diff options
Diffstat (limited to 'lib/pipe2.c')
| -rw-r--r-- | lib/pipe2.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/lib/pipe2.c b/lib/pipe2.c new file mode 100644 index 0000000..400aff0 --- /dev/null +++ b/lib/pipe2.c @@ -0,0 +1,167 @@ +/* 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 +} |