Retrieves file implementation characteristics.
Format
#include <unistd.h>
long int pathconf (const char *path, int name);
1 – Arguments
path
The pathname of a file or directory.
name
The configuration attribute to query. If this attribute is
not applicable to the file specified by the path argument, the
pathconf function returns an error.
2 – Description
The pathconf function allows an application to determine the
characteristics of operations supported by the file system
underlying the filenamed by path. Read, write, or execute
permission of the named file is not required, but you must be
able to search all directories in the path leading to the file.
Symbolic values for the name argument are defined in the
<unistd.h> header file, as follows:
_PC_LINK_MAX The maximum number of links to the file. If the
path argument refers to a directory, the value
returned applies to the directory itself.
_PC_MAX_CANON The maximum number of bytes in a canonical
input line. This is applicable only to terminal
devices.
_PC_MAX_INPUT The number of types allowed in an input queue.
This is applicable only to terminal devices.
_PC_NAME_MAX Maximum number of bytes in a filename (not
including a terminating null). The byte range
value is between 13 and 255. This is applicable
only to a directory file. The value returned
applies to filenames within the directory.
_PC_PATH_MAX Maximum number of bytes in a pathname (not
including a terminating null). The value is never
larger than 65,535. This is applicable only to a
directory file. The value returned is the maximum
length of a relative pathname when the specified
directory is the working directory.
_PC_PIPE_BUF Maximum number of bytes guaranteed to be written
atomically. This is applicable only to a FIFO.
The value returned applies to the referenced
object. If the path argument refers to a
directory, the value returned applies to any
FIFO that exists or can be created within the
directory.
_PC_CHOWN_ This is applicable only to a directory file. The
RESTRICTED value returned applies to any files (other than
directories) that exist or can be created within
the directory.
_PC_NO_TRUNC Returns 1 if supplying a component name longer
than allowed by NAME_MAX causes an error. Returns
0 (zero) if long component names are truncated.
This is applicable only to a directory file.
_PC_VDISABLE This is always 0 (zero); no disabling character
is defined. This is applicable only to a terminal
device.
3 – Return Values
x Resultant value of the configuration attribute
specified in name.
-1 Indicates an error; errno is set to one of the
following values:
o EACCES - Search permission is denied for a
component of the path prefix.
o EINVAL - The name argument specifies an
unknown or inapplicable characteristic.
o EFAULT - The path argument is an invalid
address.
o ENAMETOOLONG - The length of the path
string exceeds PATH_MAX or a pathname
component is longer than NAME_MAX.
o ENOENT - The named file does not exist
or the path argument points to an empty
string.
o ENOTDI - A component of the path prefix is
not a directory.