linux/include/sound/control.h
Gustavo A. R. Silva 9ad06ebb9a ALSA: Replace zero-length array with flexible-array
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200507192223.GA16335@embeddedor
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2020-05-07 22:30:36 +02:00

264 lines
8.5 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef __SOUND_CONTROL_H
#define __SOUND_CONTROL_H
/*
* Header file for control interface
* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
*/
#include <linux/wait.h>
#include <linux/nospec.h>
#include <sound/asound.h>
#define snd_kcontrol_chip(kcontrol) ((kcontrol)->private_data)
struct snd_kcontrol;
typedef int (snd_kcontrol_info_t) (struct snd_kcontrol * kcontrol, struct snd_ctl_elem_info * uinfo);
typedef int (snd_kcontrol_get_t) (struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol);
typedef int (snd_kcontrol_put_t) (struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol);
typedef int (snd_kcontrol_tlv_rw_t)(struct snd_kcontrol *kcontrol,
int op_flag, /* SNDRV_CTL_TLV_OP_XXX */
unsigned int size,
unsigned int __user *tlv);
/* internal flag for skipping validations */
#ifdef CONFIG_SND_CTL_VALIDATION
#define SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK (1 << 27)
#define snd_ctl_skip_validation(info) \
((info)->access & SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK)
#else
#define SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK 0
#define snd_ctl_skip_validation(info) true
#endif
enum {
SNDRV_CTL_TLV_OP_READ = 0,
SNDRV_CTL_TLV_OP_WRITE = 1,
SNDRV_CTL_TLV_OP_CMD = -1,
};
struct snd_kcontrol_new {
snd_ctl_elem_iface_t iface; /* interface identifier */
unsigned int device; /* device/client number */
unsigned int subdevice; /* subdevice (substream) number */
const unsigned char *name; /* ASCII name of item */
unsigned int index; /* index of item */
unsigned int access; /* access rights */
unsigned int count; /* count of same elements */
snd_kcontrol_info_t *info;
snd_kcontrol_get_t *get;
snd_kcontrol_put_t *put;
union {
snd_kcontrol_tlv_rw_t *c;
const unsigned int *p;
} tlv;
unsigned long private_value;
};
struct snd_kcontrol_volatile {
struct snd_ctl_file *owner; /* locked */
unsigned int access; /* access rights */
};
struct snd_kcontrol {
struct list_head list; /* list of controls */
struct snd_ctl_elem_id id;
unsigned int count; /* count of same elements */
snd_kcontrol_info_t *info;
snd_kcontrol_get_t *get;
snd_kcontrol_put_t *put;
union {
snd_kcontrol_tlv_rw_t *c;
const unsigned int *p;
} tlv;
unsigned long private_value;
void *private_data;
void (*private_free)(struct snd_kcontrol *kcontrol);
struct snd_kcontrol_volatile vd[]; /* volatile data */
};
#define snd_kcontrol(n) list_entry(n, struct snd_kcontrol, list)
struct snd_kctl_event {
struct list_head list; /* list of events */
struct snd_ctl_elem_id id;
unsigned int mask;
};
#define snd_kctl_event(n) list_entry(n, struct snd_kctl_event, list)
struct pid;
enum {
SND_CTL_SUBDEV_PCM,
SND_CTL_SUBDEV_RAWMIDI,
SND_CTL_SUBDEV_ITEMS,
};
struct snd_ctl_file {
struct list_head list; /* list of all control files */
struct snd_card *card;
struct pid *pid;
int preferred_subdevice[SND_CTL_SUBDEV_ITEMS];
wait_queue_head_t change_sleep;
spinlock_t read_lock;
struct fasync_struct *fasync;
int subscribed; /* read interface is activated */
struct list_head events; /* waiting events for read */
};
#define snd_ctl_file(n) list_entry(n, struct snd_ctl_file, list)
typedef int (*snd_kctl_ioctl_func_t) (struct snd_card * card,
struct snd_ctl_file * control,
unsigned int cmd, unsigned long arg);
void snd_ctl_notify(struct snd_card * card, unsigned int mask, struct snd_ctl_elem_id * id);
struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new * kcontrolnew, void * private_data);
void snd_ctl_free_one(struct snd_kcontrol * kcontrol);
int snd_ctl_add(struct snd_card * card, struct snd_kcontrol * kcontrol);
int snd_ctl_remove(struct snd_card * card, struct snd_kcontrol * kcontrol);
int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol, bool add_on_replace);
int snd_ctl_remove_id(struct snd_card * card, struct snd_ctl_elem_id *id);
int snd_ctl_rename_id(struct snd_card * card, struct snd_ctl_elem_id *src_id, struct snd_ctl_elem_id *dst_id);
int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
int active);
