| 1 | // Package shellrun provides a shared foreground shell runner used by the model |
| 2 | // bash 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 | "sync" |
| 14 | "time" |
| 15 | |
| 16 | "reasonix/internal/proc" |
| 17 | "reasonix/internal/tool" |
| 18 | ) |
| 19 | |
| 20 | // DefaultWaitDelay mirrors the bash tool's child-process wait grace. |
| 21 | const DefaultWaitDelay = 5 * time.Second |
| 22 | |
| 23 | var errForegroundTimeout = errors.New("shell foreground timeout") |
| 24 | |
| 25 | // Request describes one foreground shell launch. Argv must already include the |
| 26 | // interpreter and any sandbox wrapping; Command is only for diagnostics. |
| 27 | type Request struct { |
| 28 | Argv []string |
| 29 | Dir string |
| 30 | Env []string |
| 31 | Timeout time.Duration |
| 32 | WaitDelay time.Duration |
| 33 | CommandPreview string |
| 34 | ShellKind string |
| 35 | ShellPath string |
| 36 | Source string |
| 37 | Track bool |
| 38 | PreserveWaitDelay bool |
| 39 | // Progress receives live combined output chunks (optional). |
| 40 | Progress func(chunk string) |
| 41 | // Run is optional; tests inject a process runner. When nil, proc.RunCommand. |
| 42 | Run func(ctx context.Context, cmd *exec.Cmd, opts proc.RunOptions) (*proc.TrackedCommand, error) |
| 43 | } |
| 44 | |
| 45 | // Result is the structured outcome of a foreground run. |
| 46 | type Result struct { |
| 47 | Combined string |
| 48 | // OutputTail is the bounded tail of combined output, populated only when the |
| 49 | // run did not complete successfully. Stdout and stderr share one pipe so the |
| 50 | // model-visible ordering is preserved, which makes a stderr-only tail |
| 51 | // impossible; in practice the last bytes before a failure are the diagnosis. |
| 52 | OutputTail string |
| 53 | ExitCode *int |
| 54 | Started bool |
| 55 | State string |
| 56 | FailurePhase string |
| 57 | Err error |
| 58 | Tracked *proc.TrackedCommand |
| 59 | Cmd *exec.Cmd |
| 60 | } |
| 61 | |
| 62 | // RunForeground starts the process, captures combined stdout/stderr with a |
| 63 | // lock-safe collector, and classifies timeout / cancel / launch / execution |
| 64 | // failures. Combined output is always returned so callers can feed the model. |
| 65 | func RunForeground(ctx context.Context, req Request) Result { |
| 66 | if len(req.Argv) == 0 { |
| 67 | return Result{ |
| 68 | State: tool.ShellStateFailed, |
| 69 | FailurePhase: tool.ShellPhaseLaunch, |
| 70 | Err: fmt.Errorf("empty argv"), |
| 71 | } |
| 72 | } |
| 73 | waitDelay := req.WaitDelay |
| 74 | if waitDelay <= 0 { |
| 75 | waitDelay = DefaultWaitDelay |
| 76 | } |
| 77 | runCtx := ctx |
| 78 | var cancel context.CancelFunc |
| 79 | if req.Timeout > 0 { |
| 80 | runCtx, cancel = context.WithTimeoutCause(ctx, req.Timeout, errForegroundTimeout) |
| 81 | defer cancel() |
| 82 | } |
| 83 | |
| 84 | cmd := exec.CommandContext(runCtx, req.Argv[0], req.Argv[1:]...) |
| 85 | cmd.Dir = req.Dir |
| 86 | cmd.Env = req.Env |
| 87 | cmd.WaitDelay = waitDelay |
| 88 | |
| 89 | collector := newOutputCollector(tool.OutputTailMaxBytes) |
| 90 | var writers []io.Writer |
| 91 | writers = append(writers, collector.combined, collector.tail) |
