From 5c10d34a99f5c4c1eac28aca58d5d7e414fd91f2 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Mon, 24 Oct 2016 01:04:22 +0100
Subject: Build system substitutions, for absurdities

* Introduce absurddir, which is where the absurdities will go
* Substitute the absurddir into the dgit script during make all
* Install the substituted scripts rather than the originals in make install
* Provide a default in dgit, based on $0
* Clean the substitutions up in make clean

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 .gitignore |  1 +
 Makefile   | 17 ++++++++++++-----
 dgit       |  6 ++++++
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/.gitignore b/.gitignore
index 428c4cc..69c2fea 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,4 @@ debian/*.substvars
 debian/*.log
 debian/debhelper-build-stamp
 dgit-maint-merge.7
+substituted
diff --git a/Makefile b/Makefile
index 291265d..b72a1e9 100644
--- a/Makefile
+++ b/Makefile
@@ -30,6 +30,7 @@ man1dir=$(mandir)/man1
 man7dir=$(mandir)/man7
 infraexamplesdir=$(prefix)/share/doc/dgit-infrastructure/examples
 txtdocdir=$(prefix)/share/doc/dgit
+absurddir=$(prefix)/share/dgit/absurd
 
 PROGRAMS=dgit
 MAN1PAGES=dgit.1
@@ -46,10 +47,16 @@ INFRA_PERLMODULES= \
 	Debian/Dgit/Infra.pm \
 	Debian/Dgit/Policy/Debian.pm
 
-all:	$(MAN7PAGES)
+all:	$(MAN7PAGES) $(addprefix substituted/,$(PROGRAMS))
 
-install:	installdirs $(MAN7PAGES)
-	$(INSTALL_PROGRAM) $(PROGRAMS) $(DESTDIR)$(bindir)
+substituted/%:	%
+	mkdir -p substituted
+	perl -pe 's{\bundef\b}{'\''$(absurddir)'\''} if m/###substituted###/' \
+		<$< >$@
+
+install:	installdirs all
+	$(INSTALL_PROGRAM) $(addprefix substituted/,$(PROGRAMS)) \
+		$(DESTDIR)$(bindir)
 	$(INSTALL_DATA) $(MAN1PAGES) $(DESTDIR)$(man1dir)
 	$(INSTALL_DATA) $(MAN7PAGES) $(DESTDIR)$(man7dir)
 	$(INSTALL_DATA) $(TXTDOCS) $(DESTDIR)$(txtdocdir)
@@ -60,7 +67,7 @@ install:	installdirs $(MAN7PAGES)
 installdirs:
 	$(INSTALL_DIR) $(DESTDIR)$(bindir) \
 		$(DESTDIR)$(man1dir) $(DESTDIR)$(man7dir) \
-		$(DESTDIR)$(txtdocdir) \
+		$(DESTDIR)$(txtdocdir) $(DESTDIR)$(absurddir) \
 		$(addprefix $(DESTDIR)$(perldir)/, $(dir $(PERLMODULES)))
 
 install-infra:	installdirs-infra
@@ -79,7 +86,7 @@ installdirs-infra:
 check installcheck:
 
 clean distclean mostlyclean maintainer-clean:
-	rm -rf tests/tmp
+	rm -rf tests/tmp substituted
 	set -e; for m in $(MAN7PAGES); do \
 		test -e $$m.pod && rm -f $$m; \
 	done
diff --git a/dgit b/dgit
index 5fa500c..344d006 100755
--- a/dgit
+++ b/dgit
@@ -41,6 +41,7 @@ use Carp;
 use Debian::Dgit;
 
 our $our_version = 'UNRELEASED'; ###substituted###
+our $absurdity = undef; ###substituted###
 
 our @rpushprotovsn_support = qw(4 3 2); # 4 is new tag format
 our $protovsn;
@@ -146,6 +147,11 @@ our @ourdscfield = qw(Dgit Vcs-Dgit-Master);
 our $csuite;
 our $instead_distro;
 
+if (!defined $absurdity) {
+    $absurdity = $0;
+    $absurdity =~ s{/[^/]+$}{/absurd} or die;
+}
+
 sub debiantag ($$) {
     my ($v,$distro) = @_;
     return $tagformatfn->($v, $distro);
-- 
cgit v1.2.3