From 71a90d55f7797d504970c691213f2fd48bb8ab54 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Tue, 15 Jun 2021 08:42:18 +0200
Subject: Add undopatch script

---
 Makefile  |  2 +-
 README    | 16 +++++++++++-----
 undopatch | 26 ++++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 6 deletions(-)
 create mode 100755 undopatch

diff --git a/Makefile b/Makefile
index d514a8c..949d8e2 100644
--- a/Makefile
+++ b/Makefile
@@ -1,2 +1,2 @@
 install:
-	install conv /usr/local/bin
+	install conv undopatch /usr/local/bin
diff --git a/README b/README
index ca429cb..13f65cb 100644
--- a/README
+++ b/README
@@ -30,15 +30,21 @@ they are formatted correctly and placed in the correct directory.
 
 = Undoing patches =
 
-I haven't tried it yet, but the following command should work:
+In order to undo all patches, you need to extract the original
+files from the downloaded archive.
 
-	cd /usr/pkgsrc/path-to/package/work/
+	cd /usr/pkgsrc/path-to/package
+	w=/usr/pkgsrc/distfiles/$(sed -n '/.*(\(.*\)).*/{s//\1/;p;q}' distinfo)
+	cd $(dirname $w)
+	tar xf $w
+	cd -
 	find . -name '*.orig' | while read f; do
-		mv "$f" "${f%.orig}"
+		f=${f%.orig}
+		cp $w/${f#work/} $f
 	done
 
-It probably won't work if you've tried to apply patches twice, as
-each do-patch theoretically presumably creates new .orig files.
+It is not reliable to restore the original files using the .orig
+files, as multiple patches may have been applied to the same file.
 
 = Rebuilding with new patch =
 
diff --git a/undopatch b/undopatch
new file mode 100755
index 0000000..0112101
--- /dev/null
+++ b/undopatch
@@ -0,0 +1,26 @@
+#!/bin/sh
+
+case "$PWD" in
+/usr/pkgsrc/*/*) ;;
+*) echo not in package directory 1>&2; exit 1 ;;
+esac
+
+w=/usr/pkgsrc/distfiles/$(sed -n '/.*(\(.*\)).*/{s//\1/;p;q}' distinfo)
+
+done=$(dirname $w)/.$(basename $w).done
+
+if [ ! -e "$done" ]; then
+	echo extracting archive... 1>&2
+	cd $(dirname $w)
+	tar xf $w
+	touch $done
+	cd -
+fi
+
+echo undoing patches... 1>&2
+cmd=echo\ cp
+[ x"$1" = x"-x" ] && cmd=cp || echo '(preview, no -x)' 1>&2
+find . -name '*.orig' | while read f; do
+	f=${f%.orig}
+	$cmd $w/${f#work/} $f
+done
-- 
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