C: Strange symbols in shared memory (UNIX) - c

Question

I created a program to test the execution of shared memory.
One process creates the shared memory and writes to it.
The other reads from it.
It works perfectly, except for printing a string.
First program:
#define mykey 12345
#define perms 0666
struct pdata{
int ppid;
char ptype;
char *pname;
unsigned long pgenome;
};
int main(int argc, char **argv){
int shmid;
char *args[] = {"test2", NULL};
struct pdata *ap;
struct pdata p0={12, 'A', "PIPPO", 100};
shmid = shmget(mykey, sizeof(struct pdata) * 1, perms | IPC_CREAT | IPC_EXCL);
ap = (struct pdata*) shmat(shmid, NULL, 0);
ap[0] = p0;
printf("%s\n", ap[0].pname);
if(execve("test2", args, NULL) == -1){
printf("Errore execve\n");
}
shmdt(ap);
shmctl(shmid, IPC_RMID, 0);
return 0;
}
Second program:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdarg.h>
#include <errno.h>
#include <time.h>
#define mykey 12345
#define perms 0666
struct pdata{
int ppid;
char ptype;
char *pname;
unsigned long pgenome;
};
int main(){
int shmid = shmget(mykey, sizeof(struct pdata) * 1, perms);
struct pdata *ap;
ap = (struct pdata*) shmat(shmid, NULL, 0);
printf(
"ap[0].ppid=%d\nap[0].ptype=%c\nap[0].pname=%s\nap[0].pgenome=%lu\n",
ap[0].ppid,
ap[0].ptype,
ap[0].pname,
ap[0].pgenome
);
shmdt(ap);
shmctl(shmid, IPC_RMID, 0);
return 0;
}

Answer 1

It doesn't make sense to put a pointer in shared memory. The receiving process now knows the address of the string in the other process' memory space, but that doesn't do it any good. Instead, put the string itself in shared memory.
For example, change:
char *pname;
to:
char pname[512];
And adjust the rest of your program appropriately.