Import: Consolidate emails into coherent plan

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/README.dsc-import b/README.dsc-import
index f5bb0bdb2e4673a75d8b2aff6ce6c474cff06f47..ede7d9e3b299c154a3169739b48289119f3c501d 100644 (file)
--- a/README.dsc-import
+++ b/README.dsc-import
@@ -1,45 +1,4 @@
-From ijackson Mon Sep 26 15:37:19 +0100 2016
-X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil]
-       [nil "Monday" "26" "September" "2016" "15:37:19" "+0100" "Ian Jackson" "ijackson@chiark.greenend.org.uk" nil nil "Intent to commit craziness - source package unpacking" "^From:" nil nil "9" nil nil nil nil nil nil nil nil nil nil]
-       nil)
-X-Mozilla-Status: 0001
-X-Mozilla-Status2: 00000000
-MIME-Version: 1.0
-Content-Type: text/plain; charset=us-ascii
-Content-Transfer-Encoding: 7bit
-Message-ID: <22505.12959.668142.478444@chiark.greenend.org.uk>
-X-Mailer: VM 8.2.0b under 24.4.1 (i586-pc-linux-gnu)
-From: Ian Jackson <ijackson@chiark.greenend.org.uk>
-To: debian-dpkg@lists.debian.org,
-    Guido Guenther <agx@debian.org>,
-    Bernhard R. Link <brlink@debian.org>,
-    vcs-pkg-discuss@lists.alioth.debian.org
-Subject: Intent to commit craziness - source package unpacking
-Date: Mon, 26 Sep 2016 15:37:19 +0100
-
-tl;dr:
-
- * dpkg developers, please tell me whether I am making assumptions
-   that are likely to become false.  Particularly, on the behaviour of
-   successive runs of dpkg-source --before-build with successively
-   longer series files.
-
- * git-buildpackage and git-dpm developers, please point me to
-   information about what metadata to put into the commit message for
-   a git commit which represents a dpkg-source quilt patch.  I would
-   like these commits to be as convenient for gbp and git-dpm users as
-   possible.
-
-
-Hi.
-
-Currently when dgit needs to import a .dsc into git, it just uses
-dpkg-source -x, and git-add.  The result is a single commit where the
-package springs into existence fully formed.  This is not as good as
-it could be.  I would like to represent (in the git pseudohistory) the
-way that the resulting tree is constructed from the input objects.
-
-In particular, I would like to: represent the input tarballs as a
+I would like to: represent the input tarballs as a

 commit each (which all get merged together as if by git merge -s
 subtree), and for quilt packages, each patch as a commit.  But I want
 to avoid (as much as possible) reimplementing the package extraction
 commit each (which all get merged together as if by git merge -s
 subtree), and for quilt packages, each patch as a commit.  But I want
 to avoid (as much as possible) reimplementing the package extraction


@@ -68,17 +27,17 @@ So I intend to do as follows.  (Please hold your nose.)
   with the right upstream version component, and the information found
   there used for the commit object's metadata.)
 
   with the right upstream version component, and the information found
   there used for the commit object's metadata.)
 

-* dgit will then run dpkg-source -x --skip-patches.
+* For `3.0 (quilt), dgit will run
+    dpkg-source -x --skip-patches

 
 

-  Again, git plumbing will be used to make this into a tree and a
+  git plumbing will be used to make the result into a tree and a

   commit.  The commit will have as parents all the tarballs previous
   commit.  The commit will have as parents all the tarballs previous

-  mentioned.  The metadata will come from the .dsc and/or the
-  final changelog entry.
+  mentioned.  The metadata will come from the .dsc and/or the final
+  changelog entry.

 
 

-* dgit will look to see if the package is `3.0 (quilt)' and if so
-  whether it has a series file.  (dgit already rejects packages with
-  distro-specific series files, so we need worry only about a single
-  debian/patches/series file.)
+  dgit will then see if it has a series file.  (dgit already rejects
+  packages with distro-specific series files, so we need worry only
+  about a single debian/patches/series file.)

 
   If there is a series file, dgit will read it into memory.  It will
   then iterate over the series file, and each time:
 
   If there is a series file, dgit will read it into memory.  It will
   then iterate over the series file, and each time:


@@ -92,11 +51,16 @@ So I intend to do as follows.  (Please hold your nose.)
       (either the previous commit, or the commit resulting from
       dpkg-source -x)
 
       (either the previous commit, or the commit resulting from
       dpkg-source -x)
 

-  After this the series file has been completely rewritten.
+  After this the series file has been completely rewritten in
+  this way, the tree should be identical to the results of
+  dpkg-source -x.

 
 

-* dgit will then run one final invocation of dpkg-source
-  --before-build.  This ought not to produce any changes, but if
-  it does, they will be represented as another commit.
+* For source formats other than `3.0 (quilt)', dgit will do simply
+    dpkg-source -x.
+
+  Again, it will make that into a tree and a commit.  (If this commit
+  has no changes in its tree from the first tarball commit. then the
+  two are squashed together.)

 
 * As currently, there will be a final no-change-to-the-tree
   pseudomerge commit which stitches the package into the relevant dgit
 
 * As currently, there will be a final no-change-to-the-tree
   pseudomerge commit which stitches the package into the relevant dgit


@@ -155,138 +119,4 @@ This has the following properties:
   Topic".
 
 * The scheme I describe avoids introducing a dependency from dgit to
   Topic".
 
