You're trying to pass a pointer to data that is not in
the child's address space? Won't work. Try using
shared memory, if that's what you want.
If you want to pass data over a pipe or socket, you
have to serialize it first.
HTH,
Brian
--- James Matthew Miraflor <[EMAIL PROTECTED]>
wrote:
> I just want to ask, can I pass a pointer to a
> structure using pipes in
> C. I really want to pass the pointer to a head of a
> linked list, but I
> get nothing. The code is:
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <sys/types.h>
> #include <sys/wait.h>
> #include <unistd.h>
>
> typedef struct {
> int whoami;
> int data;
> struct datagram *next;
> struct datagram *prev;
> } datagram;
>
> void parent_to_child(int input[2], int output[2]) {
> datagram *head, *trav, *temp;
> int i=1, num_input;
>
> close(input[1]);
> close(output[0]);
>
> /* Receive input from console and create the
> node associated */
> do {
> printf("\nInput number %d : ",i);
> scanf("%d",&num_input);
> temp =
> (datagram*)malloc(sizeof(datagram));
> temp->whoami = i;
> temp->data = num_input;
> temp->next = temp->prev = NULL;
> i++;
> /* Passes to child created node */
>
> write(output[1],(void*)&temp,sizeof(datagram*));
> } while(num_input>0);
>
> /* Receives head node of the list */
>
> read(input[0],(void*)&head,sizeof(datagram*));
>
> /* Traverses and prints the elements of the
> list */
>
> for(trav=head,i=1;trav!=NULL;trav=trav->next,i++) {
> printf("\nNumber %d is %d, which has
> been inputed
> %dth.",i,trav->data,trav->whoami);
> }
>
> close(input[0]);
> close(output[1]);
> exit(0);
> }
>
> void child_to_parent(int input[2], int output[2]) {
> datagram *head, *tail, *temp, *trav, *mark;
> int i;
>
> close(input[1]);
> close(output[0]);
>
> /* Sentinel node */
> head = (datagram*)malloc(sizeof(datagram));
> head->whoami = -1;
> head->data = -1;
> head->next = NULL;
> tail = head;
>
> /* Receives node and adds to list until
> encountered data zero */
> while(1) {
>
> read(input[0],(void*)&temp,sizeof(datagram*));
> printf("temp->whoami = %d,
> temp->data =
> %d",temp->whoami,temp->data);
> tail->next = temp;
> temp->prev = tail;
> tail = tail->next;
> }
>
>
> write(output[1],(void*)&head,sizeof(datagram*));
>
> close(input[0]);
> close(output[1]);
> exit(0);
> }
>
> int main() {
> pid_t child_pid;
> int child_status, pipe1[2], pipe2[2],
> piperet = 0;
>
> piperet += pipe(pipe1);
> piperet += pipe(pipe2);
> if(piperet<0) {
> perror("pipe");
> exit(1);
> }
>
> child_pid = fork();
> switch(child_pid) {
> case -1 : {
> perror("fork");
> exit(1);
> }
> case 0 : {
>
> child_to_parent(pipe2,pipe1);
> }
> default : {
>
> parent_to_child(pipe1,pipe2);
> }
> }
> }
>
> Can anyone tell me what is wrong? I would appreciate
> any response.
>
> --
> James Matthew B. Miraflor
> 2002-17119
> BS Computer Science
> University of the Philippines
> Manila
>
> (+63)02-2876007
> +639197101941
> Block 49 Lot 29 Phase 3 E2
> Dagat-dagatan, Malabon City
> Philippines
>
___________________________________________________________
>
> "(One) wins his battles by making no mistakes.
> Making no mistakes
> is what establishes the certainty of victory, for it
> means conquering
> an enemy that has already been defeated."
>
> Sun Tzu
> The Art of War
>
____________________________________________________________
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> [email protected] (#PLUG @ irc.free.net.ph)
> Official Website: http://plug.linux.org.ph
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> .
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> .
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> to
>
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