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/* Default shared memory segment size. Each segment is the *
* same size. Maximum size is system-dependent (SHMMAX). */
#define SHM_SEGMENT_SIZE 65536
/* Maximum value of a semaphore. This is system-dependent (SEMVMX). */
#define MAX_SEM 32766
/* Lock constants used internally by us. They happen to be the same *
* as for flock(), but that's purely coincidental */
#ifndef LOCK_SH
#define LOCK_SH 1
#endif
#ifndef LOCK_EX
#define LOCK_EX 2
#endif
#ifndef LOCK_NB
#define LOCK_NB 4
#endif
#ifndef LOCK_UN
#define LOCK_UN 8
#endif
/* Structure at the top of every shared memory segment. *
* next_shmid is used to construct a linked-list of *
* segments. length is unused, except for the first *
* segment. */
typedef struct {
key_t next_shmid;
int length;
unsigned int shm_state;
unsigned int version;
} Header;
/* Structure for the per-process segment list. This list *
* is similar to the shared memory linked-list, but contains *
* the actual shared memory addresses returned from the *
* shmat() calls. Since the addresses are mapped into each *
* process's data segment, we cannot make them global. *
* This linked-list may be shorter than the shared memory *
* linked-list -- nodes are added on to this list on an *
* as-needed basis */
typedef struct node {
int shmid;
Header *shmaddr;
struct node *next;
} Node;
/* The primary structure for this library. We pass this back *
* and forth to perl */
typedef struct {
key_t key;
key_t next_key;
int segment_size;
int data_size;
int flags;
int semid;
short lock;
Node *head;
Node *tail;
unsigned int shm_state;
unsigned int version;
} Share;
/* prototypes */
Share *new_share( key_t key, int segment_size, int flags );
int write_share( Share * share, char *data, int length );
int read_share( Share * share, char **data );
int destroy_share( Share * share, int rmid );
int sharelite_lock( Share * share, int flags );
int sharelite_unlock( Share * share );
int sharelite_num_segments( Share * share );
unsigned int sharelite_version( Share * share );