cache: Convert file cleanup to use `os.ReadDir()`pks-refactor-ioutil-readdir-usages

Go 1.15 has deprecated the `ioutil` package and made replacements
available in the `io` or `os` packages. While we have already migrated
most callsites away, one notable omission was `ioutil.ReadDir()` as this
function doesn't have an exact replacement: the new `os.ReadDir()`
function does not stat all directory entries anymore.

Refactor the cleanup of stale cached files in the `cache` package to use
the new function.

1 files changed, 15 insertions, 4 deletions

diff --git a/internal/cache/walker.go b/internal/cache/walker.go
index 6a0b065df..b14c8adf6 100644
--- a/internal/cache/walker.go
+++ b/internal/cache/walker.go
@@ -5,10 +5,10 @@
 // worker will walk the cache directory every ten minutes.
 package cache
 
-//nolint:depguard
 import (
+	"errors"
 	"fmt"
-	"io/ioutil"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"time"
@@ -31,7 +31,7 @@ func (c *DiskCache) cleanWalk(path string) error {
 	defer time.Sleep(100 * time.Microsecond) // relieve pressure
 
 	c.walkerCheckTotal.Inc()
-	entries, err := ioutil.ReadDir(path)
+	entries, err := os.ReadDir(path)
 	if err != nil {
 		if os.IsNotExist(err) {
 			return nil
@@ -50,8 +50,19 @@ func (c *DiskCache) cleanWalk(path string) error {
 			continue
 		}
 
+		info, err := e.Info()
+		if err != nil {
+			// The file may have been cleaned up already, so we just ignore it as we
+			// wanted to remove it anyway.
+			if errors.Is(err, fs.ErrNotExist) {
+				continue
+			}
+
+			return fmt.Errorf("statting cached file: %w", err)
+		}
+
 		c.walkerCheckTotal.Inc()
-		if time.Since(e.ModTime()) < staleAge {
+		if time.Since(info.ModTime()) < staleAge {
 			continue // still fresh
 		}