Systemd/src/shared/bus-util.h
Lennart Poettering 2a66c2a1ed logind: add SetBrightness() bus call for setting brightness of leds/backlight devices associated with a seat
This augments the drm/input device management by adding a single method
call for setting the brightness of an "leds" or "backlight" kernel class
device.

This method call requires no privileges to call, but a caller can only
change the brightness on sessions that are currently active, and they
must own the session.

This does not do enumeration of such class devices, feature or range
probing, chnage notification; it doesn't help associating graphics or
input devices with their backlight or leds devices. For all that clients
should go directly to udev/sysfs. The SetBrightness() call is just for
executing the actual change operation, that is otherwise privileged.

Example line:

   busctl call org.freedesktop.login1 /org/freedesktop/login1/session/self org.freedesktop.login1.Session SetBrightness ssu "backlight" "intel_backlight" 200

The parameter the SetBrightness() call takes are the kernel subsystem
(i.e. "leds" or "backlight"), the device name, and the brightness
value.

On some hw setting the brightness is slow, and implementation and write
access to the sysfs knobs exposes this slowness. Due to this we'll fork
off a writer process in the background so that logind doesn't have to
block. Moreover, write requestes are coalesced: when a write request is
enqueued while one is already being executed it is queued. When another
write reques is then enqueued the earlier one is replaced by the newer
one, so that only one queued write request per device remains at any
time. Method replies are sent as soon as the first write request that
happens after the request was received is completed.

It is recommended that bus clients turn off the "expect_reply" flag on
the dbus messages they send though, that relieves logind from sending
completion notification and is particularly a good idea if clients
implement reactive UI sliders that send a quick secession of write
requests.

