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ddd2590a4ea2579dfcbcc88c515720ff68d6682f
systemd/src/backlight/backlight.c
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Daan De Meyer 8857aa74e5 tree-wide: Clean up includes 
This commit cleans up the includes for all the small tools across
the tree.

A few cases of returning EXIT_SUCCESS are replaced with returning
0 to avoid including <stdlib.h>.

Split out of #37344.
2025-05-14 22:34:02 +02:00

664 lines
23 KiB
C
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <sys/stat.h>
#include <unistd.h>
#include "sd-device.h"
#include "alloc-util.h"
#include "argv-util.h"
#include "device-private.h"
#include "device-util.h"
#include "escape.h"
#include "fileio.h"
#include "main-func.h"
#include "parse-util.h"
#include "percent-util.h"
#include "pretty-print.h"
#include "reboot-util.h"
#include "string-util.h"
#include "strv.h"
#include "verbs.h"
#define PCI_CLASS_GRAPHICS_CARD 0x30000
static int help(void) {
_cleanup_free_ char *link = NULL;
int r;
r = terminal_urlify_man("systemd-backlight", "8", &link);
if (r < 0)
return log_oom();
printf("%s save [backlight|leds]:DEVICE\n"
"%s load [backlight|leds]:DEVICE\n"
"\n%sSave and restore backlight brightness at shutdown and boot.%s\n\n"
" save Save current brightness\n"
" load Set brightness to be the previously saved value\n"
"\nSee the %s for details.\n",
program_invocation_short_name,
program_invocation_short_name,
ansi_highlight(),
ansi_normal(),
link);
return 0;
}
static int has_multiple_graphics_cards(void) {
_cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
bool found = false;
int r;
r = sd_device_enumerator_new(&e);
if (r < 0)
return r;
r = sd_device_enumerator_allow_uninitialized(e);
if (r < 0)
return r;
r = sd_device_enumerator_add_match_subsystem(e, "pci", /* match = */ true);
if (r < 0)
return r;
/* class is an unsigned number, let's validate the value later. */
r = sd_device_enumerator_add_match_sysattr(e, "class", NULL, /* match = */ true);
if (r < 0)
return r;
FOREACH_DEVICE(e, dev) {
const char *s;
unsigned long c;
if (sd_device_get_sysattr_value(dev, "class", &s) < 0)
continue;
if (safe_atolu(s, &c) < 0)
continue;
if (c != PCI_CLASS_GRAPHICS_CARD)
continue;
if (found)
return true; /* This is the second device. */
found = true; /* Found the first device. */
}
return false;
}
static int find_pci_or_platform_parent(sd_device *device, sd_device **ret) {
int r;
assert(device);
assert(ret);
for (;;) {
r = sd_device_get_parent(device, &device);
if (r < 0)
return r;
r = device_in_subsystem(device, "drm");
if (r < 0)
return r;
if (r > 0) {
const char *s;
r = device_sysname_startswith_strv(device, STRV_MAKE("card"), &s);
if (r < 0)
return r;
if (r == 0)
return -ENODATA;
s += strspn(s, DIGITS);
if (*s == '-' && !STARTSWITH_SET(s, "-LVDS-", "-Embedded DisplayPort-", "-eDP-"))
/* A connector DRM device, let's ignore all but LVDS and eDP! */
return -EOPNOTSUPP;
continue;
}
r = device_in_subsystem(device, "pci");
if (r < 0)
return r;
if (r > 0) {
uint32_t class;
r = device_get_sysattr_u32(device, "class", &class);
if (r == -ENOENT)
continue;
if (r < 0)
return r;
/* Graphics card */
if (class == PCI_CLASS_GRAPHICS_CARD) {
*ret = device;
return 0;
}
continue;
}
r = device_in_subsystem(device, "platform");
if (r < 0)
return r;
if (r > 0) {
*ret = device;
return 0;
}
}
}
static int same_device(sd_device *a, sd_device *b) {
const char *a_val, *b_val;
int r;
assert(a);
assert(b);
r = sd_device_get_subsystem(a, &a_val);
if (r < 0)
return r;
r = sd_device_get_subsystem(b, &b_val);
if (r < 0)
return r;
if (!streq(a_val, b_val))
return false;
r = sd_device_get_sysname(a, &a_val);
