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)
    

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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. 
   

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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. }
    

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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

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

oh, sorry

isnowran

猫抬头

isnowran

终于找到原因了，写描述符打开为 O_RDWR 模式了, 哈哈