fpathconf, pathconf — get configuration values for files
#include <unistd.h>
long
fpathconf( |
int fd, |
int name); |
long
pathconf( |
char *path, |
int name); |
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_MAXreturns 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_CANONreturns 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_INPUTreturns 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_MAXreturns 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_MAXreturns 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_BUFreturns the size of the pipe buffer, where
fd must refer
to a pipe or FIFO and path must refer to a
FIFO. The corresponding macro is _POSIX_PIPE_BUF.
_PC_CHOWN_RESTRICTEDreturns nonzero if the chown(2) call may not
be used on this file. If fd or path refer to a
directory, then this applies to all files in that
directory. The corresponding macro is _POSIX_CHOWN_RESTRICTED.
_PC_NO_TRUNCreturns nonzero if accessing filenames longer than
_POSIX_NAME_MAX generates
an error. The corresponding macro is _POSIX_NO_TRUNC.
_PC_VDISABLEreturns nonzero if special character processing can
be disabled, where fd or path must refer to a
terminal.
The limit is returned, if one exists. If the system does
not have a limit for the requested resource, −1 is
returned, and errno is
unchanged. If there is an error, −1 is returned, and
errno is set to reflect the
nature of the error.
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.