| 92 | if req.Progress != nil { |
| 93 | writers = append(writers, &progressWriter{emit: req.Progress}) |
| 94 | } |
| 95 | // Stdout and Stderr must stay the *same* writer value: os/exec then hands the |
| 96 | // child a single pipe, so the two streams interleave in the order the child |
| 97 | // wrote them and only one copy goroutine calls Progress. Two MultiWriters |
| 98 | // would mean two pipes, and combined output would be reordered per stream. |
| 99 | // The bounded tail therefore covers combined output rather than stderr only; |
| 100 | // failing commands routinely report on stdout, so the tail stays useful. |
| 101 | w := io.MultiWriter(writers...) |
| 102 | cmd.Stdout = w |
| 103 | cmd.Stderr = w |
| 104 | |
| 105 | run := req.Run |
| 106 | if run == nil { |
| 107 | run = proc.RunCommand |
| 108 | } |
| 109 | source := req.Source |
| 110 | if source == "" { |
| 111 | source = "shellrun" |
| 112 | } |
| 113 | tracked, err := run(runCtx, cmd, proc.RunOptions{ |
| 114 | Track: req.Track, |
| 115 | CancelWaitGrace: waitDelay + time.Second, |
| 116 | Source: source, |
| 117 | ShellKind: req.ShellKind, |
| 118 | ShellPath: req.ShellPath, |
| 119 | CommandPreview: req.CommandPreview, |
| 120 | }) |
| 121 | |
| 122 | out := Result{ |
| 123 | Combined: collector.combined.String(), |
| 124 | OutputTail: collector.tailString(), |
| 125 | Started: processStarted(cmd, err), |
| 126 | Tracked: tracked, |
| 127 | Cmd: cmd, |
| 128 | } |
| 129 | |
| 130 | if req.PreserveWaitDelay && runCtx.Err() == nil && errors.Is(err, exec.ErrWaitDelay) { |
| 131 | err = nil |
| 132 | } |
| 133 | |
| 134 | // Timeout takes precedence when the tool-local deadline fired. |
| 135 | if errors.Is(context.Cause(runCtx), errForegroundTimeout) { |
| 136 | out.State = tool.ShellStateTimedOut |
| 137 | out.FailurePhase = tool.ShellPhaseTimeout |
| 138 | out.ExitCode = exitCodeFromErr(err) |
| 139 | out.Err = fmt.Errorf("command timed out (> %s)", req.Timeout) |
| 140 | return out |
| 141 | } |
| 142 | // Parent cancellation (user stop / session cancel). |
| 143 | if err != nil && (errors.Is(err, context.Canceled) || errors.Is(runCtx.Err(), context.Canceled) || isCanceledWait(err)) { |
| 144 | out.State = tool.ShellStateCancelled |
| 145 | out.FailurePhase = tool.ShellPhaseCancellation |
| 146 | out.ExitCode = exitCodeFromErr(err) |
| 147 | if cause := context.Cause(runCtx); cause != nil { |
| 148 | out.Err = cause |
| 149 | } else { |
| 150 | out.Err = err |
| 151 | } |
| 152 | return out |
| 153 | } |
| 154 | if err == nil { |
| 155 | code := 0 |
| 156 | out.ExitCode = &code |
| 157 | out.State = tool.ShellStateCompleted |
| 158 | // The tail exists to explain a failure. Dropping it on success keeps |
| 159 | // successful runs from persisting up to 16 KiB of ordinary stdout into |
| 160 | // every session record and tool card. |
| 161 | out.OutputTail = "" |
| 162 | return out |
| 163 | } |
| 164 | if code := exitCodeFromErr(err); code != nil { |
| 165 | out.ExitCode = code |
| 166 | out.Started = true |
| 167 | out.State = tool.ShellStateFailed |
| 168 | out.FailurePhase = tool.ShellPhaseExecution |
| 169 | out.Err = fmt.Errorf("command exited: %w", err) |
| 170 | return out |
