fscomch--communication between multiple chess processes

1 files changed, 97 insertions, 0 deletions

diff --git a/src/fscomch.c b/src/fscomch.c
new file mode 100644
index 0000000..a9fc27b
--- /dev/null
+++ b/src/fscomch.c
@@ -0,0 +1,97 @@
+#include <fcntl.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <time.h>
+#include <sys/stat.h>
+#include "fscomch.h"
+
+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, char* cancelToken) {
+	/* await match UUID */
+	char* uuid = calloc(37, sizeof(char));
+	while (cancelToken == NULL || *cancelToken) {
+		if (fgets(uuid, 37, matchFile) != NULL) {
+			break;
+		}
+		fseek(matchFile, 0, SEEK_SET);
+		struct timespec req;
+		req.tv_sec = 0;
+		req.tv_nsec = awaitMatchNs;
+		printf("sleeping\n");
+		nanosleep(&req, NULL);
+	}
+	/* connect to files created by joining player */
+	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, "w");
+	/* connection complete, delete the match file and the join lock */
+	remove("/tmp/chess/match");
+	remove("/tmp/chess/matchjoin");
+	return init_match(uuid, streamIn, streamOut);
+}
+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;
+	}
+	/* this is definitely the only process joining the game
+	proceed to generate a uuid */
+	char* uuid = make_uuid();
+	/* make the .a and .b files based on the uuid */
+	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, "w");
+	match_t match = init_match(uuid, streamIn, streamOut);
+	/* send uuid to the host */
+	FILE* matchFile = fopen("/tmp/chess/match", "a");
+	fputs(uuid, matchFile);
+	/* joining match complete, close the descriptor */
+	close(fd);
+	return match;
+}
+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;
+}