queue.c

封装了ipc操作的常用功能

#include    <sys/types.h>
#include    <sys/ipc.h>
#include    <sys/msg.h>
#include    <stdio.h>
#include    <stdlib.h>
#include    <string.h>
#include    <ctype.h>
#include    <memory.h>
#include    <time.h>

int QueueCreate( key_t k )
{
  if( msgget( k, IPC_EXCL | IPC_NOWAIT ) < 0
      && msgget( k, IPC_CREAT | IPC_NOWAIT | 0666 ) < 0 )
    return( -1 );
  return( 0 );
}

void QueueDelete( key_t k )
{
  int r;

  if( ( r = msgget( k, IPC_EXCL | IPC_NOWAIT ) ) >= 0 )
    msgctl( r, IPC_RMID, 0 );
}

int QueueCount( key_t k )
{
  int r;
  struct msqid_ds s;

  if( ( r = msgget( k, IPC_EXCL | IPC_NOWAIT ) ) >= 0
      && msgctl( r, IPC_STAT, &s ) == 0 )
    return( s.msg_qnum );
  return( -1 );
}

int QueueWrite( key_t k, long t, void *d, int s, int w )
{
  int r;
  char *p;

  if( ( r = msgget( k, IPC_EXCL | IPC_NOWAIT ) ) >= 0
      && ( p = ( char * ) malloc( s + sizeof( long ) + 4 ) ) != NULL ){
    memcpy( p, &t, sizeof( long ) );
    memcpy( p + sizeof( long ), d, s );
    r = msgsnd( r, p, s + sizeof( long ), ( w == 0 ) ? IPC_NOWAIT : 0 );
    free( p );
    if( r == 0 )
      return( 0 );
  }
  return( -1 );
}

int QueueRead( key_t k, long *t, void *d, int s, int w )
{
  int r;
  char *p;

  if( ( r = msgget( k, IPC_EXCL | IPC_NOWAIT ) ) >= 0
      && ( p = ( char * ) malloc( s + sizeof( long ) + 4 ) ) != NULL ){
    r = msgrcv( r, p, s + sizeof( long ), *t, ( w == 0 ) ? IPC_NOWAIT : 0 );
    if( r >= 0 ){
      r -= sizeof( long );
      memcpy( t, p, sizeof( long ) );
      memcpy( d, p + sizeof( long ), s );
    }
    free( p );
    return( r );
  }
  return( -1 );
}