fix: complete target diagnostics and reset inspection

internal/target/diagnostic.go

@@ -0,0 +1,51 @@
+package target
+
+import (
+	"errors"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/sys/unix"
+
+	"proxyctl/internal/profile"
+)
+
+// ReadOnlyWriteAuthority observes whether the current process can write the
+// configured locations. It never creates a probe file or changes permissions.
+func ReadOnlyWriteAuthority(paths ...string) Check {
+	check := Check{Name: "write authority", OK: true}
+	var evidence []string
+	for _, path := range paths {
+		ok, detail := readOnlyWritablePath(path)
+		check.OK = check.OK && ok
+		evidence = append(evidence, detail)
+	}
+	check.Evidence = profile.RedactText(strings.Join(evidence, "; "))
+	return check
+}
+
+func readOnlyWritablePath(path string) (bool, string) {
+	candidate := filepath.Clean(path)
+	for {
+		info, err := os.Stat(candidate)
+		if err == nil {
+			if !info.IsDir() {
+				candidate = filepath.Dir(candidate)
+			}
+			if err := unix.Access(candidate, unix.W_OK); err != nil {
+				return false, candidate + " is not writable: " + err.Error()
+			}
+			return true, candidate + " is writable"
+		}
+		if !errors.Is(err, fs.ErrNotExist) {
+			return false, candidate + " cannot be inspected: " + err.Error()
+		}
+		parent := filepath.Dir(candidate)
+		if parent == candidate {
+			return false, path + " has no writable existing ancestor"
+		}
+		candidate = parent
+	}
+}