From cec005037f5b62cb17094df53fb25c066d6a9705 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 21 Jul 2019 01:52:05 +0100
Subject: [PATCH] git-playtree-setup: Rewrite in shell and call it from Perl

We want this because git-debpush is going to want this functionality
but doesn't want to include (or have a copy of) Dgit.pm.

The installation arrangements are rather ugly.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
Signed-off-by: Sean Whitton <spwhitton@spwhitton.name>
---
 Debian/Dgit.pm      | 26 ++++++++++++------------
 Makefile            |  2 +-
 debian/rules        |  4 ++++
 git-playtree-create | 48 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 67 insertions(+), 13 deletions(-)
 create mode 100755 git-playtree-create

diff --git a/Debian/Dgit.pm b/Debian/Dgit.pm
index 3f1d1b7b..9d4e78e1 100644
--- a/Debian/Dgit.pm
+++ b/Debian/Dgit.pm
@@ -1051,23 +1051,25 @@ sub playtree_setup (;$) {
     $t_local_git_cfg //= $local_git_cfg;
     # for use in the playtree
     # $maindir must be set, eg by calling record_maindir or fresh_playground
-    runcmd qw(git init -q);
-    runcmd qw(git config gc.auto 0);
-    foreach my $copy (qw(user.email user.name user.useConfigOnly
-                         core.sharedRepository
-                         core.compression core.looseCompression
-                         core.bigFileThreshold core.fsyncObjectFiles)) {
-	my $v = $t_local_git_cfg->{$copy};
-	next unless $v;
-	runcmd qw(git config), $copy, $_ foreach @$v;
-    }
     # this is confusing: we have
     #   .                   playtree, not a worktree, has .git/, our cwd
     #   $maindir            might be a worktree so
     #   $maindir_gitdir     contains our main working "dgit", HEAD, etc.
     #   $maindir_gitcommon  the shared stuff, including .objects
-    rmtree('.git/objects');
-    symlink "$maindir_gitcommon/objects",'.git/objects' or confess "$!";
+
+    # we need to invoke git-playtree-create via git because
+    # there may be config options it needs which are only available
+    # to us, sensibly, in @git
+
+    # And, we look for it in @INC too.  This is a bit perverse.
+    # We do this because in the Debian packages we want to have
+    # a copy of this script in each binary package, rather than
+    # making yet another .deb or tangling the dependencies.
+    # @INC is conveniently available.
+    my $newpath = join ':', +(grep { !m/:/ } @INC),
+	          '/usr/share/dgit', $ENV{PATH};
+    runcmd qw(env), "PATH=$newpath", @git, qw(playtree-create .);
+
     ensuredir '.git/info';
     open GA, "> .git/info/attributes" or confess "$!";
     print GA "* $negate_harmful_gitattrs\n" or confess "$!";
diff --git a/Makefile b/Makefile
index 3a4f9e0e..c8937fc9 100644
--- a/Makefile
+++ b/Makefile
@@ -34,7 +34,7 @@ infraexamplesdir=$(prefix)/share/doc/dgit-infrastructure/examples
 txtdocdir=$(prefix)/share/doc/dgit
 absurddir=$(prefix)/share/dgit/absurd
 
-PROGRAMS=dgit dgit-badcommit-fixup
+PROGRAMS=dgit dgit-badcommit-fixup git-playtree-create
 MAN1PAGES=dgit.1
 
 MAN7PAGES=dgit.7				\
diff --git a/debian/rules b/debian/rules
index 9c2afb38..4e44118d 100755
--- a/debian/rules
+++ b/debian/rules
@@ -43,6 +43,7 @@ override_dh_auto_install: specpkg_install_gdp \
 	make install prefix=/usr DESTDIR=debian/dgit
 	make -C po install prefix=/usr DESTDIR=../debian/tmp \
 		SUPPRESS_PO_UPDATE=1 S=''
+	mv debian/dgit/usr/bin/git-playtree-create debian/dgit/usr/share/dgit
 	make -C po4a install DESTDIR=../debian/tmp S=''
 
 override_dh_missing:
@@ -72,6 +73,8 @@ specpkg_install_%:
 #	# Most of the Perl modules in this package live in
 #	# $(specperl).  The exception is Debian::Dgit::Infra, which
 #	# lives in $(globalperl) and adds $(specperl) to @INC.
+#	# We also abuse this for git-playtree-create.  In .debs, this
+#	# goes in the per-.deb @INC dir.  See Dgit.pm::playtree_setup.
 	set -ex; \
 	 base=debian/$(p); \
 	 mod=Debian/Dgit/$(pm).pm; \
@@ -79,6 +82,7 @@ specpkg_install_%:
 	 dst=$${base}$(globalperl)/$${mod}; \
 	 mkdir -p $${dst%/*}; \
 	 mv -f $$src $$dst; \
+	 install -m 755 git-playtree-create $${base}$(specperl); \
 	 perl -i -p -e 'next unless m/###substituted###/;' \
 		-e 'next unless s/^# (?=unshift \@INC,)//;' \
 		-e 'die unless s{q\{\S+\}}{q{$(specperl)}};' \
diff --git a/git-playtree-create b/git-playtree-create
new file mode 100755
index 00000000..5d890a07
--- /dev/null
+++ b/git-playtree-create
@@ -0,0 +1,48 @@
+#!/bin/bash
+#
+# usage:
+#   rm -rf .git/some/play/thing
+#   git-playtree-setup .git/some/play/thing
+# or:
+#   mkdir .git/some/play/thing
+#   cd .git/some/play/thing
+#   git-playtree-setup .
+
+set -ex
+
+target=$1; shift
+
+case "$#.$target" in
+0.[^-]*) ;;
+*) echo >&2 'bad usage' ; exit 8 ;;
+esac
+
+[ "x$target" = x. ] || mkdir $target
+cd $target
+
+gcd=$(cd .. && git rev-parse --git-common-dir)
+case "$gcd" in
+/*) ;;
+*) gcd="../$gcd" ;;
+esac
+
+git init -q
+git config gc.auto 0
+
+unset_all () { git config --local --unset-all $key || [ $? = 5 ]; }
+
+for key in \
+                         user.email user.name user.useConfigOnly \
+                         core.sharedRepository                   \
+                         core.compression core.looseCompression  \
+                         core.bigFileThreshold core.fsyncObjectFiles \
+; do
+	unset_all
+	(
+		git --git-dir="$gcd" config -z --get-all $key || [ $? = 1 ]
+	) | xargs -n1 -0r -- \
+		git config --local --add $key
+done
+
+rm -rf .git/objects
+ln -s "$gcd/objects" .git/objects
-- 
2.30.2