if (r < 0)
return r;
r = sd_device_get_sysname(b, &b_val);
if (r < 0)
return r;
return streq(a_val, b_val);
}
static int validate_device(sd_device *device) {
_cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *enumerate = NULL;
const char *v, *sysname;
sd_device *parent;
int r;
assert(device);
/* Verify whether we should actually care for a specific backlight device. For backlight devices
* there might be multiple ways to access the same control: "firmware" (i.e. ACPI), "platform"
* (i.e. via the machine's EC), and "raw" (via the graphics card). In general we should prefer
* "firmware" (i.e. ACPI) or "platform" access over "raw" access, in order not to confuse the
* BIOS/EC, and compatibility with possible low-level hotkey handling of screen brightness. The
* kernel will already make sure to expose only one of "firmware" and "platform" for the same
* device to userspace. However, we still need to make sure that we use "raw" only if no
* "firmware" or "platform" device for the same device exists. */
r = sd_device_get_sysname(device, &sysname);
if (r < 0)
return log_device_debug_errno(device, r, "Failed to get sysname: %m");
r = device_in_subsystem(device, "leds");
if (r < 0)
return log_device_debug_errno(device, r, "Failed to check if device is in backlight subsystem: %m");
if (r > 0)
return true; /* We assume LED device is always valid. */
r = sd_device_get_sysattr_value(device, "type", &v);
if (r < 0)
return log_device_debug_errno(device, r, "Failed to read 'type' sysattr: %m");
if (!streq(v, "raw"))
return true;
r = find_pci_or_platform_parent(device, &parent);
if (r < 0)
return log_device_debug_errno(device, r, "Failed to find PCI or platform parent: %m");
if (DEBUG_LOGGING) {
const char *s = NULL, *subsystem = NULL;
(void) sd_device_get_syspath(parent, &s);
(void) sd_device_get_subsystem(parent, &subsystem);
log_device_debug(device, "Found %s parent device: %s", strna(subsystem), strna(s));
}
r = sd_device_enumerator_new(&enumerate);
if (r < 0)
return log_oom_debug();
r = sd_device_enumerator_allow_uninitialized(enumerate);
if (r < 0)
return log_debug_errno(r, "Failed to allow uninitialized devices: %m");
r = sd_device_enumerator_add_match_subsystem(enumerate, "backlight", /* match = */ true);
if (r < 0)
return log_debug_errno(r, "Failed to add subsystem match: %m");
r = sd_device_enumerator_add_nomatch_sysname(enumerate, sysname);
if (r < 0)
return log_debug_errno(r, "Failed to add sysname unmatch: %m");
r = sd_device_enumerator_add_match_sysattr(enumerate, "type", "platform", /* match = */ true);
if (r < 0)
return log_debug_errno(r, "Failed to add sysattr match: %m");
r = sd_device_enumerator_add_match_sysattr(enumerate, "type", "firmware", /* match = */ true);
if (r < 0)
return log_debug_errno(r, "Failed to add sysattr match: %m");
if (device_in_subsystem(parent, "pci") > 0) {
r = has_multiple_graphics_cards();
if (r < 0)
return log_debug_errno(r, "Failed to check if the system has multiple graphics cards: %m");
if (r > 0) {
/* If the system has multiple graphics cards, then we cannot associate platform
* devices on non-PCI bus (especially WMI bus) with PCI devices. Let's ignore all
* backlight devices that do not have the same parent PCI device. */
log_debug("Found multiple graphics cards on PCI bus; "
"skipping deduplication of platform backlight devices not on PCI bus.");
r = sd_device_enumerator_add_match_parent(enumerate, parent);
if (r < 0)
return log_debug_errno(r, "Failed to add parent match: %m");
}
}
FOREACH_DEVICE(enumerate, other) {
sd_device *other_parent;
/* OK, so there's another backlight device, and it's a platform or firmware device.
