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backlight: validate read sysattr value 

If actual_brightness is larger than max_brightness, then fall back to
use brightness attribute.

Also, if the saved value is invalid, then this makes remove the file in
/var/lib/systemd/backlight.

Hopefully fixes #17011.
This commit is contained in:
Yu Watanabe 2020-09-11 17:46:08 +09:00
parent 06d98bdc81
commit 3bacb7e73b
1 changed files with 75 additions and 50 deletions
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125
src/backlight/backlight.c
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@ -261,17 +261,13 @@ static int get_max_brightness(sd_device *device, unsigned *ret) {
* max_brightness in case of 'backlight' subsystem. This avoids preserving
* an unreadably dim screen, which would otherwise force the user to
* disable state restoration. */
static int clamp_brightness(sd_device *device, char **value, unsigned max_brightness) {
unsigned brightness, new_brightness, min_brightness;
static int clamp_brightness(sd_device *device, bool saved, unsigned max_brightness, unsigned *brightness) {
unsigned new_brightness, min_brightness;
const char *subsystem;
int r;
assert(value);
assert(*value);
r = safe_atou(*value, &brightness);
if (r < 0)
return log_device_warning_errno(device, r, "Failed to parse brightness \"%s\": %m", *value);
assert(device);
assert(brightness);
r = sd_device_get_subsystem(device, &subsystem);
if (r < 0)
@ -282,22 +278,16 @@ static int clamp_brightness(sd_device *device, char **value, unsigned max_bright
else
min_brightness = 0;
new_brightness = CLAMP(brightness, min_brightness, max_brightness);
if (new_brightness != brightness) {
char *new_value;
r = asprintf(&new_value, "%u", new_brightness);
if (r < 0)
return log_oom();
log_device_info(device, "Saved brightness %s %s to %s.", *value,
new_brightness > 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_value);
free_and_replace(*value, new_value);
}
new_brightness);
*brightness = new_brightness;
return 0;
}
@ -323,31 +313,60 @@ static bool shall_clamp(sd_device *d) {
return r;
}
static int read_brightness(sd_device *device, const char **ret) {
const char *subsystem;
static int read_brightness(sd_device *device, unsigned max_brightness, unsigned *ret_brightness) {
const char *subsystem, *value;
unsigned brightness;
int r;
assert(device);
assert(ret);
assert(ret_brightness);
r = sd_device_get_subsystem(device, &subsystem);
if (r < 0)
return log_device_debug_errno(device, r, "Failed to get subsystem: %m");
if (streq(subsystem, "backlight")) {
r = sd_device_get_sysattr_value(device, "actual_brightness", ret);
if (r >= 0)
return 0;
if (r != -ENOENT)
r = sd_device_get_sysattr_value(device, "actual_brightness", &value);
if (r == -ENOENT) {
log_device_debug_errno(device, r, "Failed to read 'actual_brightness' attribute, "
"fall back to use 'brightness' attribute: %m");
goto use_brightness;
}
if (r < 0)
return log_device_debug_errno(device, r, "Failed to read 'actual_brightness' attribute: %m");
log_device_debug_errno(device, r, "Failed to read 'actual_brightness' attribute, fall back to use 'brightness' attribute: %m");
r = safe_atou(value, &brightness);
if (r < 0) {
log_device_debug_errno(device, r, "Failed to parse 'actual_brightness' attribute, "
"fall back to use 'brightness' attribute: %s", value);
goto use_brightness;
}
if (brightness > max_brightness) {
log_device_debug(device, "actual_brightness=%u is larger than max_brightness=%u, "
"fall back to use 'brightness' attribute", brightness, max_brightness);
goto use_brightness;
}
*ret_brightness = brightness;
return 0;
}
r = sd_device_get_sysattr_value(device, "brightness", ret);
use_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);
*ret_brightness = brightness;
return 0;
}
@ -355,7 +374,7 @@ static int run(int argc, char *argv[]) {
_cleanup_(sd_device_unrefp) sd_device *device = NULL;
_cleanup_free_ char *escaped_ss = NULL, *escaped_sysname = NULL, *escaped_path_id = NULL;
const char *sysname, *path_id, *ss, *saved;
unsigned max_brightness;
unsigned max_brightness, brightness;
int r;
log_setup_service();
@ -432,44 +451,50 @@ static int run(int argc, char *argv[]) {
clamp = shall_clamp(device);
r = read_one_line_file(saved, &value);
if (IN_SET(r, -ENOENT, 0)) {
const char *curval;
if (r < 0 && r != -ENOENT)
return log_error_errno(r, "Failed to read %s: %m", saved);
if (r > 0) {
r = safe_atou(value, &brightness);
if (r < 0) {
log_error_errno(r, "Failed to parse saved brightness '%s', removing %s.",
value, saved);
(void) unlink(saved);
} else {
if (clamp)
(void) clamp_brightness(device, true, max_brightness, &brightness);
/* Fallback to clamping current brightness or exit early if
* clamping is not supported/enabled. */
/* Do not fall back to read current brightness below. */
r = 1;
}
}
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, &curval);
r = read_brightness(device, max_brightness, &brightness);
if (r < 0)
return log_device_error_errno(device, r, "Failed to read current brightness: %m");
value = strdup(curval);
if (!value)
return log_oom();
} else if (r < 0)
return log_error_errno(r, "Failed to read %s: %m", saved);
(void) clamp_brightness(device, false, max_brightness, &brightness);
}
if (clamp)
(void) clamp_brightness(device, &value, max_brightness);
r = sd_device_set_sysattr_value(device, "brightness", value);
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");
} else if (streq(argv[1], "save")) {
const char *value;
if (validate_device(device) == 0) {
(void) unlink(saved);
return 0;
}
r = read_brightness(device, &value);
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_file(saved, value, WRITE_STRING_FILE_CREATE);
r = write_string_filef(saved, WRITE_STRING_FILE_CREATE, "%u", brightness);
if (r < 0)
return log_device_error_errno(device, r, "Failed to write %s: %m", saved);