src/open3.h

   1 /* Defines for Sys V style 3-argument open call.
   2    Copyright (C) 1988 Free Software Foundation
   3
   4 This file is part of GNU Tar.
   5
   6 GNU Tar is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Tar is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Tar; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20 /*
  21  * @(#)open3.h 1.4 87/11/11
  22  *
  23  * open3.h -- #defines for the various flags for the Sys V style 3-argument
  24  * open() call.  On BSD or System 5, the system already has this in an
  25  * include file.  This file is needed for V7 and MINIX systems for the
  26  * benefit of open3() in port.c, a routine that emulates the 3-argument
  27  * call using system calls available on V7/MINIX.
  28  *
  29  * This file is needed by PD tar even if we aren't using the
  30  * emulator, since the #defines for O_WRONLY, etc. are used in
  31  * a couple of places besides the open() calls, (e.g. in the assignment
  32  * to openflag in extract.c).  We just #include this rather than
  33  * #ifdef them out.
  34  *
  35  * Written 6/10/87 by rmtodd@uokmax (Richard Todd).
  36  *
  37  * The names have been changed by John Gilmore, 31 July 1987, since
  38  * Richard called it "bsdopen", and really this change was introduced in
  39  * AT&T Unix systems before BSD picked it up.
  40  */
  41
  42 /* Only one of the next three should be specified */
  43 #define O_RDONLY         0 /* only allow read */
  44 #define O_WRONLY         1 /* only allow write */
  45 #define O_RDWR           2 /* both are allowed */
  46
  47 /* The rest of these can be OR-ed in to the above. */
  48 /*
  49  * O_NDELAY isn't implemented by the emulator.  It's only useful (to tar) on
  50  * systems that have named pipes anyway; it prevents tar's hanging by
  51  * opening a named pipe.  We #ifndef it because some systems already have
  52  * it defined.
  53  */
  54 #ifndef O_NDELAY
  55 #define O_NDELAY         4 /* don't block on opening devices that would
  56                             * block on open -- ignored by emulator. */
  57 #endif
  58 #define O_CREAT          8 /* create file if needed */
  59 #define O_EXCL          16 /* file cannot already exist */
  60 #define O_TRUNC         32 /* truncate file on open */
  61 #define O_APPEND        64 /* always write at end of file -- ignored by emul */
  62
  63 #ifdef EMUL_OPEN3
  64 /*
  65  * make emulation transparent to rest of file -- redirect all open() calls
  66  * to our routine
  67  */
  68 #define open    open3
  69 #endif