pathconf(3) Library Functions Manual pathconf(3)Name
pathconf, fpathconf - get configurable pathname variables (POSIX)
Syntax
#include <unistd.h>
long pathconf(path, name)
char *path;
int name;
long fpathconf(fildes, name)
int fildes, name;
Description
The and functions provide a method for the application to determine the current value of a configurable limit or option that is associated
with a file or directory.
For the path argument points to the pathname of a file or directory. For the fildes argument is an open file descriptor.
The name argument represents the variable to be queried relative to that file or directory. The following table lists the variables which
may be queried and the corresponding value for the name argument. The values for the name argument are defined in the <unistd.h> header
file.
Variable name Value
LINK_MAX _PC_LINK_MAX
MAX_CANON _PC_MAX_CANON
MAX_INPUT _PC_MAX_INPUT
NAME_MAX _PC_NAME_MAX
PATH_MAX _PC_PATH_MAX
PIPE_BUF _PC_PIPE_BUF
_POSIX_CHOWN_RESTRICTED _PC_CHOWN_RESTRICTED
_POSIX_NO_TRUNC _PC_NO_TRUNC
_POSIX_VDISABLE _PC_VDISABLE
Return Values
Upon successful completion, the and functions return the current variable value for the file or directory.
If name is an invalid value, and return -1 and errno is set to indicate the reason. If the variable corresponding to name is not defined on
the system, and return -1 without changing the value of errno.
Diagnostics
The and functions fail if the following occurs:
[EINVAL] The value of the name argument is invalid.
See Also
<unistd.h>
pathconf(3)
Check Out this Related Man Page
fpathconf(2) System Calls fpathconf(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 fpathconf() and pathconf() functions determine the current value of a configurable limit or option ( variable ) that is associated with
a file or directory.
For pathconf(), the path argument points to the pathname of a file or directory.
For fpathconf(), the fildes argument is an open file descriptor.
The name argument represents the variable to be queried relative to that file or directory. The variables in the following table come from
<limits.h> or <unistd.h> and the symbolic constants, defined in <unistd.h>, are the corresponding values used for name:
+---------------------------+------------------------+--------------+
| Variable | Value of name | Notes |
+---------------------------+------------------------+--------------+
|{ACL_ENABLED} | _PC_ACL_ENABLED | 10 |
+---------------------------+------------------------+--------------+
|{FILESIZEBITS} | _PC_FILESIZEBITS | 3,4 |
+---------------------------+------------------------+--------------+
|{LINK_MAX} | _PC_LINK_MAX | 1 |
+---------------------------+------------------------+--------------+
|{MAX_CANON} | _PC_MAX_CANON | 2 |
+---------------------------+------------------------+--------------+
|{MAX_INPUT} | _PC_MAX_INPUT | 2 |
+---------------------------+------------------------+--------------+
|{MIN_HOLE_SIZE} | _PC_MIN_HOLE_SIZE | 11 |
+---------------------------+------------------------+--------------+
|{NAME_MAX} | _PC_NAME_MAX | 3, 4 |
+---------------------------+------------------------+--------------+
|{PATH_MAX} | _PC_PATH_MAX | 4,5 |
+---------------------------+------------------------+--------------+
|{PIPE_BUF} | _PC_PIPE_BUF | 6 |
+---------------------------+------------------------+--------------+
|{POSIX_ALLOC_SIZE_MIN} | _PC_ALLOC_SIZE_MIN | |
+---------------------------+------------------------+--------------+
|{POSIX_REC_INCR_XFER_SIZE} | _PC_REC_INCR_XFER_SIZE | |
+---------------------------+------------------------+--------------+
|{POSIX_REC_MAX_XFER_SIZE} | _PC_REC_MAX_XFER_SIZE | |
+---------------------------+------------------------+--------------+
|{POSIX_REC_MIN_XFER_SIZE} | _PC_REC_MIN_XFER_SIZE | |
+---------------------------+------------------------+--------------+
|{POSIX_REC_XFER_ALIGN} | _PC_REC_XFER_ALIGN | |
+---------------------------+------------------------+--------------+
|{SYMLINK_MAX} | _PC_SYMLINK_MAX | 4, 9 |
+---------------------------+------------------------+--------------+
|{XATTR_ENABLED} | _PC_XATTR_ENABLED | 1 |
+---------------------------+------------------------+--------------+
|{XATTR_EXISTS} | _PC_XATTR_EXISTS | 1 |
+---------------------------+------------------------+--------------+
|_POSIX_CHOWN_RESTRICTED | _PC_CHOWN_RESTRICTED | 7 |
+---------------------------+------------------------+--------------+
|_POSIX_NO_TRUNC | _PC_NO_TRUNC | 3, 4 |
+---------------------------+------------------------+--------------+
|_POSIX_VDISABLE | _PC_VDISABLE | 2 |
+---------------------------+------------------------+--------------+
|_POSIX_ASYNC_IO | _PC_ASYNC_IO | 8 |
+---------------------------+------------------------+--------------+
|_POSIX_PRIO_IO | _PC_PRIO_IO | 8 |
+---------------------------+------------------------+--------------+
|_POSIX_SYNC_IO | _PC_SYNC_IO | 8 |
+---------------------------+------------------------+--------------+
Notes:
