compiler/clib/dup2.c

   1 /*
   2     Copyright © 1995-2003, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     ANSI C function dup2().
   6 */
   7
   8 #include <errno.h>
   9 #include "__open.h"
  10
  11 /*****************************************************************************
  12
  13     NAME */
  14 #include <unistd.h>
  15
  16         int dup2 (
  17
  18 /*  SYNOPSIS */
  19         int oldfd,
  20         int newfd
  21         )
  22
  23 /*  FUNCTION
  24         Duplicates a file descriptor.
  25
  26         The object referenced by the descriptor does not distinguish between oldd
  27         and newd in any way.  Thus if newd and oldd are duplicate references to
  28         an open file, read(),  write() and lseek() calls all move a single
  29         pointer into the file, and append mode, non-blocking I/O and asynchronous
  30         I/O options are shared between the references.  If a separate pointer
  31         into the file is desired, a different object reference to the file must be
  32         obtained by issuing an additional open(2) call.  The close-on-exec flag
  33         on the new file descriptor is unset.
  34
  35     INPUTS
  36         oldfd - The file descriptor to be duplicated
  37         newfd - The value of the new descriptor we want the old one to be duplicated in
  38
  39     RESULT
  40         -1 for error or newfd on success
  41
  42     NOTES
  43         This function must not be used in a shared library or
  44         in a threaded application.
  45
  46     EXAMPLE
  47
  48     BUGS
  49
  50     SEE ALSO
  51          accept(),  open(),  close(),  fcntl(),  pipe(),  socket()
  52
  53     INTERNALS
  54
  55 ******************************************************************************/
  56 {
  57     fdesc *oldfdesc;
  58
  59     oldfdesc = __getfdesc(oldfd);
  60     if (!oldfdesc)
  61     {
  62         errno = EBADF;
  63         return -1;
  64     }
  65
  66     newfd =__getfdslot(newfd);
  67     if (newfd != -1)
  68     {
  69         oldfdesc->opencount++;
  70         __setfdesc(newfd, oldfdesc);
  71     }
  72
  73     return newfd;
  74 }
  75