| 1 | package fileutil |
| 2 | |
| 3 | import ( |
| 4 | "errors" |
| 5 | "os" |
| 6 | "path/filepath" |
| 7 | "runtime" |
| 8 | "syscall" |
| 9 | "testing" |
| 10 | "time" |
| 11 | ) |
| 12 | |
| 13 | func TestReplaceFileNoRetryWhenTmpMissing(t *testing.T) { |
| 14 | oldBase := replaceRetryBase |
| 15 | replaceRetryBase = 10 * time.Second |
| 16 | t.Cleanup(func() { replaceRetryBase = oldBase }) |
| 17 | |
| 18 | dir := t.TempDir() |
| 19 | start := time.Now() |
| 20 | err := ReplaceFile(filepath.Join(dir, "missing.tmp"), filepath.Join(dir, "x.txt")) |
| 21 | if err == nil { |
| 22 | t.Fatal("want error when tmp source is missing") |
| 23 | } |
| 24 | if elapsed := time.Since(start); elapsed > time.Second { |
| 25 | t.Errorf("missing tmp should fail fast, took %v — it retried", elapsed) |
| 26 | } |
| 27 | } |
| 28 | |
| 29 | func TestReplaceFileRetriesThenReturnsError(t *testing.T) { |
| 30 | oldBase, oldMax := replaceRetryBase, maxReplaceRetries |
| 31 | replaceRetryBase, maxReplaceRetries = 0, 3 |
| 32 | t.Cleanup(func() { replaceRetryBase, maxReplaceRetries = oldBase, oldMax }) |
| 33 | |
| 34 | dir := t.TempDir() |
| 35 | tmp := filepath.Join(dir, "x.tmp") |
| 36 | if err := os.WriteFile(tmp, []byte("payload"), 0o644); err != nil { |
| 37 | t.Fatal(err) |
| 38 | } |
| 39 | dest := filepath.Join(dir, "blocked") |
| 40 | if err := os.Mkdir(dest, 0o755); err != nil { |
| 41 | t.Fatal(err) |
| 42 | } |
| 43 | if err := ReplaceFile(tmp, dest); err == nil { |
| 44 | t.Fatal("want error when dest can never be replaced") |
| 45 | } |
| 46 | if !fileExists(tmp) { |
| 47 | t.Error("tmp should survive a failed replace so the next launch can retry") |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | func TestReplaceFileRenamesInPlace(t *testing.T) { |
| 52 | dir := t.TempDir() |
| 53 | tmp := filepath.Join(dir, "x.tmp") |
| 54 | dest := filepath.Join(dir, "x.txt") |
| 55 | if err := os.WriteFile(tmp, []byte("hello"), 0o644); err != nil { |
| 56 | t.Fatal(err) |
| 57 | } |
| 58 | if err := ReplaceFile(tmp, dest); err != nil { |
| 59 | t.Fatal(err) |
| 60 | } |
| 61 | if b, _ := os.ReadFile(dest); string(b) != "hello" { |
| 62 | t.Errorf("dest = %q, want hello", b) |
| 63 | } |
| 64 | if _, err := os.Stat(tmp); !os.IsNotExist(err) { |
| 65 | t.Error("tmp should be gone after ReplaceFile") |
| 66 | } |
| 67 | } |
| 68 | |
| 69 | func TestReplaceFileTransientFailureNeverTruncatesDest(t *testing.T) { |
| 70 | // A rename blocked by a transient lock must surface the error, never fall |
| 71 | // back to the in-place copy: the copy truncates dest first, so a reader |
| 72 | // racing it can observe an empty or half-written file — the torn state |
| 73 | // AtomicWriteFile promises its callers (session leases, credentials, |
| 74 | // plugin state) can never happen. |
| 75 | oldBase, oldMax, oldRename := replaceRetryBase, maxReplaceRetries, renameFile |
| 76 | replaceRetryBase, maxReplaceRetries = 0, 2 |
| 77 | renameCalls := 0 |
| 78 | renameFile = func(oldpath, newpath string) error { |
| 79 | renameCalls++ |
| 80 | return &os.LinkError{Op: "rename", Old: oldpath, New: newpath, Err: errors.New("transient sharing violation")} |
| 81 | } |
| 82 | t.Cleanup(func() { replaceRetryBase, maxReplaceRetries, renameFile = oldBase, oldMax, oldRename }) |
| 83 | |
| 84 | dir := t.TempDir() |
| 85 | tmp := filepath.Join(dir, "x.tmp") |
| 86 | dest := filepath.Join(dir, "x.txt") |
| 87 | if err := os.WriteFile(tmp, []byte("new"), 0o644); err != nil { |
| 88 | t.Fatal(err) |
| 89 | } |
| 90 | if err := os.WriteFile(dest, []byte("old"), 0o644); err != nil { |
| 91 | t.Fatal(err) |
| 92 | } |
| 93 | if err := ReplaceFile(tmp, dest); err == nil { |
| 94 | t.Fatal("want the rename error to surface once retries are exhausted") |
| 95 | } |
| 96 | if want := maxReplaceRetries + 1; renameCalls != want { |