1. If path or fildes refers to a directory, the value returned applies to the directory itself.
2. If path or fildes does not refer to a terminal file, it is unspecified whether an implementation supports an association of the
variable name with the specified file.
3. If path or fildes refers to a directory, the value returned applies to filenames within the directory.
4. If path or fildes does not refer to a directory, it is unspecified whether an implementation supports an association of the
variable name with the specified file.
5. If path or fildes refers to a directory, the value returned is the maximum length of a relative pathname when the specified
directory is the working directory.
6. If path refers to a FIFO, or fildes refers to a pipe or FIFO, the value returned applies to the referenced object. If path or
fildes refers to a directory, the value returned applies to any FIFO that exists or can be created within the directory. If path
or fildes refers to any other type of file, it is unspecified whether an implementation supports an association of the variable
name with the specified file.
7. If path or fildes refers to a directory, the value returned applies to any files, other than directories, that exist or can be
created within the directory.
8. If path or fildes refers to a directory, it is unspecified whether an implementation supports an association of the variable
name with the specified file.
9. If path or fildes refers to a directory, the value returned is the maximum length of the string that a symbolic link in that
directory can contain.
10. If path or fildes refers to a file or directory in a file system that supports ACLs, the value returned is the bitwise inclusive
OR of the following flags associated with ACL types supported by the file system; otherwise 0 is returned.
_ACL_ACE_ENABLEDThe file system supports ACE ACLs.
_ACL_ACLENT_ENABLED The file system supports UFS aclent ACLs.
11. If a filesystem supports the reporting of holes (see lseek(2), pathconf() and fpathconf() return a positive number that repre-
sents the minimum hole size returned in bytes. The offsets of holes returned will be aligned to this same value. A special value
of 1 is returned if the filesystem does not specify the minimum hole size but still reports holes.
RETURN VALUES
If name is an invalid value, both pathconf() and fpathconf() return -1 and errno is set to indicate the error.
If the variable corresponding to name has no limit for the path or file descriptor, both pathconf() and fpathconf() return -1 without
changing errno. If pathconf() needs to use path to determine the value of name and pathconf() does not support the association of name with
the file specified by path, or if the process did not have appropriate privileges to query the file specified by path, or path does not
exist, pathconf() returns -1 and errno is set to indicate the error.
If fpathconf() needs to use fildes to determine the value of name and fpathconf() does not support the association of name with the file
specified by fildes, or if fildes is an invalid file descriptor, fpathconf() returns -1 and errno is set to indicate the error.
Otherwise pathconf() or fpathconf() returns the current variable value for the file or directory without changing errno. The value returned
will not be more restrictive than the corresponding value available to the application when it was compiled with <limits.h> or <unistd.h>.
ERRORS
The pathconf() function will fail if:
EINVAL The value of name is not valid.
ELOOP A loop exists in symbolic links encountered during resolution of the path argument.
The fpathconf() function will fail if:
EINVAL The value of name is not valid.
The pathconf() function may fail if:
EACCES Search permission is denied for a component of the path prefix.
EINVAL An association of the variable name with the specified file is not supported.
ENAMETOOLONG The length of the path argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.
ENAMETOOLONG As a result of encountering a symbolic link in resolution of the path argument, the length of the substituted pathname
string exceeded {PATH_MAX}.
ENOENT A component of path does not name an existing file or path is an empty string.
ENOTDIR A component of the path prefix is not a directory.
The fpathconf() function may fail if:
EBADF The fildes argument is not a valid file descriptor.
EINVAL An association of the variable name with the specified file is not supported.
USAGE
The {SYMLINK_MAX} variable applies only to the fpathconf() function.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
|MT-Level |Async-Signal-Safe |
+-----------------------------+-----------------------------+
SEE ALSO lseek(2), confstr(3C), limits.h(3HEAD), sysconf(3C), attributes(5), standards(5)SunOS 5.11 1 Apr 2005 fpathconf(2)