dvb_functions.c

来自「优龙2410linux2.6.8内核源代码」· C语言 代码 · 共 90 行

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/module.h>
#include <linux/ioctl.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>

void dvb_kernel_thread_setup (const char *thread_name)
{
        lock_kernel ();

        daemonize (thread_name);

        sigfillset (&current->blocked);

        unlock_kernel ();
}

/* if the miracle happens and "generic_usercopy()" is included into
   the kernel, then this can vanish. please don't make the mistake and
   define this as video_usercopy(). this will introduce a dependecy
   to the v4l "videodev.o" module, which is unnecessary for some
   cards (ie. the budget dvb-cards don't need the v4l module...) */
int dvb_usercopy(struct inode *inode, struct file *file,
	             unsigned int cmd, unsigned long arg,
		     int (*func)(struct inode *inode, struct file *file,
		     unsigned int cmd, void *arg))
{
        char    sbuf[128];
        void    *mbuf = NULL;
        void    *parg = NULL;
        int     err  = -EINVAL;

        /*  Copy arguments into temp kernel buffer  */
        switch (_IOC_DIR(cmd)) {
        case _IOC_NONE:
		/*
		 * For this command, the pointer is actually an integer
		 * argument.
		 */
                parg = (void *) arg;
                break;
        case _IOC_READ: /* some v4l ioctls are marked wrong ... */
        case _IOC_WRITE:
        case (_IOC_WRITE | _IOC_READ):
                if (_IOC_SIZE(cmd) <= sizeof(sbuf)) {
                        parg = sbuf;
                } else {
                        /* too big to allocate from stack */
                        mbuf = kmalloc(_IOC_SIZE(cmd),GFP_KERNEL);
                        if (NULL == mbuf)
                                return -ENOMEM;
                        parg = mbuf;
                }

                err = -EFAULT;
                if (copy_from_user(parg, (void __user *)arg, _IOC_SIZE(cmd)))
                        goto out;
                break;
        }

        /* call driver */
        if ((err = func(inode, file, cmd, parg)) == -ENOIOCTLCMD)
                err = -EINVAL;

        if (err < 0)
                goto out;

        /*  Copy results into user buffer  */
        switch (_IOC_DIR(cmd))
        {
        case _IOC_READ:
        case (_IOC_WRITE | _IOC_READ):
                if (copy_to_user((void __user *)arg, parg, _IOC_SIZE(cmd)))
                        err = -EFAULT;
                break;
        }

out:
        if (mbuf)
                kfree(mbuf);

        return err;
}

EXPORT_SYMBOL(dvb_usercopy);
EXPORT_SYMBOL(dvb_kernel_thread_setup);