Import git-blob from lawtech

1 files changed, 134 insertions, 0 deletions

diff --git a/bin/git-blob b/bin/git-blob
new file mode 100755
index 0000000..f7e3ef9
--- /dev/null
+++ b/bin/git-blob
@@ -0,0 +1,134 @@
+#!/bin/sh
+set -eu
+
+usage() {
+	cat <<-'EOF'
+		Usage:
+		  git blob init
+		  git blob -h
+	EOF
+}
+
+help() {
+	cat <<-'EOF'
+
+
+		Options:
+		  -h, --help    show this message
+
+
+		Helper to store binary data on Git.
+
+		The trouble with adding large binary data to Git repositories is that
+		as change of such data accumulates over time, all of its revisions are
+		managed by Git, and as the repository can only grow it can take a big
+		amount of space.  However that data is usually less valuable, as we
+		often don't fiddle with it directly, and treat it as big opaque files,
+		which we aren't so sure if we should keep all of its revisions forever.
+
+		Instead "git-blob" allows one to manage these large artifacts
+		out-of-band, and only keep pointer files versioned in Git.
+
+		We use rsync to push and pull these artifacts automatically, relying
+		on the existing SSH infrastructure in place.
+
+
+		Examples:
+
+		  Init "git-blob":
+
+		    $ git blob init
+
+
+		  Make "resources/*" be handled by "git-blob":
+
+		    $ echo 'resources/* filter=blob diff=blob -text' >> .gitattributes
+	EOF
+}
+
+
+for flag in "$@"; do
+	case "$flag" in
+		--)
+			break
+			;;
+		--help)
+			usage
+			help
+			exit
+			;;
+		*)
+			;;
+	esac
+done
+
+while getopts 'h' flag; do
+	case "$flag" in
+		h)
+			usage
+			help
+			exit
+			;;
+		*)
+			usage >&2
+			exit 2
+			;;
+	esac
+done
+shift $((OPTIND - 1))
+
+
+ACTION="${1:-}"
+eval "$(assert-arg "$ACTION" 'ACTION')"
+shift
+
+
+DIR="$(git rev-parse --git-dir)"
+case "$ACTION" in
+	init)
+		git config filter.blob.clean  'git blob filter-clean'
+		git config filter.blob.smudge 'git blob filter-smudge'
+		git config diff.blob.binary true
+		git config diff.blob.textconv 'git blob diff-textconv'
+		mkdir -p -- \
+			"$DIR"/hooks    \
+			"$DIR"/blob/tmp \
+			"$DIR"/blob/objects
+		cat <<-'EOF' > "$DIR"/hooks/pre-push
+			#!/bin/sh
+			set -eu
+
+			exec git blob pre-push "$@"
+		EOF
+		chmod +x "$DIR"/hooks/pre-push
+		;;
+	diff-textconv)
+		cat -- "$@" | git blob filter-clean
+		;;
+	filter-clean)
+		F="$DIR"/blob/tmp/"$(uuid)"
+		trap 'rm -f -- "$F"' EXIT
+		CHECKSUM="$(tee -- "$F" | sha512sum | cut -d' ' -f1)"
+		mv -- "$F" "$DIR"/blob/objects/"$CHECKSUM"
+		cat <<-EOF
+			git-blob v0
+			sha512sum $CHECKSUM
+		EOF
+		;;
+	filter-smudge)
+		CHECKSUM="$(awk '/^sha512sum / { print $2 }')"
+		F="$DIR"/blob/objects/"$CHECKSUM"
+		if [ ! -e "$F" ]; then
+			rsync -va -- "$(git remote get-url origin)"/blob/"$CHECKSUM" "$F" >&2
+		fi
+		cat -- "$F"
+		;;
+	pre-push)
+		rsync -va -- "$DIR"/blob/objects/ "$(git remote get-url origin)"/blob/
+		;;
+	*)
+		printf 'Unsupported ACTION: "%s".\n\n' "$ACTION" >&2
+		usage >&2
+		exit 2
+		;;
+esac