Replaces: #12413
2019-05-24 15:05:27 +02:00

184 lines
9.2 KiB
C

/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <sys/types.h>
#include "sd-bus.h"
#include "sd-event.h"
#include "hashmap.h"
#include "macro.h"
#include "string-util.h"
#include "time-util.h"
typedef enum BusTransport {
BUS_TRANSPORT_LOCAL,
BUS_TRANSPORT_REMOTE,
BUS_TRANSPORT_MACHINE,
_BUS_TRANSPORT_MAX,
_BUS_TRANSPORT_INVALID = -1
} BusTransport;
typedef int (*bus_property_set_t) (sd_bus *bus, const char *member, sd_bus_message *m, sd_bus_error *error, void *userdata);
struct bus_properties_map {
const char *member;
const char *signature;
bus_property_set_t set;
size_t offset;
};
enum {
BUS_MAP_STRDUP = 1 << 0, /* If set, each "s" message is duplicated. Thus, each pointer needs to be freed. */
BUS_MAP_BOOLEAN_AS_BOOL = 1 << 1, /* If set, each "b" message is written to a bool pointer. If not set, "b" is written to a int pointer. */
};
int bus_map_id128(sd_bus *bus, const char *member, sd_bus_message *m, sd_bus_error *error, void *userdata);
int bus_message_map_all_properties(sd_bus_message *m, const struct bus_properties_map *map, unsigned flags, sd_bus_error *error, void *userdata);
int bus_map_all_properties(sd_bus *bus, const char *destination, const char *path, const struct bus_properties_map *map,
unsigned flags, sd_bus_error *error, sd_bus_message **reply, void *userdata);
int bus_async_unregister_and_exit(sd_event *e, sd_bus *bus, const char *name);
typedef bool (*check_idle_t)(void *userdata);
int bus_event_loop_with_idle(sd_event *e, sd_bus *bus, const char *name, usec_t timeout, check_idle_t check_idle, void *userdata);
int bus_name_has_owner(sd_bus *c, const char *name, sd_bus_error *error);
int bus_check_peercred(sd_bus *c);
int bus_test_polkit(sd_bus_message *call, int capability, const char *action, const char **details, uid_t good_user, bool *_challenge, sd_bus_error *e);
int bus_verify_polkit_async(sd_bus_message *call, int capability, const char *action, const char **details, bool interactive, uid_t good_user, Hashmap **registry, sd_bus_error *error);
void bus_verify_polkit_async_registry_free(Hashmap *registry);
int bus_connect_system_systemd(sd_bus **_bus);
int bus_connect_user_systemd(sd_bus **_bus);
int bus_connect_transport(BusTransport transport, const char *host, bool user, sd_bus **bus);
int bus_connect_transport_systemd(BusTransport transport, const char *host, bool user, sd_bus **bus);
typedef int (*bus_message_print_t) (const char *name, const char *expected_value, sd_bus_message *m, bool value, bool all);
int bus_print_property_value(const char *name, const char *expected_value, bool only_value, const char *value);
int bus_print_property_valuef(const char *name, const char *expected_value, bool only_value, const char *fmt, ...) _printf_(4,5);
int bus_message_print_all_properties(sd_bus_message *m, bus_message_print_t func, char **filter, bool value, bool all, Set **found_properties);
int bus_print_all_properties(sd_bus *bus, const char *dest, const char *path, bus_message_print_t func, char **filter, bool value, bool all, Set **found_properties);
int bus_property_get_bool(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error);
int bus_property_set_bool(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *value, void *userdata, sd_bus_error *error);
int bus_property_get_id128(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error);
#define bus_property_get_usec ((sd_bus_property_get_t) NULL)
#define bus_property_set_usec ((sd_bus_property_set_t) NULL)
assert_cc(sizeof(int) == sizeof(int32_t));
#define bus_property_get_int ((sd_bus_property_get_t) NULL)
assert_cc(sizeof(unsigned) == sizeof(uint32_t));
#define bus_property_get_unsigned ((sd_bus_property_get_t) NULL)
/* On 64bit machines we can use the default serializer for size_t and
* friends, otherwise we need to cast this manually */
#if __SIZEOF_SIZE_T__ == 8
#define bus_property_get_size ((sd_bus_property_get_t) NULL)
#else
int bus_property_get_size(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error);
#endif
#if __SIZEOF_LONG__ == 8
#define bus_property_get_long ((sd_bus_property_get_t) NULL)
#define bus_property_get_ulong ((sd_bus_property_get_t) NULL)
#else
int bus_property_get_long(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error);
int bus_property_get_ulong(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error);
#endif
/* uid_t and friends on Linux 32 bit. This means we can just use the
* default serializer for 32bit unsigned, for serializing it, and map
* it to NULL here */
assert_cc(sizeof(uid_t) == sizeof(uint32_t));
#define bus_property_get_uid ((sd_bus_property_get_t) NULL)
assert_cc(sizeof(gid_t) == sizeof(uint32_t));
#define bus_property_get_gid ((sd_bus_property_get_t) NULL)
assert_cc(sizeof(pid_t) == sizeof(uint32_t));
#define bus_property_get_pid ((sd_bus_property_get_t) NULL)
assert_cc(sizeof(mode_t) == sizeof(uint32_t));
#define bus_property_get_mode ((sd_bus_property_get_t) NULL)
int bus_log_parse_error(int r);
int bus_log_create_error(int r);
#define BUS_DEFINE_PROPERTY_GET_GLOBAL(function, bus_type, val) \
int function(sd_bus *bus, \
const char *path, \
const char *interface, \
const char *property, \
sd_bus_message *reply, \
void *userdata, \
sd_bus_error *error) { \
\
assert(bus); \
assert(reply); \
\
return sd_bus_message_append(reply, bus_type, val); \
}
#define BUS_DEFINE_PROPERTY_GET2(function, bus_type, data_type, get1, get2) \
int function(sd_bus *bus, \
const char *path, \
const char *interface, \
const char *property, \
sd_bus_message *reply, \
void *userdata, \
sd_bus_error *error) { \
\
data_type *data = userdata; \
\
assert(bus); \
assert(reply); \
assert(data); \
\
return sd_bus_message_append(reply, bus_type, \
get2(get1(data))); \
}
#define ident(x) (x)
#define BUS_DEFINE_PROPERTY_GET(function, bus_type, data_type, get1) \
BUS_DEFINE_PROPERTY_GET2(function, bus_type, data_type, get1, ident)
#define ref(x) (*(x))
#define BUS_DEFINE_PROPERTY_GET_REF(function, bus_type, data_type, get) \
BUS_DEFINE_PROPERTY_GET2(function, bus_type, data_type, ref, get)
#define BUS_DEFINE_PROPERTY_GET_ENUM(function, name, type) \
BUS_DEFINE_PROPERTY_GET_REF(function, "s", type, name##_to_string)
#define BUS_PROPERTY_DUAL_TIMESTAMP(name, offset, flags) \
SD_BUS_PROPERTY(name, "t", bus_property_get_usec, (offset) + offsetof(struct dual_timestamp, realtime), (flags)), \
SD_BUS_PROPERTY(name "Monotonic", "t", bus_property_get_usec, (offset) + offsetof(struct dual_timestamp, monotonic), (flags))
int bus_path_encode_unique(sd_bus *b, const char *prefix, const char *sender_id, const char *external_id, char **ret_path);
int bus_path_decode_unique(const char *path, const char *prefix, char **ret_sender, char **ret_external);
int bus_property_get_rlimit(sd_bus *bus, const char *path, const char *interface, const char *property, sd_bus_message *reply, void *userdata, sd_bus_error *error);
int bus_track_add_name_many(sd_bus_track *t, char **l);
int bus_open_system_watch_bind_with_description(sd_bus **ret, const char *description);
static inline int bus_open_system_watch_bind(sd_bus **ret) {
return bus_open_system_watch_bind_with_description(ret, NULL);
}
int bus_reply_pair_array(sd_bus_message *m, char **l);
extern const struct hash_ops bus_message_hash_ops;