control.c

linux 内核源代码

 * @id: the id to search
 *
 * Finds the control instance with the given id from the card.
 *
 * Returns the pointer of the instance if found, or NULL if not.
 *
 * The caller must down card->controls_rwsem before calling this function
 * (if the race condition can happen).
 */
struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
				     struct snd_ctl_elem_id *id)
{
	struct snd_kcontrol *kctl;

	snd_assert(card != NULL && id != NULL, return NULL);
	if (id->numid != 0)
		return snd_ctl_find_numid(card, id->numid);
	list_for_each_entry(kctl, &card->controls, list) {
		if (kctl->id.iface != id->iface)
			continue;
		if (kctl->id.device != id->device)
			continue;
		if (kctl->id.subdevice != id->subdevice)
			continue;
		if (strncmp(kctl->id.name, id->name, sizeof(kctl->id.name)))
			continue;
		if (kctl->id.index > id->index)
			continue;
		if (kctl->id.index + kctl->count <= id->index)
			continue;
		return kctl;
	}
	return NULL;
}

EXPORT_SYMBOL(snd_ctl_find_id);

static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,
			     unsigned int cmd, void __user *arg)
{
	struct snd_ctl_card_info *info;

	info = kzalloc(sizeof(*info), GFP_KERNEL);
	if (! info)
		return -ENOMEM;
	down_read(&snd_ioctl_rwsem);
	info->card = card->number;
	strlcpy(info->id, card->id, sizeof(info->id));
	strlcpy(info->driver, card->driver, sizeof(info->driver));
	strlcpy(info->name, card->shortname, sizeof(info->name));
	strlcpy(info->longname, card->longname, sizeof(info->longname));
	strlcpy(info->mixername, card->mixername, sizeof(info->mixername));
	strlcpy(info->components, card->components, sizeof(info->components));
	up_read(&snd_ioctl_rwsem);
	if (copy_to_user(arg, info, sizeof(struct snd_ctl_card_info))) {
		kfree(info);
		return -EFAULT;
	}
	kfree(info);
	return 0;
}

static int snd_ctl_elem_list(struct snd_card *card,
			     struct snd_ctl_elem_list __user *_list)
{
	struct list_head *plist;
	struct snd_ctl_elem_list list;
	struct snd_kcontrol *kctl;
	struct snd_ctl_elem_id *dst, *id;
	unsigned int offset, space, first, jidx;
	
	if (copy_from_user(&list, _list, sizeof(list)))
		return -EFAULT;
	offset = list.offset;
	space = list.space;
	first = 0;
	/* try limit maximum space */
	if (space > 16384)
		return -ENOMEM;
	if (space > 0) {
		/* allocate temporary buffer for atomic operation */
		dst = vmalloc(space * sizeof(struct snd_ctl_elem_id));
		if (dst == NULL)
			return -ENOMEM;
		down_read(&card->controls_rwsem);
		list.count = card->controls_count;
		plist = card->controls.next;
		while (plist != &card->controls) {
			if (offset == 0)
				break;
			kctl = snd_kcontrol(plist);
			if (offset < kctl->count)
				break;
			offset -= kctl->count;
			plist = plist->next;
		}
		list.used = 0;
		id = dst;
		while (space > 0 && plist != &card->controls) {
			kctl = snd_kcontrol(plist);
			for (jidx = offset; space > 0 && jidx < kctl->count; jidx++) {
				snd_ctl_build_ioff(id, kctl, jidx);
				id++;
				space--;
				list.used++;
			}
			plist = plist->next;
			offset = 0;
		}
		up_read(&card->controls_rwsem);
		if (list.used > 0 &&
		    copy_to_user(list.pids, dst,
				 list.used * sizeof(struct snd_ctl_elem_id))) {
			vfree(dst);
			return -EFAULT;
		}
		vfree(dst);
	} else {
		down_read(&card->controls_rwsem);
		list.count = card->controls_count;
		up_read(&card->controls_rwsem);
	}
	if (copy_to_user(_list, &list, sizeof(list)))
		return -EFAULT;
	return 0;
}

