Eliminate some magic numbers and correct description of _PC_NO_TRUNC.

Slight emendation to _PC_CHOWN_RESTRICTED, which is in a very similar
boat.

1 files changed, 23 insertions, 4 deletions

diff --git a/lib/libc/sys/pathconf.2 b/lib/libc/sys/pathconf.2
index e0679a0..b3d61ad 100644
--- a/lib/libc/sys/pathconf.2
+++ b/lib/libc/sys/pathconf.2
@@ -90,11 +90,24 @@ The maximum number of bytes in a pathname.
 .It Li _PC_PIPE_BUF
 The maximum number of bytes which will be written atomically to a pipe.
 .It Li _PC_CHOWN_RESTRICTED
-Return 1 if appropriate privileges are required for the
+Return 1 if appropriate privilege is required for the
 .Xr chown 2
 system call, otherwise 0.
+.St -p1003.1-2001
+requires appropriate privilege in all cases, but this behavior was optional
+in prior editions of the standard.
 .It Li _PC_NO_TRUNC
-Return 1 if file names longer than _POSIX_NAME_MAX are truncated.
+Return greater than zero if attempts to use pathname components longer than
+.Brq Li NAME_MAX
+will result in an
+.Bq Er ENAMETOOLONG
+error; otherwise, such components will be truncated to
+.Brq Li NAME_MAX .
+.St -p1003.1-2001
+requires the error in all cases, but this behavior was optional in prior
+editions of the standard, and some
+.No non- Ns Tn POSIX Ns \&-compliant
+filesystems do not support this behavior.
 .It Li _PC_VDISABLE
 Returns the terminal character disabling value.
 .It Li _PC_ASYNC_IO
@@ -175,8 +188,14 @@ will fail if:
 .It Bq Er ENOTDIR
 A component of the path prefix is not a directory.
 .It Bq Er ENAMETOOLONG
-A component of a pathname exceeded 255 characters,
-or an entire path name exceeded 1023 characters.
+A component of a pathname exceeded 
+.Brq Dv NAME_MAX
+characters (but see
+.Dv _PC_NO_TRUNC
+above),
+or an entire path name exceeded 
+.Brq Dv PATH_MAX
+characters.
 .It Bq Er ENOENT
 The named file does not exist.
 .It Bq Er EACCES