minix/lib/libsys/closenb.c

   1 #include "syslib.h"
   2
   3 #include <string.h>
   4
   5 /*
   6  * Non-blocking variant of close(2).  This call is to be used by system
   7  * services that need to close arbitrary local file descriptors.  The purpose
   8  * of the call is to avoid that such services end up blocking on closing socket
   9  * file descriptors with the SO_LINGER socket option enabled.  They cannot put
  10  * the file pointer in non-blocking mode to that end, because the file pointer
  11  * may be shared with other processes.
  12  *
  13  * Even though this call is defined for system services only, there is no harm
  14  * in letting arbitrary user processes use this functionality.  Thus, it needs
  15  * no separate VFS call number.
  16  */
  17 int
  18 closenb(int fd)
  19 {
  20         message m;
  21
  22         memset(&m, 0, sizeof(m));
  23         m.m_lc_vfs_close.fd = fd;
  24         m.m_lc_vfs_close.nblock = 1;
  25
  26         return _taskcall(VFS_PROC_NR, VFS_CLOSE, &m);
  27 }