static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
			     struct snd_ctl_elem_info *info)
{
	struct snd_card *card = ctl->card;
	struct snd_kcontrol *kctl;
	struct snd_kcontrol_volatile *vd;
	unsigned int index_offset;
	int result;
	
	down_read(&card->controls_rwsem);
	kctl = snd_ctl_find_id(card, &info->id);
	if (kctl == NULL) {
		up_read(&card->controls_rwsem);
		return -ENOENT;
	}
#ifdef CONFIG_SND_DEBUG
	info->access = 0;
#endif
	result = kctl->info(kctl, info);
	if (result >= 0) {
		snd_assert(info->access == 0, );
		index_offset = snd_ctl_get_ioff(kctl, &info->id);
		vd = &kctl->vd[index_offset];
		snd_ctl_build_ioff(&info->id, kctl, index_offset);
		info->access = vd->access;
		if (vd->owner) {
			info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
			if (vd->owner == ctl)
				info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
			info->owner = vd->owner_pid;
		} else {
			info->owner = -1;
		}
	}
	up_read(&card->controls_rwsem);
	return result;
}

static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
				  struct snd_ctl_elem_info __user *_info)
{
	struct snd_ctl_elem_info info;
	int result;

	if (copy_from_user(&info, _info, sizeof(info)))
		return -EFAULT;
	snd_power_lock(ctl->card);
	result = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);
	if (result >= 0)
		result = snd_ctl_elem_info(ctl, &info);
	snd_power_unlock(ctl->card);
	if (result >= 0)
		if (copy_to_user(_info, &info, sizeof(info)))
			return -EFAULT;
	return result;
}

int snd_ctl_elem_read(struct snd_card *card, struct snd_ctl_elem_value *control)
{
	struct snd_kcontrol *kctl;
	struct snd_kcontrol_volatile *vd;
	unsigned int index_offset;
	int result, indirect;

	down_read(&card->controls_rwsem);
	kctl = snd_ctl_find_id(card, &control->id);
	if (kctl == NULL) {
		result = -ENOENT;
	} else {
		index_offset = snd_ctl_get_ioff(kctl, &control->id);
		vd = &kctl->vd[index_offset];
		indirect = vd->access & SNDRV_CTL_ELEM_ACCESS_INDIRECT ? 1 : 0;
		if (control->indirect != indirect) {
			result = -EACCES;
		} else {
			if ((vd->access & SNDRV_CTL_ELEM_ACCESS_READ) && kctl->get != NULL) {
				snd_ctl_build_ioff(&control->id, kctl, index_offset);
				result = kctl->get(kctl, control);
			} else {
				result = -EPERM;
			}
		}
	}
	up_read(&card->controls_rwsem);
	return result;
}

static int snd_ctl_elem_read_user(struct snd_card *card,
				  struct snd_ctl_elem_value __user *_control)
{
	struct snd_ctl_elem_value *control;
	int result;
	
	control = kmalloc(sizeof(*control), GFP_KERNEL);
	if (control == NULL)
		return -ENOMEM;	
	if (copy_from_user(control, _control, sizeof(*control))) {
		kfree(control);
		return -EFAULT;
	}
	snd_power_lock(card);
	result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
	if (result >= 0)
		result = snd_ctl_elem_read(card, control);
	snd_power_unlock(card);
	if (result >= 0)
		if (copy_to_user(_control, control, sizeof(*control)))
			result = -EFAULT;
	kfree(control);
	return result;
}

int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
		       struct snd_ctl_elem_value *control)
{
	struct snd_kcontrol *kctl;
	struct snd_kcontrol_volatile *vd;
	unsigned int index_offset;
	int result, indirect;

