FIFO难道不会引发SIGPIPE吗？

isnowran

我的系统是redhat-2.4.32，向一个对端未打开的FIFO进行写操作，不会引发SIGPIPE，但是man 4 fifo上面说这样做会引发SIGPIPE

1. 
   
2. NOTES
   
3.        When a process tries to write to a FIFO that is not opened for read  on
   
4.        the other side, the process is sent a SIGPIPE signal.
   
5. 
   
6.        FIFO special files can be created by mkfifo(3), and are specially indi-
   
7.        cated in ls -l.
   
8. 
   
9. SEE ALSO
   
10.        mkfifo(3),  mkfifo(1),  pipe(2),  socketpair(2),  open(2),   signal(2),
    
11.        sigaction(2)
    
12. 
    
13. Linux Man Page                    1999-06-20                           FIFO(4)
    
14. (END)
    

复制代码

在man 2 write 中对于EPIPE是这么描述的，不知道它所说的 "pipe or socket" 中的 pipe是否包含fifo( named pipe )

1. 
   
2.        EPIPE  fd is connected to a pipe or socket whose reading end is closed.
   
3.               When  this  happens the writing process will also receive a SIG-
   
4.               PIPE signal.  (Thus, the write return value is seen only if  the
   
5.               program catches, blocks or ignores this signal.)
   
6. 
   

复制代码

疑惑中，测试代码

1. 
   
2. #include <unistd.h>
   
3. #include <sys/types.h>
   
4. #include <sys/stat.h>
   
5. #include <fcntl.h>
   
6. #include <errno.h>
   
7. #include <stdio.h>
   
8. #include <string.h>
   
9. #include <signal.h>
   
10. 
    
11. void sigpipe( int )
    
12. {
    
13.         printf( "caught signal\n" );
    
14. }
    
15. 
    
16. int main( int argc, char* argv[] )
    
17. {
    
18.         const char* msg = "test";
    
19.         mkfifo( "fifo", 00777 );
    
20.         int fd = open( "fifo", O_RDWR );
    
21.         if( -1 == fd )
    
22.         {
    
23.                 perror( "open" );
    
24.                 return -1;
    
25.         }
    
26. 
    
27.         struct sigaction sigact;
    
28.         sigact.sa_handler = sigpipe;
    
29.         sigemptyset( &sigact.sa_mask );
    
30.         sigact.sa_flags = 0;
    
31.         if( -1 == sigaction( SIGPIPE, &sigact, NULL ) )
    
32.         {
    
33.                 perror( "sigaction" );
    
34.                 return -1;
    
35.         }
    
36. 
    
37.         while( 1 )
    
38.         {
    
39.                 // should lead to caught SIGPIPE
    
40.                 if( -1 == write( fd, msg, strlen( msg ) ) )
    
41.                 {
    
42.                         perror( "write" );
    
43.                         return -2;
    
44.                 }
    
45.         }
    
46. 
    
47.         return 0;
    
48. }
    

复制代码

isnowran

终于找到原因了，写描述符打开为 O_RDWR 模式了, 哈哈

isnowran

猫抬头

fanyunfei

oh, sorry

isnowran

原帖由 fanyunfei 于 2006-8-10 17:52 发表
because you have no set O_NONBLOCK flag, so process block until read open by other process

sorry, my system have no chinese language and my english is poor

写管道是否会引发SIGPIPE跟写文件描述符是否阻塞是没有关系的

fanyunfei

because you have no set O_NONBLOCK flag, so process block until read open by other process

sorry, my system have no chinese language and my english is poor