Pass a whole struct in c through a pipe

Question

I need to pass this struct through a pipe:

typedef struct Student {
  char * name;
  char * average;
} Student;

typedef struct Connection {
  int fd;
  int dataSize;
  void * data;
} Connection;

typedef struct Request {    
  int action;
  Connection * connection;
} Request;

My problem is that I don't know how to write the Student struct and how to read it. I can read correctly the fd, action and dataSize, but I could't fix it for the structure. I Hope you can help me. Perhaps there is an easier way to do this and pass the whole entire request structure.

So I did this on the client side: (writeNamedPipe uses write)

requestState writeRequest(Request * request, int fd) {
  writeNamedPipe(fd, &request -> action, sizeof(int));
  writeNamedPipe(fd, &request -> connection -> fd, sizeof(int));
  writeNamedPipe(fd, &request -> connection -> dataSize, sizeof(int));
  writeNamedPipe(fd, &request -> connection -> data, request -> connection -> dataSize);
  return REQUEST_OK;
}

And this in the server side:

Request * getRequest(Connection * connection) {
  Request *request; 
  int action, fd = 0;
  int dataSize;
  void * data;
  read(connection-> fd, &action, sizeof(int));
  read(connection-> fd, &fd, sizeof(int));
  read(connection-> fd, &dataSize, sizeof(int));
  data = malloc (dataSize);
  read(connection-> fd, data, dataSize);
  request = createRequest(action, fd, dataSize, data);
  return request;
}

score 1 · Accepted Answer · edited May 23 '17 at 12:07

1

The Student struct only contain pointers, so you cannot send the whole struct at once. It would be possible if you had fix array instead of dynamically allocated ones.

example:

struct Student {
    char name[32];
    char average[16];
};

I guess this would probably answers your question:

C - serialization techniques

edited May 23 '17 at 12:07

Community

1
1

answered May 14 '16 at 21:00

mgagnon

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Pass a whole struct in c through a pipe

1 Answers1