DragonFly On-Line Manual Pages
PATHCONF(2) DragonFly System Calls Manual PATHCONF(2)
NAME
pathconf, lpathconf, fpathconf - get configurable pathname variables
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
long
pathconf(const char *path, int name);
long
lpathconf(const char *path, int name);
long
fpathconf(int fd, int name);
DESCRIPTION
The pathconf(), lpathconf() and fpathconf() functions provide a method
for applications to determine the current value of a configurable system
limit or option variable associated with a pathname or file descriptor.
For pathconf() and lpathconf(), the path argument is the name of a file
or directory. For fpathconf(), the fd argument is an open file
descriptor. The name argument specifies the system variable to be
queried. Symbolic constants for each name value are found in the include
file <unistd.h>.
The lpathconf() system call is like pathconf() except in the case where
the named file is a symbolic link, in which case lpathconf() returns
information about the link, while pathconf() returns information about
the file the link references.
The available values are as follows:
_PC_LINK_MAX The maximum file link count.
_PC_MAX_CANON The maximum number of bytes in terminal
canonical input line.
_PC_MAX_INPUT The minimum maximum number of bytes for which
space is available in a terminal input queue.
_PC_NAME_MAX The maximum number of bytes in a file name.
_PC_PATH_MAX The maximum number of bytes in a pathname.
_PC_PIPE_BUF The maximum number of bytes which will be
written atomically to a pipe.
_PC_CHOWN_RESTRICTED Return 1 if appropriate privileges are required
for the chown(2) system call, otherwise 0.
_PC_NO_TRUNC Return 1 if file names longer than
KERN_NAME_MAX are truncated.
_PC_VDISABLE Returns the terminal character disabling value.
_PC_MIN_HOLE_SIZE If a file system supports the reporting of
holes (see lseek(2)), pathconf() and
fpathconf() return a positive number that
represents the minimum hole size returned in
bytes. The offsets of holes returned will be
aligned to this same value. A special value of
1 is returned if the file system does not
specify the minimum hole size but still reports
holes.
RETURN VALUES
If the call to pathconf() or fpathconf() is not successful, -1 is
returned and errno is set appropriately. Otherwise, if the variable is
associated with functionality that does not have a limit in the system,
-1 is returned and errno is not modified. Otherwise, the current
variable value is returned.
ERRORS
If any of the following conditions occur, the pathconf(), lpathconf() and
fpathconf() functions shall return -1 and set errno to the corresponding
value.
[EINVAL] The value of the name argument is invalid.
[EINVAL] The implementation does not support an association of
the variable name with the associated file.
Pathconf() and lpathconf() will fail if:
[ENOTDIR] A component of the path prefix is not a directory.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or
an entire path name exceeded 1023 characters.
[ENOENT] The named file does not exist.
[EACCES] Search permission is denied for a component of the
path prefix.
[ELOOP] Too many symbolic links were encountered in
translating the pathname.
[EIO] An I/O error occurred while reading from or writing to
the file system.
Fpathconf() will fail if:
[EBADF] fd is not a valid open file descriptor.
[EIO] An I/O error occurred while reading from or writing to
the file system.
SEE ALSO
getconf(1), lseek(2), confstr(3), sysconf(3), sysctl(3)
HISTORY
The pathconf() and fpathconf() functions first appeared in 4.4BSD. The
lpathconf() system call first appeared in DragonFly 3.5.
DragonFly 6.5-DEVELOPMENT May 12, 2019 DragonFly 6.5-DEVELOPMENT