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janus-key.c
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janus-key.c
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/*
janus-key. Give keys a double function.
Copyright (C) 2021, 2022, 2023 Giulio Pietroiusti
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
// `janus keys`: those keys that have beeen assigned a secondary
// function.
#include "./config.h"
#include <assert.h>
#include <bits/time.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/input.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <time.h>
#include <stdlib.h>
#include "libevdev/libevdev.h"
#include "libevdev/libevdev-uinput.h"
#include "poll.h"
#define COUNTOF(x) (sizeof(x)/sizeof(*(x)))
// max delay set by user stored as a timespec struct
struct timespec delay_timespec;
int last_input_was_special_combination = 0;
// For calculating delay
struct timespec now;
struct timespec tp_sum;
// If any of the janus keys is down or held return the index of the
// first one of them in the mod_map. Otherwise, return -1.
static int some_jk_are_down_or_held() {
for (size_t i = 0; i < COUNTOF(mod_map); i++) {
if (mod_map[i].state == 1 || mod_map[i].state == 2 && mod_map[i].secondary_function > 0)
return i;
}
return -1;
}
// If `key` is in the mod_map, then return its index. Otherwise return
// -1.
static int is_in_mod_map(unsigned int key) {
for (size_t i = 0; i < COUNTOF(mod_map); i++) {
if (mod_map[i].key == key)
return i;
}
return -1;
};
// If `key` is a janus key, then return its index. Otherwise return
// -1.
static int is_janus(unsigned int key) {
int i = is_in_mod_map(key);
if (i >= 0)
if (mod_map[i].secondary_function > 0)
return i;
return -1;
}
// Compare two timespec structs.
// Return -1 if *tp1 > *tp2, 0 if *tp1 == *tp2, 1 if *tp1 < *tp2
static int timespec_cmp(struct timespec *tp1, struct timespec *tp2) {
if (tp1->tv_sec > tp2->tv_sec) {
return -1;
}
else if (tp1->tv_sec < tp2->tv_sec) {
return 1;
} else { // tp1->tv_sec == tp2->tv_sec
if (tp1->tv_nsec > tp2->tv_nsec)
return -1;
else if (tp1->tv_nsec < tp2->tv_nsec)
return 1;
else
return 0;
}
}
// Add two timespec structs.
static void timespec_add(struct timespec* a, struct timespec* b, struct timespec* c) {
c->tv_sec = a->tv_sec + b->tv_sec;
c->tv_nsec = a->tv_nsec + b->tv_nsec;
if (c->tv_nsec >= 1000000000) { // overflow
c->tv_nsec -= 1000000000;
c->tv_sec++;
}
}
// Subtracts timespec b from timespec a and stores the result in timespec c.
// Assumes a >= b.
static void timespec_subtract(const struct timespec* a, const struct timespec* b, struct timespec* c) {
c->tv_sec = a->tv_sec - b->tv_sec;
c->tv_nsec = a->tv_nsec - b->tv_nsec;
if (c->tv_nsec < 0) { // Underflow
c->tv_nsec += 1000000000;
c->tv_sec--;
}
}
// Converts a timespec struct to milliseconds.
static long timespec_to_ms(const struct timespec *ts) {
long milliseconds = ts->tv_sec * 1000 + ts->tv_nsec / 1000000;
return milliseconds;
}
// Converts milliseconds to a timespec struct.
static void ms_to_timespec(long ms, struct timespec *ts) {
ts->tv_sec = ms / 1000; // Convert milliseconds to seconds
ts->tv_nsec = (ms % 1000) * 1000000; // Convert the remainder to nanoseconds
}
// Post the EV_KEY event of code `code` and `value` through the
// uinput device `*uidev` and send a (EV_SYN, SYN_REPORT, 0) event
// through that same device.
static void send_key_ev_and_sync(const struct libevdev_uinput *uidev, unsigned int code, int value)
{
int err;
err = libevdev_uinput_write_event(uidev, EV_KEY, code, value);
if (err != 0) {
perror("Error in writing EV_KEY event\n");
exit(err);
}
err = libevdev_uinput_write_event(uidev, EV_SYN, SYN_REPORT, 0);
if (err != 0) {
perror("Error in writing EV_SYN, SYN_REPORT, 0.\n");
exit(err);
}
//printf("Sending %u %u\n", code, value);
}
// For each janus key down or held send an EV_KEY event with its
// secondary function code and value `value`.
