From f5050b11e6f8269224c7fa7edb88a67ee981cc0a Mon Sep 17 00:00:00 2001
From: Peter Fern <github@0xc0dedbad.com>
Date: Sat, 14 Aug 2021 10:56:12 +1000
Subject: [PATCH] feat(zfs): Add local ZFS CLI parsing

Preparing for removal of go-zfs dependency.
---
 zfs/dataset.go | 72 ++++++++++++++++++++++++++++++++++++++++++++
 zfs/pool.go    | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++
 zfs/zfs.go     | 50 +++++++++++++++++++++++++++++++
 3 files changed, 203 insertions(+)
 create mode 100644 zfs/dataset.go
 create mode 100644 zfs/pool.go
 create mode 100644 zfs/zfs.go

diff --git a/zfs/dataset.go b/zfs/dataset.go
new file mode 100644
index 0000000..f27d803
--- /dev/null
+++ b/zfs/dataset.go
@@ -0,0 +1,72 @@
+package zfs
+
+import (
+	"strings"
+)
+
+// DatasetKind enum of supported dataset types
+type DatasetKind string
+
+const (
+	// DatasetFilesystem enum entry
+	DatasetFilesystem DatasetKind = `filesystem`
+	// DatasetVolume enum entry
+	DatasetVolume DatasetKind = `volume`
+	// DatasetSnapshot enum entry
+	DatasetSnapshot DatasetKind = `snapshot`
+)
+
+// Dataset holds the properties for an individual dataset
+type Dataset struct {
+	Pool       string
+	Name       string
+	Properties map[string]string
+}
+
+// DatasetProperties returns the requested properties for all datasets in the given pool
+func DatasetProperties(pool string, kind DatasetKind, properties ...string) ([]Dataset, error) {
+	handler := newDatasetHandler()
+	if err := execute(pool, handler, `zfs`, `get`, `-Hprt`, string(kind), `-o`, `name,property,value`, strings.Join(properties, `,`)); err != nil {
+		return nil, err
+	}
+	return handler.datasets(), nil
+}
+
+// datasetHandler handles parsing of the data returned from the CLI into Dataset structs
+type datasetHandler struct {
+	store map[string]Dataset
+}
+
+// processLine implements the handler interface
+func (h *datasetHandler) processLine(pool string, line []string) error {
+	if len(line) != 3 {
+		return ErrInvalidOutput
+	}
+	if _, ok := h.store[line[0]]; !ok {
+		h.store[line[0]] = newDataset(pool, line[0])
+	}
+	h.store[line[0]].Properties[line[1]] = line[2]
+	return nil
+}
+
+func (h *datasetHandler) datasets() []Dataset {
+	result := make([]Dataset, len(h.store))
+	i := 0
+	for _, dataset := range h.store {
+		result[i] = dataset
+		i++
+	}
+	return result
+}
+
+func newDataset(pool string, name string) Dataset {
+	return Dataset{
+		Pool:       pool,
+		Name:       name,
+		Properties: make(map[string]string),
+	}
+}
+
+func newDatasetHandler() *datasetHandler {
+	return &datasetHandler{store: make(map[string]Dataset)}
+}
diff --git a/zfs/pool.go b/zfs/pool.go
new file mode 100644
index 0000000..f3c446e
--- /dev/null
+++ b/zfs/pool.go
@@ -0,0 +1,81 @@
+package zfs
+
+import (
+	"bufio"
+	"os/exec"
+	"strings"
+)
+
+// PoolStatus enum contains status text
+type PoolStatus string
+
+const (
+	// PoolOnline enum entry
+	PoolOnline PoolStatus = `ONLINE`
+	// PoolDegraded enum entry
+	PoolDegraded PoolStatus = `DEGRADED`
+	// PoolFaulted enum entry
+	PoolFaulted PoolStatus = `FAULTED`
+	// PoolOffline enum entry
+	PoolOffline PoolStatus = `OFFLINE`
+	// PoolUnavail enum entry
+	PoolUnavail PoolStatus = `UNAVAIL`
+	// PoolRemoved enum entry
+	PoolRemoved PoolStatus = `REMOVED`
+)
+
+// Pool holds the properties for an individual pool
+type Pool struct {
+	Name       string
+	Properties map[string]string
+}
+
+// processLine implements the handler interface
+func (p Pool) processLine(pool string, line []string) error {
+	if len(line) != 3 || line[0] != pool {
+		return ErrInvalidOutput
+	}
+	p.Properties[line[1]] = line[2]
+
+	return nil
+}
+
+// PoolNames returns a list of available pool names
+func PoolNames() ([]string, error) {
+	pools := make([]string, 0)
+	cmd := exec.Command(`zpool`, `list`, `-Ho`, `name`)
+	out, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, err
+	}
+	scanner := bufio.NewScanner(out)
+
+	if err = cmd.Start(); err != nil {
+		return nil, err
+	}
+
+	for scanner.Scan() {
+		pools = append(pools, scanner.Text())
+	}
+	if err = cmd.Wait(); err != nil {
+		return nil, err
+	}
+
+	return pools, nil
+}
+
+// PoolProperties returns the requested properties for the given pool
+func PoolProperties(pool string, properties ...string) (Pool, error) {
+	handler := newPool(pool)
+	if err := execute(pool, handler, `zpool`, `get`, `-Hpo`, `name,property,value`, strings.Join(properties, `,`)); err != nil {
+		return handler, err
+	}
+	return handler, nil
+}
+
+func newPool(name string) Pool {
+	return Pool{
+		Name:       name,
+		Properties: make(map[string]string),
+	}
+}
diff --git a/zfs/zfs.go b/zfs/zfs.go
new file mode 100644
index 0000000..514ce41
--- /dev/null
+++ b/zfs/zfs.go
@@ -0,0 +1,50 @@
+package zfs
+
+import (
+	"encoding/csv"
+	"errors"
+	"io"
+	"os/exec"
+)
+
+var (
+	// ErrInvalidOutput is returned on unparseable CLI output
+	ErrInvalidOutput = errors.New(`Invalid output executing command`)
+)
+
+type handler interface {
+	processLine(pool string, line []string) error
+}
+
+func execute(pool string, h handler, cmd string, args ...string) error {
+	c := exec.Command(cmd, append(args, pool)...)
+	out, err := c.StdoutPipe()
+	if err != nil {
+		return err
+	}
+
+	r := csv.NewReader(out)
+	r.Comma = '\t'
+	r.LazyQuotes = true
+	r.ReuseRecord = true
+	r.FieldsPerRecord = 3
+
+	if err = c.Start(); err != nil {
+		return err
+	}
+
+	for {
+		line, err := r.Read()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return err
+		}
+		if err = h.processLine(pool, line); err != nil {
+			return err
+		}
+	}
+
+	return c.Wait()
+}