[Splashy-devel] Bug#473101: splashy: getpass/getstring don't work

[John Hughes]

Package: splashy
Version: 0.3.8-1
Severity: normal
Tags: patch

When this simple test is run (on a single cpu system):

	splashy boot
	sleep 5
	splashy_update "getstring enter your name"
	splashy_update "exit"

splashy appears to hang.  The getstring prompt is not printed and splashy does not exit.

If the F2 key is pressed a few times the getstring box suddenlt pops up and when the string is entered splasy exits.

The problem is caused by a race between the socket loop and the keyevent loop.

In the keyevent_loop we have:

	while (1)
	{
		...
		pthread_mutex_lock (&key_mut);
		splashy_wait_for_event ();
		while ((key = splashy_get_key_event ()) > 0)
		{
			...
		}
		pthread_mutex_unlock (&key_mut);
		...
	} 

In the socket loop we try to synchronise with the keyevent loop using key_mut, for example to do a getpass we do:

	splashy_wake_up (); 	/* causes splashy_wait_for_event to exit */
	pthread_mutex_lock (&key_mut);
	splashy_get_password (...);
	pthread_mutex_lock (&key_mut);

Normaly keyevent_loop will be sleeping in splashy_wait_for_event, with the mutex locked.  When a getpass command is read 
on the socket we call splashy_wake_up, which makes the keyevent_loop runnable.  We then call pthread_mutex_lock, and so 
go to sleep.  Now keyevent loop falls out of splashy_wait_for event, sees there are no keys to process, unlocks the 
mutex, LOOPS BACK AND RELOCKS THE MUTEX.

The problem is that unlocking the mutex does not yield the cpu - the other thread stays asleep in pthread_mutex_lock.

The fix is to inverse locking and waiting, in keyevent_loop do:

	while (1)
	{
		...
		splashy_wait_for_event ();
		pthread_mutex_lock (&key_mut);
		...
		pthread_mutex_unlock (&key_mut);
	}

and in getpass:

	pthread_mutex_lock (&key_mut);
	splashy_wake_up ();
	splashy_get_password (...);
	pthread_mutex_unlock (&key_mut);

Patch attached.

-- System Information:
Debian Release: lenny/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable')
Architecture: i386 (i686)

Kernel: Linux 2.6.24-1-686 (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages splashy depends on:
ii  initramfs-tools        0.91e             tools for generating an initramfs
ii  libc6                  2.7-9             GNU C Library: Shared libraries
ii  libdirectfb-1.0-0      1.0.1-8           direct frame buffer graphics - sha
ii  libgcc1                1:4.3.0-2         GCC support library
ii  libglib2.0-0           2.16.1-2          The GLib library of C routines
ii  libmagic1              4.23-2            File type determination library us
ii  libsplashy1            0.3.8-1           Library to draw splash screen on b
ii  lsb-base               3.2-4             Linux Standard Base 3.2 init scrip
ii  zlib1g                 1:1.2.3.3.dfsg-11 compression library - runtime

splashy recommends no packages.

-- no debconf information
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