int main()
{
int key = 123 ;
int memsize = sizeof(int) ;
int shmemId = open_shmem(key, memsize) ;
if (shmemId == -1) {
perror("shared segment opening error") ;
exit(EXIT_FAILURE) ;
}
int* buffer = (int*) attach_shmem(shmemId) ;
*buffer = 0 ;
int emptySemKey = 100 ;
int emptySemId = open_semaphore(emptySemKey) ;
int fullSemKey = 101 ;
int fullSemId = open_semaphore(fullSemKey) ;
if ((emptySemId == -1) || (fullSemId == -1)) {
perror("semaphore opening error") ;
exit(EXIT_FAILURE) ;
}
while (*buffer >= 0) {
down(fullSemId) ;
if (*buffer >= 0)
printf("%d\n", *buffer) ;
up(emptySemId) ;
}
detach_shmem(buffer) ;
}
int main()
{
int key = 123 ;
int memsize = sizeof(int) ;
int shmemId = create_shmem(key, memsize) ;
if (shmemId == -1) {
perror("shared segment creation error") ;
exit(EXIT_FAILURE) ;
}
int* buffer = (int*) attach_shmem(shmemId) ;
*buffer = 0 ;
int emptySemKey = 100 ;
int emptySemId = create_semaphore(emptySemKey) ;
int fullSemKey = 101 ;
int fullSemId = create_semaphore(fullSemKey) ;
if ((emptySemId == -1) || (fullSemId == -1)) {
perror("semaphore creation error") ;
exit(EXIT_FAILURE) ;
}
init_semaphore(fullSemId, 0) ;
init_semaphore(emptySemId, 1) ;
while (*buffer >= 0) {
down(emptySemId) ;
if (!scanf("%d", buffer))
*buffer = -1 ;
up(fullSemId) ;
}
remove_semaphore(fullSemId) ;
remove_semaphore(emptySemId) ;
detach_shmem(buffer) ;
remove_shmem(shmemId) ;
}
int main(int argc, char *argv[])
{
int size = 0;
int shared_memory_key = -1;
int sem_r = -1;
int sem_w = -1;
int cnt = -1;
int buf = -1;
int *shared_memory = NULL;
errno = 0;
/* check command line arguments */
if ((size = check_arguments(argc, argv))==ERROR)
{
print_usage();
return ERROR;
}
/* get both semaphores */
if((shared_memory_key = get_shmem(SHMEMKEY, size)) == -1)
{
clean_up(sem_r, &shared_memory, shared_memory_key, ERROR);
return ERROR;
}
attach_shmem(shared_memory_key, &shared_memory, SEMKEY_R);
if(shared_memory == NULL)
{
clean_up(sem_r, &shared_memory, shared_memory_key, ERROR);
return ERROR;
}
/* initialize shared memory */
if((sem_r= get_semid(SEMKEY_R, 0)) == ERROR)
{
clean_up(sem_r, &shared_memory, shared_memory_key, ERROR);
return ERROR;
}
/* attach memory to process */
if((sem_w= get_semid(SEMKEY_W, size))==ERROR)
{
clean_up(sem_r, &shared_memory, shared_memory_key, ERROR);
return ERROR;
}
/* start the reader */
do
{
if(P(sem_r)==-1)
{
if(errno == EINTR)
{
/*EINTR sagt uns, dass ein Interrupt vorliegt. */
errno = 0;
continue;
}
else
{
clean_up(sem_r, &shared_memory, shared_memory_key, ERROR);
fprintf(stderr, "Error bei P, reader. %s", strerror(errno));
return ERROR;
}
}
cnt++;
cnt = cnt%size;
buf = (*(shared_memory+cnt));
if(V(sem_w)==-1)
{
if(errno == EINTR)
{
/*EINTR sagt uns, dass ein Interrupt vorliegt. */
errno = 0;
continue;
}
else
{
clean_up(sem_r, &shared_memory, shared_memory_key, ERROR);
fprintf(stderr, "Error bei V, reader. %s", strerror(errno));
return ERROR;
}
}
if(buf!=EOF)
{
/* Do ouput and check for Output error */
if (fputc(buf, stdout) == EOF) {
fprintf(stderr, "Fehler fputc");
clean_up(sem_r, &shared_memory, shared_memory_key, ERROR);
return ERROR;
}
}
}while(buf!=EOF);
errno = 0;
if(fflush(stdout)!=0)
{
fprintf(stderr, "fflush failed");
if(errno != 0)
{
fprintf(stderr, "%s", strerror(errno));
return ERROR;
}
}
detach_shmem(shared_memory_key,SEMKEY_R);
clean_up(sem_r, &shared_memory, shared_memory_key, SEMKEY_R);
return 0;
}
