sem.c

封装了ipc操作的常用功能

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>

int SemCreate( key_t k, int v )
{
  int r;

  if( ( r = semget( k, 1, IPC_CREAT | IPC_NOWAIT | 0666 ) ) >= 0 ){
    if( semctl( r, 0, SETVAL, v ) == 0 )
      return( 0 );
    semctl( r, IPC_RMID | IPC_NOWAIT, 0 );
  }
  return( -1 );
}

void SemDelete( key_t k )
{
  int r;

  if( ( r = semget( k, 1, IPC_EXCL | IPC_NOWAIT | 0666 ) ) >= 0 )
    semctl( r, IPC_RMID | IPC_NOWAIT, 0 );
}

int SemOperate( key_t k, int v, int w )
{
  int r;
  struct sembuf p = { 0, 0, SEM_UNDO };

  if( w )
    p.sem_flg |= 0;
  else
    p.sem_flg |= IPC_NOWAIT;
  p.sem_op = v;
  if( ( r = semget( k, 1, IPC_EXCL | IPC_NOWAIT | 0666 ) ) >= 0
      && semop( r, &p, 1 ) == 0 )
    return( 0 );
  return( -1 );
}

int SemInfo( key_t k, int *v, int *p, int *n, int *z )
{
  int r;

  if( ( r = semget( k, 1, IPC_EXCL | IPC_NOWAIT | 0666 ) ) >= 0 )
  {
    *v=semctl( r, 0, GETVAL,  0 );
    *p=semctl( r, 0, GETPID,  0 );
    *n=semctl( r, 0, GETNCNT, 0 );
    *z=semctl( r, 0, GETZCNT, 0 );
    return(0);
  }
  return(-1);
}