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/*-------------------------------------------------------------------------
*
* sem.c
* BeOS System V Semaphores Emulation
*
* Copyright (c) 1999-2000, Cyril VELTER
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <stdio.h>
#include <errno.h>
#include <OS.h>
#include "utils/elog.h"
/* Control of a semaphore pool. The pool is an area in which we stored all
the semIds of the pool. The first 4 bytes are the number of semaphore allocated
in the pool followed by SemIds */
int semctl(int semId,int semNum,int flag,union semun semun)
{
int32* Address;
area_info info;
/* Try to find the pool */
if (get_area_info(semId,&info)!=B_OK)
{
/* pool is invalid (BeOS area id is invalid) */
errno=EINVAL;
return -1;
}
/* Get the pool address */
Address=(int32*)info.address;
/* semNum might be 0 */
/* semun.array contain the sem initial values */
/* Fix the count of all sem of the pool to semun.array */
if (flag==SETALL)
{
long i;
for (i=0;i<Address[0];i++)
{
int32 cnt;
/* Get the current count */
get_sem_count(Address[i+1],&cnt);
/* Compute and set the new count (relative to the old one) */
cnt-=semun.array[i];
if (cnt > 0)
while(acquire_sem_etc(Address[i+1],cnt,0,0)==B_INTERRUPTED);
if (cnt < 0)
release_sem_etc(Address[i+1],-cnt,0);
}
return 1;
}
/* Fix the count of one semaphore to semun.val */
if (flag==SETVAL)
{
int32 cnt;
/* Get the current count */
get_sem_count(Address[semNum+1],&cnt);
/* Compute and set the new count (relative to the old one) */
cnt-=semun.val;
if (cnt > 0)
while(acquire_sem_etc(Address[semNum+1],cnt,0,0)==B_INTERRUPTED);
if (cnt < 0)
release_sem_etc(Address[semNum+1],-cnt,0);
return 1;
}
/* Delete the pool */
if (flag==IPC_RMID)
{
long i;
thread_info ti;
get_thread_info(find_thread(NULL),&ti);
/* Loop over all semaphore to delete them */
for (i=0;i<Address[0];i++)
{
/* Don't remember why I do that */
set_sem_owner(Address[i+1],ti.team);
/* Delete the semaphore */
delete_sem(Address[i+1]);
/* Reset to an invalid semId (in case other process try to get the infos from a cloned area */
Address[i+1]=0;
}
/* Set the semaphore count to 0 */
Address[0]=0;
/* Delete the area (it might be cloned by other process. Let them live with it,
in all cases semIds are 0 so if another process try to use it, it will fail */
delete_area(semId);
return 1;
}
/* Get the current semaphore count */
if (flag==GETNCNT)
{
/* TO BE IMPLEMENTED */
elog(ERROR,"beos : semctl error : GETNCNT not implemented");
return 0;
}
/* Get the current semaphore count of the first semaphore in the pool */
if (flag==GETVAL)
{
int32 cnt;
get_sem_count(Address[semNum+1],&cnt);
return cnt;
}
elog(ERROR,"beos : semctl error : unknown flag");
return 0;
}
/* Find a pool id based on IPC key */
int semget(int semKey, int semNum, int flags)
{
char Nom[50];
area_id parea;
void* Address;
/* Name of the area to find */
sprintf(Nom,"SYSV_IPC_SEM : %d",semKey);
/* find area */
parea=find_area(Nom);
/* Test of area existance */
if (parea!=B_NAME_NOT_FOUND)
{
/* Area exist and creation is requested, error */
if ((flags&IPC_CREAT)&&(flags&IPC_EXCL))
{
errno=EEXIST;
return -1;
}
/* Get an area clone (in case it's not in our address space) */
/* TODO : a check of address space might be done to avoid duplicate areas in the same address space*/
parea=clone_area(Nom,&Address,B_ANY_ADDRESS,B_READ_AREA | B_WRITE_AREA,parea);
return parea;
}
else
{
/* Area does not exist, but creation is requested, so create it */
if (flags&IPC_CREAT)
{
int32* Address;
void* Ad;
long i;
/* Limit to 500 semaphore in a pool */
if (semNum>500)
{
errno=ENOSPC;
return -1;
}
/* Create the shared memory area which will hold the pool */
parea=create_area(Nom,&Ad,B_ANY_ADDRESS,4096,B_NO_LOCK,B_READ_AREA | B_WRITE_AREA);
if ((parea==B_BAD_VALUE)|| (parea==B_NO_MEMORY)||(parea==B_ERROR))
{
errno=ENOMEM;
return -1;
}
/* fill up informations (sem number and sem ids) */
Address=(int32*)Ad;
Address[0]=semNum;
for (i=1;i<=Address[0];i++)
{
/* Create the semaphores */
Address[i]=create_sem(0,Nom);
if ((Address[i]==B_BAD_VALUE)|| (Address[i]==B_NO_MEMORY)||(Address[i]==B_NO_MORE_SEMS))
{
errno=ENOMEM;
return -1;
}
}
return parea;
}
else
{
/* Area does not exist and no creation is requested */
errno=ENOENT;
return -1;
}
}
}
/* Acquire or release in the semaphore pool */
int semop(int semId, struct sembuf *sops, int nsops)
{
int32* Address; /*Pool address*/
area_info info;
long i;
/* Get the pool address (semId IS an area id) */
get_area_info(semId,&info);
Address=(int32*)info.address;
/* Check the validity of semId (it should be an area id) */
if ((semId==B_BAD_VALUE)||(semId==B_NO_MEMORY)||(semId==B_ERROR))
{
errno=EINVAL;
return -1;
}
/* Perform acquire or release */
for(i=0;i<nsops;i++)
{
/* For each sem in the pool, check the operation to perform */
if (sops[i].sem_op < 0)
{
/* Try acuiring the semaphore till we are not inteerupted by a signal */
while (acquire_sem_etc(Address[sops[i].sem_num+1],-sops[i].sem_op,0,0)==B_INTERRUPTED);
}
if (sops[i].sem_op > 0)
{
release_sem_etc(Address[sops[i].sem_num+1],sops[i].sem_op,0);
}
}
return 0;
}
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