1 | /* Create a pipe, with specific opening flags. |
2 | Copyright (C) 2009-2019 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 <https://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 __CYGWIN__ |
33 | /* Native Windows API. */ |
34 | |
35 | # include <io.h> |
36 | |
37 | #endif |
38 | |
39 | int |
40 | pipe2 (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 __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 | set_binary_mode (fd[1], O_BINARY); |
142 | set_binary_mode (fd[0], O_BINARY); |
143 | } |
144 | else if (flags & O_TEXT) |
145 | { |
146 | set_binary_mode (fd[1], O_TEXT); |
147 | set_binary_mode (fd[0], O_TEXT); |
148 | } |
149 | # endif |
150 | |
151 | return 0; |
152 | |
153 | #endif |
154 | |
155 | #if GNULIB_defined_O_NONBLOCK || !(defined _WIN32 && ! defined __CYGWIN__) |
156 | fail: |
157 | { |
158 | int saved_errno = errno; |
159 | close (fd[0]); |
160 | close (fd[1]); |
161 | fd[0] = tmp[0]; |
162 | fd[1] = tmp[1]; |
163 | errno = saved_errno; |
164 | return -1; |
165 | } |
166 | #endif |
167 | } |
168 | |