Partially non-traditional(2) tftp write access control:
  tftpd(8):
  (1) files may be written only if they already exist and are publicly writable.

  (2)	-w	Allow writes requests to create new files.  By default tftpd
		requires that the file specified in a write request exist.


Condition: `-w' allow writes requests to create new files.

Summary, creation new files:
absolute filenames - incorrect
relative filenames - correct

Fix: for example: variants (1), (2), and (3).


variant (1):
  tftpd(8) manual correction only:

	-w	Allow writes requests to create new files.  By default tftpd
		requires that the file specified in a write request exist.
+		File creation are allowed for relative file names only.




variant (2):
  small code correction (create request w/ absolute file names):

variant (3):
  non-traditional read/write access control:

tftpd(8):
-	-w	Allow writes requests to create new files.  By default tftpd
-		requires that the file specified in a write request exist.
+	-w	Offers a non-traditional (for tftp) access control, which
+		will allows to read, write, and create files, with credentials
+		to tftpd ``user'' (default ``nobody'') only.
How-To-Repeat: 
~# grep '^tftp' /etc/inetd.conf
tftp	dgram	udp	wait	root	/usr/libexec/tftpd	tftpd -l -w -s /spool/tftp

~# touch a
~# mkdir /spool/tftp/1
~# chown nobody:nogroup /spool/tftp/1
~# chmod 755 /spool/tftp/1
~# rm -f /spool/tftp/1/a
~# tftp localhost
tftp| put a /1/a
Error code 1: File not found
  ! error - incorrect (for `tftpd -w')
tftp| put a 1/a
  ! no error - correct (for `tftpd -w')