	down_read(&card->controls_rwsem);
	kctl = snd_ctl_find_id(card, &control->id);
	if (kctl == NULL) {
		result = -ENOENT;
	} else {
		index_offset = snd_ctl_get_ioff(kctl, &control->id);
		vd = &kctl->vd[index_offset];
		indirect = vd->access & SNDRV_CTL_ELEM_ACCESS_INDIRECT ? 1 : 0;
		if (control->indirect != indirect) {
			result = -EACCES;
		} else {
			if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_WRITE) ||
			    kctl->put == NULL ||
			    (file && vd->owner != NULL && vd->owner != file)) {
				result = -EPERM;
			} else {
				snd_ctl_build_ioff(&control->id, kctl, index_offset);
				result = kctl->put(kctl, control);
			}
			if (result > 0) {
				up_read(&card->controls_rwsem);
				snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, &control->id);
				return 0;
			}
		}
	}
	up_read(&card->controls_rwsem);
	return result;
}

static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
				   struct snd_ctl_elem_value __user *_control)
{
	struct snd_ctl_elem_value *control;
	struct snd_card *card;
	int result;

	control = kmalloc(sizeof(*control), GFP_KERNEL);
	if (control == NULL)
		return -ENOMEM;	
	if (copy_from_user(control, _control, sizeof(*control))) {
		kfree(control);
		return -EFAULT;
	}
	card = file->card;
	snd_power_lock(card);
	result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
	if (result >= 0)
		result = snd_ctl_elem_write(card, file, control);
	snd_power_unlock(card);
	if (result >= 0)
		if (copy_to_user(_control, control, sizeof(*control)))
			result = -EFAULT;
	kfree(control);
	return result;
}

static int snd_ctl_elem_lock(struct snd_ctl_file *file,
			     struct snd_ctl_elem_id __user *_id)
{
	struct snd_card *card = file->card;
	struct snd_ctl_elem_id id;
	struct snd_kcontrol *kctl;
	struct snd_kcontrol_volatile *vd;
	int result;
	
	if (copy_from_user(&id, _id, sizeof(id)))
		return -EFAULT;
	down_write(&card->controls_rwsem);
	kctl = snd_ctl_find_id(card, &id);
	if (kctl == NULL) {
		result = -ENOENT;
	} else {
		vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
		if (vd->owner != NULL)
			result = -EBUSY;
		else {
			vd->owner = file;
			vd->owner_pid = current->pid;
			result = 0;
		}
	}
	up_write(&card->controls_rwsem);
	return result;
}

static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
			       struct snd_ctl_elem_id __user *_id)
{
	struct snd_card *card = file->card;
	struct snd_ctl_elem_id id;
	struct snd_kcontrol *kctl;
	struct snd_kcontrol_volatile *vd;
	int result;
	
	if (copy_from_user(&id, _id, sizeof(id)))
		return -EFAULT;
	down_write(&card->controls_rwsem);
	kctl = snd_ctl_find_id(card, &id);
	if (kctl == NULL) {
		result = -ENOENT;
	} else {
		vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
		if (vd->owner == NULL)
			result = -EINVAL;
		else if (vd->owner != file)
			result = -EPERM;
		else {
			vd->owner = NULL;
			vd->owner_pid = 0;
			result = 0;
		}
	}
	up_write(&card->controls_rwsem);
	return result;
}

struct user_element {
	struct snd_ctl_elem_info info;
	void *elem_data;		/* element data */
	unsigned long elem_data_size;	/* size of element data in bytes */
	void *tlv_data;			/* TLV data */
	unsigned long tlv_data_size;	/* TLV data size */
	void *priv_data;		/* private data (like strings for enumerated type) */
	unsigned long priv_data_size;	/* size of private data in bytes */
};

static int snd_ctl_elem_user_info(struct snd_kcontrol *kcontrol,
				  struct snd_ctl_elem_info *uinfo)
{
	struct user_element *ue = kcontrol->private_data;

