xterm_kern.c

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/* 
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <linux/slab.h>
#include <linux/completion.h>
#include <linux/irqreturn.h>
#include <asm/irq.h>
#include <irq_kern.h>
#include <os.h>

struct xterm_wait {
    struct completion ready;
    int fd;
    int pid;
    int new_fd;
};

static irqreturn_t xterm_interrupt(int irq, void *data)
{
    struct xterm_wait *xterm = data;
    int fd;

    fd = os_rcv_fd(xterm->fd, &xterm->pid);
    if (fd == -EAGAIN)
        return IRQ_NONE;

    xterm->new_fd = fd;
    complete(&xterm->ready);

    return IRQ_HANDLED;
}

int xterm_fd(int socket, int *pid_out)
{
    struct xterm_wait *data;
    int err, ret;

    data = kmalloc(sizeof(*data), GFP_KERNEL);
    if (data == NULL) {
        printk(KERN_ERR "xterm_fd : failed to allocate xterm_wait\n");
        return -ENOMEM;
    }

    /* This is a locked semaphore... */
    *data = ((struct xterm_wait) { .fd      = socket,
                       .pid         = -1,
                       .new_fd      = -1 });
    init_completion(&data->ready);

    err = um_request_irq(XTERM_IRQ, socket, IRQ_READ, xterm_interrupt,
                 IRQF_SHARED, "xterm", data);
    if (err) {
        printk(KERN_ERR "xterm_fd : failed to get IRQ for xterm, "
               "err = %d\n",  err);
        ret = err;
        goto out;
    }

    /* ... so here we wait for an xterm interrupt.
     *
     * XXX Note, if the xterm doesn't work for some reason (eg. DISPLAY
     * isn't set) this will hang... */
    wait_for_completion(&data->ready);

    um_free_irq(XTERM_IRQ, data);

    ret = data->new_fd;
    *pid_out = data->pid;
 out:
    kfree(data);

    return ret;
}