| 1 | // Package shellrun provides a shared foreground shell runner used by the model |
| 2 | // shell tool and the user !command path. It classifies exits, collects a bounded |
| 3 | // output tail, and keeps combined stdout/stderr model-visible output intact. |
| 4 | package shellrun |
| 5 | |
| 6 | import ( |
| 7 | "bytes" |
| 8 | "context" |
| 9 | "errors" |
| 10 | "fmt" |
| 11 | "io" |
| 12 | "os/exec" |
| 13 | "strings" |
| 14 | "sync" |
| 15 | "time" |
| 16 | |
| 17 | fileenc "reasonix/internal/fileutil/encoding" |
| 18 | "reasonix/internal/proc" |
| 19 | "reasonix/internal/tool" |
| 20 | ) |
| 21 | |
| 22 | // DefaultWaitDelay mirrors the shell tool's child-process wait grace. |
| 23 | const DefaultWaitDelay = 5 * time.Second |
| 24 | |
| 25 | const ( |
| 26 | // combinedOutputMaxBytes bounds the foreground output retained in memory. |
| 27 | // Tool-result truncation happens only after the process exits, so it cannot |
| 28 | // protect the host from a command that prints forever (#6473, #6528). |
| 29 | combinedOutputMaxBytes = 10 << 20 |
| 30 | // Keep the final diagnostics as well as the command's opening context after |
| 31 | // the cap is crossed. Build and test failures are commonly printed last. |
| 32 | combinedOutputTailBytes = 64 << 10 |
| 33 | combinedOutputTruncated = "\n\n...[shell output truncated at 10 MiB; showing the final 64 KiB]...\n\n" |
| 34 | // Live progress crosses async UI queues and append-only reducers before the |
| 35 | // final bounded result replaces it. Keep that transient path small too, or a |
| 36 | // never-ending command can still exhaust memory while Combined stays bounded. |
| 37 | progressOutputMaxBytes = 64 << 10 |
| 38 | progressOutputTruncated = "\n\n...[live shell output capped at 64 KiB; final diagnostics will appear when the command exits]...\n\n" |
| 39 | ) |
| 40 | |
| 41 | var errForegroundTimeout = errors.New("shell foreground timeout") |
| 42 | |
| 43 | // Request describes one foreground shell launch. Argv must already include the |
| 44 | // interpreter and any sandbox wrapping; Command is only for diagnostics. |
| 45 | type Request struct { |
| 46 | Argv []string |
| 47 | Dir string |
| 48 | Env []string |
| 49 | Timeout time.Duration |
| 50 | WaitDelay time.Duration |
| 51 | CommandPreview string |
| 52 | ShellKind string |
| 53 | ShellPath string |
| 54 | Source string |
| 55 | Track bool |
| 56 | PreserveWaitDelay bool |
| 57 | // Progress receives live combined output chunks (optional). |
| 58 | Progress func(chunk string) |
| 59 | // Run is optional; tests inject a process runner. When nil, proc.RunCommand. |
| 60 | Run func(ctx context.Context, cmd *exec.Cmd, opts proc.RunOptions) (*proc.TrackedCommand, error) |
| 61 | } |
| 62 | |
| 63 | // Result is the structured outcome of a foreground run. |
| 64 | type Result struct { |
| 65 | Combined string |
| 66 | // OutputTail is the bounded tail of combined output, populated only when the |
| 67 | // run did not complete successfully. Stdout and stderr share one pipe so the |
| 68 | // model-visible ordering is preserved, which makes a stderr-only tail |
| 69 | // impossible; in practice the last bytes before a failure are the diagnosis. |
| 70 | OutputTail string |
| 71 | ExitCode *int |
| 72 | Started bool |
| 73 | State string |
| 74 | FailurePhase string |
| 75 | Err error |
| 76 | Tracked *proc.TrackedCommand |
| 77 | Cmd *exec.Cmd |
| 78 | } |
| 79 | |
| 80 | // RunForeground starts the process, captures combined stdout/stderr with a |
| 81 | // lock-safe collector, and classifies timeout / cancel / launch / execution |
| 82 | // failures. Combined output is always returned so callers can feed the model. |