static void send_down_or_held_jks_secondary_function(const struct libevdev_uinput *uidev, int value) {
for (size_t i = 0; i < COUNTOF(mod_map); i++) {
if ((mod_map[i].state == 1 || mod_map[i].state == 2) && mod_map[i].secondary_function > 0) {
mod_map[i].delayed_down = 0;
if (mod_map[i].last_secondary_function_value_sent != value) {
send_key_ev_and_sync(uidev, mod_map[i].secondary_function, value);
}
mod_map[i].last_secondary_function_value_sent = value;
}
}
}
// Post through uidev, with value `value, the primary function
// associated of `code`.
static void send_primary_function(const struct libevdev_uinput *uidev, unsigned int code, int value) {
int i = is_in_mod_map(code);
if (i >= 0) {
unsigned int primary_function = mod_map[i].primary_function > 0 ? mod_map[i].primary_function : mod_map[i].key;
send_key_ev_and_sync(uidev, primary_function, value);
} else {
send_key_ev_and_sync(uidev, code, value);
}
}
static void handle_ev_key(const struct libevdev_uinput *uidev, unsigned int code, int value) {
int jk_index = is_janus(code);
if (jk_index >= 0) {
mod_key *jk = &mod_map[jk_index];
if (value == 1) {
jk->state = 1;
clock_gettime(CLOCK_MONOTONIC, &jk->last_time_down);
last_input_was_special_combination = 0;
// calculate time in which the delayed down event should
// happen (if relevant conditions are fulfilled)
struct timespec scheduled_delayed_down;
timespec_add(&jk->last_time_down, &delay_timespec, &scheduled_delayed_down);
jk->send_down_at = scheduled_delayed_down;
jk->delayed_down = 1;
} else if (value == 2) {
jk->state = 2;
last_input_was_special_combination = 0;
} else {
jk->delayed_down = 0;
jk->state = 0;
clock_gettime(CLOCK_MONOTONIC, &now);
//timespec_add(&jk->last_time_down, &tp_max_delay, &tp_sum);
timespec_add(&jk->last_time_down, &delay_timespec, &tp_sum);
if (timespec_cmp(&now, &tp_sum) == 1) { // is considered as tap
if (last_input_was_special_combination) {
if (jk->last_secondary_function_value_sent != 0) {
send_key_ev_and_sync(uidev, jk->secondary_function, 0);
}
jk->last_secondary_function_value_sent = 0;
} else {
if (some_jk_are_down_or_held() >= 0) {
last_input_was_special_combination = 1;
send_down_or_held_jks_secondary_function(uidev, 1);
} else {
send_down_or_held_jks_secondary_function(uidev, 0);
}
send_primary_function(uidev, jk->key, 1);
send_primary_function(uidev, jk->key, 0);
}
} else { // is not considered as tap
if (jk->last_secondary_function_value_sent != 0) {
send_key_ev_and_sync(uidev, jk->secondary_function, 0);
}
jk->last_secondary_function_value_sent = 0;
}
}
} else {
if (value == 1) {
if (some_jk_are_down_or_held() >= 0) {
last_input_was_special_combination = 1;
send_down_or_held_jks_secondary_function(uidev, 1);
} else {
last_input_was_special_combination = 0;
}
send_primary_function(uidev, code, 1);
} else if (value == 2) {
if (some_jk_are_down_or_held() >= 0) {
last_input_was_special_combination = 1;
send_down_or_held_jks_secondary_function(uidev, 1);
} else {
last_input_was_special_combination = 0;
}
send_primary_function(uidev, code, 2);
} else { // if (value == 0)
send_primary_function(uidev, code, 0);
}
}
}
int main(int argc, char **argv) {
ms_to_timespec(max_delay, &delay_timespec);
struct libevdev *dev = NULL;
const char *file;
int read_fd;
int rc = 1;
if (argc < 2) {
exit(1);
}
usleep(100000); // let (KEY_ENTER), value 0 go through
file = argv[1];
read_fd = open(file, O_RDONLY);
if (read_fd < 0) {
perror("Failed to open device\n");
exit(1);
}
// variables to manage timeout
struct input_event event;
