C言語 FreeBSDで共有メモリを使う shmget/shmat/shmdt

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <err.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>

#include <sys/ipc.h>
#include <sys/shm.h>

#include <sysexits.h>
#define SHM_SIZE	1000


int
shm_reader()
{
	int	shmid;
	char	*shmptr;

	shmid = shmget (IPC_PRIVATE, SHM_SIZE, IPC_CREAT|0666);

	if (shmid == -1)
	{
		err (EX_OSERR, "can not get shm");
	}

	shmptr = shmat (shmid, 0, 0);
	if (shmptr == (void *) -1)
	{
		err (EX_OSERR, "can not shmat(%d)", shmid);
	}
	else
	{

		(void) printf ("shmid: %d\n", shmid);
		(void) printf ("shared memory: 0x%x\n", shmptr);

		(void) strcpy (shmptr, "init");

		for ( ; ; )
		{
			printf ("%s\n", shmptr);
			if (strcmp (shmptr, "exit") == 0)
			{
				break;
			}
			sleep (2);
		}

		if (shmdt (shmptr) < 0)
		{
			//err (EX_OSERR, "can not shmdt %x", ptr);
			err (EX_OSERR, "can not shmdt");
		}
	}

	if (shmctl (shmid, IPC_RMID, 0) < 0)
	{
		err (EX_OSERR, "can not shmctl(%d, IPC_RMDIR)", shmid);
	}

	return (0);
}

int
main (int argc, char *argv[])
{
	shm_reader ();

	exit (EXIT_SUCCESS);
}

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <err.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>

#include <sys/ipc.h>
#include <sys/shm.h>

#include <sysexits.h>
#define SHM_SIZE	1000


int
shm_writer(int shmid)
{
	char	*shmptr;

	shmptr = shmat (shmid, 0, 0);
	if (shmptr == (void *) -1)
	{
		err (EX_OSERR, "can not shmat(%d)", shmid);
	}
	else
	{
		(void) printf ("shmid: %d\n", shmid);
		(void) printf ("shared memory: 0x%x\n", shmptr);

		(void) printf ("Exit command is 'exit'\n");

		for ( ; ; )
		{
			fgets (shmptr, SHM_SIZE, stdin);
			shmptr[strlen(shmptr) - 1] = '\0';
			if (strcmp (shmptr, "exit") == 0)
			{
				break;
			}
		}

		if (shmdt (shmptr) < 0)
		{
			//err (EX_OSERR, "can not shmdt %x", ptr);
			err (EX_OSERR, "can not shmdt");
		}
	}
	return (0);
}

int
main (int argc, char *argv[])
{
	if (argc != 2)
	{
		errx (EXIT_FAILURE, "shm_write shmid");
	}

	shm_writer (atoi(argv[1]));

	exit (EXIT_SUCCESS);
}

make shm_read shm_write

% ./shm_read
shmid: 31522834
shared memory: 0x28177000
init

% ./shm_write 31522834
shmid: 31522834
shared memory: 0x28177000
Exit command is 'exit'
hoge
foo
bar
exit
%