| 83 | func RunForeground(ctx context.Context, req Request) Result { |
| 84 | if len(req.Argv) == 0 { |
| 85 | return Result{ |
| 86 | State: tool.ShellStateFailed, |
| 87 | FailurePhase: tool.ShellPhaseLaunch, |
| 88 | Err: fmt.Errorf("empty argv"), |
| 89 | } |
| 90 | } |
| 91 | waitDelay := req.WaitDelay |
| 92 | if waitDelay <= 0 { |
| 93 | waitDelay = DefaultWaitDelay |
| 94 | } |
| 95 | runCtx := ctx |
| 96 | var cancel context.CancelFunc |
| 97 | if req.Timeout > 0 { |
| 98 | runCtx, cancel = context.WithTimeoutCause(ctx, req.Timeout, errForegroundTimeout) |
| 99 | defer cancel() |
| 100 | } |
| 101 | |
| 102 | cmd := proc.CommandContext(runCtx, req.Argv[0], req.Argv[1:]...) |
| 103 | cmd.Dir = req.Dir |
| 104 | cmd.Env = req.Env |
| 105 | cmd.WaitDelay = waitDelay |
| 106 | |
| 107 | collector := newOutputCollector(combinedOutputMaxBytes, tool.OutputTailMaxBytes) |
| 108 | var writers []io.Writer |
| 109 | writers = append(writers, collector.combined, collector.tail) |
| 110 | var progress *progressWriter |
| 111 | if req.Progress != nil { |
| 112 | progress = newProgressWriter(req.Progress, progressOutputMaxBytes, progressOutputTruncated) |
| 113 | writers = append(writers, progress) |
| 114 | } |
| 115 | // Stdout and Stderr must stay the *same* writer value: os/exec then hands the |
| 116 | // child a single pipe, so the two streams interleave in the order the child |
| 117 | // wrote them and only one copy goroutine calls Progress. Two MultiWriters |
| 118 | // would mean two pipes, and combined output would be reordered per stream. |
| 119 | // The bounded tail therefore covers combined output rather than stderr only; |
| 120 | // failing commands routinely report on stdout, so the tail stays useful. |
| 121 | w := io.MultiWriter(writers...) |
| 122 | cmd.Stdout = w |
| 123 | cmd.Stderr = w |
| 124 | |
| 125 | run := req.Run |
| 126 | if run == nil { |
| 127 | run = proc.RunCommand |
| 128 | } |
| 129 | source := req.Source |
| 130 | if source == "" { |
| 131 | source = "shellrun" |
| 132 | } |
| 133 | tracked, err := run(runCtx, cmd, proc.RunOptions{ |
| 134 | Track: req.Track, |
| 135 | CancelWaitGrace: waitDelay + time.Second, |
| 136 | Source: source, |
| 137 | ShellKind: req.ShellKind, |
| 138 | ShellPath: req.ShellPath, |
| 139 | CommandPreview: req.CommandPreview, |
| 140 | }) |
| 141 | |
| 142 | if progress != nil { |
| 143 | progress.Flush() |
| 144 | } |
| 145 | out := Result{ |
| 146 | Combined: collector.combined.String(), |
| 147 | OutputTail: collector.tailString(), |
| 148 | Started: processStarted(cmd, err), |
| 149 | Tracked: tracked, |
| 150 | Cmd: cmd, |
| 151 | } |
| 152 | |
| 153 | return classifyForegroundResult(runCtx, req, out, err) |
| 154 | } |
| 155 | |
| 156 | func classifyForegroundResult(runCtx context.Context, req Request, out Result, err error) Result { |
| 157 | if req.PreserveWaitDelay && runCtx.Err() == nil && errors.Is(err, exec.ErrWaitDelay) { |
| 158 | err = nil |
| 159 | } |
| 160 | |
| 161 | // Timeout takes precedence when the tool-local deadline fired. |
| 162 | if errors.Is(context.Cause(runCtx), errForegroundTimeout) { |
| 163 | out.State = tool.ShellStateTimedOut |
| 164 | out.FailurePhase = tool.ShellPhaseTimeout |
| 165 | out.ExitCode = exitCodeFromErr(err) |
| 166 | out.Err = fmt.Errorf("command timed out (> %s)", req.Timeout) |
| 167 | return out |
| 168 | } |
| 169 | // Parent cancellation (user stop / session cancel). |
| 170 | if err != nil && (errors.Is(err, context.Canceled) || errors.Is(runCtx.Err(), context.Canceled) || isCanceledWait(err)) { |
| 171 | out.State = tool.ShellStateCancelled |
