1/* Create a pipe, with specific opening flags.
2   Copyright (C) 2009-2012 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 General Public License as published by
6   the Free Software Foundation; either version 3, 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 General Public License for more details.
13
14   You should have received a copy of the GNU General Public License along
15   with this program; if not, see <http://www.gnu.org/licenses/>.  */
16
17#include <config.h>
18
19/* Specification.  */
20#include <unistd.h>
21
22#include <errno.h>
23#include <fcntl.h>
24
25#include "binary-io.h"
26#include "verify.h"
27
28#if GNULIB_defined_O_NONBLOCK
29# include "nonblocking.h"
30#endif
31
32#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
33/* Native Windows API.  */
34
35# include <io.h>
36
37#endif
38
39int
40pipe2 (int fd[2], int flags)
41{
42  /* Mingw _pipe() corrupts fd on failure; also, if we succeed at
43     creating the pipe but later fail at changing fcntl, we want
44     to leave fd unchanged: http://austingroupbugs.net/view.php?id=467  */
45  int tmp[2];
46  tmp[0] = fd[0];
47  tmp[1] = fd[1];
48
49#if HAVE_PIPE2
50# undef pipe2
51  /* Try the system call first, if it exists.  (We may be running with a glibc
52     that has the function but with an older kernel that lacks it.)  */
53  {
54    /* Cache the information whether the system call really exists.  */
55    static int have_pipe2_really; /* 0 = unknown, 1 = yes, -1 = no */
56    if (have_pipe2_really >= 0)
57      {
58        int result = pipe2 (fd, flags);
59        if (!(result < 0 && errno == ENOSYS))
60          {
61            have_pipe2_really = 1;
62            return result;
63          }
64        have_pipe2_really = -1;
65      }
66  }
67#endif
68
69  /* Check the supported flags.  */
70  if ((flags & ~(O_CLOEXEC | O_NONBLOCK | O_BINARY | O_TEXT)) != 0)
71    {
72      errno = EINVAL;
73      return -1;
74    }
75
76#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
77/* Native Windows API.  */
78
79  if (_pipe (fd, 4096, flags & ~O_NONBLOCK) < 0)
80    {
81      fd[0] = tmp[0];
82      fd[1] = tmp[1];
83      return -1;
84    }
85
86  /* O_NONBLOCK handling.
87     On native Windows platforms, O_NONBLOCK is defined by gnulib.  Use the
88     functions defined by the gnulib module 'nonblocking'.  */
89# if GNULIB_defined_O_NONBLOCK
90  if (flags & O_NONBLOCK)
91    {
92      if (set_nonblocking_flag (fd[0], true) != 0
93          || set_nonblocking_flag (fd[1], true) != 0)
94        goto fail;
95    }
96# else
97  {
98    verify (O_NONBLOCK == 0);
99  }
100# endif
101
102  return 0;
103
104#else
105/* Unix API.  */
106
107  if (pipe (fd) < 0)
108    return -1;
109
110  /* POSIX <http://www.opengroup.org/onlinepubs/9699919799/functions/pipe.html>
111     says that initially, the O_NONBLOCK and FD_CLOEXEC flags are cleared on
112     both fd[0] and fd[1].  */
113
114  /* O_NONBLOCK handling.
115     On Unix platforms, O_NONBLOCK is defined by the system.  Use fcntl().  */
116  if (flags & O_NONBLOCK)
117    {
118      int fcntl_flags;
119
120      if ((fcntl_flags = fcntl (fd[1], F_GETFL, 0)) < 0
121          || fcntl (fd[1], F_SETFL, fcntl_flags | O_NONBLOCK) == -1
122          || (fcntl_flags = fcntl (fd[0], F_GETFL, 0)) < 0
123          || fcntl (fd[0], F_SETFL, fcntl_flags | O_NONBLOCK) == -1)
124        goto fail;
125    }
126
127  if (flags & O_CLOEXEC)
128    {
129      int fcntl_flags;
130
131      if ((fcntl_flags = fcntl (fd[1], F_GETFD, 0)) < 0
132          || fcntl (fd[1], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1
133          || (fcntl_flags = fcntl (fd[0], F_GETFD, 0)) < 0
134          || fcntl (fd[0], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1)
135        goto fail;
136    }
137
138# if O_BINARY
139  if (flags & O_BINARY)
140    {
141      setmode (fd[1], O_BINARY);
142      setmode (fd[0], O_BINARY);
143    }
144  else if (flags & O_TEXT)
145    {
146      setmode (fd[1], O_TEXT);
147      setmode (fd[0], O_TEXT);
148    }
149# endif
150
151  return 0;
152
153#endif
154
155#if GNULIB_defined_O_NONBLOCK || \
156  !((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__)
157 fail:
158  {
159    int saved_errno = errno;
160    close (fd[0]);
161    close (fd[1]);
162    fd[0] = tmp[0];
163    fd[1] = tmp[1];
164    errno = saved_errno;
165    return -1;
166  }
167#endif
168}
169