNCHRONOUS_IO_NONALERT );
@@ -1086,6 +1102,7 @@ static void console_server_ioctl( struct fd *fd, ioctl_code_t code, struct async
             struct file *file;
             int unix_fd;
 
+            server->once_input = 1;
             if (get_req_data_size() != sizeof(unsigned int) || get_reply_max_size())
             {
                 set_error( STATUS_INVALID_PARAMETER );
@@ -1315,7 +1332,7 @@ static int console_input_add_queue( struct object *obj, struct wait_queue_entry
         set_error( STATUS_ACCESS_DENIED );
         return 0;
     }
-    return add_queue( &current->process->console->obj, entry );
+    return console_add_queue( &current->process->console->obj, entry );
 }
 
 static struct fd *console_input_get_fd( struct object *obj )