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Safemode code revision and documentation
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@Tungstwenty
Tungstwenty committed Feb 10, 2014
1 parent d01609c commit 2572fa2
Showing 1 changed file with 53 additions and 22 deletions.
75 changes: 53 additions & 22 deletions xposed_safemode.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@
#define VIBRATOR_CONTROL "/sys/class/timed_output/vibrator/enable"
#define VIBRATION_SHORT 150
#define VIBRATION_LONG 500
#define VIBRATION_INTERVAL 50

static const char *DEVICE_PATH = "/dev/input";
#define MAX_DEVICES 4
Expand Down Expand Up @@ -67,14 +68,29 @@ static void vibrate(int count, int duration_ms, int interval_ms) {
}



/*
* Enumerates the existing input devices and opens handles for the ones that
* report the relevant keys.
*
* Arguments:
* - *fds: is filled on output with the file handles for the opened devices
* - max_fds: maximum available entries in the fds array
* - *pressedKey: is filled on output with
* 0 if no key was found being held down at this instant
* -1 if more than one key was found being held down
* id of the pressed key, if only a single one was being held down
* Returns:
* - the number of opened device handles, filled in the *fds output parameter
* - 0 if no devices were opened
*/
static int openKeyDevices(int *fds, int max_fds, int *pressedKey) {
char devname[PATH_MAX];
char *filename;
DIR *dir;
struct dirent *de;

int count = 0;
// No key was detected as pressed, for the moment
*pressedKey = 0;

dir = opendir(DEVICE_PATH);
Expand Down Expand Up @@ -110,6 +126,7 @@ static int openKeyDevices(int *fds, int max_fds, int *pressedKey) {
}
if (!reportsKeys) {
// This device doesn't report any of the relevant keys
// Skip to the next one
close(fd);
continue;
}
Expand All @@ -121,11 +138,14 @@ static int openKeyDevices(int *fds, int max_fds, int *pressedKey) {
ioctl(fd, EVIOCGKEY(sizeof(keyBitmask)), keyBitmask);
for (size_t i = 0; i < sizeof(physical_keycodes) / sizeof(physical_keycodes[0]); i++) {
if (test_bit(physical_keycodes[i], keyBitmask)) {
// One of the relevant keys was detected as held down
// We'll report it to be pressed, but only if there isn't more than one key being pressed
if (*pressedKey == 0) {
// No key was being pressed, this one will be reported
*pressedKey = physical_keycodes[i];
} else {
// More than one key is pressed, abort
*pressedKey = 0;
// Another key was already found to be pressed, report multiple keys to the caller
*pressedKey = -1;
break;
}
}
Expand All @@ -137,6 +157,9 @@ static int openKeyDevices(int *fds, int max_fds, int *pressedKey) {
}


/*
* Computes the remaining time, in ms, from the current time to the supplied expiration moment
*/
int getRemainingTime(struct timespec expiration) {
struct timespec now;
clock_gettime(CLOCK_MONOTONIC, &now);
Expand Down Expand Up @@ -165,8 +188,13 @@ bool detectSafemodeTrigger(bool skipInitialDelay) {
// No input devices found, abort detection
goto leave;

if (pressedKey == 0 && skipInitialDelay)
// None of the keys was held down and the initial delay is disabled
if (pressedKey < 0)
// More than one key was initially pressed
// Immediately report a negative detection, with no further delays
goto leave;

if (pressedKey <= 0 && skipInitialDelay)
// A single key wasn't held down and the initial delay is disabled
// Immediately report a negative detection, with no further delays
goto leave;

Expand All @@ -176,34 +204,33 @@ bool detectSafemodeTrigger(bool skipInitialDelay) {
goto leave;

