pandemonium_engine_minimal/platform/frt/bits/linux_input.h

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2023-12-14 21:54:22 +01:00
// linux_input.h
/*
* FRT - A Godot platform targeting single board computers
* Copyright (c) 2017-2019 Emanuele Fornara
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <dirent.h>
#include <fcntl.h>
#include <linux/input.h>
namespace frt {
static const char *dev_input_id_dir = "/dev/input/by-id";
enum KeyValue { KV_Released,
KV_Pressed,
KV_Repeated };
class LinuxInput {
private:
int fd;
bool grabbed;
bool find_by_name(char *buf, int size, const char *name) {
const char *s_name = "N: Name=\"";
const char *s_handlers = "H: Handlers=";
const char *s_event = "event";
FILE *f = fopen("/proc/bus/input/devices", "r");
if (!f)
return false;
char s[1024];
bool found = false;
int state = 0, nn = strlen(name), ns;
while (fgets(s, sizeof(s), f) && !found) {
switch (state) {
case 0:
if (!strncmp(s_name, s, strlen(s_name))) {
ns = strlen(s);
if (((int)(ns - strlen(s_name) - strlen("\"\n")) == nn)
&& !memcmp(&s[strlen(s_name)], name, nn))
state = 1;
}
break;
case 1:
if (!strncmp(s_handlers, s, strlen(s_handlers))) {
state = 0;
char *event = strstr(s, s_event);
if (!event)
break;
int id = atoi(event + strlen(s_event));
snprintf(buf, size, "/dev/input/event%d", id);
found = true;
}
break;
}
}
fclose(f);
return found;
}
bool open_file(const char *file_name) {
fd = ::open(file_name, O_RDONLY | O_NONBLOCK);
if (fd == -1)
return false;
return true;
}
bool parse_dir(const char *pattern, char *buf, int size) {
bool found = false;
DIR *dirp = opendir(dev_input_id_dir);
if (!dirp)
return false;
while (1) {
struct dirent *dp;
if (!(dp = readdir(dirp)))
break;
const char *id = dp->d_name;
if (strstr(id, pattern)) {
snprintf(buf, size, "%s/%s", dev_input_id_dir, id);
buf[size - 1] = '\0';
found = true;
break;
}
}
closedir(dirp);
return found;
}
bool open_by_id_substr(const char *substr) {
char buf[512];
if (!parse_dir(substr, buf, sizeof(buf)))
return false;
return open_file(buf);
}
protected:
LinuxInput()
: fd(-1), grabbed(false) {}
bool open(const char *env_tag, const char *substr) {
char *id = getenv(env_tag);
if (id) {
char buf[512];
const char *s = 0;
if (id[0] == '/')
s = id;
else if (find_by_name(buf, sizeof(buf), id))
s = buf;
if (s)
return open_file(s);
} else {
return open_by_id_substr(substr);
}
return false;
}
bool grab(bool grab, int wait_ms) {
/*
HACK to let other clients get release keys at startup
TODO: better handling
*/
if (this->grabbed == grab)
return true;
usleep(wait_ms * 1000);
if (ioctl(fd, EVIOCGRAB, grab ? 1 : 0))
return false;
this->grabbed = grab;
return true;
}
void close() {
if (fd != -1) {
::close(fd);
fd = -1;
}
}
bool poll() {
input_event events[64];
while (1) {
int bytes = read(fd, events, sizeof(events));
if (bytes <= 0)
return false;
int n = bytes / sizeof(input_event);
for (int i = 0; i < n; i++)
handle(events[i]);
}
}
// LinuxInput
virtual void handle(const input_event &ev) = 0;
};
} // namespace frt