* Let's see if we can verify it belongs to the same device as ours. */
r = find_pci_or_platform_parent(other, &other_parent);
if (r < 0) {
log_device_debug_errno(other, r, "Failed to get PCI or platform parent, ignoring: %m");
continue;
}
if (same_device(parent, other_parent) > 0) {
/* Both have the same PCI parent, that means we are out. */
if (DEBUG_LOGGING) {
const char *other_sysname = NULL, *other_type = NULL;
(void) sd_device_get_sysname(other, &other_sysname);
(void) sd_device_get_sysattr_value(other, "type", &other_type);
log_device_debug(device,
"Found another %s backlight device %s on the same PCI, skipping.",
strna(other_type), strna(other_sysname));
}
return false;
}
if (device_in_subsystem(other_parent, "platform") > 0 && device_in_subsystem(parent, "pci") > 0) {
/* The other is connected to the platform bus and we are a PCI device, that also means we are out. */
if (DEBUG_LOGGING) {
const char *other_sysname = NULL, *other_type = NULL;
(void) sd_device_get_sysname(other, &other_sysname);
(void) sd_device_get_sysattr_value(other, "type", &other_type);
log_device_debug(device,
"Found another %s backlight device %s, which has higher precedence, skipping.",
strna(other_type), strna(other_sysname));
}
return false;
}
}
return true;
}
static int read_max_brightness(sd_device *device, unsigned *ret) {
unsigned max_brightness;
int r;
assert(device);
assert(ret);
r = device_get_sysattr_unsigned(device, "max_brightness", &max_brightness);
if (r < 0)
return log_device_warning_errno(device, r, "Failed to read/parse 'max_brightness' attribute: %m");
/* If max_brightness is 0, then there is no actual backlight device. This happens on desktops
* with Asus mainboards that load the eeepc-wmi module. */
if (max_brightness == 0) {
log_device_warning(device, "Maximum brightness is 0, ignoring device.");
*ret = 0;
return 0;
}
log_device_debug(device, "Maximum brightness is %u", max_brightness);
*ret = max_brightness;
return 1; /* valid max brightness */
}
static int clamp_brightness(
sd_device *device,
unsigned percent,
bool saved,
unsigned max_brightness,
unsigned *brightness) {
unsigned new_brightness, min_brightness;
int r;
assert(device);
assert(brightness);
/* Some systems turn the backlight all the way off at the lowest levels. This clamps the saved
* brightness to at least 1 or 5% of max_brightness in case of 'backlight' subsystem. This
* avoids preserving an unreadably dim screen, which would otherwise force the user to disable
* state restoration. */
min_brightness = (unsigned) ((double) max_brightness * percent / 100);
r = device_in_subsystem(device, "backlight");
if (r < 0)
return r;
if (r > 0)
min_brightness = MAX(1U, min_brightness);
new_brightness = CLAMP(*brightness, min_brightness, max_brightness);
if (new_brightness != *brightness)
log_device_info(device, "%s brightness %u is %s to %u.",
saved ? "Saved" : "Current",
*brightness,
new_brightness > *brightness ?
