ex16_1.c

linux 高级编程的例子源码,包括了本书上的所有代码

/*filename:ex16_1.c*/
#include <utmp.h>
#include <rpc/xdr.h>
#include <rpc/types.h>
#include "ourhead.h"
void usage(char  *name)
{
   printf("Usage: %s outfilename\n",name);
   exit(1);
}
int main(int argc,char **argv)
{
   FILE  *fp;
   XDR  xh;
   struct  utmp  *up;
   int  err=0;
  
   if (argc!=2)
     usage(argv[0]);

   if (utmpname("/var/run/utmp")!=0)
   {
      printf("utmpname error:%s\n",strerror(errno));
	  exit(1);
   }
   if ((fp=fopen(argv[1],"w"))==NULL)
   {
       printf("error: cannot open file %s\n",argv[1]);
	   exit(1);
   }
   xdrstdio_create(&xh,fp,XDR_ENCODE);
   
   while((up=getutent())!=NULL)
   {
      if (xdr_vector(&xh,up->ut_user,sizeof(up->ut_user),sizeof(char),(xdrproc_t)xdr_char)==FALSE)
      {
         err=1;
         break;
      }
      if (xdr_vector(&xh,up->ut_id,sizeof(up->ut_id),sizeof(char),(xdrproc_t)xdr_char)==FALSE)
      {
         err=2;
         break;
      }
      if (xdr_vector(&xh,up->ut_line,sizeof(up->ut_line),sizeof(char),(xdrproc_t)xdr_char)==FALSE)
      {
         err=3;
         break;
      }
      if (xdr_vector(&xh,up->ut_line,sizeof(up->ut_line),sizeof(char),(xdrproc_t)xdr_char)==FALSE)
      {
         err=3;
         break;
      }
      if (xdr_short(&xh,&up->ut_pid)==FALSE)
      {
         err=4;
         break;
      }
      if (xdr_short(&xh,&up->ut_type)==FALSE)
      {
         err=5;
         break;
      }
      if (xdr_short(&xh,&up->ut_exit.e_termination)==FALSE)
      {
         err=6;
         break;
      }
      if (xdr_short(&xh,&up->ut_exit.e_exit)==FALSE)
      {
         err=7;
         break;
      }
      if (xdr_long(&xh,&up->ut_time)==FALSE)
      {
         err=8;
         break;
      }

   }
    
   if (err)
   {
      printf("error  %d: XDR converting data\n",err);
	  exit(1);
   }
   exit(0);
}