Sweden-Number/ipc/shm_block.c

194 lines
5.3 KiB
C

/***************************************************************************
* Copyright 1995, Technion, Israel Institute of Technology
* Electrical Eng, Software Lab.
* Author: Michael Veksler.
***************************************************************************
* File: shm_block.c
* Purpose: Treat a shared memory block.
***************************************************************************
*/
#ifdef CONFIG_IPC
#define inline __inline__
#include <sys/types.h>
#include <sys/sem.h>
#include <assert.h>
#include <unistd.h>
#include <stdlib.h>
#include "debug.h"
#include "global.h"
#include "selectors.h"
#include "shm_fragment.h"
#include "shm_block.h"
#include "shm_semaph.h"
#include "dde_proc.h"
#include "xmalloc.h"
/* How each shmid is maped to local pointer */
/* Only attached shm blocks are in this construct */
struct local_shm_map *shm_map=NULL;
/* setup a new shm block (construct a shm block object).
* block: The pointer to the memory block (local mapping)
* first: The first data byte (excluding header stuff),
* if 0 (zero) Use the default.
* size: The size of the memory block.
*/
void shm_setup_block(struct shm_block *block, int first, int size)
{
TRACE(shm,"Setting up shm block at 0x%08x\n",(int )block);
/* setup block internal data structure */
if (first <= 0) {
first=sizeof(*block);
/* round up - so everything starts on cache line boundary
* (assume cache line=32 bytes, may be bigger/smaller for
* different processors and different L2 caches .)
*/
first=(first+0x1f) & ~0x1f;
}
block->free=size-first;
block->next_shm_id=-1; /* IPC shm ID (for initial linking) */
block->proc_idx= curr_proc_idx;
/* block->size is initialized in shm_FragmentInit */
shm_FragmentInit(block, first, size); /* first item in the free list */
TRACE(shm, "block was set up at 0x%08x, size=0x%04xKB, 1st usable=%02x\n",
(int )block,size/1024,first);
}
/* shm_attach_block: attach existing shm block, setup selectors
* shm_id - id of the block to attach.
* proc_idx - if not -1, puts this data into local mapping
* map - localy mapped info about this block.
*/
/* NOTE: there is no check if this block is already attached.
* Attaching the same block more than once - is possible
* In case of doubt use shm_locate_block.
*/
struct shm_block *shm_attach_block(int shm_id, int proc_idx,
struct local_shm_map *map)
{
struct shm_block *block;
struct shmid_ds ds;
struct local_shm_map *this;
shmctl(shm_id, IPC_STAT, &ds );
block=(struct shm_block*)shmat(shm_id, NULL, 0);
if (block==NULL || block == (struct shm_block*) -1) return NULL;
this=(struct local_shm_map *)xmalloc(sizeof(*this));
this->next= shm_map;
shm_map = this;
this->shm_id= shm_id;
this->ptr = block;
if (proc_idx < 0)
this->proc_idx=block->proc_idx;
else
this->proc_idx=proc_idx;
if (map != NULL) {
memcpy(map, this, sizeof(map));
map->next= NULL; /* don't pass private info */
}
return block;
}
struct shm_block *shm_create_block(int first, int size, int *shm_id)
{
struct shm_block *block;
if (size==0)
size=SHM_MINBLOCK;
else
/* round up size to a multiple of SHM_MINBLOCK */
size= (size+SHM_MINBLOCK-1) & ~(SHM_MINBLOCK-1);
*shm_id= shmget ( IPC_PRIVATE, size ,0700);
if (*shm_id==-1)
return NULL;
block=shm_attach_block(*shm_id, curr_proc_idx, NULL);
if (block!=NULL)
shm_setup_block(block, first, size);
return block;
}
/*
** Locate attached block. (return it, or NULL on failure)
** shm_id is the block we look for.
** *map - will get all the info related to this local map + proc_idx
** (may be NULL)
** *seg - will get the segment this block is attached to.
*/
struct shm_block *shm_locate_attached_block(int shm_id,
struct local_shm_map *map)
{
struct local_shm_map *curr;
for (curr= shm_map ; curr != NULL ; curr= curr->next) {
if (curr->shm_id == shm_id) {
if (map) {
memcpy(map, curr, sizeof(*curr) );
map->next = NULL; /* this is private info ! */
}
return curr->ptr;
}
}
/* block not found ! */
return 0;
}
/* shm_locate_block: see shm_attach_block.
In addition to shm_attach_block, make sure this
block is not already attached.
*/
struct shm_block *shm_locate_block(int shm_id, struct local_shm_map *map)
{
struct shm_block *ret;
ret= shm_locate_attached_block(shm_id, map);
if (ret!=NULL)
return ret;
/* block not found ! , try to attach */
return shm_attach_block(shm_id, -1, map);
}
static void forget_attached(int shmid)
{
struct local_shm_map *curr, **point_to_curr;
for (curr= shm_map, point_to_curr= &shm_map ;
curr != NULL ;
curr= curr->next, point_to_curr= &curr->next ) {
if (curr->shm_id == shmid) {
*point_to_curr= curr->next;
return;
}
}
}
/* delete chain of shm blocks (pointing to each other)
* Do it in reverse order. (This is what the recursion is for)
*/
void shm_delete_chain(int *shmid)
{
struct shm_block *block;
if (*shmid == -1)
return;
block= shm_locate_block(*shmid, NULL);
forget_attached( *shmid );
if (block == NULL)
return;
shm_delete_chain(&block->next_shm_id);
shmctl(*shmid, IPC_RMID, NULL);
*shmid=-1;
shmdt((char *)block);
}
#endif /* CONFIG_IPC */