trdwr.c

采用Fork方式的

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/times.h>
#include <sys/select.h>
#include <signal.h>

static int TimeOut;
static int RestTime;
static void ( *OldAlarm )();

static void SetAlarm( int Seconds )
{
  void SetTimeOut();

  TimeOut = 0;
  OldAlarm = signal( SIGALRM, SetTimeOut );
  RestTime = alarm( Seconds );
}

static void ResetAlarm()
{
  alarm( RestTime );
  signal( SIGALRM, OldAlarm );
}

static void SetTimeOut()
{
  ResetAlarm();
  TimeOut = 1;
}

static int TimedIO( int (*IO)(), int Seconds, int Handle, char *Data, int Size )
{
  int l, s;
  fd_set f;
  struct timeval t;

  FD_ZERO( &f );
  FD_SET( Handle, &f );
  t.tv_sec = 0;
  t.tv_usec = 1;
  if( Seconds > 0 )
    SetAlarm( Seconds );
  s = 0;
  while( Size > 0 ){
    if( Seconds > 0 )
      if( TimeOut )
        break;
    if( Seconds != 0 )
      select( 0, &f, 0, 0, &t );
    l = ( *IO )( Handle, Data, Size );
    if( l <= 0 )
      break;
    s += l;
    if( Seconds == 0 )
      break;
    Size -= l;
    Data += l;
  }
  if( Seconds > 0 && !TimeOut )
    ResetAlarm();
  if( s == 0 && l <= 0 && ( Seconds <= 0 || !TimeOut ) )
    return( -1 );
  return( s );
}

int TimedRead( int Seconds, int Handle, char *Data, int Size )
{
  return( TimedIO( read, Seconds, Handle, Data, Size ) );
}

int TimedWrite( int Seconds, int Handle, char *Data, int Size )
{
  return( TimedIO( write, Seconds, Handle, Data, Size ) );
}