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Date:      Sun, 20 Aug 2000 04:35:50 -0700 (PDT)
From:      Kris Kennaway <kris@FreeBSD.org>
To:        ports@freebsd.org
Subject:   Proposal: PORTREVISION and PORTEPOCH
Message-ID:  <Pine.BSF.4.21.0008200434470.24448-100000@freefall.freebsd.org>

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PROPOSAL FOR PACKAGE NAMING CONVENTIONS

0) EXECUTIVE SUMMARY

The current versioning scheme for packages built from FreeBSD ports is
insufficient to convey all the information about the port it is based
on, since it doesn't reflect FreeBSD-specific
patches/fixes/alterations made to the generating port.

The proposal is that we adopt two new version numbers: PORTREVISION
and PORTEPOCH which are used to construct the package name as follows:

${PORTNAME}-${PORTVERSION}[_${PORTREVISION}][:${PORTEPOCH}]

compared to the current system of:

${PORTNAME}-${PORTVERSION}

1) PORTREVISION

The PORTREVISION variable is a monotonically increasing value which is
reset to 0 with every increase of PORTVERSION (i.e. every time a new
official vendor release is made), and appended to the package name if
non-zero. PORTREVISION is increased each time a change is made to the
FreeBSD port which significantly affects the content or stucture of
the derived package.

Examples of when PORTREVISION should be bumped:

	* Addition of patches to correct security vulnerabilities,
	  bugs, or to add new functionality to the FreeBSD port

	* Changes to the port makefile to enable or disable
	  compile-time options

	* Changes in the packing list or the install-time behaviour of
	  the package (e.g. change to a script which generates initial
	  data for the package, like ssh host keys)

	* Version bump of a port's shared library dependency (in this
	  case, someone trying to install the old package after
	  installing a newer version of the dependency will fail since
	  it will look for the old libfoo.x instead of libfoo.(x+1))

	* "Silent" changes to the port distfile which have significant
	  functional differences, i.e. changes to the distfile
	  requiring a correction to files/md5 with no corresponding
	  change to PORTVERSION, where a diff -ruN of the old and new
	  versions shows non-trivial changes to the code.

Examples of changes which do not require a PORTREVISION bump:

	* Style changes to the port skeleton with no functional change
	  to what it does

	* Changes to MASTER_SITES or other functional changes to the
	  port which do not effect the resulting package

	* Trivial patches to the distfile such as correction of typos,
	  which are not important enough that users of the package
	  should go to the trouble of upgrading.

A rule of thumb is to ask yourself whether a change committed to a
port is something which someone, somewhere, would benefit from having
(either because of an enhancement, fix, or by virtue that the new
package will actually work for them). If yes, the PORTREVISION should
be bumped so that automated tools (e.g. pkg_version) will hilight the
fact that a new package is available.

2) PORTEPOCH

From time to time a software vendor or FreeBSD porter will do
something silly and release a version of their software which is
actually numerically less than the previous version. An example of
this is a port which goes from foo-20000801 to foo-1.0 (the former
will be incorrectly treated as a newer version since 20000801 is a
numerically greater value than 1).

In situations such as this, the PORTEPOCH version should be
increased. If PORTEPOCH is nonzero it is appended to the package name
as described in section 0 above. PORTEPOCH is never decreased or reset
to zero, because that would cause comparison to a package from an
earlier epoch to fail (i.e. the package would not be detected as out
of date): the new version number (e.g. "1.0:1" in the above example) is
still numerically less than the previous version (2000801), but the
":1" suffix is treated specially by automated tools and found to be
greater than the implied suffix ":0" on the earlier package)

It is expected that PORTEPOCH will not be used for the majority of
ports, and that sensible use of PORTVERSION can often pre-empt it
becoming necessary if a future release of the software should change
the version structure.

3) EXAMPLE

The gtkmumble port, version 0.10, is committed to the ports collection.

PORTNAME=	gtkmumble
PORTVERSION=	0.10

PKGNAME becomes "gtkmumble-0.10"

A security hole is discovered which requires a local FreeBSD
patch. PORTREVISION is bumped accordingly.

PORTNAME=	gtkmumble
PORTVERSIOn=	0.10
PORTREVISION=	1

PKGNAME becomes "gtkmumble-0.10_1"

A new version is released by the vendor, numbered 0.2 (it turns out
the author actually intended "0.10" to actually mean "0.1.0", not
"what comes after 0.9" - oops, too late now). Since the new minor
version "2" is numerically less than the previous version "10" the
PORTEPOCH must be bumped to manually force the new package to be
detected as "newer". Since it is a new vendor release of the code,
PORTREVISION is reset to 0 (or removed from the makefile)

PORTNAME=	gtkmumble
PORTVERSION=	0.2
PORTEPOCH=	1

PKGNAME becomes "gtkmumble-0.2:1"

The next release is 0.3. Since PORTEPOCH never decreases, the version
variables are now:

PORTNAME=	gtkmumble
PORTVERSION=	0.3
PORTEPOCH=	1

PKGNAME becomes "gtkmumble-0.3:1"

Note that if PORTEPOCH were reset to 0 with this upgrade, someone who
had installed the gtkmumble-0.10_1 package would not detect the
gtkmumble-0.3 package as newer, since "3" is still numerically less
than "10".

4) BENEFITS

There are three main benefits to a more granular naming scheme:

* Finer control over external references to packages. For example,
  when a security fix is made to the port, and PORTREVISION is
  increased accordinging, the relevant security advisory can point
  unambigiously to the new package name, instead of referring vaguely
  to "packages dated after the correction date", which is ambiguous
  and error-prone.

* The ability for end-users to tell when a significant change has been
  made to the FreeBSD version of a port, and to unambiguously detect
  newer versions of the package (the current version is error-prone
  due to the lack of PORTEPOCH)

* It lays the foundation for future automated upgrade systems, which
  can rebuild complex dependency chains of packages when changes are
  made.

5) IMPACT

These changes should not require modification of the existing
port/package infrastructure beyond the trivial change to bsd.port.mk
to generate the new names, and changes to pkg_version (and other
tools, if they exist), to make full use of the new format. In
particular, the new format should be completely backwards-compatible
with old tools (i.e. they will work as well as before), while allowing
future improvements to provide increased functionality.


--
In God we Trust -- all others must submit an X.509 certificate.
    -- Charles Forsythe <forsythe@alum.mit.edu>



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