fixup: address PR review comments

- Merge io.h/c back into protocol.h/c
- Change send_data to take Data* argument
- Remove redundant file_load_data from send_chunk
- Move compression into file_send_single_calls
- Move file_receive from multiprocessing.c to file.c

src/shared/protocol.c

@@ -1,9 +1,53 @@
 #include "protocol.h"
-#include "io.h"
 #include "log.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
+
+static __thread int io_read_fd = -1;
+static __thread int io_write_fd = -1;
+
+void io_set_fds(int read_fd, int write_fd) {
+  io_read_fd = read_fd;
+  io_write_fd = write_fd;
+}
+
+static int io_fd(int dir_fd, int file_descriptor) {
+  return (dir_fd != -1) ? dir_fd : file_descriptor;
+}
+
+void send_n_data(int file_descriptor, void *data, size_t data_size) {
+  log_message(LOG_LEVEL_DEBUG, "    Sending n Data: %zu", data_size);
+  int fd = io_fd(io_write_fd, file_descriptor);
+  ssize_t total_bytes_send = 0;
+  while (total_bytes_send < data_size) {
+    ssize_t bytes_send =
+        write(fd, (char *)data + total_bytes_send, data_size - total_bytes_send);
+    if (bytes_send <= 0) {
+      perror("Could not send data!");
+      exit(EXIT_FAILURE);
+    }
+    total_bytes_send += bytes_send;
+  }
+  log_message(LOG_LEVEL_DEBUG, "    Send n Data: %zu", total_bytes_send);
+}
+
+void receive_n_data(int file_descriptor, void *data, size_t data_size) {
+  log_message(LOG_LEVEL_DEBUG, "    Receiving n Data: %zu", data_size);
+  int fd = io_fd(io_read_fd, file_descriptor);
+  size_t total_bytes_received = 0;
+  while (total_bytes_received < data_size) {
+    ssize_t bytes_received =
+        read(fd, (char *)data + total_bytes_received, data_size - total_bytes_received);
+    if (bytes_received == -1 || bytes_received == 0) {
+      perror("Could not receive bytes!");
+      exit(EXIT_FAILURE);
+    }
+    total_bytes_received += bytes_received;
+  }
+  log_message(LOG_LEVEL_DEBUG, "    Received n Data: %zu", total_bytes_received);
+}
 
 static const char *status_to_string(Status status) {
   switch (status) {
@@ -39,9 +83,10 @@ char *receive_str(int file_descriptor) {
   return data;
 }
 
-void send_data(int file_descriptor, void *data, unsigned long long data_size) {
+void send_data(int file_descriptor, Data *data) {
+  unsigned long long data_size = data->size;
   send_n_data(file_descriptor, &data_size, sizeof(unsigned long long));
-  send_n_data(file_descriptor, data, data_size);
+  send_n_data(file_descriptor, data->data, data_size);
   log_message(LOG_LEVEL_DEBUG, "Send %lld data", data_size);
 }