c - write pointers to pipe, are there any strict aliasing or pun type issues? -

i need create many fifo queues in program, used communication between threads in same process.

i think can use pipe() purpose, because in way, can use select or poll on thread fetch nodes queue.

        int* fd_pipe = (int*)malloc(2*sizeof(int));         pipe(fd_pipe); 

now problem how put pointer queue since each node strucutre, want put pointer queue, like

typedef{ struct packet *pkt; struct info *info; int seq; }node;

  on threads put node queue:     node* node = (node*)malloc(sizeof(node));    node->info = ...;    node->seq = ...;    node->pkt = ...;    write(fd_pipe[1], node, sizeof(node));    on threads read node queue:     char buf[1000];    read(fd_pipe[0], buf, sizeof(node))    node* mynode = (node*)buf; 

then mynode want.

is there wrong in program? strict aliasing or pun type problems? thanks!

you not have aliasing issues. here issue see read(fd_pipe[0], buf, sizeof(node)), should read(fd_pipe[0], buf, sizeof(node *)).

i not sure why use char buffer here, prefer

node *node; if (read(fd_pipe[0], &node, sizeof(node)) <= 0) {     // error, deal } 

it's simpler , clearer.

now, code work if use blocking i/o default. also, technically, should handle short read/writes writing/reading on pipe atomic if read/written size less pipe_buf (which larger pointer)

you have bit of grey area in code memory synchronization before write since system call, work.

a pipe unusual way communicate between threads. usually, people use in-memory queues communicate between threads. 1 example http://www.boost.org/doc/libs/1_53_0/doc/html/boost/lockfree/queue.html