| 172 | out.FailurePhase = tool.ShellPhaseCancellation |
| 173 | out.ExitCode = exitCodeFromErr(err) |
| 174 | if cause := context.Cause(runCtx); cause != nil { |
| 175 | out.Err = cause |
| 176 | } else { |
| 177 | out.Err = err |
| 178 | } |
| 179 | return out |
| 180 | } |
| 181 | if err == nil { |
| 182 | code := 0 |
| 183 | out.ExitCode = &code |
| 184 | out.State = tool.ShellStateCompleted |
| 185 | // The tail exists to explain a failure. Dropping it on success keeps |
| 186 | // successful runs from persisting up to 16 KiB of ordinary stdout into |
| 187 | // every session record and tool card. |
| 188 | out.OutputTail = "" |
| 189 | return out |
| 190 | } |
| 191 | if code := exitCodeFromErr(err); code != nil { |
| 192 | out.ExitCode = code |
| 193 | out.Started = true |
| 194 | out.State = tool.ShellStateFailed |
| 195 | out.FailurePhase = tool.ShellPhaseExecution |
| 196 | out.Err = fmt.Errorf("command exited: %w", err) |
| 197 | if diagnostic := WindowsRuntimeDiagnostic(out.Combined); diagnostic != "" { |
| 198 | out.Err = fmt.Errorf("%s: %w", diagnostic, out.Err) |
| 199 | } |
| 200 | return out |
| 201 | } |
| 202 | // Process never produced an exit status — launch / dependency style failure. |
| 203 | out.State = tool.ShellStateFailed |
| 204 | if out.Started { |
| 205 | out.FailurePhase = tool.ShellPhaseExecution |
| 206 | } else { |
| 207 | out.FailurePhase = tool.ShellPhaseLaunch |
| 208 | } |
| 209 | out.Err = err |
| 210 | return out |
| 211 | } |
| 212 | |
| 213 | func processStarted(cmd *exec.Cmd, err error) bool { |
| 214 | if cmd != nil && cmd.Process != nil { |
| 215 | return true |
| 216 | } |
| 217 | // ExitError means the process ran. |
| 218 | var ee *exec.ExitError |
| 219 | return errors.As(err, &ee) |
| 220 | } |
| 221 | |
| 222 | func exitCodeFromErr(err error) *int { |
| 223 | if err == nil { |
| 224 | code := 0 |
| 225 | return &code |
| 226 | } |
| 227 | var ee *exec.ExitError |
| 228 | if errors.As(err, &ee) { |
| 229 | code := ee.ExitCode() |
| 230 | return &code |
| 231 | } |
| 232 | return nil |
| 233 | } |
| 234 | |
| 235 | func isCanceledWait(err error) bool { |
| 236 | var c proc.CanceledWaitError |
| 237 | return errors.As(err, &c) |
| 238 | } |
| 239 | |
| 240 | // outputCollector owns the combined buffer and a bounded tail ring. Writes stay |
| 241 | // serialized behind one mutex so a caller that does wire two pipes cannot race |
| 242 | // on the Buffer. |
| 243 | type outputCollector struct { |
| 244 | mu sync.Mutex |
| 245 | combined *boundedBuffer |
| 246 | tail *tailWriter |
| 247 | } |
| 248 | |
| 249 | func newOutputCollector(combinedLimit, tailLimit int) *outputCollector { |
| 250 | c := &outputCollector{} |
| 251 | c.combined = &boundedBuffer{ |
| 252 | mu: &c.mu, |
| 253 | limit: combinedLimit, |
| 254 | tailLimit: combinedOutputTailBytes, |
| 255 | marker: combinedOutputTruncated, |
| 256 | } |
| 257 | c.tail = &tailWriter{mu: &c.mu, limit: tailLimit} |
| 258 | return c |
| 259 | } |
| 260 | |
| 261 | func (c *outputCollector) tailString() string { |
| 262 | c.mu.Lock() |
| 263 | defer c.mu.Unlock() |
| 264 | return string(fileenc.DecodeOutput(c.tail.buf, fileenc.Cut{Head: c.tail.cut})) |
| 265 | } |
| 266 | |
| 267 | // boundedBuffer keeps complete output up to limit. Once output crosses the |
| 268 | // limit it retains a head plus a rolling tail separated by marker. Write always |
| 269 | // reports the full input consumed so a safety cap never changes child-process |
| 270 | // behavior into an artificial short-write failure. |
| 271 | type boundedBuffer struct { |
| 272 | mu *sync.Mutex |
| 273 | buf bytes.Buffer |