	*uinfo = ue->info;
	return 0;
}

static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
				 struct snd_ctl_elem_value *ucontrol)
{
	struct user_element *ue = kcontrol->private_data;

	memcpy(&ucontrol->value, ue->elem_data, ue->elem_data_size);
	return 0;
}

static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
				 struct snd_ctl_elem_value *ucontrol)
{
	int change;
	struct user_element *ue = kcontrol->private_data;
	
	change = memcmp(&ucontrol->value, ue->elem_data, ue->elem_data_size) != 0;
	if (change)
		memcpy(ue->elem_data, &ucontrol->value, ue->elem_data_size);
	return change;
}

static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol,
				 int op_flag,
				 unsigned int size,
				 unsigned int __user *tlv)
{
	struct user_element *ue = kcontrol->private_data;
	int change = 0;
	void *new_data;

	if (op_flag > 0) {
		if (size > 1024 * 128)	/* sane value */
			return -EINVAL;
		new_data = kmalloc(size, GFP_KERNEL);
		if (new_data == NULL)
			return -ENOMEM;
		if (copy_from_user(new_data, tlv, size)) {
			kfree(new_data);
			return -EFAULT;
		}
		change = ue->tlv_data_size != size;
		if (!change)
			change = memcmp(ue->tlv_data, new_data, size);
		kfree(ue->tlv_data);
		ue->tlv_data = new_data;
		ue->tlv_data_size = size;
	} else {
		if (! ue->tlv_data_size || ! ue->tlv_data)
			return -ENXIO;
		if (size < ue->tlv_data_size)
			return -ENOSPC;
		if (copy_to_user(tlv, ue->tlv_data, ue->tlv_data_size))
			return -EFAULT;
	}
	return change;
}

static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)
{
	struct user_element *ue = kcontrol->private_data;
	if (ue->tlv_data)
		kfree(ue->tlv_data);
	kfree(ue);
}

static int snd_ctl_elem_add(struct snd_ctl_file *file,
			    struct snd_ctl_elem_info *info, int replace)
{
	struct snd_card *card = file->card;
	struct snd_kcontrol kctl, *_kctl;
	unsigned int access;
	long private_size;
	struct user_element *ue;
	int idx, err;
	
	if (card->user_ctl_count >= MAX_USER_CONTROLS)
		return -ENOMEM;
	if (info->count > 1024)
		return -EINVAL;
	access = info->access == 0 ? SNDRV_CTL_ELEM_ACCESS_READWRITE :
		(info->access & (SNDRV_CTL_ELEM_ACCESS_READWRITE|
				 SNDRV_CTL_ELEM_ACCESS_INACTIVE|
				 SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE));
	info->id.numid = 0;
	memset(&kctl, 0, sizeof(kctl));
	down_write(&card->controls_rwsem);
	_kctl = snd_ctl_find_id(card, &info->id);
	err = 0;
	if (_kctl) {
		if (replace)
			err = snd_ctl_remove(card, _kctl);
		else
			err = -EBUSY;
	} else {
		if (replace)
			err = -ENOENT;
	}
	up_write(&card->controls_rwsem);
	if (err < 0)
		return err;
	memcpy(&kctl.id, &info->id, sizeof(info->id));
	kctl.count = info->owner ? info->owner : 1;
	access |= SNDRV_CTL_ELEM_ACCESS_USER;
	kctl.info = snd_ctl_elem_user_info;
	if (access & SNDRV_CTL_ELEM_ACCESS_READ)
		kctl.get = snd_ctl_elem_user_get;
	if (access & SNDRV_CTL_ELEM_ACCESS_WRITE)
		kctl.put = snd_ctl_elem_user_put;
	if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE) {
		kctl.tlv.c = snd_ctl_elem_user_tlv;
		access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
	}
	switch (info->type) {
	case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
	case SNDRV_CTL_ELEM_TYPE_INTEGER:
		private_size = sizeof(long);
		if (info->count > 128)
			return -EINVAL;
		break;
	case SNDRV_CTL_ELEM_TYPE_INTEGER64:
		private_size = sizeof(long long);
		if (info->count > 64)