Retrieves file implementation characteristics.
Format
#include <unistd.h>
long int fpathconf (int filedes, int name);
1 – Arguments
filedes
An open file descriptor.
name
The configuration attribute to query. If this attribute is
not applicable to the file specified by the filesdes argument,
fpathconf returns an error.
2 – Description
The fpathconf function allows an application to retrieve the
characteristics of operations supported by the file system
underlying the filenamed by the filesdes argument. 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
filedes argument refers to a directory, the value
returned applies to the directory itself.
_PC_MAX_ The maximum number of bytes in a canonical input
CANON line. This is applicable only to terminal devices.
_PC_MAX_ The number of types allowed in an input queue.
INPUT 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_ The value returned applies to any files (other
RESTRICTED than directories) that exist or can be created
within the directory. This is applicable only to a
directory file.
_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 The resultant value for the configuration
attribute specified in the name argument.
-1 Indicates an error; errno is set to one of the
following values:
o EINVAL - The name argument specifies an
unknown or inapplicable characteristic.
o EBADF - the filedes argument is not a valid
file descriptor.