struct snd_kcontrol *snd_ctl_find_numid(struct snd_card * card, unsigned int numid);
struct snd_kcontrol *snd_ctl_find_id(struct snd_card * card, struct snd_ctl_elem_id *id);
int snd_ctl_create(struct snd_card *card);
int snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn);
int snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn);
#ifdef CONFIG_COMPAT
int snd_ctl_register_ioctl_compat(snd_kctl_ioctl_func_t fcn);
int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn);
#else
#define snd_ctl_register_ioctl_compat(fcn)
#define snd_ctl_unregister_ioctl_compat(fcn)
#endif
int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type);
static inline unsigned int snd_ctl_get_ioffnum(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id)
{
unsigned int ioff = id->numid - kctl->id.numid;
return array_index_nospec(ioff, kctl->count);
}
static inline unsigned int snd_ctl_get_ioffidx(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id)
{
unsigned int ioff = id->index - kctl->id.index;
return array_index_nospec(ioff, kctl->count);
}
static inline unsigned int snd_ctl_get_ioff(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id)
{
if (id->numid) {
return snd_ctl_get_ioffnum(kctl, id);
} else {
return snd_ctl_get_ioffidx(kctl, id);
}
}
static inline struct snd_ctl_elem_id *snd_ctl_build_ioff(struct snd_ctl_elem_id *dst_id,
struct snd_kcontrol *src_kctl,
unsigned int offset)
{
*dst_id = src_kctl->id;
dst_id->index += offset;
dst_id->numid += offset;
return dst_id;
}
/*
* Frequently used control callbacks/helpers
*/
int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
struct snd_ctl_elem_info *uinfo);
int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
struct snd_ctl_elem_info *uinfo);
int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
unsigned int items, const char *const names[]);
/*
* virtual master control
*/
struct snd_kcontrol *snd_ctl_make_virtual_master(char *name,
const unsigned int *tlv);
int _snd_ctl_add_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave,
unsigned int flags);
/* optional flags for slave */
#define SND_CTL_SLAVE_NEED_UPDATE (1 << 0)
/**
* snd_ctl_add_slave - Add a virtual slave control
* @master: vmaster element
* @slave: slave element to add
*
* Add a virtual slave control to the given master element created via
* snd_ctl_create_virtual_master() beforehand.
*
* All slaves must be the same type (returning the same information
* via info callback). The function doesn't check it, so it's your
* responsibility.
*
* Also, some additional limitations:
* at most two channels,
* logarithmic volume control (dB level) thus no linear volume,
* master can only attenuate the volume without gain
*
* Return: Zero if successful or a negative error code.
*/
static inline int
snd_ctl_add_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave)
{
return _snd_ctl_add_slave(master, slave, 0);
}
/**
* snd_ctl_add_slave_uncached - Add a virtual slave control
* @master: vmaster element
* @slave: slave element to add
*
* Add a virtual slave control to the given master.
* Unlike snd_ctl_add_slave(), the element added via this function
* is supposed to have volatile values, and get callback is called
* at each time queried from the master.
*
* When the control peeks the hardware values directly and the value
* can be changed by other means than the put callback of the element,
* this function should be used to keep the value always up-to-date.
*
* Return: Zero if successful or a negative error code.
*/
static inline int
snd_ctl_add_slave_uncached(struct snd_kcontrol *master,
struct snd_kcontrol *slave)
{
return _snd_ctl_add_slave(master, slave, SND_CTL_SLAVE_NEED_UPDATE);
}
int snd_ctl_add_vmaster_hook(struct snd_kcontrol *kctl,
void (*hook)(void *private_data, int),
void *private_data);
void snd_ctl_sync_vmaster(struct snd_kcontrol *kctl, bool hook_only);
#define snd_ctl_sync_vmaster_hook(kctl) snd_ctl_sync_vmaster(kctl, true)
int snd_ctl_apply_vmaster_slaves(struct snd_kcontrol *kctl,
int (*func)(struct snd_kcontrol *vslave,
struct snd_kcontrol *slave,
void *arg),
void *arg);
/*
* Helper functions for jack-detection controls
*/
struct snd_kcontrol *
snd_kctl_jack_new(const char *name, struct snd_card *card);
void snd_kctl_jack_report(struct snd_card *card,
struct snd_kcontrol *kctl, bool status);
#endif /* __SOUND_CONTROL_H */