Date: Mon, 30 Jan 95 20:21:55 PST
From: wmb@FirmWorks.COM (Mitch Bradley)
To: p1275-wg@prombo.eng.sun.com
Reply-To: p1275-wg@prombo.eng.sun.com
Subject: Item #225: Alias expansion bug

P1275 Openboot Working Group Proposal -- Proposal #:225 Ver 1

Title:		Alias expansion bug

Author:		Mitch Bradley

Date:		1/30/95

Ed/Tech:	Technical

Synopsis:	Alias expansion fails with short expansions

Doc & Version:	1275-1994  ->  Errata document

Problem:	If "foo" is an alias for "/bar", the alias expansion
		algorithm in section 4.3.1 expands "foo:0" to "bar:0"
		instead of "/bar:0" (as reported by Brian Horn).

Proposal:

* Add the following to the Errata document.

(The following page and line numbers refer to P1275-D12.)

* Replace Page 46 lines 44-46 with:

	split-before(string, 'x') -> initial, remainder

    split-before is similar to left-split, except that if 'x' occurs in
    'string', 'remainder' begins with the first occurrence of 'x' (left-split
    removes the first occurrence of 'x' from 'remainder')

	split-after(string, 'x') -> initial, remainder

    split-after is similar to split-before, except that the division of the
    string occurs after the last occurrence of the character 'x'.  If 'x'
    occurs in 'string', 'initial' ends with 'x', and 'remainder' begins with
    the first character, if any, following that last occurrence of 'x'.
    If 'x' does not occur in 'string', 'initial' is set to 'string' and
    'remainder' is set to the empty string.

* On page 47 lines 1 and 2, replace "left-split and right-split" with
  "left-split, split-before, and split-after"

* Replace page 47 lines 14-26 with:

	1) Split-before(PATH_NAME, "/") -> HEAD,TAIL
	2) Split-before(HEAD, ":") -> ALIAS_NAME, ALIAS_ARGS
	3) If ALIAS_NAME matches a defined alias:
	   i)    Replace ALIAS_NAME with its alias value.
	   ii)   If ALIAS_ARGS is not empty:
		a) Split-after(ALIAS_NAME, "/") -> ALIAS_HEAD, ALIAS_TAIL
		b) Split-before(ALIAS_TAIL, ":") -> ALIAS_TAIL, DEAD_ARGS
		c) Concatenate(ALIAS_HEAD,ALIAS_TAIL,ALIAS_ARGS) -> ALIAS_NAME
	   iii)  Concatentate(ALIAS_NAME, TAIL) -> PATH_NAME

[ P1275 Item #225 -- Received: Mon Jan 30 20:23:55 PST 1995 ]