int pipe_release(struct inode *inode, struct file *file)
{
struct pipe_private *pipe = file->f_private;
if (file == pipe->read_end) {
pipe->read_end = NULL;
wake_all(&pipe->write_wait, 0);
}
if (file == pipe->write_end) {
pipe->write_end = NULL;
wake_all(&pipe->read_wait, 0);
}
if (!pipe->read_end && !pipe->write_end)
slab_free(pipe_cachep, pipe);
return 0;
}
ssize_t pipe_read(struct file *file, char *dst, size_t len, unsigned long *pos)
{
ssize_t nr_bytes;
struct pipe_private *pipe = file->f_private;
while (!(nr_bytes = flexbuf_dequeue(pipe->buf, dst, len))) {
// pipe is empty
if (!pipe->write_end)
return 0; // no writers: EOF
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
if (wait_interruptible(&pipe->read_wait))
return -EINTR;
}
wake_all(&pipe->write_wait, 0);
return nr_bytes;
}
/*
* Write @len bytes to @pipe atomically with respect to other writers.
*/
static ssize_t pipe_do_write(struct pipe_private *pipe, const char *src, size_t len)
{
size_t nr_bytes = 0;
while (1) {
// write as much as we can
size_t this_len = MIN(len-nr_bytes, pipe_headroom(pipe));
size_t this_bytes = flexbuf_enqueue(&pipe->buf, src+nr_bytes, this_len);
if (this_bytes)
wake_all(&pipe->read_wait, 0);
// termination condition in the middle of the loop...
nr_bytes += this_bytes;
if (nr_bytes == len)
break;
if (wait_interruptible(&pipe->write_wait))
return nr_bytes ? (ssize_t)nr_bytes : -EINTR;
}
return nr_bytes;
}
void keyboard_handler(struct regs *r)
{
(void)r; /* prevent 'unused parameter' warning */
/* read from keyboard data register */
uint8_t data = inportb(KBD_DATA_REG);
uint8_t scancode = data & 0x7F;
if (data & 0x80) {
/* key released */
if (scancode == 1) {
toggle_caps_lock_light();
}
} else {
/* key pressed, add it to keycode queue and wake up
* all threads waiting on the keycode thread queue */
uint16_t keycode = kdbus[scancode];
enqueue_keycode(keycode);
/* wake all threads waiting for keyboard presses */
wake_all(&keycode_wait_queue);
}
}
// A function responsible for de-initialising the variable.
inline void ConditionVariable::_deinitialise() { wake_all(); };