fix(metis): recognize scratch-backed bind mounts

pkg/sentinel/collector.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"os"
 	"os/exec"
+	"path/filepath"
 	"strings"
 
 	"metis/pkg/facts"
@@ -182,8 +183,60 @@ func bindHealthy(target, source string) bool {
 	if target == "" || source == "" {
 		return false
 	}
+
+	targetReal := realPath(target)
+	sourceReal := realPath(source)
+	if sourceReal != "" && pathWithin(targetReal, sourceReal) {
+		return true
+	}
+
 	mountSource, _, mounted := mountInfo(target)
-	return mounted && strings.TrimSpace(mountSource) == source
+	if !mounted {
+		return false
+	}
+	if strings.TrimSpace(mountSource) == source {
+		return true
+	}
+
+	rootSource, _, rootMounted := mountInfo(source)
+	if !rootMounted {
+		return false
+	}
+	device, subpath := splitFindmntSource(mountSource)
+	return device != "" && device == rootSource && subpath == filepath.Clean(target)
+}
+
+func realPath(path string) string {
+	path = strings.TrimSpace(path)
+	if path == "" {
+		return ""
+	}
+	out, err := commandOutput("readlink", "-f", path)
+	if err != nil {
+		return ""
+	}
+	return strings.TrimSpace(string(out))
+}
+
+func pathWithin(path, root string) bool {
+	path = filepath.Clean(strings.TrimSpace(path))
+	root = filepath.Clean(strings.TrimSpace(root))
+	if path == "" || root == "" || path == "." || root == "." {
+		return false
+	}
+	return path == root || strings.HasPrefix(path, root+string(os.PathSeparator))
+}
+
+func splitFindmntSource(source string) (string, string) {
+	source = strings.TrimSpace(source)
+	if source == "" {
+		return "", ""
+	}
+	start := strings.Index(source, "[")
+	if start == -1 || !strings.HasSuffix(source, "]") {
+		return source, ""
+	}
+	return source[:start], source[start+1 : len(source)-1]
 }
 
 func resolveDeviceByUUID(uuid string) string {

pkg/sentinel/collector_test.go

@@ -120,6 +120,82 @@ esac`,
 	}
 }
 
+func TestBindHealthyAcceptsScratchSymlinksAndDeviceSubpaths(t *testing.T) {
+	dir := fakeCollectorCommands(t, map[string]string{
+		"readlink": `case "${2:-}" in
+  /mnt/scratch) printf '/mnt/scratch\n' ;;
+  /var/log/pods) printf '/mnt/scratch/var/log/pods\n' ;;
+  *) exit 1 ;;
+esac`,
+		"findmnt": `target=""
+for ((i=1; i<=$#; i++)); do
+  if [[ "${!i}" == "-T" ]]; then
+    j=$((i + 1))
+    target="${!j}"
+    break
+  fi
+done
+case "${target}" in
+  /mnt/scratch) printf 'SOURCE="/dev/sdz1" TARGET="/mnt/scratch" FSTYPE="ext4"\n' ;;
+  /var/tmp) printf 'SOURCE="/dev/sdz1[/var/tmp]" TARGET="/var/tmp" FSTYPE="ext4"\n' ;;
+  /other) printf 'SOURCE="/dev/sdz1[/unexpected]" TARGET="/other" FSTYPE="ext4"\n' ;;
+  *) exit 1 ;;
+esac`,
+	})
+	t.Setenv("PATH", dir+string(os.PathListSeparator)+os.Getenv("PATH"))
+
+	if !bindHealthy("/var/log/pods", "/mnt/scratch") {
+		t.Fatal("scratch-backed symlink target should be healthy")
+	}
+	if !bindHealthy("/var/tmp", "/mnt/scratch") {
+		t.Fatal("device subpath bind target should be healthy")
+	}
+	if bindHealthy("/other", "/mnt/scratch") {
+		t.Fatal("unrelated device subpath should be unhealthy")
+	}
+	if device, subpath := splitFindmntSource(`/dev/sdz1[/var/tmp]`); device != "/dev/sdz1" || subpath != "/var/tmp" {
+		t.Fatalf("splitFindmntSource device/subpath = %q %q", device, subpath)
+	}
+	if device, subpath := splitFindmntSource("/dev/sdz1"); device != "/dev/sdz1" || subpath != "" {
+		t.Fatalf("plain splitFindmntSource device/subpath = %q %q", device, subpath)
+	}
+	if device, subpath := splitFindmntSource(""); device != "" || subpath != "" {
+		t.Fatalf("empty splitFindmntSource device/subpath = %q %q", device, subpath)
+	}
+	if got := realPath(""); got != "" {
+		t.Fatalf("empty realPath = %q", got)
+	}
+	if got := realPath("/missing"); got != "" {
+		t.Fatalf("missing realPath = %q", got)
+	}
+	if pathWithin("", "/mnt/scratch") || pathWithin("/mnt/scratch/file", "") {
+		t.Fatal("empty pathWithin inputs should be false")
+	}
+}
+
+func TestBindHealthyRejectsDeviceSubpathWithoutRootMount(t *testing.T) {
+	dir := fakeCollectorCommands(t, map[string]string{
+		"readlink": `exit 1`,
+		"findmnt": `target=""
+for ((i=1; i<=$#; i++)); do
+  if [[ "${!i}" == "-T" ]]; then
+    j=$((i + 1))
+    target="${!j}"
+    break
+  fi
+done
+case "${target}" in
+  /var/tmp) printf 'SOURCE="/dev/sdz1[/var/tmp]" TARGET="/var/tmp" FSTYPE="ext4"\n' ;;
+  *) exit 1 ;;
+esac`,
+	})
+	t.Setenv("PATH", dir+string(os.PathListSeparator)+os.Getenv("PATH"))
+
+	if bindHealthy("/var/tmp", "/mnt/scratch") {
+		t.Fatal("device subpath should be unhealthy when root scratch mount is unknown")
+	}
+}
+
 func TestCollectUSBScratchDefaultsAndParserEdges(t *testing.T) {
 	dir := fakeCollectorCommands(t, map[string]string{
 		"cat":     `printf '%s\n' '{"usb_scratch":{"mountpoint":"/mnt/scratch"}}'`,