| 97 | t.Errorf("rename attempts = %d, want %d (initial try plus retries)", renameCalls, want) |
| 98 | } |
| 99 | if b, _ := os.ReadFile(dest); string(b) != "old" { |
| 100 | t.Fatalf("dest = %q, want the old content intact — anything else means the non-atomic copy ran", b) |
| 101 | } |
| 102 | if !fileExists(tmp) { |
| 103 | t.Error("tmp should survive a failed replace so the caller can clean up") |
| 104 | } |
| 105 | } |
| 106 | |
| 107 | func TestReplaceFileCrossDeviceCopiesImmediately(t *testing.T) { |
| 108 | // The cross-device class (Windows encryption filter drivers, #2696) fails |
| 109 | // identically on every retry, so ReplaceFile must take the copy fallback |
| 110 | // straight away instead of sleeping through the retry ladder. |
| 111 | oldBase, oldMax, oldRename := replaceRetryBase, maxReplaceRetries, renameFile |
| 112 | // Any retry sleep would trip the elapsed-time check below. |
| 113 | replaceRetryBase, maxReplaceRetries = 10*time.Second, 8 |
| 114 | renameCalls := 0 |
| 115 | renameFile = func(oldpath, newpath string) error { |
| 116 | renameCalls++ |
| 117 | return &os.LinkError{Op: "rename", Old: oldpath, New: newpath, Err: syscall.EXDEV} |
| 118 | } |
| 119 | t.Cleanup(func() { replaceRetryBase, maxReplaceRetries, renameFile = oldBase, oldMax, oldRename }) |
| 120 | |
| 121 | dir := t.TempDir() |
| 122 | tmp := filepath.Join(dir, "x.tmp") |
| 123 | dest := filepath.Join(dir, "x.txt") |
| 124 | if err := os.WriteFile(tmp, []byte("new"), 0o644); err != nil { |
| 125 | t.Fatal(err) |
| 126 | } |
| 127 | if err := os.WriteFile(dest, []byte("old"), 0o644); err != nil { |
| 128 | t.Fatal(err) |
| 129 | } |
| 130 | start := time.Now() |
| 131 | if err := ReplaceFile(tmp, dest); err != nil { |
| 132 | t.Fatalf("ReplaceFile should succeed via the copy fallback: %v", err) |
| 133 | } |
| 134 | if renameCalls != 1 { |
| 135 | t.Errorf("rename attempts = %d, want 1 — a structurally impossible rename must not be retried", renameCalls) |
| 136 | } |
| 137 | if elapsed := time.Since(start); elapsed > time.Second { |
| 138 | t.Errorf("cross-device fallback took %v — it slept through the retry ladder", elapsed) |
| 139 | } |
| 140 | if b, _ := os.ReadFile(dest); string(b) != "new" { |
| 141 | t.Errorf("dest = %q, want the new content from the copy fallback", b) |
| 142 | } |
| 143 | if fileExists(tmp) { |
| 144 | t.Error("tmp should be consumed by the copy fallback") |
| 145 | } |
| 146 | } |
| 147 | |
| 148 | func TestAtomicWriteFileStrictCrossDeviceKeepsExistingDestination(t *testing.T) { |
| 149 | oldRename := renameFile |
| 150 | renameFile = func(oldpath, newpath string) error { |
| 151 | return &os.LinkError{Op: "rename", Old: oldpath, New: newpath, Err: syscall.EXDEV} |
| 152 | } |
| 153 | t.Cleanup(func() { renameFile = oldRename }) |
| 154 | |
| 155 | dir := t.TempDir() |
| 156 | dest := filepath.Join(dir, "current.json") |
| 157 | if err := os.WriteFile(dest, []byte("old-pointer"), 0o644); err != nil { |
| 158 | t.Fatal(err) |
| 159 | } |
| 160 | if err := AtomicWriteFileStrict(dest, []byte("new-pointer"), 0o644); err == nil { |
| 161 | t.Fatal("strict atomic write accepted a cross-device rename") |
| 162 | } |
| 163 | if got, err := os.ReadFile(dest); err != nil || string(got) != "old-pointer" { |
| 164 | t.Fatalf("destination changed after strict replace failure: %q, %v", got, err) |
| 165 | } |
| 166 | entries, err := os.ReadDir(dir) |
| 167 | if err != nil { |
| 168 | t.Fatal(err) |
| 169 | } |
| 170 | if len(entries) != 1 || entries[0].Name() != "current.json" { |
| 171 | t.Fatalf("strict write left temporary files: %v", entries) |
| 172 | } |
| 173 | } |
| 174 | |
| 175 | func TestCopyOntoOverwritesAndPreservesMode(t *testing.T) { |
| 176 | dir := t.TempDir() |
| 177 | tmp := filepath.Join(dir, "x.tmp") |