"too low; increasing" : "too high; decreasing",
new_brightness);
*brightness = new_brightness;
return 0;
}
static int shall_clamp(sd_device *device, unsigned *ret) {
const char *property, *s;
unsigned default_percent;
int r;
assert(device);
assert(ret);
r = device_in_subsystem(device, "backlight");
if (r < 0)
return r;
if (r > 0) {
property = "ID_BACKLIGHT_CLAMP";
default_percent = 5;
} else {
property = "ID_LEDS_CLAMP";
default_percent = 0;
}
r = sd_device_get_property_value(device, property, &s);
if (r < 0) {
if (r != -ENOENT)
log_device_debug_errno(device, r, "Failed to get %s property, ignoring: %m", property);
*ret = default_percent;
return default_percent > 0;
}
r = parse_boolean(s);
if (r >= 0) {
*ret = r ? 5 : 0;
return r;
}
r = parse_percent(s);
if (r < 0) {
log_device_debug_errno(device, r, "Failed to parse %s property, ignoring: %m", property);
*ret = default_percent;
return default_percent > 0;
}
*ret = r;
return true;
}
static int read_brightness(sd_device *device, unsigned max_brightness, unsigned *ret_brightness) {
const char *value;
unsigned brightness;
int r;
assert(device);
assert(ret_brightness);
r = sd_device_get_sysattr_value(device, "brightness", &value);
if (r < 0)
return log_device_debug_errno(device, r, "Failed to read 'brightness' attribute: %m");
r = safe_atou(value, &brightness);
if (r < 0)
return log_device_debug_errno(device, r, "Failed to parse 'brightness' attribute: %s", value);
if (brightness > max_brightness)
return log_device_debug_errno(device, SYNTHETIC_ERRNO(EINVAL),
"brightness=%u is larger than max_brightness=%u",
brightness, max_brightness);
log_device_debug(device, "Current brightness is %u", brightness);
*ret_brightness = brightness;
return 0;
}
static int build_save_file_path(sd_device *device, char **ret) {
_cleanup_free_ char *escaped_subsystem = NULL, *escaped_sysname = NULL, *path = NULL;
const char *s;
int r;
assert(device);
assert(ret);
r = sd_device_get_subsystem(device, &s);
if (r < 0)
return log_device_error_errno(device, r, "Failed to get subsystem: %m");
escaped_subsystem = cescape(s);
if (!escaped_subsystem)
return log_oom();
r = sd_device_get_sysname(device, &s);
if (r < 0)
return log_device_error_errno(device, r, "Failed to get sysname: %m");
escaped_sysname = cescape(s);
if (!escaped_sysname)
return log_oom();
if (sd_device_get_property_value(device, "ID_PATH", &s) >= 0) {
_cleanup_free_ char *escaped_path_id = cescape(s);
if (!escaped_path_id)
return log_oom();
path = strjoin("/var/lib/systemd/backlight/", escaped_path_id, ":", escaped_subsystem, ":", escaped_sysname);
} else
path = strjoin("/var/lib/systemd/backlight/", escaped_subsystem, ":", escaped_sysname);
if (!path)
return log_oom();
*ret = TAKE_PTR(path);
return 0;
}
static int read_saved_brightness(sd_device *device, unsigned *ret) {
_cleanup_free_ char *path = NULL, *value = NULL;
int r;
assert(device);
assert(ret);
r = build_save_file_path(device, &path);
if (r < 0)
return r;
r = read_one_line_file(path, &value);
if (r < 0) {
if (r != -ENOENT)
log_device_error_errno(device, r, "Failed to read %s: %m", path);
return r;
}
r = safe_atou(value, ret);
if (r < 0) {
log_device_warning_errno(device, r,
"Failed to parse saved brightness '%s', removing %s.",
value, path);
(void) unlink(path);
return r;
}
log_device_debug(device, "Using saved brightness %u.", *ret);
return 0;
}
static int device_new_from_arg(const char *s, sd_device **ret) {
_cleanup_(sd_device_unrefp) sd_device *device = NULL;
_cleanup_free_ char *subsystem = NULL;
const char *sysname;
int r;
assert(s);
assert(ret);
sysname = strchr(s, ':');
if (!sysname)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Requires a subsystem and sysname pair specifying a backlight or LED device.");
subsystem = strndup(s, sysname - s);
if (!subsystem)
return log_oom();
sysname++;
if (!STR_IN_SET(subsystem, "backlight", "leds"))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Not a backlight or LED device: '%s:%s'",
subsystem, sysname);
r = sd_device_new_from_subsystem_sysname(&device, subsystem, sysname);
if (r == -ENODEV) {
/* Some drivers, e.g. for AMD GPU, removes acpi backlight device soon after it is added.
