shm.c

封装了ipc操作的常用功能

#include    <sys/types.h>
#include    <sys/ipc.h>
#include    <sys/shm.h>
#include    <stdio.h>
#include    <string.h>
#include    <ctype.h>

int ShmCreate( key_t k, int s )
{
  int r;
  struct shmid_ds shm_stat;

  if( ( r = shmget( k, s, IPC_CREAT | IPC_NOWAIT | 0666 ) ) >= 0 ){
    if( shmctl( r, IPC_STAT, &shm_stat ) == 0 && shm_stat.shm_segsz >= s )
      return( 0 );
    shmctl( r, IPC_RMID, 0 );
  }
  return( -1 );
}

void ShmDelete( key_t k )
{
  int r;

  if( ( r = shmget( k, 0, IPC_EXCL | IPC_NOWAIT ) ) >= 0 )
    shmctl( r, IPC_RMID, 0 );
}

void *ShmAttach( key_t k )
{
  int r;
  void *p;

  if( ( r = shmget( k, 0, IPC_EXCL | IPC_NOWAIT ) ) >= 0
      && ( p = shmat( r, 0, 0 ) ) != NULL )
    return( p );
  return( NULL );
}

void ShmDetach( void *p )
{
  if( p )
    shmdt( p );
}