| 178 | dest := filepath.Join(dir, "x.txt") |
| 179 | if err := os.WriteFile(tmp, []byte("new"), 0o600); err != nil { |
| 180 | t.Fatal(err) |
| 181 | } |
| 182 | if err := os.WriteFile(dest, []byte("old-and-longer"), 0o644); err != nil { |
| 183 | t.Fatal(err) |
| 184 | } |
| 185 | if err := copyOnto(tmp, dest); err != nil { |
| 186 | t.Fatal(err) |
| 187 | } |
| 188 | if b, _ := os.ReadFile(dest); string(b) != "new" { |
| 189 | t.Errorf("dest = %q, want new (fully overwritten)", b) |
| 190 | } |
| 191 | if _, err := os.Stat(tmp); !os.IsNotExist(err) { |
| 192 | t.Error("tmp should be removed after copyOnto") |
| 193 | } |
| 194 | // Mode preservation is meaningful on Unix; Windows only tracks the read-only bit. |
| 195 | if info, err := os.Stat(dest); err == nil && info.Mode().Perm() != 0o600 { |
| 196 | t.Logf("dest mode = %o (want 0600 on Unix)", info.Mode().Perm()) |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | func TestAtomicWriteFileReplacesExisting(t *testing.T) { |
| 201 | dir := t.TempDir() |
| 202 | path := filepath.Join(dir, "config.toml") |
| 203 | if err := os.WriteFile(path, []byte("old"), 0o644); err != nil { |
| 204 | t.Fatal(err) |
| 205 | } |
| 206 | if err := AtomicWriteFile(path, []byte("new-content"), 0o600); err != nil { |
| 207 | t.Fatalf("AtomicWriteFile: %v", err) |
| 208 | } |
| 209 | got, err := os.ReadFile(path) |
| 210 | if err != nil { |
| 211 | t.Fatal(err) |
| 212 | } |
| 213 | if string(got) != "new-content" { |
| 214 | t.Fatalf("content = %q, want %q", got, "new-content") |
| 215 | } |
| 216 | info, err := os.Stat(path) |
| 217 | if err != nil { |
| 218 | t.Fatal(err) |
| 219 | } |
| 220 | if perm := info.Mode().Perm(); runtime.GOOS != "windows" && perm != 0o600 { |
| 221 | t.Fatalf("perm = %o, want 600", perm) |
| 222 | } |
| 223 | // No leftover tmp files in the directory. |
| 224 | entries, _ := os.ReadDir(dir) |
| 225 | for _, e := range entries { |
| 226 | if e.Name() != "config.toml" { |
| 227 | t.Fatalf("unexpected leftover file: %s", e.Name()) |
| 228 | } |
| 229 | } |
| 230 | } |
| 231 | |
| 232 | func TestAtomicWriteFileCreatesParentDir(t *testing.T) { |
| 233 | dir := t.TempDir() |
| 234 | path := filepath.Join(dir, "nested", "deep", "creds") |
| 235 | if err := AtomicWriteFile(path, []byte("x"), 0o600); err != nil { |
| 236 | t.Fatalf("AtomicWriteFile into missing dir: %v", err) |
| 237 | } |
| 238 | if _, err := os.Stat(path); err != nil { |
| 239 | t.Fatalf("file not created: %v", err) |
| 240 | } |
| 241 | } |
| 242 | |
| 243 | func TestAtomicCreateFileNeverOverwritesExisting(t *testing.T) { |
| 244 | dir := t.TempDir() |
| 245 | path := filepath.Join(dir, "config.toml") |
| 246 | if err := os.WriteFile(path, []byte("concurrent"), 0o600); err != nil { |
| 247 | t.Fatal(err) |
| 248 | } |
| 249 | if err := AtomicCreateFile(path, []byte("confirmed"), 0o600); err == nil { |
| 250 | t.Fatal("AtomicCreateFile overwrote an existing target") |
| 251 | } |
| 252 | if got, err := os.ReadFile(path); err != nil || string(got) != "concurrent" { |
| 253 | t.Fatalf("existing target changed: %q, %v", got, err) |
| 254 | } |
| 255 | entries, err := os.ReadDir(dir) |
| 256 | if err != nil { |
| 257 | t.Fatal(err) |
| 258 | } |
| 259 | if len(entries) != 1 || entries[0].Name() != "config.toml" { |
| 260 | t.Fatalf("temporary files leaked: %v", entries) |
| 261 | } |
| 262 | } |
| 263 | |
| 264 | func TestAtomicCreateFilePublishesCompleteContent(t *testing.T) { |
| 265 | path := filepath.Join(t.TempDir(), "nested", "config.toml") |
| 266 | if err := AtomicCreateFile(path, []byte("confirmed"), 0o600); err != nil { |
| 267 | t.Fatal(err) |
| 268 | } |
| 269 | if got, err := os.ReadFile(path); err != nil || string(got) != "confirmed" { |
| 270 | t.Fatalf("created target = %q, %v", got, err) |
| 271 | } |
| 272 | } |
| 273 |