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#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <time.h>
#include <sys/stat.h>
#include <string.h>
#include <pthread.h>
#include "fscomch.h"
cancelToken_t init_cancel_token_timeout(int seconds) {
cancelToken_t token;
token.timeout = seconds;
token.value = calloc(1, sizeof(char));
pthread_t cancelTimer;
cancelToken_t* memToken = malloc(sizeof(cancelToken_t));
*memToken = token;
pthread_create(&cancelTimer, NULL, cancel_in_secs, (void*)memToken);
return token;
}
cancelToken_t init_cancel_token_never() {
cancelToken_t token;
token.timeout = -1;
token.value = NULL;
return token;
}
match_t init_match(char* uuid, FILE* streamIn, FILE* streamOut) {
match_t match;
match.uuid = uuid;
match.streamIn = streamIn;
match.streamOut = streamOut;
return match;
}
void destroy_match(match_t match) {
free(match.uuid);
fclose(match.streamIn);
fclose(match.streamOut);
}
FILE* try_lock_match() {
mkdir("/tmp/chess/", 0777);
mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
int fd = open("/tmp/chess/match", O_RDONLY | O_CREAT | O_EXCL, mode);
if (fd == -1) {
return NULL;
}
return fdopen(fd, "r");
}
match_t await_match(FILE* matchFile, cancelToken_t cancelToken) {
/* await match UUID */
char* uuid = calloc(37, sizeof(char));
while (cancelToken.value == NULL || !*cancelToken.value) {
if (fgets(uuid, 37, matchFile) != NULL) {
break;
}
fseek(matchFile, 0, SEEK_SET);
struct timespec req;
req.tv_sec = 0;
req.tv_nsec = awaitMatchNs;
nanosleep(&req, NULL);
}
/* connect to streams */
char aName[256];
char bName[256];
snprintf(aName, 256, "/tmp/chess/%s.a", uuid);
snprintf(bName, 256, "/tmp/chess/%s.b", uuid);
FILE* streamIn = fopen(aName, "r");
FILE* streamOut = fopen(bName, "a");
/* connection complete, delete the match file and the join lock */
remove("/tmp/chess/match");
remove("/tmp/chess/matchjoin");
match_t match = init_match(uuid, streamIn, streamOut);
send_message("ping", match);
return match;
}
match_t join_match() {
/* create a join lock so that no one else can join this match */
mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
int fd = open("/tmp/chess/matchjoin", O_WRONLY | O_CREAT | O_EXCL, mode);
if (fd == -1) {
/* another process is in the process of joining this game */
match_t match;
return match;
}
close(fd);
/* this is definitely the only process joining the game
proceed to generate a uuid */
char* uuid = make_uuid();
/* create and connect to streams */
char aName[256];
char bName[256];
snprintf(aName, 256, "/tmp/chess/%s.a", uuid);
snprintf(bName, 256, "/tmp/chess/%s.b", uuid);
FILE* streamIn = fopen(bName, "w+");
FILE* streamOut = fopen(aName, "a");
match_t match = init_match(uuid, streamIn, streamOut);
/* send uuid to the host */
FILE* matchFile = fopen("/tmp/chess/match", "a");
fputs(uuid, matchFile);
fclose(matchFile);
/* handshake */
cancelToken_t token = init_cancel_token_timeout(2);
char* message = read_message(match, token);
if (message != NULL) {
if (strcmp(message, "ping") == 0) {
return match;
}
else {
printf("Extreme de-sync. Aborting\n");
exit(1);
}
}
printf("Host is dead. Cleaning up\n");
fclose(streamIn);
fclose(streamOut);
remove("/tmp/chess/match");
remove("/tmp/chess/matchjoin");
remove(aName);
remove(bName);
exit(1);
}
void send_message(char* content, match_t match) {
fprintf(match.streamOut, "%s\n", content);
fflush(match.streamOut);
}
char* read_message(match_t match, cancelToken_t cancelToken) {
char* buffer = calloc(256, sizeof(char));
while (cancelToken.value == NULL || !*cancelToken.value) {
if (fgets(buffer, 256, match.streamIn) != NULL) {
break;
}
/* wtf? */
fseek(match.streamIn, ftell(match.streamIn), SEEK_SET);
struct timespec req;
req.tv_sec = 0;
req.tv_nsec = awaitMoveNs;
nanosleep(&req, NULL);
}
/* if we cancelled via token, return NULL */
if (cancelToken.value != NULL && *cancelToken.value == 1) {
free(buffer);
return NULL;
}
/* overwrite potential newline */
buffer[strlen(buffer) - 1] = '\0';
return buffer;
}
char* make_uuid() {
char sym[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', 'a', 'b', 'c', 'd', 'e', 'f'};
char* out = calloc(37, sizeof(char));
srand(time(NULL));
for (int i = 0; i < 36; i++) {
if (i == 8 || i == 13 || i == 18 || i == 23) {
out[i] = '-';
}
else {
out[i] = sym[rand() % 16];
}
}
out[37] = '\0';
return out;
}
void* cancel_in_secs(void* token) {
sleep(((cancelToken_t*)token)->timeout);
*(((cancelToken_t*)token)->value) = 1;
free(token);
}
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