cmd/app: alternative merged template layout

This implements an optional, alternative template layout to accommodate
ZFS and equivalent setups where each template occupies a different
filesystem. In such a setup, the default, separate workdir is unusable
as overlayfs requires the workdir to reside on the same filesystem as
the writable upperdir. The "merge" build tag enables this alternative
behaviour.

Signed-off-by: Ophestra <cat@gensokyo.uk>

1 files changed, 15 insertions, 0 deletions

diff --git a/cmd/app/app_merged.go b/cmd/app/app_merged.go
new file mode 100644
index 00000000..e0a31f94
--- /dev/null
+++ b/cmd/app/app_merged.go
@@ -0,0 +1,15 @@
+//go:build merge
+
+package main
+
+import "hakurei.app/check"
+
+// template returns the pathname of an upperdir.
+func (b *base) template(template string) *check.Absolute {
+	return b.append("template", template, "upper")
+}
+
+// work returns the pathname of a workdir.
+func (b *base) work(template string) *check.Absolute {
+	return b.append("template", template, "work")
+}