// Register each device descriptor in the epoll handle
struct epoll_event eventPollItems[MAX_DEVICES];
for (int i = 0; i < deviceCount; i++) {
struct epoll_event eventItem;
memset(&eventItem, 0, sizeof(eventItem));
eventItem.events = EPOLLIN;
eventItem.data.fd = fds[i];
if (epoll_ctl(efd, EPOLL_CTL_ADD, fds[i], &eventItem))
memset(&eventPollItems[i], 0, sizeof(eventPollItems[i]));
eventPollItems[i].events = EPOLLIN;
eventPollItems[i].data.fd = fds[i];
if (epoll_ctl(efd, EPOLL_CTL_ADD, fds[i], &eventPollItems[i]))
// Failed to add device descriptor to the epoll handle, abort
goto leave;
}


struct epoll_event mEvents[MAX_DEVICES];

int timeout_ms;
struct timespec expiration;
clock_gettime(CLOCK_MONOTONIC, &expiration);
expiration.tv_sec += INITIAL_DELAY;

// Wait up to INITIAL_DELAY seconds for an initial keypress, it no key was initially down
while (pressedKey == 0 && (timeout_ms = getRemainingTime(expiration)) > 0) {
// Wait for next input event
int pollResult = epoll_wait(efd, mEvents, sizeof(mEvents) / sizeof(mEvents[0]), timeout_ms);
// Wait for next input event in one of the opened devices
int pollResult = epoll_wait(efd, eventPollItems, sizeof(eventPollItems) / sizeof(eventPollItems[0]), timeout_ms);
if (pollResult < 0)
// Failed to wait for event, abort
goto leave;

// Loop through the opened devices where a new event is available
for (int i = 0; i < pollResult; i++) {
struct input_event evt;
int32_t readSize = read(mEvents[i].data.fd, &evt, sizeof(evt));
int32_t readSize = read(eventPollItems[i].data.fd, &evt, sizeof(evt));
if (readSize != sizeof(evt))
// Invalid size read, ignore
continue;
Expand All @@ -218,6 +245,8 @@ bool detectSafemodeTrigger(bool skipInitialDelay) {
for (size_t j = 0; j < sizeof(physical_keycodes) / sizeof(physical_keycodes[0]); j++) {
if (evt.code == physical_keycodes[j]) {
// One of the keys was pressed, end the initial detection
// No need to check for duplicate keys, as the events are reported sequentially
// and multiple presses can't be reported at once
pressedKey = evt.code;
break;
}
Expand All @@ -230,28 +259,29 @@ bool detectSafemodeTrigger(bool skipInitialDelay) {

// Notify the user that the safemode sequence has been started and we're waiting for
// the remaining key presses
vibrate(2, VIBRATION_SHORT, 200);
vibrate(2, VIBRATION_SHORT, VIBRATION_SHORT + VIBRATION_INTERVAL);


// Detection will wait at most DETECTION_TIMEOUT seconds
clock_gettime(CLOCK_MONOTONIC, &expiration);
expiration.tv_sec += DETECTION_TIMEOUT;


// Initial key press is counted as well
triggerPresses++;

// Loop waiting for the same key to be pressed the appropriate number of times, a different key to
// be pressed, or the timeout to be reached
while (pressedKey != 0 && triggerPresses < DETECTION_PRESSES && (timeout_ms = getRemainingTime(expiration)) > 0) {
// Wait for next input event
int pollResult = epoll_wait(efd, mEvents, sizeof(mEvents) / sizeof(mEvents[0]), timeout_ms);
int pollResult = epoll_wait(efd, eventPollItems, sizeof(eventPollItems) / sizeof(eventPollItems[0]), timeout_ms);
if (pollResult < 0)
// Failed to wait for event, abort
goto leave;

// Loop through the opened devices where a new event is available
for (int i = 0; i < pollResult; i++) {
struct input_event evt;
int32_t readSize = read(mEvents[i].data.fd, &evt, sizeof(evt));
int32_t readSize = read(eventPollItems[i].data.fd, &evt, sizeof(evt));
if (readSize != sizeof(evt))
// Invalid size read, ignore
continue;
Expand All @@ -271,8 +301,9 @@ bool detectSafemodeTrigger(bool skipInitialDelay) {
if (triggerPresses < DETECTION_PRESSES)
vibrate(1, VIBRATION_SHORT, 0);
} else {
// A different key was pressed, abort
pressedKey = 0;
// A key was pressed other than the initial one
// Abort the detection and avoid further delays
goto leave;
}
break;
}
Expand Down

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