contrib/plan9/9diff

plan9: initial support for plan 9 from bell labs

This patch contains support for Plan 9 from Bell Labs. A README is
provided in contrib/plan9 which describes the port in greater detail.
A new extension is also provided named factotum which permits the
factotum(4) authentication agent to provide credentials for HTTP
repositories. This extension is also applicable to other POSIX
platforms which make use of Plan 9 from User Space (aka plan9ports).

#!/bin/rc
# 9diff - Mercurial extdiff wrapper for diff(1)

rfork e

fn getfiles{
	cd $1 && \
	for(f in `{du -as | awk '{print $2}'})
		test -f $f && echo `{cleanname $f}
}

fn usage{
	echo >[1=2] usage: 9diff [diff options] parent child root
	exit usage
}

opts=()
while(~ $1 -*){
	opts=($opts $1)
	shift
}
if(! ~ $#* 3)
	usage

# extdiff will set the parent and child to a single file if there is
# only one change. If there are multiple changes, directories will be
# set. diff(1) does not cope particularly with directories; instead we
# do the recursion ourselves and diff each file individually.
if(test -f $1)
	diff $opts $1 $2
if not{
	# extdiff will create a snapshot of the working copy to prevent
	# conflicts during the diff. We circumvent this behavior by
	# diffing against the repository root to produce plumbable
	# output. This is antisocial.
	for(f in `{sort -u <{getfiles $1} <{getfiles $2}}){
		file1=$1/$f; test -f $file1 || file1=/dev/null
		file2=$3/$f; test -f $file2 || file2=/dev/null
		diff $opts $file1 $file2
	}
}
exit ''