v0.1.13 follow a replaced, removed, moved log file properly

storage_unix_test.go

@@ -0,0 +1,51 @@
+//go:build linux || freebsd || darwin
+
+package log
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
+	"testing"
+	"time"
+)
+
+// A symlink or FIFO planted at the log path is neither followed nor allowed to
+// block the processor; a FIFO that opens is still not a regular file. The
+// refusal is reported once.
+func TestReopenRefusesNonRegularPath(t *testing.T) {
+	plant := map[string]func(t *testing.T, path, target string){
+		"symlink": func(t *testing.T, path, target string) {
+			mustNoErr(t, os.WriteFile(target, nil, 0644), "target")
+			mustNoErr(t, os.Symlink(target, path), "symlink")
+		},
+		"fifo": func(t *testing.T, path, _ string) {
+			mustNoErr(t, syscall.Mkfifo(path, 0644), "mkfifo")
+		},
+		"fifo with a reader": func(t *testing.T, path, _ string) {
+			mustNoErr(t, syscall.Mkfifo(path, 0644), "mkfifo")
+			r, err := os.OpenFile(path, os.O_RDONLY|syscall.O_NONBLOCK, 0)
+			mustNoErr(t, err, "reader")
+			t.Cleanup(func() { _ = r.Close() })
+		},
+	}
+	for name, fn := range plant {
+		t.Run(name, func(t *testing.T) {
+			l, path, diags := followLogger(t, 0)
+			logFlush(t, l, "before")
+			target := filepath.Join(t.TempDir(), "target")
+			mustNoErr(t, os.Remove(path), "rm")
+			fn(t, path, target)
+			time.Sleep(fileCheckInterval + 5*time.Millisecond)
+			logFlush(t, l, "after") // a blocked processor fails the Flush
+			if data, err := os.ReadFile(target); err == nil {
+				equal(t, len(data), 0, "bytes written through the symlink")
+			}
+			equal(t, l.state.TotalReopens.Load(), uint64(0), "reopens")
+			if d := diags(); len(d) != 1 || !strings.Contains(d[0], "not reopened") {
+				t.Errorf("diagnostics %q", d)
+			}
+		})
+	}
+}