| 171 | } |
| 172 | // Process never produced an exit status — launch / dependency style failure. |
| 173 | out.State = tool.ShellStateFailed |
| 174 | if out.Started { |
| 175 | out.FailurePhase = tool.ShellPhaseExecution |
| 176 | } else { |
| 177 | out.FailurePhase = tool.ShellPhaseLaunch |
| 178 | } |
| 179 | out.Err = err |
| 180 | return out |
| 181 | } |
| 182 | |
| 183 | func processStarted(cmd *exec.Cmd, err error) bool { |
| 184 | if cmd != nil && cmd.Process != nil { |
| 185 | return true |
| 186 | } |
| 187 | // ExitError means the process ran. |
| 188 | var ee *exec.ExitError |
| 189 | return errors.As(err, &ee) |
| 190 | } |
| 191 | |
| 192 | func exitCodeFromErr(err error) *int { |
| 193 | if err == nil { |
| 194 | code := 0 |
| 195 | return &code |
| 196 | } |
| 197 | var ee *exec.ExitError |
| 198 | if errors.As(err, &ee) { |
| 199 | code := ee.ExitCode() |
| 200 | return &code |
| 201 | } |
| 202 | return nil |
| 203 | } |
| 204 | |
| 205 | func isCanceledWait(err error) bool { |
| 206 | var c proc.CanceledWaitError |
| 207 | return errors.As(err, &c) |
| 208 | } |
| 209 | |
| 210 | // outputCollector owns the combined buffer and a bounded tail ring. Writes stay |
| 211 | // serialized behind one mutex so a caller that does wire two pipes cannot race |
| 212 | // on the Buffer. |
| 213 | type outputCollector struct { |
| 214 | mu sync.Mutex |
| 215 | combined *lockedBuffer |
| 216 | tail *tailWriter |
| 217 | } |
| 218 | |
| 219 | func newOutputCollector(tailLimit int) *outputCollector { |
| 220 | c := &outputCollector{} |
| 221 | c.combined = &lockedBuffer{mu: &c.mu} |
| 222 | c.tail = &tailWriter{mu: &c.mu, limit: tailLimit} |
| 223 | return c |
| 224 | } |
| 225 | |
| 226 | func (c *outputCollector) tailString() string { |
| 227 | c.mu.Lock() |
| 228 | defer c.mu.Unlock() |
| 229 | return string(c.tail.buf) |
| 230 | } |
| 231 | |
| 232 | // lockedBuffer is a bytes.Buffer guarded by an external mutex so MultiWriter |
| 233 | // concurrent writes from stdout and stderr stay race-free. |
| 234 | type lockedBuffer struct { |
| 235 | mu *sync.Mutex |
| 236 | buf bytes.Buffer |
| 237 | } |
| 238 | |
| 239 | func (b *lockedBuffer) Write(p []byte) (int, error) { |
| 240 | b.mu.Lock() |
| 241 | defer b.mu.Unlock() |
| 242 | return b.buf.Write(p) |
| 243 | } |
| 244 | |
| 245 | func (b *lockedBuffer) String() string { |
| 246 | b.mu.Lock() |
| 247 | defer b.mu.Unlock() |
| 248 | return b.buf.String() |
| 249 | } |
| 250 | |
| 251 | type tailWriter struct { |
| 252 | mu *sync.Mutex |
| 253 | limit int |
| 254 | buf []byte |
| 255 | } |
| 256 | |
| 257 | func (w *tailWriter) Write(p []byte) (int, error) { |
| 258 | w.mu.Lock() |
| 259 | defer w.mu.Unlock() |
| 260 | w.buf = append(w.buf, p...) |
| 261 | if w.limit > 0 && len(w.buf) > w.limit { |
| 262 | w.buf = append([]byte(nil), w.buf[len(w.buf)-w.limit:]...) |
| 263 | } |
| 264 | return len(p), nil |
| 265 | } |
| 266 | |
| 267 | type progressWriter struct{ emit func(string) } |
| 268 | |
| 269 | func (w *progressWriter) Write(p []byte) (int, error) { |
| 270 | if w.emit != nil && len(p) > 0 { |
| 271 | w.emit(string(p)) |
| 272 | } |
| 273 | return len(p), nil |
| 274 | } |
| 275 |