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-rw-r--r--lib/pipe2.c167
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diff --git a/lib/pipe2.c b/lib/pipe2.c
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+/* Create a pipe, with specific opening flags.
+ Copyright (C) 2009-2022 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+/* Specification. */
+#include <unistd.h>
+
+#include <errno.h>
+#include <fcntl.h>
+
+#include "binary-io.h"
+#include "verify.h"
+
+#if GNULIB_defined_O_NONBLOCK
+# include "nonblocking.h"
+#endif
+
+#if defined _WIN32 && ! defined __CYGWIN__
+/* Native Windows API. */
+
+# include <io.h>
+
+#endif
+
+int
+pipe2 (int fd[2], int flags)
+{
+ /* Mingw _pipe() corrupts fd on failure; also, if we succeed at
+ creating the pipe but later fail at changing fcntl, we want
+ to leave fd unchanged: http://austingroupbugs.net/view.php?id=467 */
+ int tmp[2];
+ tmp[0] = fd[0];
+ tmp[1] = fd[1];
+
+#if HAVE_PIPE2
+# undef pipe2
+ /* Try the system call first, if it exists. (We may be running with a glibc
+ that has the function but with an older kernel that lacks it.) */
+ {
+ /* Cache the information whether the system call really exists. */
+ static int have_pipe2_really; /* 0 = unknown, 1 = yes, -1 = no */
+ if (have_pipe2_really >= 0)
+ {
+ int result = pipe2 (fd, flags);
+ if (!(result < 0 && errno == ENOSYS))
+ {
+ have_pipe2_really = 1;
+ return result;
+ }
+ have_pipe2_really = -1;
+ }
+ }
+#endif
+
+ /* Check the supported flags. */
+ if ((flags & ~(O_CLOEXEC | O_NONBLOCK | O_BINARY | O_TEXT)) != 0)
+ {
+ errno = EINVAL;
+ return -1;
+ }
+
+#if defined _WIN32 && ! defined __CYGWIN__
+/* Native Windows API. */
+
+ if (_pipe (fd, 4096, flags & ~O_NONBLOCK) < 0)
+ {
+ fd[0] = tmp[0];
+ fd[1] = tmp[1];
+ return -1;
+ }
+
+ /* O_NONBLOCK handling.
+ On native Windows platforms, O_NONBLOCK is defined by gnulib. Use the
+ functions defined by the gnulib module 'nonblocking'. */
+# if GNULIB_defined_O_NONBLOCK
+ if (flags & O_NONBLOCK)
+ {
+ if (set_nonblocking_flag (fd[0], true) != 0
+ || set_nonblocking_flag (fd[1], true) != 0)
+ goto fail;
+ }
+# else
+ {
+ verify (O_NONBLOCK == 0);
+ }
+# endif
+
+ return 0;
+
+#else
+/* Unix API. */
+
+ if (pipe (fd) < 0)
+ return -1;
+
+ /* POSIX <https://pubs.opengroup.org/onlinepubs/9699919799/functions/pipe.html>
+ says that initially, the O_NONBLOCK and FD_CLOEXEC flags are cleared on
+ both fd[0] and fd[1]. */
+
+ /* O_NONBLOCK handling.
+ On Unix platforms, O_NONBLOCK is defined by the system. Use fcntl(). */
+ if (flags & O_NONBLOCK)
+ {
+ int fcntl_flags;
+
+ if ((fcntl_flags = fcntl (fd[1], F_GETFL, 0)) < 0
+ || fcntl (fd[1], F_SETFL, fcntl_flags | O_NONBLOCK) == -1
+ || (fcntl_flags = fcntl (fd[0], F_GETFL, 0)) < 0
+ || fcntl (fd[0], F_SETFL, fcntl_flags | O_NONBLOCK) == -1)
+ goto fail;
+ }
+
+ if (flags & O_CLOEXEC)
+ {
+ int fcntl_flags;
+
+ if ((fcntl_flags = fcntl (fd[1], F_GETFD, 0)) < 0
+ || fcntl (fd[1], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1
+ || (fcntl_flags = fcntl (fd[0], F_GETFD, 0)) < 0
+ || fcntl (fd[0], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1)
+ goto fail;
+ }
+
+# if O_BINARY
+ if (flags & O_BINARY)
+ {
+ set_binary_mode (fd[1], O_BINARY);
+ set_binary_mode (fd[0], O_BINARY);
+ }
+ else if (flags & O_TEXT)
+ {
+ set_binary_mode (fd[1], O_TEXT);
+ set_binary_mode (fd[0], O_TEXT);
+ }
+# endif
+
+ return 0;
+
+#endif
+
+#if GNULIB_defined_O_NONBLOCK || !(defined _WIN32 && ! defined __CYGWIN__)
+ fail:
+ {
+ int saved_errno = errno;
+ close (fd[0]);
+ close (fd[1]);
+ fd[0] = tmp[0];
+ fd[1] = tmp[1];
+ errno = saved_errno;
+ return -1;
+ }
+#endif
+}