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/*-------------------------------------------------------------------------
*
* shm.c
* System V Shared Memory Emulation
*
* Copyright (c) 1999, repas AEG Automation GmbH
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/port/qnx/Attic/shm.c,v 1.1 1999/12/16 01:25:06 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/shm.h>
#define MODE 0777
#define SHMMAX 1024
struct shm_info {
int shmid;
key_t key;
size_t size;
void *addr;
};
static struct shm_info *ShmInfo;
static int shm_putinfo( struct shm_info *info );
static int shm_updinfo( int i, struct shm_info *info );
static int shm_getinfo( int shmid, struct shm_info *info );
static int shm_getinfobyaddr( const void *addr, struct shm_info *info );
static int shm_putinfo( struct shm_info *info )
{
int i;
if( ShmInfo == NULL ) {
ShmInfo = calloc( SHMMAX, sizeof( struct shm_info ) );
if( ShmInfo == NULL ) return -1;
/* initialize ShmInfo */
for( i = 0; i < SHMMAX; i++ ) {
ShmInfo[i].shmid = -1;
}
}
/* search first free element */
i = 0;
while( i < SHMMAX && ShmInfo[i].shmid != -1 ) i++;
if( i >= SHMMAX ) {
errno = ENOSPC;
return -1;
}
memcpy( &ShmInfo[i], info, sizeof( struct shm_info ) );
return i;
}
static int shm_updinfo( int i, struct shm_info *info )
{
if( i >= SHMMAX ) return -1;
if( ShmInfo == NULL ) return -1;
memcpy( &ShmInfo[i], info, sizeof( struct shm_info ) );
return i;
}
static int shm_getinfo( int shmid, struct shm_info *info )
{
int i;
if( ShmInfo == NULL ) return -1;
/* search element */
i = 0;
while( i < SHMMAX && ShmInfo[i].shmid != shmid ) i++;
if( i >= SHMMAX ) return -1;
memcpy( info, &ShmInfo[i], sizeof( struct shm_info ) );
return i;
}
static int shm_getinfobyaddr( const void *addr, struct shm_info *info )
{
int i;
if( ShmInfo == ( struct shm_info * )-1 ) return -1;
/* search element */
i = 0;
while( i < SHMMAX && ShmInfo[i].addr != addr ) i++;
if( i >= SHMMAX ) return -1;
memcpy( info, &ShmInfo[i], sizeof( struct shm_info ) );
return i;
}
void *shmat( int shmid, const void *shmaddr, int shmflg )
{
struct shm_info info;
int i;
i = shm_getinfo( shmid, &info );
if( i == -1 ) {
errno = EACCES;
return ( void * )-1;
}
info.addr = mmap( ( void * )shmaddr, info.size,
PROT_READ | PROT_WRITE, MAP_SHARED, shmid, 0 );
if( info.addr == MAP_FAILED ) return info.addr;
if( shm_updinfo( i, &info ) == -1 ) {
errno = EACCES;
return ( void * )-1;
}
return info.addr;
}
int shmdt( const void *addr )
{
struct shm_info info;
if( shm_getinfobyaddr( addr, &info ) == -1 ) {
errno = EACCES;
return -1;
}
return munmap( ( void * )addr, info.size );
}
int shmctl( int shmid, int cmd, struct shmid_ds *buf )
{
struct shm_info info;
char name[NAME_MAX+1];
/* IPC_RMID supported only */
if( cmd != IPC_RMID ) {
errno = EINVAL;
return -1;
}
if( shm_getinfo( shmid, &info ) == -1 ) {
errno = EACCES;
return -1;
}
return shm_unlink( itoa( info.key, name, 16 ) );
}
int shmget( key_t key, size_t size, int flags )
{
char name[NAME_MAX+1];
int oflag = 0;
struct shm_info info;
if( flags & IPC_CREAT ) oflag |= O_CREAT;
if( flags & IPC_EXCL ) oflag |= O_EXCL;
if( flags & SHM_R ) {
if( flags & SHM_W ) oflag |= O_RDWR;
else oflag |= O_RDONLY;
}
info.shmid = shm_open( itoa( key, name, 16 ), oflag, MODE );
/* store shared memory information */
if( info.shmid != -1 ) {
info.key = key;
info.size = size;
info.addr = NULL;
if( shm_putinfo( &info ) == -1 ) return -1;
}
/* The size may only be set once. Ignore errors. */
ltrunc( info.shmid, size, SEEK_SET );
return info.shmid;
}
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