OSF

NAME

pathconf, fpathconf − Retrieves file implementation characteristics

LIBRARY

Standard C Library (libc.a)

SYNOPSIS

#include <unistd.h> long pathconf(
const char ∗path,
int name ); long fpathconf(
int filedes,
int name );

PARAMETERS

pathSpecifies the pathname.  If the final component of path is a symbolic link, it will be traversed and filename resolution will continue. 

filedesSpecifies an open file descriptor. 

nameSpecifies the configuration attribute to be queried.  If this attribute is not applicable to the file specified by the path or filedes parameter, the pathconf() function returns an error. 

DESCRIPTION

The pathconf() function allows an application to determine the characteristics of operations supported by the file system underlying the file named by the path parameter.  Read, write, or execute permission of the named file is not required, but all directories in the path leading to the file must be searchable. 

The fpathconf() function allows an application to retrieve the same information for an open file. 

Symbolic values for the name parameter are defined in the unistd.h header file, as follows:

_PC_LINK_MAX
The maximum number of links to the file. If the path or filedes parameter 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). This may be as small as 13, but is never larger than 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). This 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 or filedes parameter refers to a directory, the value returned applies to any FIFO that exists or can be created within the directory. 

_PC_CHOWN_RESTRICTED
This is applicable only to a directory file. The 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 will cause 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.

NOTES

AES Support Level:
Full use

RETURN VALUES

Upon successful completion, the pathconf() or fpathconf() function returns the specified parameter. Otherwise, a value of -1 is returned and errno is set to indicate the error. 

ERRORS

If the pathconf() function fails, errno may be set to the following value:

[EACCES]Search permission is denied for a component of the path prefix. 

[ELOOP]Too many links were encountered in translating a pathname. 

[EINVAL]The name parameter specifies an unknown or inapplicable characteristic. 

[EFAULT]The path argument is an invalid address. 

[ENAMETOOLONG]
The length of the path string exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}. 

[ENOENT]The named file does not exist or the path argument points to an empty strng. 

[ENOTDIR]A component of the path prefix is not a directory. 

If the fpathconf() function fails, errno may be set to the following value:

[ELOOP]Too many links were encountered in translating a pathname. 

[EINVAL]The name parameter specifies an unknown or inapplicable characteristic. 

[EBADF]The fildes argument is not a valid file descriptor.