feat[OS/lab5]: completed part B

OSs/lab5/part-B/common.h

@@ -0,0 +1,45 @@
+#ifndef COMMON_H_
+#define COMMON_H_
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#define FIFO_SERVER_PATH "/tmp/fifo.to_server" // server reads this file
+#define FIFO_CLIENT_PATH "/tmp/fifo.to_client" // client reads this file
+
+#define __DATA_STRUCT_MSG_LEN 4096
+
+enum ds_types {
+    DS_MESSAGE,
+    DS_FAIL
+};
+
+struct custom_ds {
+    struct {
+        long len;
+        long type;
+    } hdr;
+    char msg[__DATA_STRUCT_MSG_LEN];
+};
+
+static inline ssize_t send_msg(int fd, const struct custom_ds *ds)
+{
+    return write(fd, ds, sizeof(ds->hdr) + ds->hdr.len);
+}
+
+static inline ssize_t recv_msg(int fd, struct custom_ds *reciever)
+{
+    size_t n_hdr = read(fd, reciever, sizeof(reciever->hdr));
+    if (n_hdr == 0) return 0; // eof reached
+    if (n_hdr != sizeof(reciever->hdr)) return -ENOMSG;
+    if (reciever->hdr.len == 0) return 0;
+
+    size_t n_payload = read(fd, &reciever->msg, reciever->hdr.len);
+    if (n_payload != reciever->hdr.len) return -EFAULT;
+    return n_hdr + n_payload;
+}
+
+#define FAIL_ON(cond) if (cond) return EXIT_FAILURE
+
+#endif