From 4ed4a3244da9acedf0df6894aec8ae4ddaf0ecf3 Mon Sep 17 00:00:00 2001
From: Pierre Labastie <pierre.labastie@neuf.fr>
Date: Sat, 1 May 2021 09:22:06 +0200
Subject: [PATCH] Allow using any branch/tag in BLFS Makefile

Still WIP because of the *_TREE names
---
 BLFS/Makefile | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/BLFS/Makefile b/BLFS/Makefile
index d4d01bd..a95f141 100644
--- a/BLFS/Makefile
+++ b/BLFS/Makefile
@@ -56,8 +56,11 @@ define INITIAL_TRACK
 </sublist>
 endef
 
+# Git locations and branches
 LFS-GIT = git://git.linuxfromscratch.org/lfs.git
+LFS-BRANCH = trunk
 GIT = git://git.linuxfromscratch.org/blfs.git
+BLFS-BRANCH = trunk
 
 ALLXML := $(filter-out $(RENDERTMP)/%, \
               $(shell if [ -d $(BLFS_XML) ]; then \
@@ -178,18 +181,34 @@ $(BLFS_FULL): $(BLFS_XML) $(BLFS_XML)/general.ent $(ALLXML) $(ALLXSL)
 
 all: update $(BOOK_XML)
 
+# If in detached head state, "git pull" returns an error, so switch back to
+# trunk before updating, and switch back to the branch/tag afterwards
 update: $(BLFS_XML) $(LFS_XML)
 	@echo Updating the book sources
-	$(Q)cd $(LFS_XML) && git pull
-	$(Q)cd $(BLFS_XML) && git pull
+	$(Q)cd $(LFS_XML) && \
+	if [ $(LFS-BRANCH) != trunk ]; then git switch -; fi && \
+	git pull && \
+	git checkout $(LFS-BRANCH)
+	$(Q)cd $(BLFS_XML) && \
+        if [ $(BLFS-BRANCH) != trunk ]; then git switch -; fi && \
+        git pull && \
+        git checkout $(BLFS-BRANCH)
 
 $(LFS_XML):
 	@echo Getting the LFS book sources...
 	$(Q)git clone $(LFS-GIT) $@
+	if [ $(LFS-BRANCH) != trunk ]; then \
+	    cd $@ && \
+	    git checkout $(LFS-BRANCH); \
+	fi
 
 $(BLFS_XML):
 	@echo Getting the BLFS book sources...
 	$(Q)git clone $(GIT) $@
+	if [ $(BLFS-BRANCH) != trunk ]; then \
+	    cd $@ && \
+	    git checkout $(BLFS-BRANCH); \
+	fi
 
 # Clean up