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#include "port.h"
#include <stdio.h>
#include "semaphore.h"
#include <unistd.h>
#include <stdlib.h>
Semaphore::Semaphore(int semKey, int numSems, int val)
: m_semid(0)
, m_semflg(IPC_CREAT | 0666)
, m_semopen(false)
, m_semKey(semKey)
, m_numSems(numSems)
{
m_arg.val = (0);
if(val)
{
if(create(val))
exit(1);
}
}
int Semaphore::clear_sem()
{
int semid;
// have num-sems set to 1 so that we remove regardless of how many
// semaphores were present.
if((semid = semget(m_semKey, 1, 0666)) == -1)
{
perror("Can't get semaphore ID");
return 1;
}
if(semctl(semid, 0, IPC_RMID, m_arg) == -1)
{
perror("Can't get remove semaphore");
return 1;
}
printf("Semaphore removed.\n");
return 0;
}
int Semaphore::create(int count)
{
if((m_semid = semget(m_semKey, m_numSems, m_semflg)) == -1)
{
perror("Can't get semaphore");
return 1;
}
m_arg.val = count;
int i;
for(i = 0; i < m_numSems; ++i)
{
if(semctl(m_semid, i, SETVAL, m_arg) == -1)
{
perror("Can't set semaphore value");
return 1;
}
}
m_semopen = true;
printf("Creating semaphore for %d procs.\n", count);
return 0;
}
int Semaphore::get_semid()
{
int semflg = 0666;
if ((m_semid = semget(m_semKey, m_numSems, semflg)) == -1)
{
perror("Can't get semaphore ID");
return 1;
}
m_semopen = true;
return 0;
}
int Semaphore::decrement_and_wait(int nr_sem)
{
if(!m_semopen)
return 0;
struct sembuf sops;
sops.sem_num = nr_sem;
sops.sem_op = -1;
sops.sem_flg = IPC_NOWAIT;
if(semop(m_semid, &sops, 1) == -1)
{
perror("semop: semop failed.\n");
return 1;
}
sops.sem_num = nr_sem;
sops.sem_op = 0;
sops.sem_flg = SEM_UNDO;
if(semop(m_semid, &sops, 1) == -1)
{
perror("semop: semop failed.\n");
return 1;
}
return 0;
}
int Semaphore::get_mutex()
{
if(!m_semopen)
return 0;
struct sembuf sops;
sops.sem_num = 0;
sops.sem_op = -1;
sops.sem_flg = SEM_UNDO;
if(semop(m_semid, &sops, 1) == -1)
{
perror("semop: semop failed.\n");
return 1;
}
return 0;
}
int Semaphore::put_mutex()
{
if(!m_semopen)
return 0;
struct sembuf sops;
sops.sem_num = 0;
sops.sem_op = 1;
sops.sem_flg = IPC_NOWAIT;
if(semop(m_semid, &sops, 1) == -1)
{
perror("semop: semop failed.\n");
return 1;
}
return 0;
}
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