eleni@3: /*
eleni@3:  * DTMS Copyright (C) 2016 Eleni Maria Stea <elene.mst@gmail.com>
eleni@3:  *
eleni@3:  * This program is free software: you can redistribute it and/or modify
eleni@3:  * it under the terms of the GNU General Public License as published by
eleni@3:  * the Free Software Foundation, either version 3 of the License, or
eleni@3:  * (at your option) any later version.
eleni@3:  *
eleni@3:  * This program is distributed in the hope that it will be useful,
eleni@3:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
eleni@3:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
eleni@3:  * GNU General Public License for more details.
eleni@3: 
eleni@3:  * You should have received a copy of the GNU General Public License
eleni@3:  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
eleni@3:  * */
eleni@3: 
eleni@0: #include <errno.h>
eleni@0: #include <fcntl.h>
eleni@0: #include <pwd.h>
eleni@0: #include <stdio.h>
eleni@0: #include <stdlib.h>
eleni@0: #include <string.h>
eleni@0: #include <sys/select.h>
eleni@0: #include <sys/stat.h>
eleni@0: #include <sys/types.h>
eleni@0: #include <time.h>
eleni@0: #include <unistd.h>
eleni@0: 
eleni@0: static int parse_args(int argc, char **argv);
eleni@0: static void print_help();
eleni@4: static int check_device(char *device_path);
eleni@0: 
eleni@4: static int uid = -1;
eleni@4: static char *player_path;
eleni@0: static char *dev_path;
eleni@0: 
eleni@4: #ifdef PREFIX
eleni@4: static const char* player_arg = PREFIX "/share/dtms/dtms.mp3";
eleni@4: #else
eleni@4: static const char* player_arg = "data/dtms.mp3";
eleni@4: #endif
eleni@4: 
eleni@0: int main(int argc, char **argv)
eleni@0: {
eleni@0:     time_t last_touch_time = 0;
eleni@0:     int fd;
eleni@0: 
eleni@4:     if(parse_args(argc, argv) == -1)
eleni@0: 	return 1;
eleni@0: 
eleni@4:     if(getuid() == 0 && uid == -1) {
eleni@4: 	fprintf(stderr, "It's a bad idea to run this program as root, either make it setuid-root, or use the -u option to specify an unprivileged user.\n");
eleni@4: 	return 1;
eleni@4:     }
eleni@4: 
eleni@4:     if(check_device(dev_path) == -1)
eleni@4: 	return 1;
eleni@0: 
eleni@0:     if((fd = open(dev_path, O_RDONLY | O_NONBLOCK)) == -1) {
eleni@0: 	fprintf(stderr, "Failed to open device: %s, error: %s\n", dev_path, strerror(errno));
eleni@0: 	return 1;
eleni@0:     }
eleni@0: 
eleni@4:     if(uid == -1) {
eleni@4: 	uid = getuid();
eleni@4:     }
eleni@4: 
eleni@0:     if(seteuid(uid) == -1) {
eleni@0: 	perror("Set uid failed");
eleni@4: 	return 1;
eleni@0:     }
eleni@0: 
eleni@0:     if(!uid) {
eleni@4: 	if(player_path[0] != '/') {
eleni@0: 	    fprintf(stderr, "If you run this program as root you should pass the absolute path to a valid mp3 player.\n");
eleni@0: 	    return 1;
eleni@0: 	}
eleni@0:     }
eleni@0: 
eleni@4:     char *cmd = malloc(strlen(player_path) + 1 + strlen(player_arg) + 1);
eleni@4:     sprintf(cmd, "%s %s", player_path, player_arg);
eleni@4: 
eleni@0:     while(1) {
eleni@0: 	fd_set read_set;
eleni@0: 	FD_ZERO(&read_set);
eleni@0: 	FD_SET(fd, &read_set);
eleni@0: 
eleni@0: 	int res;
