feat: command timeouts (#2898)

errors/errors_task.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"strings"
+	"time"
 
 	"mvdan.cc/sh/v3/interp"
 )
@@ -51,6 +52,10 @@ func (err *TaskRunError) TaskExitCode() int {
 	if errors.As(err.Err, &exit) {
 		return int(exit)
 	}
+	var timeout *TaskTimeoutError
+	if errors.As(err.Err, &timeout) {
+		return TimeoutExitCode
+	}
 	return err.Code()
 }
 
@@ -58,6 +63,25 @@ func (err *TaskRunError) Unwrap() error {
 	return err.Err
 }
 
+// TimeoutExitCode is what a killed command reports in place of the exit status
+// it never got, following the convention of timeout(1).
+const TimeoutExitCode = 124
+
+// TaskTimeoutError is returned when a command exceeds the timeout it declared.
+// It must not unwrap to context.DeadlineExceeded, which --watch swallows.
+type TaskTimeoutError struct {
+	TaskName string
+	Timeout  time.Duration
+}
+
+func (err *TaskTimeoutError) Error() string {
+	return fmt.Sprintf(`task: [%s] command timeout exceeded (%s)`, err.TaskName, err.Timeout)
+}
+
+func (err *TaskTimeoutError) Code() int {
+	return CodeTaskTimedOut
+}
+
 // TaskInternalError when the user attempts to invoke a task that is internal.
 type TaskInternalError struct {
 	TaskName string