From 145244f63d2589203b1450af61987f16fb87aff3 Mon Sep 17 00:00:00 2001
From: Jeff Carr <jcarr@wit.com>
Date: Sun, 17 Aug 2025 17:43:34 -0500
Subject: more sanity checks

---
 isDriveInUse.go | 95 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 isDriveInUse.go

(limited to 'isDriveInUse.go')

diff --git a/isDriveInUse.go b/isDriveInUse.go
new file mode 100644
index 0000000..912ae07
--- /dev/null
+++ b/isDriveInUse.go
@@ -0,0 +1,95 @@
+package main
+
+import (
+	"bufio"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"go.wit.com/log"
+)
+
+func isBlockDeviceInUse(dev string) bool {
+	base := filepath.Base(dev)
+
+	// 1. Check /proc/mounts
+	if isMounted(dev, base) {
+		log.Info(dev, "dev is mounted (/proc/mounts)")
+		return true
+	}
+
+	// 2. Check /proc/swaps
+	if isSwap(dev) {
+		log.Info(dev, "dev is used by swap (/proc/swaps)")
+		return true
+	}
+
+	// 3. Check /proc/mdstat for RAID
+	if isInRAID(base) {
+		log.Info(dev, "dev is in software raid (/proc/mdstat)")
+		return true
+	}
+
+	// 4. Check sysfs for device-mapper or LVM use
+	if hasDMHolders(base) {
+		log.Info(dev, "dev has lvm partitions")
+		return true
+	}
+
+	log.Info(dev, "dev appears to be unused")
+	return false
+}
+
+func isMounted(dev, base string) bool {
+	f, err := os.Open("/proc/mounts")
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		if strings.HasPrefix(scanner.Text(), dev) || strings.Contains(scanner.Text(), base) {
+			return true
+		}
+	}
+	return false
+}
+
+func isSwap(dev string) bool {
+	f, err := os.Open("/proc/swaps")
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		if strings.HasPrefix(scanner.Text(), dev) {
+			return true
+		}
+	}
+	return false
+}
+
+func isInRAID(base string) bool {
+	f, err := os.Open("/proc/mdstat")
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		if strings.Contains(scanner.Text(), base) {
+			return true
+		}
+	}
+	return false
+}
+
+func hasDMHolders(base string) bool {
+	path := filepath.Join("/sys/block", base, "holders")
+	entries, err := os.ReadDir(path)
+	return err == nil && len(entries) > 0
+}
-- 
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