Add support for "freebsd-update -r newrelease upgrade" -- binary

upgrading to new releases.  Important parts of this code include
 * automatically determining which optional components (e.g., src,
info, proflibs) are installed.
 * merging changes in files which are modified locally and have
changed between the currently running and new release.
 * prompting the user to rebuild all 3rd party software before
deleting old shared libraries.

Yes, this is compatible with "freebsd-update rollback" -- you can
test a new -BETA and roll back to the old release if you don't
like it.

Subject to re@ approval, this will be MFCed before 7.0-BETA3 and
6.3-RC1.

MFC after:	2 days

etc/freebsd-update.conf

@@ -23,9 +23,13 @@ IgnorePaths
 
 # Paths which start with anything matching an entry in an UpdateIfUnmodified
 # statement will only be updated if the contents of the file have not been
-# modified by the user.
+# modified by the user (unless changes are merged; see below).
 UpdateIfUnmodified /etc/ /var/
 
+# When upgrading to a new FreeBSD release, files which match MergeChanges
+# will have any local changes merged into the version from the new release.
+MergeChanges /etc/ /var/named/etc/
+
 ### Default configuration options:
 
 # Directory in which to store downloaded updates and temporary
@@ -46,3 +50,9 @@ UpdateIfUnmodified /etc/ /var/
 # FreeBSD Update retain this modified metadata when installing a new version
 # of that file?
 # KeepModifiedMetadata yes
+
+# When upgrading between releases, should the list of Components be
+# read strictly (StrictComponents yes) or merely as a list of components
+# which *might* be installed of which FreeBSD Update should figure out
+# which actually are installed and upgrade those (StrictComponents no)?
+# StrictComponents no

share/man/man5/freebsd-update.conf.5

@@ -93,7 +93,15 @@ accumulate.
 The parameters following this keyword are regular expressions;
 updates to paths which start with a string matching one of
 these regular expressions will be ignored if the files have
-been modified locally.
+been modified locally (unless they are merged -- see MergeChanges
+below).
+.Pp
+This option can be specified multiple times, and the parameters
+accumulate.
+.It Cm MergeChanges
+The parameters following this keyword are regular expressions;
+updates to paths which start with a string matching one of
+these regular expressions will be merged with local modifications.
 .Pp
 This option can be specified multiple times, and the parameters
 accumulate.
@@ -138,6 +146,24 @@ and specifies whether
 .Cm freebsd-update
 should keep existing file ownership, permissions, and flags
 when installing updates if these have been modified locally.
+.It Cm StrictComponents
+The single parameter following this keyword must be
+.Dq yes
+or
+.Dq no
+and specifies whether
+.Cm freebsd-update
+should interpret the list of components of
+.Fx
+specified via the
+.Cm Components
+option strictly as a list of components installed which
+should be upgraded when the
+.Cm upgrade
+command is used ("yes"), or merely as a list of components
+which might be installed, of which
+.Cm freebsd-update
+should identify which in fact are present ("no").
 .El
 .Sh FILES
 .Bl -tag -width "/etc/freebsd-update.conf"

usr.sbin/freebsd-update/freebsd-update.8

@@ -1,5 +1,5 @@
 .\"-
-.\" Copyright 2006 Colin Percival
+.\" Copyright 2006, 2007 Colin Percival
 .\" All rights reserved
 .\"
 .\" Redistribution and use in source and binary forms, with or without
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 30, 2006
+.Dd November 11, 2007
 .Dt FREEBSD-UPDATE 8
 .Os FreeBSD
 .Sh NAME
@@ -37,6 +37,7 @@
 .Op Fl d Ar workdir
 .Op Fl f Ar conffile
 .Op Fl k Ar KEY
+.Op Fl r Ar newrelease
 .Op Fl s Ar server
 .Op Fl t Ar address
 .Cm command ...
@@ -84,6 +85,10 @@ Read configuration options from
 Trust an RSA key with SHA256 of
 .Ar KEY .
 (default: read value from configuration file.)
+.It Fl r Ar newrelease
+Specify the new release to which
+.Nm
+should upgrade (upgrade command only).
 .It Fl s Ar server
 Fetch files from the specified server or server pool.
 (default: read value from configuration file.)
@@ -118,8 +123,13 @@ from
 the random delay serves to minimize the probability that
 a large number of machines will simultaneously attempt to
 fetch updates.
+.It Cm upgrade
+Fetch files necessary for upgrading to a new release.
+Before using this command, make sure that you read the
+announcement and release notes for the new release in
+case there are any special steps needed for upgrading.
 .It Cm install
-Install the most recently fetched updates.
+Install the most recently fetched updates or upgrade.
 .It Cm rollback
 Uninstall the most recently installed updates.
 .El