| 1 | // SPDX-License-Identifier: AGPL-3.0-or-later |
| 2 | |
| 3 | package storage |
| 4 | |
| 5 | import ( |
| 6 | "bytes" |
| 7 | "errors" |
| 8 | "io" |
| 9 | "os" |
| 10 | "path/filepath" |
| 11 | "strings" |
| 12 | "testing" |
| 13 | ) |
| 14 | |
| 15 | func TestWriteAtomic_HappyPath(t *testing.T) { |
| 16 | t.Parallel() |
| 17 | dir := t.TempDir() |
| 18 | path := filepath.Join(dir, "out.txt") |
| 19 | body := "hello atomic" |
| 20 | if err := WriteAtomic(path, strings.NewReader(body)); err != nil { |
| 21 | t.Fatalf("WriteAtomic: %v", err) |
| 22 | } |
| 23 | got, err := os.ReadFile(path) |
| 24 | if err != nil { |
| 25 | t.Fatalf("ReadFile: %v", err) |
| 26 | } |
| 27 | if string(got) != body { |
| 28 | t.Fatalf("got %q, want %q", got, body) |
| 29 | } |
| 30 | } |
| 31 | |
| 32 | // failingReader returns N bytes then an error. Used to inject a failure |
| 33 | // after partial write — WriteAtomic must NOT leave a file at path. |
| 34 | type failingReader struct { |
| 35 | data []byte |
| 36 | off int |
| 37 | failAt int |
| 38 | failErr error |
| 39 | } |
| 40 | |
| 41 | func (f *failingReader) Read(p []byte) (int, error) { |
| 42 | if f.off >= f.failAt { |
| 43 | return 0, f.failErr |
| 44 | } |
| 45 | n := copy(p, f.data[f.off:]) |
| 46 | if f.off+n > f.failAt { |
| 47 | n = f.failAt - f.off |
| 48 | } |
| 49 | f.off += n |
| 50 | if f.off >= f.failAt { |
| 51 | return n, f.failErr |
| 52 | } |
| 53 | return n, nil |
| 54 | } |
| 55 | |
| 56 | func TestWriteAtomic_PartialWriteLeavesNoFile(t *testing.T) { |
| 57 | t.Parallel() |
| 58 | dir := t.TempDir() |
| 59 | path := filepath.Join(dir, "should-not-exist.txt") |
| 60 | |
| 61 | r := &failingReader{ |
| 62 | data: bytes.Repeat([]byte("x"), 1024), |
| 63 | failAt: 256, |
| 64 | failErr: errors.New("simulated crash"), |
| 65 | } |
| 66 | err := WriteAtomic(path, r) |
| 67 | if err == nil { |
| 68 | t.Fatal("expected error from failing reader") |
| 69 | } |
| 70 | |
| 71 | // Destination must not exist. |
| 72 | if _, err := os.Stat(path); !os.IsNotExist(err) { |
| 73 | t.Fatalf("destination exists after failed atomic write: stat err=%v", err) |
| 74 | } |
| 75 | |
| 76 | // No leftover .tmp.* files in the same directory either. |
| 77 | entries, err := os.ReadDir(dir) |
| 78 | if err != nil { |
| 79 | t.Fatalf("ReadDir: %v", err) |
| 80 | } |
| 81 | for _, e := range entries { |
| 82 | if strings.Contains(e.Name(), ".tmp.") { |
| 83 | t.Fatalf("leftover temp file: %s", e.Name()) |
| 84 | } |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | func TestWriteAtomic_OverwritesExisting(t *testing.T) { |
| 89 | t.Parallel() |
| 90 | dir := t.TempDir() |
| 91 | path := filepath.Join(dir, "out.txt") |
| 92 | if err := os.WriteFile(path, []byte("old content"), 0o600); err != nil { |
| 93 | t.Fatalf("seed: %v", err) |
| 94 | } |
| 95 | if err := WriteAtomic(path, strings.NewReader("new content")); err != nil { |
| 96 | t.Fatalf("WriteAtomic: %v", err) |
| 97 | } |
| 98 | got, _ := os.ReadFile(path) |
| 99 | if string(got) != "new content" { |
| 100 | t.Fatalf("got %q, want %q", got, "new content") |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | func TestWriteAtomic_LargeBody(t *testing.T) { |
| 105 | t.Parallel() |
| 106 | dir := t.TempDir() |
| 107 | path := filepath.Join(dir, "big.bin") |
| 108 | body := bytes.Repeat([]byte{0xab}, 5*1024*1024) // 5 MiB |
| 109 | if err := WriteAtomic(path, bytes.NewReader(body)); err != nil { |
| 110 | t.Fatalf("WriteAtomic: %v", err) |
| 111 | } |
| 112 | f, err := os.Open(path) |
| 113 | if err != nil { |
| 114 | t.Fatalf("Open: %v", err) |
| 115 | } |
| 116 | defer func() { _ = f.Close() }() |
| 117 | h, err := io.ReadAll(f) |
| 118 | if err != nil { |
| 119 | t.Fatalf("ReadAll: %v", err) |
| 120 | } |
| 121 | if !bytes.Equal(h, body) { |
| 122 | t.Fatalf("body mismatch (len got=%d want=%d)", len(h), len(body)) |
| 123 | } |
| 124 | } |
| 125 |