 * The scheme I describe avoids introducing a dependency from dgit to

-  git-buildpackage.  I might be able to replace the
-  successive-patch-application part with an appropriate invocation of
-  gbp-pq.  Would that be better ?
-
-  Bear in mind that because the output of gbp-pq import doesn't
-  contain debian/patches, I would need to rewrite its output (perhaps
-  with git-filter-branch).
-
-
-Comments welcome.  Please be quick - this is very close to the top of
-my dgit todo list.
-
-
-Thanks,
-Ian.
-
-
--- 
-Ian Jackson <ijackson@chiark.greenend.org.uk>   These opinions are my own.
-
-If I emailed you from an address @fyvzl.net or @evade.org.uk, that is
-a private address which bypasses my fierce spamfilter.
-
-From ijackson Wed Sep 28 10:50:49 +0100 2016
-X-VM-v5-Data: ([nil nil nil nil t nil nil nil nil nil nil nil nil nil nil nil]
-       [nil "Wednesday" "28" "September" "2016" "10:50:49" "+0100" "Ian Jackson" "ijackson@chiark.greenend.org.uk" "<22507.37497.633622.843659@chiark.greenend.org.uk>" nil "Re: Intent to commit craziness - source package unpacking" "^From:" nil nil "9" nil nil nil nil nil nil nil nil nil nil]
-       nil)
-X-Mozilla-Status: 0003
-X-Mozilla-Status2: 00000000
-MIME-Version: 1.0
-Content-Type: text/plain; charset=iso-8859-1
-Content-Transfer-Encoding: quoted-printable
-Message-ID: <22507.37497.633622.843659@chiark.greenend.org.uk>
-In-Reply-To: <20160928010117.nqe2prbsbaqkbjza@gaara.hadrons.org>
-References: <22505.12959.668142.478444@chiark.greenend.org.uk>
-       <20160928010117.nqe2prbsbaqkbjza@gaara.hadrons.org>
-X-Mailer: VM 8.2.0b under 24.4.1 (i586-pc-linux-gnu)
-From: Ian Jackson <ijackson@chiark.greenend.org.uk>
-To: Guillem Jover <guillem@debian.org>
-Cc: debian-dpkg@lists.debian.org,
-    Guido Guenther <agx@debian.org>,
-    "Bernhard R. Link" <brlink@debian.org>,
-    vcs-pkg-discuss@lists.alioth.debian.org
-Subject: Re: Intent to commit craziness - source package unpacking
-Date: Wed, 28 Sep 2016 10:50:49 +0100
-
-Guillem Jover writes ("Re: Intent to commit craziness - source package =
-unpacking"):
-> On Mon, 2016-09-26 at 15:37:19 +0100, Ian Jackson wrote:
-> > tl;dr:
-> >=20
-> >  * dpkg developers, please tell me whether I am making assumptions
-> >    that are likely to become false.  Particularly, on the behaviour=
- of
-> >    successive runs of dpkg-source --before-build with successively
-> >    longer series files.
->=20
-> For format =AB3.0 (quilt)=BB, that seems fine, to the point I'm fine =
-even
-> documenting this, which I can probably do for 1.18.11.
-
-Great.
-
-> For other formats, such as =AB2.0=BB, I don't think that's true, but =
-I
-> assume you don't care about that one anyway. But just mentioning
-> because this behavior is probably format-specific. For =AB2.0=BB I
-> think it could be fixed, and should not be too hard (not sure if it's=
-
-> worth it though).
-
-I think the right approach is perhaps to use --skip-patches and
---before-build only with 3.0 (quilt).  The that would leave 2.0 (or
-other strange or future formats) producing a correct (although
-possibly sub-optimal) import.
-
-> > dpkg-source does not currently provide interfaces that look like th=
-ey
-> > are intended for what I want to do.  And dgit wants to work with ol=
-d
-> > versions of dpkg, so I don't want to block on getting such interfac=
-es
-> > added (even supposing that a sane interface could be designed, whic=
-h
-> > is doubtful).
->=20
-> Even then I'm still interested in a decription of what you'd need
-> ideally, to take into account when having a pass at cleaning up that
-> part of the interface. I think you could be interested in a cleaner
-> Dpkg::Source::* hierarchy, for the mid/long-term?
-
-For `3.0 (quilt)' explicit interfaces for applying and unapplying
-individual patches would help.  But really IMO such an interface ought
-to be exposed on the command line rather than (or as well as) via a
-Perl module.
-
-Beyond that I find it hard to see what could make dgit's life easier.
-Since dgit wants to construct a commit graph representing the source
-package's innards, unless dpkg-source explicitly provides an interface
-along those lines ("please output a graph of unpacked source tree
-states and corresponding commit messages") dgit is still going to have
-to know specially about most of the source package formats.
-
-> > * dgit will untar each input tarball (other than the Debian tarball=
-).
-> >=20
-> >   This will be done by scanning the .dsc for things whose names loo=
-k
-> >   like (compressed) tarballs, and using the interfaces provided by
-> >   Dpkg::Compression to get at the tarball.
->=20
-> Hmm, Dpkg::Source::Archive is currently private, but I might have a
-> look at making it public if that would be helpful here.
-
-I think the amount of logic I would have to replicate is minimal.
-
-> > * As currently, dgit will take steps so that none of the git trees
-> >   discussed above contain a .pc directory.
->=20
-> As long as the directory does not disappear from the working tree,
-> that should work.
-
-Right, indeed it won't.
-
-Thanks for your comments.  I feel unblocked :-).
-
-Ian.
-
---=20
-Ian Jackson <ijackson@chiark.greenend.org.uk>   These opinions are my o=
-wn.
-
-If I emailed you from an address @fyvzl.net or @evade.org.uk, that is
-a private address which bypasses my fierce spamfilter.
-
+  git-buildpackage.