shm-utils

Purpose :

This repository provide a C library for shared memory in the connecktail project in order to know the pid of the different processes.

Build the library :

• clone the repository
• execute the following commands :

make
make install

The headers have been added to the /usr/include/shm-utils repository

In your code, you have just to include the shmutils.h header file :

#include <shm-utils/shmutils.h>

Because the functions to get or modify the shared memory need the shared memory id, you have to declare a global variable in your code :

int shmid;

Its value will be the result of the init_shared_memory() function.

Compilation :

If you want to use the static library, you have just to specify the path of the lib and its name :

gcc file.c -L path/to/libshm-utils.a -lshm-utils -o file

On the other hand, if you want to use the dynamic library, specify the name of the lib during the links edition :

gcc file.c -lshm-utils -o file

Shared memory data structure :

typedef struct
{
    pid_t main_pid;
    pid_t websocket_pid;
    pid_t device_handler_pid;
} shm_t;

Functions :

Utils

• Initialize the shared memory :

int init_shared_memory()

• Retrieve the shared memory (readonly):

shm_t *get_shm();

• Modify the pid of the main process :

void change_main_pid(int pid)

• Modify the pid of the websocket process :

void change_websocket_pid(int pid)

• Modify the pid of the device handler process :

void change_device_handler_pid(int pid)

• Create and set the shared memory :

void set_init_shm()