eleni@0: 	while((res = select(fd + 1, &read_set, 0, 0, 0)) == -1 && errno == EINTR);
eleni@0: 	if(res < 0) {
eleni@0: 	    perror("Select failed");
eleni@0: 	    break;
eleni@0: 	}
eleni@0: 	if(res == 0) //nothing to read
eleni@0: 	    continue;
eleni@0: 
eleni@0: 	if(FD_ISSET(fd, &read_set)) {
eleni@0: 	    char buf[1024];
eleni@0: 	    time_t now = time(0);
eleni@0: 	    while(read(fd, buf, sizeof buf) > 0);
eleni@0: 	    if (now - last_touch_time > 2) {
eleni@0: 		system(cmd);
eleni@0: 		last_touch_time = now;
eleni@0: 	    }
eleni@0: 	}
eleni@0:     }
eleni@4: 
eleni@4:     free(cmd);
eleni@0:     close(fd);
eleni@4: 
eleni@4:     return 0;
eleni@0: }
eleni@0: 
eleni@0: static int parse_args(int argc, char **argv)
eleni@0: {
eleni@0:     for(int i=1; i<argc; i++) {
eleni@0: 	if((strcmp(argv[i], "-h") == 0)) {
eleni@0: 	    print_help();
eleni@0: 	    exit(0);
eleni@0: 	}
eleni@4: 
eleni@4: 	else if((strcmp(argv[i], "-p") == 0)) {
eleni@4: 	    if(argv[++i]) {
eleni@4: 		player_path = argv[i];
eleni@0: 	    }
eleni@0: 	    else {
eleni@0: 		fprintf(stderr, "Invalid path. Please give the absolute path to an mp3 player.\n");
eleni@4: 		return -1;
eleni@0: 	    }
eleni@0: 	}
eleni@0: 
eleni@4: 	else if((strcmp(argv[i], "-u") == 0)) {
eleni@4: 	    if(argv[++i]) {
eleni@4: 		struct passwd *passwd = getpwnam(argv[i]);
eleni@0: 		if(!passwd) {
eleni@4: 		    fprintf(stderr, "Failed to get uid for: %s : %s.\n", argv[i], strerror(errno));
eleni@4: 		    return -1;
eleni@0: 		}
eleni@0: 		uid = passwd->pw_uid;
eleni@4: 		if(uid == 0) {
eleni@4: 		    fprintf(stderr, "You should pass an unprivileged username.\n");
eleni@4: 		    return -1;
eleni@4: 		}
eleni@0: 	    }
eleni@0: 	    else {
eleni@4: 		fprintf(stderr, "Missing username.\n");
eleni@4: 		return -1;
eleni@0: 	    }
eleni@0: 	}
eleni@4: 	else if((strcmp(argv[i], "-d") == 0)) {
eleni@4: 	    if(argv[++i]) {
eleni@4: 		dev_path = argv[i];
eleni@0: 	    }
eleni@0: 	    else {
eleni@0: 		fprintf(stderr, "Invalid device file.\n");
eleni@4: 		return -1;
eleni@0: 	    }
eleni@0: 	}
eleni@4: 	else {
eleni@4: 	    fprintf(stderr, "Unknown argument: %s\n", argv[i]);
eleni@4: 	    return -1;
eleni@4: 	}
eleni@0:     }
eleni@0:     return 0;
eleni@0: }
eleni@0: 
eleni@0: static void print_help()
eleni@0: {
eleni@0:     printf("Options:\n");
eleni@0:     printf("-h, prints this help\n");
eleni@0:     printf("-d, path to the device\n");
eleni@0:     printf("-p, path to the mp3 player\n");
eleni@0:     printf("-u. username of the user that runs the program\n");
eleni@0:     printf("--------\n");
eleni@0:     printf("Examples:\n");
eleni@0:     printf("--------\n");
eleni@0:     printf("./dtms -d /dev/usb/hiddev0 -u eleni -p /usr/bin/mpv\n");
eleni@0: }
eleni@0: 
eleni@4: static int check_device(char *device_path)
eleni@0: {
eleni@0:     struct stat sb;
eleni@0:     if(stat(dev_path, &sb) == -1) {
eleni@0: 	perror("stat");
eleni@4: 	return -1;
eleni@0:     }
eleni@0:     if(((sb.st_mode & S_IFMT) != S_IFBLK) && ((sb.st_mode & S_IFMT) != S_IFCHR)) {
eleni@4: 	fprintf(stderr, "%s is not a device file.\n", device_path);
eleni@4: 	return -1;
eleni@0:     }
eleni@4:     return 0;
eleni@0: }