phoenix-rtos-doc / libc / functions / m / mkfifo.part-impl.md

mkfifo

Synopsis

#include <sys/stat.h>

int mkfifo(const char *path, mode_t mode);

#include <fcntl.h>

int mkfifoat(int fd, const char *path, mode_t mode);

Status

Partially implemented

Conformance

IEEE Std 1003.1-2017

Description

The mkfifo() function shall create a new FIFO special file named by the path name pointed to by path. The file permission bits of the new FIFO shall be initialized from mode. The file permission bits of the mode argument shall be modified by the process' file creation mask.

When bits in mode other than the file permission bits are set, the effect is implementation-defined.

If path names a symbolic link, mkfifo() shall fail and set errno to EEXIST.

The FIFO's user ID shall be set to the process' effective user ID. The FIFO's group ID shall be set to the group ID of the parent directory or to the effective group ID of the process. Implementations shall provide a way to initialize the FIFO's group ID to the group ID of the parent directory. Implementations may, but need not, provide an implementation-defined way to initialize the FIFO's group ID to the effective group ID of the calling process.

Upon successful completion, mkfifo() shall mark for update the last data access, last data modification, and last file status change timestamps of the file. Also, the last data modification and last file status change timestamps of the directory that contains the new entry shall be marked for update.

The mkfifoat() function shall be equivalent to the mkfifo() function except in the case where path specifies a relative path. In this case the newly created FIFO is created relative to the directory associated with the file descriptor fd instead of the current working directory. If the access mode of the open file description associated with the file descriptor is not O_SEARCH, the function shall check whether directory searches are permitted using the current permissions of the directory underlying the file descriptor. If the access mode is O_SEARCH, the function shall not perform the check.

If mkfifoat() is passed the special value AT_FDCWD in the fd parameter, the current working directory shall be used and the behavior shall be identical to a call to mkfifo().

Return value

Upon successful completion, these functions shall return 0. Otherwise, these functions shall return -1 and set errno to indicate the error. If -1 is returned, no FIFO shall be created.

Errors

These functions shall fail if:

EACCES - A component of the path prefix denies search permission, or write permission is denied on the parent directory of the FIFO to be created.
EEXIST - The named file already exists.
ELOOP - A loop exists in symbolic links encountered during resolution of the path argument.
ENAMETOOLONG - The length of a component of a path name is longer than NAME_MAX.
ENOENT - A component of the path prefix of path does not name an existing file or path is an empty string.
ENOENT or ENOTDIR - The path argument contains at least one non- <slash> character and ends with one or more trailing <slash> characters. If path without the trailing <slash> characters would name an existing file, a ENOENT error shall not occur.
ENOSPC - The directory that would contain the new file cannot be extended, or the file system is out of file-allocation resources.
ENOTDIR - A component of the path prefix names an existing file that is neither a directory nor a symbolic link to a directory.
EROFS - The named file resides on a read-only file system.

The mkfifoat() function shall fail if:

EACCES - The access mode of the open file description associated with fd is not O_SEARCH and the permissions of the directory underlying fd do not permit directory searches.
EBADF - The path argument does not specify an absolute path and the fd argument is neither AT_FDCWD nor a valid file descriptor open for reading or searching.
ENOTDIR - The path argument is not an absolute path and fd is a file descriptor associated with a non-directory file.

These functions may fail if:

ELOOP - More than SYMLOOP_MAX symbolic links were encountered during resolution of the path argument.
ENAMETOOLONG - The length of a path name exceeds PATH_MAX, or path name resolution of a symbolic link produced an intermediate result with a length that exceeds PATH_MAX.

Tests

Untested

Known bugs

None