1 files changed, 55 insertions, 0 deletions
diff --git a/internal/zfsutil/zfsutil.go b/internal/zfsutil/zfsutil.go
new file mode 100644
index 0000000..3d3bd40
--- /dev/null
+++ b/internal/zfsutil/zfsutil.go
@@ -0,0 +1,55 @@
+// Package zfsutil wraps the zfs(8)/jail(8) CLI operations Skiff relies on as
+// its only state store - no separate app-metadata database.
+package zfsutil
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"strings"
+
+	"skiff/internal/sh"
+)
+
+func Exists(ctx context.Context, dataset string) bool {
+	_, err := sh.Output(ctx, "", "zfs", "list", "-H", "-o", "name", dataset)
+	return err == nil
+}
+
+// Clone creates a new dataset from a (read-only) snapshot of base, mounted
+// at mountpoint. base must already have a snapshot named baseSnapshot.
+func Clone(ctx context.Context, out io.Writer, base, baseSnapshot, dataset, mountpoint string) error {
+	src := fmt.Sprintf("%s@%s", base, baseSnapshot)
+	return sh.Run(ctx, out, "", "zfs", "clone", "-o", "mountpoint="+mountpoint, src, dataset)
+}
+
+func Snapshot(ctx context.Context, out io.Writer, dataset, tag string) error {
+	return sh.Run(ctx, out, "", "zfs", "snapshot", fmt.Sprintf("%s@%s", dataset, tag))
+}
+
+// Rollback discards everything written to dataset since the snapshot named
+// tag, including any newer snapshots. This is Skiff's entire undo mechanism:
+// used both for the automatic post-health-check-failure rollback and for a
+// manual `skiff rollback` days later.
+func Rollback(ctx context.Context, out io.Writer, dataset, tag string) error {
+	return sh.Run(ctx, out, "", "zfs", "rollback", "-r", fmt.Sprintf("%s@%s", dataset, tag))
+}
+
+// Snapshots lists snapshot names (without the dataset@ prefix), newest last.
+func Snapshots(ctx context.Context, dataset string) ([]string, error) {
+	raw, err := sh.Output(ctx, "", "zfs", "list", "-H", "-t", "snapshot", "-o", "name", "-s", "creation", "-r", dataset)
+	if err != nil {
+		return nil, err
+	}
+	var names []string
+	for _, line := range strings.Split(strings.TrimSpace(raw), "\n") {
+		if line == "" {
+			continue
+		}
+		parts := strings.SplitN(line, "@", 2)
+		if len(parts) == 2 {
+			names = append(names, parts[1])
+		}
+	}
+	return names, nil
+}