NAME
fpathconf, pathconf - get configuration values for files
SYNOPSIS
#include <unistd.h>
long
fpathconf(int fd, int name);
long pathconf(const char *path, int
name);
DESCRIPTION
fpathconf() gets a value for the configuration option name for the open file descriptor fd.
pathconf() gets a value for configuration option name for the filename path.
The corresponding macros defined in <unistd.h> are minimum values; if an application wants to take advantage of values which may change, a call to fpathconf() or pathconf() can be made, which may yield more liberal results.
Setting
name equal to one of the following constants returns
the following configuration options:
_PC_LINK_MAX
The maximum number of links to the file. If fd or path refer to a directory, then the value applies to the whole directory. The corresponding macro is _POSIX_LINK_MAX.
_PC_MAX_CANON
The maximum length of a formatted input line, where fd or path must refer to a terminal. The corresponding macro is _POSIX_MAX_CANON.
_PC_MAX_INPUT
The maximum length of an input line, where fd or path must refer to a terminal. The corresponding macro is _POSIX_MAX_INPUT.
_PC_NAME_MAX
The maximum length of a filename in the directory path or fd that the process is allowed to create. The corresponding macro is _POSIX_NAME_MAX.
_PC_PATH_MAX
The maximum length of a relative pathname when path or fd is the current working directory. The corresponding macro is _POSIX_PATH_MAX.
_PC_PIPE_BUF
The maximum number of bytes that can be written atomically to a pipe of FIFO. For fpathconf(), fd should refer to a pipe or FIFO. For fpathconf(), path should refer to a FIFO or a directory; in the latter case, the returned value corresponds to FIFOs created in that directory. The corresponding macro is _POSIX_PIPE_BUF.
_PC_CHOWN_RESTRICTED
This returns a positive value if the use of chown(2) and fchown(2) for changing a file’s user ID is restricted to a process with appropriate privileges, and changing a file’s group ID to a value other than the process’s effective group ID or one of its supplementary group IDs is restricted to a process with appropriate privileges. According to POSIX.1, this variable shall always be defined with a value other than -1. The corresponding macro is _POSIX_CHOWN_RESTRICTED.
If fd or path refers to a directory, then the return value applies to all files in that directory.
_PC_NO_TRUNC
This returns nonzero if accessing filenames longer than _POSIX_NAME_MAX generates an error. The corresponding macro is _POSIX_NO_TRUNC.
_PC_VDISABLE
This returns nonzero if special character processing can be disabled, where fd or path must refer to a terminal.
RETURN VALUE
The return value of these functions is one of the following:
|
* |
On error, -1 is returned and errno is set to indicate the cause of the error (for example, EINVAL, indicating that name is invalid). | ||
|
* |
If name corresponds to a maximum or minimum limit, and that limit is indeterminate, -1 is returned and errno is not changed. (To distinguish an indeterminate limit from an error, set errno to zero before the call, and then check whether errno is nonzero when -1 is returned.) | ||
|
* |
If name corresponds to an option, a positive value is returned if the option is supported, and -1 is returned if the option is not supported. | ||
|
* |
Otherwise, the current value of the option or limit is returned. This value will not be more restrictive than the corresponding value that was described to the application in <unistd.h> or <limits.h> when the application was compiled. |
ERRORS
|
EACCES |
(pathconf()) Search permission is denied for one of the directories in the path prefix of path. | ||
|
EBADF |
(fpathconf()) fd is not a valid file descriptor. | ||
|
EINVAL |
name is invalid. | ||
|
EINVAL |
The implementation does not support an association of name with the specified file. | ||
|
ELOOP |
(pathconf()) Too many symbolic links were encountered while resolving path. |
ENAMETOOLONG
(pathconf()) path is too long.
|
ENOENT |
(pathconf()) A component of path does not exist, or path is an empty string. |
ENOTDIR
(pathconf()) A component used as a directory in path is not in fact a directory.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
NOTES
Files with name lengths longer than the value returned for name equal to _PC_NAME_MAX may exist in the given directory.
Some returned values may be huge; they are not suitable for allocating memory.
SEE ALSO
getconf(1), open(2), statfs(2), confstr(3), sysconf(3)
COLOPHON
This page is part of release 5.09 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.