unsigned got_event = 0; // if true then we have got an event, otherwise we have timed out
struct pollfd poll_fd;
poll_fd.fd = read_fd;
poll_fd.events = POLLIN;
rc = libevdev_new_from_fd(read_fd, &dev);
if (rc < 0) {
fprintf(stderr, "Failed to init libevdev (%s)\n", strerror(-rc));
exit(1);
}
int err;
int write_fd;
struct libevdev_uinput *uidev;
write_fd = open("/dev/uinput", O_RDWR);
if (write_fd < 0) {
printf("uifd < 0 (Do you have the right privileges?)\n");
return -errno;
}
err = libevdev_uinput_create_from_device(dev, write_fd, &uidev);
if (err != 0)
return err;
int grab = libevdev_grab(dev, LIBEVDEV_GRAB);
if (grab < 0) {
printf("grab < 0\n");
return -errno;
}
while (rc == LIBEVDEV_READ_STATUS_SYNC || rc == LIBEVDEV_READ_STATUS_SUCCESS || rc == -EAGAIN) {
int has_pending_events = libevdev_has_event_pending(dev);
got_event = 0;
struct timespec timeout;
if (has_pending_events < 0) {
perror("pending");
exit(1);
}
if (has_pending_events == 1) {
got_event = 1;
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL|LIBEVDEV_READ_FLAG_BLOCKING, &event);
if (rc == LIBEVDEV_READ_STATUS_SYNC) {
printf("janus_key: dropped\n");
while (rc == LIBEVDEV_READ_STATUS_SYNC) {
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_SYNC, &event);
}
printf("janus_key: re-synced\n");
}
} else {
// find that mod_key whose `delayed_down` is true and has the
// soonest `send_down_at`, if any (there might not be a mod_key that
// satisfies those conditions)
int soonest_index = -1;
struct timespec soonest_val = {.tv_sec = 0, .tv_nsec = 0};
for (size_t i = 1; i < COUNTOF(mod_map); i++) {
if (mod_map[i].delayed_down && timespec_cmp(&mod_map[i].send_down_at, &soonest_val) == 1) {
soonest_val = mod_map[i].send_down_at;
soonest_index = i;
}
}
// decide whether to poll and calculate timeout
long poll_timeout = -1;
int should_poll = 0;
if (soonest_index == -1) {
// we should poll until a new event (second arg to poll will be -1)
should_poll = 1;
} else {
clock_gettime(CLOCK_MONOTONIC, &now);
if (timespec_cmp(&now, &(mod_map[soonest_index].send_down_at)) == 1) {
should_poll = 1;
timespec_subtract(&now, &(mod_map[soonest_index].send_down_at), &timeout);
}
}
if (should_poll && poll(&poll_fd, 1, poll_timeout)) {
got_event = 1;
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL|LIBEVDEV_READ_FLAG_BLOCKING, &event);
if (rc == LIBEVDEV_READ_STATUS_SYNC) {
printf("janus_key: dropped (after poll returned true)\n");
while (rc == LIBEVDEV_READ_STATUS_SYNC) {
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_SYNC, &event);
}
printf("janus_key: re-synced (after poll returned true)\n");
}
}
}
// handle timers
for (size_t i = 0; i < COUNTOF(mod_map); i++) {
clock_gettime(CLOCK_MONOTONIC, &now);
timespec_subtract(&now, &(mod_map[i].send_down_at), &timeout);
int send_delay_down = mod_map[i].delayed_down && timespec_cmp(&now, &(mod_map[i].send_down_at)) != 1;
if (send_delay_down) {
if (mod_map[i].last_secondary_function_value_sent != 1) {
send_key_ev_and_sync(uidev, mod_map[i].secondary_function, 1);
}
mod_map[i].last_secondary_function_value_sent = 1;
mod_map[i].delayed_down = 0;
}
}
// handle new event if we have one
if (got_event && rc == LIBEVDEV_READ_STATUS_SUCCESS) {
if (event.type == EV_KEY) {
handle_ev_key(uidev, event.code, event.value);
}
}
}
if (rc != LIBEVDEV_READ_STATUS_SUCCESS && rc != -EAGAIN)
fprintf(stderr, "Failed to handle events: %s\n", strerror(-rc));
// No need to use free memory (e.g., using libevdev_free) if the
// program is shutting down.
return 0;
}