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/* S H A R E D M E M O R Y D R I V E R
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=======================================
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by Jerzy.Borkowski@obs.unige.ch
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09-Mar-98 : initial version 1.0 released
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23-Mar-98 : shared_malloc now accepts new handle as an argument
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#include <sys/ipc.h> /* this is necessary for Solaris/Linux */
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#include <sys/fcntl.h>
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/* configuration parameters */
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#define SHARED_MAXSEG (16) /* maximum number of shared memory blocks */
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#define SHARED_KEYBASE (14011963) /* base for shared memory keys, may be overriden by getenv */
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#define SHARED_FDNAME ("/tmp/.shmem-lockfile") /* template for lock file name */
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#define SHARED_ENV_KEYBASE ("SHMEM_LIB_KEYBASE") /* name of environment variable */
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#define SHARED_ENV_MAXSEG ("SHMEM_LIB_MAXSEG") /* name of environment variable */
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/* useful constants */
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#define SHARED_RDONLY (0) /* flag for shared_(un)lock, lock for read */
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#define SHARED_RDWRITE (1) /* flag for shared_(un)lock, lock for write */
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#define SHARED_WAIT (0) /* flag for shared_lock, block if cannot lock immediate */
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#define SHARED_NOWAIT (2) /* flag for shared_lock, fail if cannot lock immediate */
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#define SHARED_NOLOCK (0x100) /* flag for shared_validate function */
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#define SHARED_RESIZE (4) /* flag for shared_malloc, object is resizeable */
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#define SHARED_PERSIST (8) /* flag for shared_malloc, object is not deleted after last proc detaches */
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#define SHARED_INVALID (-1) /* invalid handle for semaphore/shared memory */
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#define SHARED_EMPTY (0) /* entries for shared_used table */
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#define SHARED_USED (1)
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#define SHARED_GRANUL (16384) /* granularity of shared_malloc allocation = phys page size, system dependent */
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/* checkpoints in shared memory segments - might be omitted */
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#define SHARED_ID_0 ('J') /* first byte of identifier in BLKHEAD */
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#define SHARED_ID_1 ('B') /* second byte of identifier in BLKHEAD */
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#define BLOCK_REG (0) /* value for tflag member of BLKHEAD */
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#define BLOCK_SHARED (1) /* value for tflag member of BLKHEAD */
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/* generic error codes */
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#define SHARED_ERR_MIN_IDX SHARED_BADARG
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#define SHARED_ERR_MAX_IDX SHARED_NORESIZE
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#define DAL_SHM_FREE (0)
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#define DAL_SHM_USED (1)
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#define DAL_SHM_ID0 ('D')
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#define DAL_SHM_ID1 ('S')
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#define DAL_SHM_ID2 ('M')
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#define DAL_SHM_SEGHEAD_ID (0x19630114)
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/* BLKHEAD object is placed at the beginning of every memory segment (both
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shared and regular) to allow automatic recognition of segments type */
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{ struct BLKHEADstruct
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{ char ID[2]; /* ID = 'JB', just as a checkpoint */
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char tflag; /* is it shared memory or regular one ? */
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int handle; /* this is not necessary, used only for non-resizeable objects via ptr */
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double d; /* for proper alignment on every machine */
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typedef void *SHARED_P; /* generic type of shared memory pointer */
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typedef struct SHARED_GTABstruct /* data type used in global table */
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{ int sem; /* access semaphore (1 field): process count */
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int semkey; /* key value used to generate semaphore handle */
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int key; /* key value used to generate shared memory handle (realloc changes it) */
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int handle; /* handle of shared memory segment */
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int size; /* size of shared memory segment */
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int nprocdebug; /* attached proc counter, helps remove zombie segments */
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char attr; /* attributes of shared memory object */
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typedef struct SHARED_LTABstruct /* data type used in local table */
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{ BLKHEAD *p; /* pointer to segment (may be null) */
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int tcnt; /* number of threads in this process attached to segment */
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int lkcnt; /* >=0 <- number of read locks, -1 - write lock */
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long seekpos; /* current pointer position, read/write/seek operations change it */
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/* system dependent definitions */
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typedef struct flock flock_t;
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#ifndef HAVE_UNION_SEMUN
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struct semid_ds *buf;
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unsigned short *array;
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#define HAVE_UNION_SEMUN
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typedef struct DAL_SHM_SEGHEAD_STRUCT DAL_SHM_SEGHEAD;
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struct DAL_SHM_SEGHEAD_STRUCT
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{ int ID; /* ID for debugging */
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int h; /* handle of sh. mem */
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int size; /* size of data area */
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int nodeidx; /* offset of root object (node struct typically) */
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void shared_cleanup(void); /* must be called at exit/abort */
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int shared_init(int debug_msgs); /* must be called before any other shared memory routine */
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int shared_recover(int id); /* try to recover dormant segment(s) after applic crash */
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int shared_malloc(long size, int mode, int newhandle); /* allocate n-bytes of shared memory */
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int shared_attach(int idx); /* attach to segment given index to table */
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int shared_free(int idx); /* release shared memory */
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SHARED_P shared_lock(int idx, int mode); /* lock segment for reading */
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SHARED_P shared_realloc(int idx, long newsize); /* reallocate n-bytes of shared memory (ON LOCKED SEGMENT ONLY) */
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int shared_size(int idx); /* get size of attached shared memory segment (ON LOCKED SEGMENT ONLY) */
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int shared_attr(int idx); /* get attributes of attached shared memory segment (ON LOCKED SEGMENT ONLY) */
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int shared_set_attr(int idx, int newattr); /* set attributes of attached shared memory segment (ON LOCKED SEGMENT ONLY) */
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int shared_unlock(int idx); /* unlock segment (ON LOCKED SEGMENT ONLY) */
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int shared_set_debug(int debug_msgs); /* set/reset debug mode */
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int shared_set_createmode(int mode); /* set/reset debug mode */
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int shared_list(int id); /* list segment(s) */
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int shared_uncond_delete(int id); /* uncondintionally delete (NOWAIT operation) segment(s) */
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int smem_shutdown(void);
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int smem_setoptions(int options);
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int smem_getoptions(int *options);
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int smem_getversion(int *version);
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int smem_open(char *filename, int rwmode, int *driverhandle);
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int smem_create(char *filename, int *driverhandle);
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int smem_close(int driverhandle);
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int smem_remove(char *filename);
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int smem_size(int driverhandle, OFF_T *size);
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int smem_flush(int driverhandle);
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int smem_seek(int driverhandle, OFF_T offset);
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int smem_read(int driverhandle, void *buffer, long nbytes);
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int smem_write(int driverhandle, void *buffer, long nbytes);
added
removed
drvrsmem.h
