compiler/clib/dup2.c

   1 /*
   2     Copyright © 1995-2009, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     ANSI C function dup2().
   6 */
   7
   8 #include <stdlib.h>
   9 #include <errno.h>
  10 #include "__open.h"
  11
  12 /*****************************************************************************
  13
  14     NAME */
  15 #include <unistd.h>
  16
  17         int dup2 (
  18
  19 /*  SYNOPSIS */
  20         int oldfd,
  21         int newfd
  22         )
  23
  24 /*  FUNCTION
  25         Duplicates a file descriptor.
  26
  27         The object referenced by the descriptor does not distinguish between oldd
  28         and newd in any way.  Thus if newd and oldd are duplicate references to
  29         an open file, read(),  write() and lseek() calls all move a single
  30         pointer into the file, and append mode, non-blocking I/O and asynchronous
  31         I/O options are shared between the references.  If a separate pointer
  32         into the file is desired, a different object reference to the file must be
  33         obtained by issuing an additional open(2) call.  The close-on-exec flag
  34         on the new file descriptor is unset.
  35
  36     INPUTS
  37         oldfd - The file descriptor to be duplicated
  38         newfd - The value of the new descriptor we want the old one to be duplicated in
  39
  40     RESULT
  41         -1 for error or newfd on success
  42
  43     NOTES
  44         This function must not be used in a shared library or
  45         in a threaded application.
  46
  47     EXAMPLE
  48
  49     BUGS
  50
  51     SEE ALSO
  52          bsdsocket.library/accept(),  open(),  close(),  fcntl(),  pipe()
  53          bsdsocket.library/socket()
  54
  55     INTERNALS
  56
  57 ******************************************************************************/
  58 {
  59     fdesc *oldfdesc;
  60     fdesc *newfdesc;
  61
  62     oldfdesc = __getfdesc(oldfd);
  63     if (!oldfdesc)
  64     {
  65         errno = EBADF;
  66         return -1;
  67     }
  68
  69     newfdesc = __alloc_fdesc();
  70     if(!newfdesc)
  71     {
  72         errno = ENOMEM;
  73         return -1;
  74     }
  75
  76     newfdesc->fdflags = 0;
  77     newfdesc->fcb = oldfdesc->fcb;
  78
  79     newfd =__getfdslot(newfd);
  80     if (newfd != -1)
  81     {
  82         newfdesc->fcb->opencount++;
  83         __setfdesc(newfd, newfdesc);
  84     }
  85
  86     return newfd;
  87 }
  88