lib/pipe2.c

   1 /* Create a pipe, with specific opening flags.
   2    Copyright (C) 2009-2011 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License along
  15    with this program; if not, write to the Free Software Foundation,
  16    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include <unistd.h>
  22
  23 #include <errno.h>
  24 #include <fcntl.h>
  25
  26 #include "binary-io.h"
  27 #include "verify.h"
  28
  29 #if GNULIB_defined_O_NONBLOCK
  30 # include "nonblocking.h"
  31 #endif
  32
  33 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  34 /* Native Woe32 API.  */
  35
  36 # include <io.h>
  37
  38 #endif
  39
  40 int
  41 pipe2 (int fd[2], int flags)
  42 {
  43 #if HAVE_PIPE2
  44 # undef pipe2
  45   /* Try the system call first, if it exists.  (We may be running with a glibc
  46      that has the function but with an older kernel that lacks it.)  */
  47   {
  48     /* Cache the information whether the system call really exists.  */
  49     static int have_pipe2_really; /* 0 = unknown, 1 = yes, -1 = no */
  50     if (have_pipe2_really >= 0)
  51       {
  52         int result = pipe2 (fd, flags);
  53         if (!(result < 0 && errno == ENOSYS))
  54           {
  55             have_pipe2_really = 1;
  56             return result;
  57           }
  58         have_pipe2_really = -1;
  59       }
  60   }
  61 #endif
  62
  63   /* Check the supported flags.  */
  64   if ((flags & ~(O_CLOEXEC | O_NONBLOCK | O_BINARY | O_TEXT)) != 0)
  65     {
  66       errno = EINVAL;
  67       return -1;
  68     }
  69
  70 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  71 /* Native Woe32 API.  */
  72
  73   if (_pipe (fd, 4096, flags & ~O_NONBLOCK) < 0)
  74     return -1;
  75
  76   /* O_NONBLOCK handling.
  77      On native Windows platforms, O_NONBLOCK is defined by gnulib.  Use the
  78      functions defined by the gnulib module 'nonblocking'.  */
  79 # if GNULIB_defined_O_NONBLOCK
  80   if (flags & O_NONBLOCK)
  81     {
  82       if (set_nonblocking_flag (fd[0], true) != 0
  83           || set_nonblocking_flag (fd[1], true) != 0)
  84         goto fail;
  85     }
  86 # else
  87   verify (O_NONBLOCK == 0);
  88 # endif
  89
  90   return 0;
  91
  92 #else
  93 /* Unix API.  */
  94
  95   if (pipe (fd) < 0)
  96     return -1;
  97
  98   /* POSIX <http://www.opengroup.org/onlinepubs/9699919799/functions/pipe.html>
  99      says that initially, the O_NONBLOCK and FD_CLOEXEC flags are cleared on
 100      both fd[0] and fd[1].  */
 101
 102   /* O_NONBLOCK handling.
 103      On Unix platforms, O_NONBLOCK is defined by the system.  Use fcntl().  */
 104   if (flags & O_NONBLOCK)
 105     {
 106       int fcntl_flags;
 107
 108       if ((fcntl_flags = fcntl (fd[1], F_GETFL, 0)) < 0
 109           || fcntl (fd[1], F_SETFL, fcntl_flags | O_NONBLOCK) == -1
 110           || (fcntl_flags = fcntl (fd[0], F_GETFL, 0)) < 0
 111           || fcntl (fd[0], F_SETFL, fcntl_flags | O_NONBLOCK) == -1)
 112         goto fail;
 113     }
 114
 115   if (flags & O_CLOEXEC)
 116     {
 117       int fcntl_flags;
 118
 119       if ((fcntl_flags = fcntl (fd[1], F_GETFD, 0)) < 0
 120           || fcntl (fd[1], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1
 121           || (fcntl_flags = fcntl (fd[0], F_GETFD, 0)) < 0
 122           || fcntl (fd[0], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1)
 123         goto fail;
 124     }
 125
 126 # if O_BINARY
 127   if (flags & O_BINARY)
 128     {
 129       setmode (fd[1], O_BINARY);
 130       setmode (fd[0], O_BINARY);
 131     }
 132   else if (flags & O_TEXT)
 133     {
 134       setmode (fd[1], O_TEXT);
 135       setmode (fd[0], O_TEXT);
 136     }
 137 # endif
 138
 139   return 0;
 140
 141 #endif
 142
 143  fail:
 144   {
 145     int saved_errno = errno;
 146     close (fd[0]);
 147     close (fd[1]);
 148     errno = saved_errno;
 149     return -1;
 150   }
 151 }