update-doc-branches: add command to update man and html

Create a new command to update the man and html branches, and move the
related code there from the Makefile.

Update the branches based on the current (clean) tree, rather than
consulting the git origin, and rely on ls-files rather than globbing
so that the file lists will always be correct -- we'll immediately
notice deletions, avoid picking up stray files in the directory, etc.

Signed-off-by: Rob Browning <[email protected]>
Tested-by: Rob Browning <[email protected]>

Makefile

@@ -247,25 +247,12 @@ Documentation/%.html: Documentation/%.md Documentation/substvars
 Documentation/clean:
 	cd Documentation && rm -f *~ .*~ *.[0-9] *.html substvars
 
-# update the local 'man' and 'html' branches with pregenerated output files, for
-# people who don't have pandoc (and maybe to aid in google searches or something)
-export-docs: Documentation/all
-	git update-ref refs/heads/man origin/man '' 2>/dev/null || true
-	git update-ref refs/heads/html origin/html '' 2>/dev/null || true
-	set -eo pipefail; \
-	GIT_INDEX_FILE=gitindex.tmp; export GIT_INDEX_FILE; \
-	rm -f $${GIT_INDEX_FILE} && \
-	git add -f Documentation/*.1 && \
-	git update-ref refs/heads/man \
-		$$(echo "Autogenerated man pages for $$(git describe --always)" \
-		    | git commit-tree $$(git write-tree --prefix=Documentation) \
-				-p refs/heads/man) && \
-	rm -f $${GIT_INDEX_FILE} && \
-	git add -f Documentation/*.html && \
-	git update-ref refs/heads/html \
-		$$(echo "Autogenerated html pages for $$(git describe --always)" \
-		    | git commit-tree $$(git write-tree --prefix=Documentation) \
-				-p refs/heads/html)
+# Note: this adds commits containing the current manpages in roff and
+# html format to the man and html branches respectively.  The version
+# is determined by "git describe --always".
+.PHONY: update-doc-branches
+update-doc-branches: Documentation/all
+	dev/update-doc-branches refs/heads/man refs/heads/html
 
 # push the pregenerated doc files to origin/man and origin/html
 push-docs: export-docs

dev/update-doc-branches

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+
+# Ensures that the working tree is clean, and Documentation/ is up to
+# date, and then commits Documentation/*.1 to the man branch, and
+# Documentation/*.html to the html branch.
+
+set -uexo pipefail
+
+test "$#" -eq 2
+
+# Must be full ref name, i.e. refs/heads/man, etc.
+man_ref="$1"
+html_ref="$2"
+
+git diff-index --quiet HEAD --  # no uncommitted changes
+git rev-parse --verify "$man_ref"
+git rev-parse --verify "$html_ref"
+echo "$man_ref" | grep -qE '^refs/heads'
+echo "$html_ref" | grep -qE '^refs/heads'
+
+"${MAKE:-make}"
+
+tmpdir="$(mktemp -d "t/tmp/update-doc-branches-XXXXXX")"
+trap "$(printf 'rm -rf %q' "$tmpdir")" EXIT
+tmpidx="$tmpdir/git-index.tmp"
+
+for fmt in man html; do
+    rm -f "$tmpidx"
+    for f in $(git ls-files 'Documentation/*.md'); do
+        base="$(basename "$f" .md)"
+        if test "$fmt" = man; then
+            ref="$man_ref"
+            GIT_INDEX_FILE="$tmpidx" git add -f "Documentation/$base.1"
+        else
+            ref="$html_ref"
+            GIT_INDEX_FILE="$tmpidx" git add -f "Documentation/$base.html"
+        fi
+    done
+    msg="Update $fmt pages for $(git describe --always)"
+    tree=$(GIT_INDEX_FILE="$tmpidx" git write-tree --prefix=Documentation)
+    commit=$(echo "$msg" | git commit-tree "$tree" -p refs/heads/"$fmt")
+    git update-ref "$ref" "$commit"
+done