создать специальный файл FIFO (именованный канал) (make a FIFO special file (a named pipe))
Имя (Name)
mkfifo, mkfifoat - make a FIFO special file (a named pipe)
Синопсис (Synopsis)
#include <sys/types.h>
#include <sys/stat.h>
int mkfifo(const char *pathname, mode_t mode);
#include <fcntl.h> /* Definition of AT_* constants */
#include <sys/stat.h>
int mkfifoat(int dirfd, const char *pathname, mode_t mode);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
mkfifoat():
Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
_ATFILE_SOURCE
Описание (Description)
mkfifo() makes a FIFO special file with name pathname. mode
specifies the FIFO's permissions. It is modified by the
process's umask in the usual way: the permissions of the created
file are (mode & ~umask).
A FIFO special file is similar to a pipe, except that it is
created in a different way. Instead of being an anonymous
communications channel, a FIFO special file is entered into the
filesystem by calling mkfifo().
Once you have created a FIFO special file in this way, any
process can open it for reading or writing, in the same way as an
ordinary file. However, it has to be open at both ends
simultaneously before you can proceed to do any input or output
operations on it. Opening a FIFO for reading normally blocks
until some other process opens the same FIFO for writing, and
vice versa. See fifo(7) for nonblocking handling of FIFO special
files.
mkfifoat()
The mkfifoat() function operates in exactly the same way as
mkfifo(), except for the differences described here.
If the pathname given in pathname is relative, then it is
interpreted relative to the directory referred to by the file
descriptor dirfd (rather than relative to the current working
directory of the calling process, as is done by mkfifo() for a
relative pathname).
If pathname is relative and dirfd is the special value AT_FDCWD,
then pathname is interpreted relative to the current working
directory of the calling process (like mkfifo()).
If pathname is absolute, then dirfd is ignored.
See openat(2) for an explanation of the need for mkfifoat().
Возвращаемое значение (Return value)
On success mkfifo() and mkfifoat() return 0. On error, -1 is
returned and errno is set to indicate the error.
Ошибки (Error)
EACCES One of the directories in pathname did not allow search
(execute) permission.
EBADF (mkfifoat()) pathname is relative but dirfd is neither
AT_FDCWD nor a valid file descriptor.
EDQUOT The user's quota of disk blocks or inodes on the
filesystem has been exhausted.
EEXIST pathname already exists. This includes the case where
pathname is a symbolic link, dangling or not.
ENAMETOOLONG
Either the total length of pathname is greater than
PATH_MAX, or an individual filename component has a length
greater than NAME_MAX. In the GNU system, there is no
imposed limit on overall filename length, but some
filesystems may place limits on the length of a component.
ENOENT A directory component in pathname does not exist or is a
dangling symbolic link.
ENOSPC The directory or filesystem has no room for the new file.
ENOTDIR
A component used as a directory in pathname is not, in
fact, a directory.
ENOTDIR
(mkfifoat()) pathname is a relative pathname and dirfd is
a file descriptor referring to a file other than a
directory.
EROFS pathname refers to a read-only filesystem.
Версии (Versions)
mkfifoat() was added to glibc in version 2.4. It is implemented
using mknodat(2), available on Linux since kernel 2.6.16.
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│mkfifo(), mkfifoat() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
Стандарты (Conforming to)
mkfifo(): POSIX.1-2001, POSIX.1-2008.
mkfifoat(): POSIX.1-2008.
Смотри также (See also)
mkfifo(1), close(2), open(2), read(2), stat(2), umask(2),
write(2), fifo(7)
