Segmentation fault when modifying struct in C

Question

I'm developing a client/server chat using C for a University project.

Everything is going fine, but i cannot fix this problem.

I created a struct to store the sockets of the two clients who have to communicate:

typedef struct pairing_Clients{
  int client1fd;
  int client2fd;
} pairedClients;

When i use it in a function that manages the communication between two clients, it gives me segfault. I tried with the following lines:

• Declared it as a global variable:

pairedClients *clients;

• Then, doing this gives me the segfault:

void client_handler(void *p_client) {

  pairedClients *clients = (pairedClients *)malloc(sizeof(pairedClients));
  clients->client1fd = 15;
}

It seems strange to me. I don't see any big problem. Any help?

Answer 1

When allocating you are creating a new variable and global clients left uninitialized. Since the context is not clear, I guess that clients->client1fd = 15; line is not in the same scope with the allocation line.

Just change the malloc line to:

clients = (pairedClients *)malloc(sizeof(pairedClients));

Also you should check the return value of malloc .