Reorganised sys_open.

vfs_create and mknod now returns the newly created vnode.
(which might be used by upper layers).

tasks/test0/src/fileio.c

@@ -12,22 +12,51 @@ int fileio(void)
 	int fd;
 	ssize_t cnt;
 	int err;
+	char buf[128];
+	off_t offset;
 
 	char *str = "I WROTE TO THIS FILE\n";
 
 	if ((fd = open("/home/bahadir/newfile.txt", O_RDWR | O_CREAT | O_TRUNC, S_IRWXU)) < 0) {
 		perror("OPEN");
-		return 0;
+		return -1;
 	}
 
 	if ((int)(cnt = write(fd, str, strlen(str))) < 0) {
 		perror("WRITE");
-		return 0;
+		return -1;
 	}
 
-	if ((err = close(fd)) < 0)
+	if ((int)(offset = lseek(fd, 0, SEEK_SET)) < 0) {
+		perror("LSEEK");
+		return -1;
+	}
+	if ((int)(cnt = read(fd, buf, strlen(str))) < 0) {
+		perror("WRITE");
+		return -1;
+	}
+
+	printf("Read: %d bytes from file.\n", cnt);
+	if (cnt) {
+		printf("Read string: %s\n", buf);
+	}
+
+	if ((err = close(fd)) < 0) {
 		perror("CLOSE");
+		return -1;
+	}
 
 	return 0;
 }
 
+#if defined(HOST_TESTS)
+int main(void)
+{
+	printf("File IO test:\n");
+	if (fileio() == 0)
+		printf("-- PASSED --\n");
+
+	return 0;
+}
+#endif
+