pathconf(2) BSD System Calls Manual pathconf(2)
NAME
fpathconf, pathconf -- get configurable pathname variables
SYNOPSIS
#include <unistd.h>
long
fpathconf(int fildes, int name);
long
pathconf(const char *path, int name);
DESCRIPTION
The pathconf() and fpathconf() functions provides a method for applica-
tions to determine the current value of a configurable system limit or
option variable associated with a pathname or file descriptor.
For pathconf, the path argument is the name of a file or directory. For
fpathconf, the fildes 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 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_XATTR_SIZE_BITS
Returns the number of bits used to store maximum extended
attribute size in bytes. For example, if the maximum attribute
size supported by a file system is 128K, the value returned will
be 18. However a value 18 can mean that the maximum attribute
size can be anywhere from (256KB - 1) to 128KB. As a special
case, the resource fork can have much larger size, and some file
system specific extended attributes can have smaller and preset
size; for example, Finder Info is always 32 bytes.
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 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() will fail if:
[EACCES] Search permission is denied for a component of the path
prefix.
[EIO] An I/O error occurs while reading from or writing to the
file system.
[ELOOP] Too many symbolic links are encountered in translating
the pathname. This is taken to be indicative of a loop-
ing symbolic link.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an
entire path name exceeded 1023 characters.
[ENOENT] The named file does not exist.
[ENOTDIR] A component of the path prefix is not a directory.
Fpathconf() will fail if:
[EBADF] fildes is not a valid open file descriptor.
[EIO] An I/O error occurs while reading from or writing to the
file system.
SEE ALSO
sysctl(3)
HISTORY
The pathconf and fpathconf functions first appeared in 4.4BSD.
4th Berkeley Distribution June 4, 1993 4th Berkeley Distribution
Mac OS X 10.9.1 - Generated Mon Jan 6 09:42:54 CST 2014