drvrsmem.h

#ifndef drvrsmem_h
#define drvrsmem_h
/*      S H A R E D   M E M O R Y   D R I V E R
        =======================================

          by Jerzy.Borkowski@obs.unige.ch

09-Mar-98 : initial version 1.0 released
23-Mar-98 : shared_malloc now accepts new handle as an argument
*/


#include <sys/ipc.h>        /* this is necessary for Solaris/Linux */
#include <sys/shm.h>
#include <sys/sem.h>

#ifdef _AIX
#include <fcntl.h>
#else
#include <sys/fcntl.h>
#endif

        /* configuration parameters */

#define SHARED_MAXSEG   (16)        /* maximum number of shared memory blocks */

#define SHARED_KEYBASE  (14011963)  /* base for shared memory keys, may be overriden by getenv */
#define SHARED_FDNAME   ("/tmp/.shmem-lockfile") /* template for lock file name */

#define SHARED_ENV_KEYBASE ("SHMEM_LIB_KEYBASE") /* name of environment variable */
#define SHARED_ENV_MAXSEG ("SHMEM_LIB_MAXSEG")  /* name of environment variable */

        /* useful constants */

#define SHARED_RDONLY   (0)     /* flag for shared_(un)lock, lock for read */
#define SHARED_RDWRITE  (1)     /* flag for shared_(un)lock, lock for write */
#define SHARED_WAIT (0)     /* flag for shared_lock, block if cannot lock immediate */
#define SHARED_NOWAIT   (2)     /* flag for shared_lock, fail if cannot lock immediate */
#define SHARED_NOLOCK   (0x100)     /* flag for shared_validate function */

#define SHARED_RESIZE   (4)     /* flag for shared_malloc, object is resizeable */
#define SHARED_PERSIST  (8)     /* flag for shared_malloc, object is not deleted after last proc detaches */

#define SHARED_INVALID  (-1)        /* invalid handle for semaphore/shared memory */

#define SHARED_EMPTY    (0)     /* entries for shared_used table */
#define SHARED_USED (1)

#define SHARED_GRANUL   (16384)     /* granularity of shared_malloc allocation = phys page size, system dependent */



        /* checkpoints in shared memory segments - might be omitted */

#define SHARED_ID_0 ('J')       /* first byte of identifier in BLKHEAD */
#define SHARED_ID_1 ('B')       /* second byte of identifier in BLKHEAD */

#define BLOCK_REG   (0)     /* value for tflag member of BLKHEAD */
#define BLOCK_SHARED    (1)     /* value for tflag member of BLKHEAD */

        /* generic error codes */

#define SHARED_OK   (0)

#define SHARED_ERR_MIN_IDX  SHARED_BADARG
#define SHARED_ERR_MAX_IDX  SHARED_NORESIZE


#define DAL_SHM_FREE    (0)
#define DAL_SHM_USED    (1)

#define DAL_SHM_ID0 ('D')
#define DAL_SHM_ID1 ('S')
#define DAL_SHM_ID2 ('M')

#define DAL_SHM_SEGHEAD_ID  (0x19630114)



        /* data types */

/* BLKHEAD object is placed at the beginning of every memory segment (both
  shared and regular) to allow automatic recognition of segments type */

typedef union
      { struct BLKHEADstruct
          { char    ID[2];      /* ID = 'JB', just as a checkpoint */
        char    tflag;      /* is it shared memory or regular one ? */
        int handle;     /* this is not necessary, used only for non-resizeable objects via ptr */
          } s;
    double  d;          /* for proper alignment on every machine */
      } BLKHEAD;

typedef void *SHARED_P;         /* generic type of shared memory pointer */

typedef struct SHARED_GTABstruct    /* data type used in global table */
      { int sem;            /* access semaphore (1 field): process count */
    int semkey;         /* key value used to generate semaphore handle */
    int key;            /* key value used to generate shared memory handle (realloc changes it) */
    int handle;         /* handle of shared memory segment */
    int size;           /* size of shared memory segment */
    int nprocdebug;     /* attached proc counter, helps remove zombie segments */
    char    attr;           /* attributes of shared memory object */
      } SHARED_GTAB;

typedef struct SHARED_LTABstruct    /* data type used in local table */
      { BLKHEAD *p;         /* pointer to segment (may be null) */
    int tcnt;           /* number of threads in this process attached to segment */
    int lkcnt;          /* >=0 <- number of read locks, -1 - write lock */
    long    seekpos;        /* current pointer position, read/write/seek operations change it */
      } SHARED_LTAB;


    /* system dependent definitions */

#ifndef HAVE_FLOCK_T
typedef struct flock flock_t;
#define HAVE_FLOCK_T
#endif

#ifndef HAVE_UNION_SEMUN
union semun
      { int val;
    struct semid_ds *buf;
    unsigned short *array;
      };
#define HAVE_UNION_SEMUN
#endif


typedef struct DAL_SHM_SEGHEAD_STRUCT   DAL_SHM_SEGHEAD;

struct DAL_SHM_SEGHEAD_STRUCT
      { int ID;         /* ID for debugging */
    int h;          /* handle of sh. mem */
    int size;           /* size of data area */
    int nodeidx;        /* offset of root object (node struct typically) */
      };

        /* API routines */

#ifdef __cplusplus
extern "C" {
#endif

void    shared_cleanup(void);           /* must be called at exit/abort */
int shared_init(int debug_msgs);        /* must be called before any other shared memory routine */
int shared_recover(int id);         /* try to recover dormant segment(s) after applic crash */
int shared_malloc(long size, int mode, int newhandle);  /* allocate n-bytes of shared memory */
int shared_attach(int idx);         /* attach to segment given index to table */
int shared_free(int idx);           /* release shared memory */
SHARED_P shared_lock(int idx, int mode);    /* lock segment for reading */
SHARED_P shared_realloc(int idx, long newsize); /* reallocate n-bytes of shared memory (ON LOCKED SEGMENT ONLY) */
int shared_size(int idx);           /* get size of attached shared memory segment (ON LOCKED SEGMENT ONLY) */
int shared_attr(int idx);           /* get attributes of attached shared memory segment (ON LOCKED SEGMENT ONLY) */
int shared_set_attr(int idx, int newattr);  /* set attributes of attached shared memory segment (ON LOCKED SEGMENT ONLY) */
int shared_unlock(int idx);         /* unlock segment (ON LOCKED SEGMENT ONLY) */
int shared_set_debug(int debug_msgs);   /* set/reset debug mode */
int shared_set_createmode(int mode);    /* set/reset debug mode */
int shared_list(int id);            /* list segment(s) */
int shared_uncond_delete(int id);       /* uncondintionally delete (NOWAIT operation) segment(s) */

int smem_init(void);
int smem_shutdown(void);
int smem_setoptions(int options);
int smem_getoptions(int *options);
int smem_getversion(int *version);
int smem_open(char *filename, int rwmode, int *driverhandle);
int smem_create(char *filename, int *driverhandle);
int smem_close(int driverhandle);
int smem_remove(char *filename);
int smem_size(int driverhandle, OFF_T *size);
int smem_flush(int driverhandle);
int smem_seek(int driverhandle, OFF_T offset);
int smem_read(int driverhandle, void *buffer, long nbytes);
int smem_write(int driverhandle, void *buffer, long nbytes);

#ifdef __cplusplus
}
#endif
#endif