| 274 | tail []byte |
| 275 | limit int |
| 276 | tailLimit int |
| 277 | marker string |
| 278 | truncated bool |
| 279 | } |
| 280 | |
| 281 | func (b *boundedBuffer) Write(p []byte) (int, error) { |
| 282 | b.mu.Lock() |
| 283 | defer b.mu.Unlock() |
| 284 | if len(p) == 0 { |
| 285 | return 0, nil |
| 286 | } |
| 287 | if !b.truncated && (b.limit <= 0 || b.buf.Len()+len(p) <= b.limit) { |
| 288 | _, err := b.buf.Write(p) |
| 289 | return len(p), err |
| 290 | } |
| 291 | if !b.truncated { |
| 292 | b.truncated = true |
| 293 | headLimit := max(0, b.limit-b.tailLimit-len(b.marker)) |
| 294 | previous := b.buf.Bytes() |
| 295 | b.tail = appendBoundedTail(b.tail, previous, b.tailLimit) |
| 296 | if b.buf.Len() > headLimit { |
| 297 | b.buf.Truncate(headLimit) |
| 298 | } else if remaining := headLimit - b.buf.Len(); remaining > 0 { |
| 299 | b.buf.Write(p[:min(remaining, len(p))]) |
| 300 | } |
| 301 | } |
| 302 | b.tail = appendBoundedTail(b.tail, p, b.tailLimit) |
| 303 | return len(p), nil |
| 304 | } |
| 305 | |
| 306 | // String decodes the output in the encoding the child wrote it in; a Windows |
| 307 | // console tool answers in the machine's code page, not UTF-8. Once truncated, |
| 308 | // the head lost its end and the tail its start, so each is decoded on its own. |
| 309 | func (b *boundedBuffer) String() string { |
| 310 | b.mu.Lock() |
| 311 | defer b.mu.Unlock() |
| 312 | if !b.truncated { |
| 313 | return string(fileenc.DecodeOutput(b.buf.Bytes(), fileenc.Cut{})) |
| 314 | } |
| 315 | var out strings.Builder |
| 316 | out.Grow(b.buf.Len() + len(b.marker) + len(b.tail)) |
| 317 | out.Write(fileenc.DecodeOutput(b.buf.Bytes(), fileenc.Cut{Tail: true})) |
| 318 | out.WriteString(b.marker) |
| 319 | out.Write(fileenc.DecodeOutput(b.tail, fileenc.Cut{Head: true})) |
| 320 | return out.String() |
| 321 | } |
| 322 | |
| 323 | func appendBoundedTail(dst, p []byte, limit int) []byte { |
| 324 | if limit <= 0 || len(p) >= limit { |
| 325 | if limit <= 0 { |
| 326 | return nil |
| 327 | } |
| 328 | return append(dst[:0], p[len(p)-limit:]...) |
| 329 | } |
| 330 | if overflow := len(dst) + len(p) - limit; overflow > 0 { |
| 331 | copy(dst, dst[overflow:]) |
| 332 | dst = dst[:len(dst)-overflow] |
| 333 | } |
| 334 | return append(dst, p...) |
| 335 | } |
| 336 | |
| 337 | type tailWriter struct { |
| 338 | mu *sync.Mutex |
| 339 | limit int |
| 340 | buf []byte |
| 341 | cut bool // bytes before buf were dropped to hold the limit |
| 342 | } |
| 343 | |
| 344 | func (w *tailWriter) Write(p []byte) (int, error) { |
| 345 | w.mu.Lock() |
| 346 | defer w.mu.Unlock() |
| 347 | w.buf = append(w.buf, p...) |
| 348 | if w.limit > 0 && len(w.buf) > w.limit { |
| 349 | w.buf = append([]byte(nil), w.buf[len(w.buf)-w.limit:]...) |
| 350 | w.cut = true |
| 351 | } |
| 352 | return len(p), nil |
| 353 | } |
| 354 | |
| 355 | type progressWriter struct { |
| 356 | mu sync.Mutex |
| 357 | emit func(string) |
| 358 | limit int |
| 359 | forwarded int |
| 360 | marker string |
| 361 | truncated bool |
| 362 | pending []byte |
| 363 | } |
| 364 | |
| 365 | func newProgressWriter(emit func(string), limit int, marker string) *progressWriter { |
| 366 | return &progressWriter{emit: emit, limit: max(0, limit), marker: marker} |
| 367 | } |
| 368 | |
| 369 | func (w *progressWriter) Write(p []byte) (int, error) { |
| 370 | if len(p) == 0 { |
| 371 | return 0, nil |
| 372 | } |
| 373 | w.mu.Lock() |
| 374 | defer w.mu.Unlock() |
| 375 | if w.emit == nil || w.truncated { |
| 376 | return len(p), nil |
| 377 | } |
| 378 | w.writeUTF8(p, false) |
| 379 | return len(p), nil |
| 380 | } |
| 381 |