1 files changed, 135 insertions, 0 deletions
diff --git a/entries/adirar111/c-filesystem/fib-fs.c b/entries/adirar111/c-filesystem/fib-fs.c
new file mode 100644
index 0000000..d07c205
--- /dev/null
+++ b/entries/adirar111/c-filesystem/fib-fs.c
@@ -0,0 +1,135 @@
+/* fib, but the cache is a directory of files
+ *  cache/
+ *    0 -> 0
+ *    1 -> 1
+ *    2 -> 1
+ *    3 -> 2
+ *    ...
+ * unix filesystem required
+*/
+#include <dirent.h>
+#include <string.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+static const char CACHE_DIR[] = "cache";
+static const int BUF_SIZE = 30;
+static const int PATH_SIZE = 30;
+static const int N_STR_SIZE = 30;
+static const int LOF_INITIAL_SIZE = 1;
+
+long read_from_cache(char* path) {
+	char buf[BUF_SIZE];
+	int fd = open(path, O_RDONLY);
+
+	if (fd == -1) {
+		close(fd);
+		return 0;
+	}
+
+	if (!read(fd, buf, BUF_SIZE)) {
+		close(fd);
+		return 0;
+	}
+
+	close(fd);
+	return strtol(buf, NULL, 10);
+}
+
+long write_to_cache(char* path, long result) {
+	char buf[BUF_SIZE];
+	int fd = open(path, O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);
+	sprintf(buf, "%ld", result);
+
+	if (fd == -1) {
+		close(fd);
+		return 0;
+	}
+
+	if (!write(fd, buf, strlen(buf))) {
+		close(fd);
+		return 0;
+	}
+
+	close(fd);
+	return 1;
+}
+
+long init_cache() {
+	char path_to_0[PATH_SIZE];
+	char path_to_1[PATH_SIZE];
+	sprintf(path_to_0, "%s/%s", CACHE_DIR, "0");
+	sprintf(path_to_1, "%s/%s", CACHE_DIR, "1");
+
+	if (!write_to_cache(path_to_0, 0)) {
+		return 0;
+	}
+
+	if (!write_to_cache(path_to_1, 1)) {
+		return 0;
+	}
+
+	return 1;
+}
+
+long get_list_of_files(long** list_of_files, long curr_size) {
+	mkdir("cache", 0777);
+	struct dirent *d;
+	DIR* cache_dir = opendir(CACHE_DIR);
+
+	if (!cache_dir) {
+		closedir(cache_dir);
+		return 0;
+	}
+
+	init_cache();
+
+	while ((d = readdir(cache_dir)) != NULL) {
+		if (d->d_type == DT_REG) {
+			*((*list_of_files) + curr_size - 1) = strtol(d->d_name, NULL, 10);
+			curr_size++;
+			*list_of_files = realloc(*list_of_files, curr_size * sizeof(long));
+		}
+	}
+
+	closedir(cache_dir);
+	return curr_size - 1;
+}
+
+
+int is_in_cache(long* list_of_files, long size_of_lof, long n) {
+	for (int i = 0; i < size_of_lof; i++) {
+		if (list_of_files[i] == n) return 1;
+	}
+	return 0;
+}
+
+long fib(long n) {
+	char n_str[N_STR_SIZE];
+	char path[PATH_SIZE];
+	long* list_of_files = malloc(sizeof(long));
+	long size_of_lof = get_list_of_files(&list_of_files, LOF_INITIAL_SIZE);
+
+	sprintf(n_str, "%ld", n);
+	sprintf(path, "%s/%s", CACHE_DIR, n_str);
+
+	if (is_in_cache(list_of_files, size_of_lof, n)) {
+		free(list_of_files);
+		long cached_value = read_from_cache(path);
+		return cached_value;
+	}
+
+	free(list_of_files);
+	long toCache = fib(n-1) + fib(n-2);
+	write_to_cache(path,  toCache);
+	return toCache;
+}
+
+
+int main() {
+	printf("FIB RESULT: %ld\n", fib(13));
+}