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   /* Mingw _pipe() corrupts fd on failure; also, if we succeed at
  44      creating the pipe but later fail at changing fcntl, we want
  45      to leave fd unchanged: http://austingroupbugs.net/view.php?id=467  */
  46   int tmp[2];
  47   tmp[0] = fd[0];
  48   tmp[1] = fd[1];
  49
  50 #if HAVE_PIPE2
  51 # undef pipe2
  52   /* Try the system call first, if it exists.  (We may be running with a glibc
  53      that has the function but with an older kernel that lacks it.)  */
  54   {
  55     /* Cache the information whether the system call really exists.  */
  56     static int have_pipe2_really; /* 0 = unknown, 1 = yes, -1 = no */
  57     if (have_pipe2_really >= 0)
  58       {
  59         int result = pipe2 (fd, flags);
  60         if (!(result < 0 && errno == ENOSYS))
  61           {
  62             have_pipe2_really = 1;
  63             return result;
  64           }
  65         have_pipe2_really = -1;
  66       }
  67   }
  68 #endif
  69
  70   /* Check the supported flags.  */
  71   if ((flags & ~(O_CLOEXEC | O_NONBLOCK | O_BINARY | O_TEXT)) != 0)
  72     {
  73       errno = EINVAL;
  74       return -1;
  75     }
  76
  77 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  78 /* Native Woe32 API.  */
  79
  80   if (_pipe (fd, 4096, flags & ~O_NONBLOCK) < 0)
  81     {
  82       fd[0] = tmp[0];
  83       fd[1] = tmp[1];
  84       return -1;
  85     }
  86
  87   /* O_NONBLOCK handling.
  88      On native Windows platforms, O_NONBLOCK is defined by gnulib.  Use the
  89      functions defined by the gnulib module 'nonblocking'.  */
  90 # if GNULIB_defined_O_NONBLOCK
  91   if (flags & O_NONBLOCK)
  92     {
  93       if (set_nonblocking_flag (fd[0], true) != 0
  94           || set_nonblocking_flag (fd[1], true) != 0)
  95         goto fail;
  96     }
  97 # else
  98   {
  99     verify (O_NONBLOCK == 0);
 100   }
 101 # endif
 102
 103   return 0;
 104
 105 #else
 106 /* Unix API.  */
 107
 108   if (pipe (fd) < 0)
 109     return -1;
 110
 111   /* POSIX <http://www.opengroup.org/onlinepubs/9699919799/functions/pipe.html>
 112      says that initially, the O_NONBLOCK and FD_CLOEXEC flags are cleared on
 113      both fd[0] and fd[1].  */
 114
 115   /* O_NONBLOCK handling.
 116      On Unix platforms, O_NONBLOCK is defined by the system.  Use fcntl().  */
 117   if (flags & O_NONBLOCK)
 118     {
 119       int fcntl_flags;
 120
 121       if ((fcntl_flags = fcntl (fd[1], F_GETFL, 0)) < 0
 122           || fcntl (fd[1], F_SETFL, fcntl_flags | O_NONBLOCK) == -1
 123           || (fcntl_flags = fcntl (fd[0], F_GETFL, 0)) < 0
 124           || fcntl (fd[0], F_SETFL, fcntl_flags | O_NONBLOCK) == -1)
 125         goto fail;
 126     }
 127
 128   if (flags & O_CLOEXEC)
 129     {
 130       int fcntl_flags;
 131
 132       if ((fcntl_flags = fcntl (fd[1], F_GETFD, 0)) < 0
 133           || fcntl (fd[1], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1
 134           || (fcntl_flags = fcntl (fd[0], F_GETFD, 0)) < 0
 135           || fcntl (fd[0], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1)
 136         goto fail;
 137     }
 138
 139 # if O_BINARY
 140   if (flags & O_BINARY)
 141     {
 142       setmode (fd[1], O_BINARY);
 143       setmode (fd[0], O_BINARY);
 144     }
 145   else if (flags & O_TEXT)
 146     {
 147       setmode (fd[1], O_TEXT);
 148       setmode (fd[0], O_TEXT);
 149     }
 150 # endif
 151
 152   return 0;
 153
 154 #endif
 155
 156 #if GNULIB_defined_O_NONBLOCK || \
 157   !((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__)
 158  fail:
 159   {
 160     int saved_errno = errno;
 161     close (fd[0]);
 162     close (fd[1]);
 163     fd[0] = tmp[0];
 164     fd[1] = tmp[1];
 165     errno = saved_errno;
 166     return -1;
 167   }
 168 #endif
 169 }