进程间传送句柄

               进程间传送句柄

  不同进程间传送句柄是通过sendmsg和recvmsg函数发送和接收msghdr结构的辅助数据实现的.

  struct msghdr

       {

         void           *msg_name;

         socklen_t      msg_namelen;

         struct iovec   *msg_iov;

         int            msg_iovlen;

         viod           *msg_control;

         socklen_t      msg_controllen;

         int            msg_flags;

       }

   struct iovec

      {

         void          *iov_base;

         size_t        iov_len;

      }

   struct cmsghdr

      {

         socklen_t      cmsg_len;

         int            cmsg_level;

         int            cmsg_type;

         /* data存放数据,数据的多少由用户决定   */

      }

 例子:

 服务器端:

#include
#include
#include
#include
#include
#include
#define filename "/home/huang/temp.unix"
int main()
{
  int s;
  int client_s;
  struct sockaddr_un  addr;
  struct sockaddr_un  client_addr;
  int len=sizeof(client_addr);
  char buff[100];
  int recv_num=0;
  int n;
  int file;
  struct msghdr msg;
  struct iovec iov;
  struct cmsghdr cm;
  struct cmsghdr *cmsghdrptr;
  union
   {
           struct cmsghdr cm;
           char data[CMSG_SPACE(sizeof(int))];
   }control_msg;
                                                                                                                                              
   bzero(buff,sizeof(buff));
   iov.iov_base=buff;
   iov.iov_len=sizeof(buff);
                                                                                                                                              
   msg.msg_name=NULL;
   msg.msg_namelen=0;
   msg.msg_iov=&iov;
   msg.msg_iovlen=1;
   msg.msg_control=control_msg.data;
   msg.msg_controllen=CMSG_SPACE(sizeof(int));
   msg.msg_flags=0;

   bzero(buff,sizeof(buff));

  s=socket(AF_UNIX,SOCK_STREAM,0);
  if(s<0)
       {
               printf("create socket fail\n");
               exit(0);
       }
  unlink(filename);
  bzero(&addr,sizeof(addr));
  addr.sun_family=AF_UNIX;
  strcpy(addr.sun_path,filename);
  if(-1==bind(s,(struct sockaddr *)&addr,sizeof(addr)))
       {
               printf("bind socket fail\n");
               exit(0);
       }
  chmod(filename,0777);
  if(-1==listen(s,5))
       {
               printf("create listen socket fail!\n");
               exit(0);
       }
  client_s=accept(s,(struct sockaddr *)&client_addr,&len);
                                                                                                                                              
  recv_num=recvmsg(client_s,&msg,0);
  if(recv_num==-1)
          {
            printf("recvmsg fail and the errno=%d\n",errno);
            exit(0);
          }
                                                                                                                                              
  if((cmsghdrptr=CMSG_FIRSTHDR(&msg))!=NULL&&cmsghdrptr->cmsg_len==CMSG_LEN(sizeof(int)))
        {
         if(cmsghdrptr->cmsg_level!=SOL_SOCKET||cmsghdrptr->cmsg_type!=SCM_RIGHTS)
               {
                       printf("paramter error!\n");
                       exit(0);
               }
         file=*((int *)CMSG_DATA(cmsghdrptr));
             }
  write(file,(char *)msg.msg_iov->iov_base,recv_num);
  close(file);
  close(client_s);
  close(s);
  unlink(filename);
  return 1;
 }

 

客户端:

include
#include
#include
 #include
 #include
 #include
 #include
 #include
#define filename "/home/huang/temp.unix"
 int main()
 {
   int s;
   int client_s;
   struct sockaddr_un  addr;
   char buff[100];
   char ser_buff[15]="to the service";
   int n;
   int file;
   struct msghdr msg;
   struct iovec iov;
   struct cmsghdr cm;
   int number;
   union
   {
           struct cmsghdr cm;
           char data[CMSG_SPACE(sizeof(int))];
   }control_msg;
                                                                                                                                              
   struct cmsghdr *p;
                                                                                                                                              
   iov.iov_base=ser_buff;
   iov.iov_len=strlen(ser_buff);
   printf("%d\n",iov.iov_len);
                                                                                                                                              
   file=open("/home/huang/text.file",O_RDWR|O_CREAT);
   printf("%s\n",ser_buff);
   msg.msg_name=NULL;
   msg.msg_namelen=0;
   msg.msg_iov=&iov;
   msg.msg_iovlen=1;

   msg.msg_control=control_msg.data;
   msg.msg_controllen=CMSG_SPACE(sizeof(int));
   msg.msg_flags=0;
                                                                                                                                              
   p=CMSG_FIRSTHDR(&msg);
                                                                                                                                              
   p->cmsg_len=CMSG_LEN(sizeof(int));
   p->cmsg_level=SOL_SOCKET;
   p->cmsg_type=SCM_RIGHTS;
   *((int *)CMSG_DATA(p))=file;
                                                                                                                                              
   s=socket(AF_UNIX,SOCK_STREAM,0);
   if(s<0)
       {
             printf("create socket fail\n");
             exit(0);
        }
 bzero(&addr,sizeof(addr));
 addr.sun_family=AF_UNIX;
 strcpy(addr.sun_path,filename);
 if(-1==connect(s,(struct sockaddr *)&addr,sizeof(addr)))
                                  {
                     printf("connect socket fail and the errno=%d\n",errno);
                     exit(0);
                                  }
 number=sendmsg(s,&msg,0);
 printf("%d\n",number);
 if(number==-1)
     {
       printf("sendmsg fail and the errno= %d",errno);
       exit(0);
     }
                                                                                                                                              
  close(s);
  close(file);
 return 1;
 }