* See issue #21997. */
log_debug_errno(r, "Failed to get backlight or LED device '%s:%s', ignoring: %m", subsystem, sysname);
*ret = NULL;
return 0;
}
if (r < 0)
return log_error_errno(r, "Failed to get backlight or LED device '%s:%s': %m", subsystem, sysname);
*ret = TAKE_PTR(device);
return 1; /* Found. */
}
static int verb_load(int argc, char *argv[], void *userdata) {
_cleanup_(sd_device_unrefp) sd_device *device = NULL;
unsigned max_brightness, brightness, percent;
bool clamp;
int r;
assert(argc == 2);
if (!shall_restore_state())
return 0;
r = device_new_from_arg(argv[1], &device);
if (r <= 0)
return r;
r = read_max_brightness(device, &max_brightness);
if (r <= 0)
return r;
/* Ignore any errors in validation, and use the device as is. */
if (validate_device(device) == 0)
return 0;
r = shall_clamp(device, &percent);
if (r < 0)
return r;
clamp = r;
r = read_saved_brightness(device, &brightness);
if (r < 0) {
/* Fallback to clamping current brightness or exit early if clamping is not
* supported/enabled. */
if (!clamp)
return 0;
r = read_brightness(device, max_brightness, &brightness);
if (r < 0)
return log_device_error_errno(device, r, "Failed to read current brightness: %m");
(void) clamp_brightness(device, percent, /* saved = */ false, max_brightness, &brightness);
} else if (clamp)
(void) clamp_brightness(device, percent, /* saved = */ true, max_brightness, &brightness);
r = sd_device_set_sysattr_valuef(device, "brightness", "%u", brightness);
if (r < 0)
return log_device_error_errno(device, r, "Failed to write system 'brightness' attribute: %m");
return 0;
}
static int verb_save(int argc, char *argv[], void *userdata) {
_cleanup_(sd_device_unrefp) sd_device *device = NULL;
_cleanup_free_ char *path = NULL;
unsigned max_brightness, brightness;
int r;
assert(argc == 2);
r = device_new_from_arg(argv[1], &device);
if (r <= 0)
return r;
r = read_max_brightness(device, &max_brightness);
if (r <= 0)
return r;
r = build_save_file_path(device, &path);
if (r < 0)
return r;
/* If there are multiple conflicting backlight devices, then their probing at boot-time might
* happen in any order. This means the validity checking of the device then is not reliable,
* since it might not see other devices conflicting with a specific backlight. To deal with
* this, we will actively delete backlight state files at shutdown (where device probing should
* be complete), so that the validity check at boot time doesn't have to be reliable. */
if (validate_device(device) == 0) {
(void) unlink(path);
return 0;
}
r = read_brightness(device, max_brightness, &brightness);
if (r < 0)
return log_device_error_errno(device, r, "Failed to read current brightness: %m");
r = write_string_filef(path, WRITE_STRING_FILE_CREATE | WRITE_STRING_FILE_MKDIR_0755, "%u", brightness);
if (r < 0)
return log_device_error_errno(device, r, "Failed to write %s: %m", path);
return 0;
}
static int run(int argc, char *argv[]) {
static const Verb verbs[] = {
{ "load", 2, 2, VERB_ONLINE_ONLY, verb_load },
{ "save", 2, 2, VERB_ONLINE_ONLY, verb_save },
{}
};
log_setup();
if (argv_looks_like_help(argc, argv))
return help();
umask(0022);
return dispatch_verb(argc, argv, verbs, NULL);
}
DEFINE_MAIN_FUNCTION(run);
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