bastion 0.55.3

client-go/harness_tar_linux_test.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"golang.org/x/sys/unix"
+)
+
+// A name swapped for a special file between the walk's look and its open must
+// never be opened: opening a device runs its driver (a watchdog arms, a tape
+// rewinds on close, a serial line raises DTR), whatever is read after. A named
+// pipe stands in for any of them, since anyone can make one, and inotify
+// reports every open of it except one made only as a path (O_PATH), which runs
+// no driver code. Both a name looked at as a plain file and one looked at as
+// a folder are swapped.
+func TestMakeTarNeverOpensASpecialFileSwappedInBeforeTheOpen(t *testing.T) {
+	for _, swap := range []string{"a.txt", "sub"} {
+		t.Run(swap, func(t *testing.T) {
+			_, _, tree := outsideAndTree(t)
+			in, err := unix.InotifyInit1(unix.IN_NONBLOCK | unix.IN_CLOEXEC)
+			if err != nil {
+				t.Skipf("no inotify: %v", err)
+			}
+			defer unix.Close(in)
+			watched := false
+			packTreeBeforeOpen = func(rel string) {
+				if rel != swap {
+					return
+				}
+				p := filepath.Join(tree, swap)
+				if err := os.RemoveAll(p); err != nil {
+					t.Errorf("remove %s: %v", p, err)
+					return
+				}
+				if err := unix.Mkfifo(p, 0o644); err != nil {
+					t.Errorf("mkfifo %s: %v", p, err)
+					return
+				}
+				if _, err := unix.InotifyAddWatch(in, p, unix.IN_OPEN); err != nil {
+					t.Errorf("watch %s: %v", p, err)
+					return
+				}
+				watched = true
+			}
+			defer func() { packTreeBeforeOpen = nil }()
+			b, skipped, err := packWorktree(tree)
+			if err != nil {
+				t.Fatalf("packWorktree: %v", err)
+			}
+			if !watched {
+				t.Fatal("the swap never ran")
+			}
+			buf := make([]byte, 4096)
+			if n, err := unix.Read(in, buf); n > 0 {
+				t.Fatalf("the special file swapped in for %s was opened (%d bytes of inotify events)", swap, n)
+			} else if err != unix.EAGAIN {
+				t.Fatalf("read inotify: %d %v", n, err)
+			}
+			if _, ok := tarEntries(t, b)[swap]; ok {
+				t.Fatalf("%s was a named pipe when it was opened and must be left out", swap)
+			}
+			if !strings.Contains(","+strings.Join(skipped, ",")+",", ","+swap+",") {
+				t.Fatalf("%s must be named as left out, got %v", swap, skipped)
+			}
+		})
+	}
+}