Index: head/lib/libc/gen/directory.3
===================================================================
--- head/lib/libc/gen/directory.3	(revision 305153)
+++ head/lib/libc/gen/directory.3	(revision 305154)
@@ -1,286 +1,308 @@
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 .\" modification, are permitted provided that the following conditions
 .\" are met:
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 .\"    notice, this list of conditions and the following disclaimer.
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 .\"
 .\"     @(#)directory.3	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd February 19, 2016
+.Dd August 31, 2016
 .Dt DIRECTORY 3
 .Os
 .Sh NAME
 .Nm opendir ,
 .Nm fdopendir ,
 .Nm readdir ,
 .Nm readdir_r ,
 .Nm telldir ,
 .Nm seekdir ,
 .Nm rewinddir ,
 .Nm closedir ,
 .Nm fdclosedir ,
 .Nm dirfd
 .Nd directory operations
 .Sh LIBRARY
 .Lb libc
 .Sh SYNOPSIS
 .In dirent.h
 .Ft DIR *
 .Fn opendir "const char *filename"
 .Ft DIR *
 .Fn fdopendir "int fd"
 .Ft struct dirent *
 .Fn readdir "DIR *dirp"
 .Ft int
 .Fn readdir_r "DIR *dirp" "struct dirent *entry" "struct dirent **result"
 .Ft long
 .Fn telldir "DIR *dirp"
 .Ft void
 .Fn seekdir "DIR *dirp" "long loc"
 .Ft void
 .Fn rewinddir "DIR *dirp"
 .Ft int
 .Fn closedir "DIR *dirp"
 .Ft int
 .Fn fdclosedir "DIR *dirp"
 .Ft int
 .Fn dirfd "DIR *dirp"
 .Sh DESCRIPTION
+.Bf -symbolic
 The
+.Fn readdir_r
+interface is deprecated
+because it cannot be used correctly unless
+.Brq Va NAME_MAX
+is a fixed value.
+.Ef
+.Pp
+The
 .Fn opendir
 function
 opens the directory named by
 .Fa filename ,
 associates a
 .Em directory stream
 with it
 and
 returns a pointer to be used to identify the
 .Em directory stream
 in subsequent operations.
 The pointer
 .Dv NULL
 is returned if
 .Fa filename
 cannot be accessed, or if it cannot
 .Xr malloc 3
 enough memory to hold the whole thing.
 .Pp
 The
 .Fn fdopendir
 function is equivalent to the
 .Fn opendir
 function except that the directory is specified by a file descriptor
 .Fa fd
 rather than by a name.
 The file offset associated with the file descriptor at the time of the call
 determines which entries are returned.
 .Pp
 Upon successful return from
 .Fn fdopendir ,
 the file descriptor is under the control of the system,
 and if any attempt is made to close the file descriptor,
 or to modify the state of the associated description other than by means
 of
 .Fn closedir ,
 .Fn readdir ,
 .Fn readdir_r ,
 or
 .Fn rewinddir ,
 the behavior is undefined.
 Upon calling
 .Fn closedir
 the file descriptor is closed.
 The
 .Dv FD_CLOEXEC
 flag is set on the file descriptor by a successful call to
 .Fn fdopendir .
 .Pp
 The
 .Fn readdir
 function
 returns a pointer to the next directory entry.
-It returns
+The directory entry remains valid until the next call to
+.Fn readdir
+or
+.Fn closedir
+on the same
+.Em directory stream .
+The function returns
 .Dv NULL
 upon reaching the end of the directory or on error.
 In the event of an error,
 .Va errno
 may be set to any of the values documented for the
 .Xr getdirentries 2
 system call.
 .Pp
 The
 .Fn readdir_r
 function
 provides the same functionality as
 .Fn readdir ,
 but the caller must provide a directory
 .Fa entry
 buffer to store the results in.
+The buffer must be large enough for a
+.Vt struct dirent
+with a
+.Va d_name
+array with
+.Brq Va NAME_MAX
++ 1 elements.
 If the read succeeds,
 .Fa result
 is pointed at the
 .Fa entry ;
 upon reaching the end of the directory
 .Fa result
 is set to
 .Dv NULL .
 The
 .Fn readdir_r
 function
 returns 0 on success or an error number to indicate failure.
 .Pp
 The
 .Fn telldir
 function
 returns a token representing the current location associated with the named
 .Em directory stream .
 Values returned by
 .Fn telldir
 are good only for the lifetime of the
 .Dv DIR
 pointer,
 .Fa dirp ,
 from which they are derived.
 If the directory is closed and then
 reopened, prior values returned by
 .Fn telldir
 will no longer be valid.
 Values returned by
 .Fn telldir
 are also invalidated by a call to
 .Fn rewinddir .
 .Pp
 The
 .Fn seekdir
 function
 sets the position of the next
 .Fn readdir
 operation on the
 .Em directory stream .
 The new position reverts to the one associated with the
 .Em directory stream
 when the
 .Fn telldir
 operation was performed.
 .Pp
 The
 .Fn rewinddir
 function
 resets the position of the named
 .Em directory stream
 to the beginning of the directory.
 .Pp
 The
 .Fn closedir
 function
 closes the named
 .Em directory stream
 and frees the structure associated with the
 .Fa dirp
 pointer,
 returning 0 on success.
 On failure, \-1 is returned and the global variable
 .Va errno
 is set to indicate the error.
 .Pp
 The
 .Fn fdclosedir
 function is equivalent to the
 .Fn closedir
 function except that this function returns directory file descriptor instead of
 closing it.
 .Pp
 The
 .Fn dirfd
 function
 returns the integer file descriptor associated with the named
 .Em directory stream ,
 see
 .Xr open 2 .
 .Pp
 Sample code which searches a directory for entry ``name'' is:
 .Bd -literal -offset indent
 dirp = opendir(".");
 if (dirp == NULL)
 	return (ERROR);
 len = strlen(name);
 while ((dp = readdir(dirp)) != NULL) {
 	if (dp->d_namlen == len && strcmp(dp->d_name, name) == 0) {
 		(void)closedir(dirp);
 		return (FOUND);
 	}
 }
 (void)closedir(dirp);
 return (NOT_FOUND);
 .Ed
 .Sh SEE ALSO
 .Xr close 2 ,
 .Xr lseek 2 ,
 .Xr open 2 ,
 .Xr read 2 ,
 .Xr dir 5
 .Sh HISTORY
 The
 .Fn opendir ,
 .Fn readdir ,
 .Fn telldir ,
 .Fn seekdir ,
 .Fn rewinddir ,
 .Fn closedir ,
 and
 .Fn dirfd
 functions appeared in
 .Bx 4.2 .
 The
 .Fn fdopendir
 function appeared in
 .Fx 8.0 .
 .Fn fdclosedir
 function appeared in
 .Fx 10.0 .
 .Sh BUGS
 The behaviour of
 .Fn telldir
 and
 .Fn seekdir
 is likely to be wrong if there are parallel unlinks happening
 and the directory is larger than one page.
 There is code to ensure that a
 .Fn seekdir
 to the location given by a 
 .Fn telldir
 immediately before the last 
 .Fn readdir
 will always set the correct location to return the same value as that last
 .Fn readdir
 performed.
 This is enough for some applications which want to "push back the last entry read" E.g. Samba. 
 Seeks back to any other location,
 other than the beginning of the directory,
 may result in unexpected behaviour if deletes are present.
 It is hoped that this situation will be resolved with changes to
 .Fn getdirentries
 and the VFS.