518 lines
20 KiB
Python
518 lines
20 KiB
Python
#!/usr/bin/env python3
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"""
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Module for running interactive subprocesses with output capture,
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with full raw input passthrough for interactive commands.
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It uses a pseudo-tty and integrates pyte's HistoryScreen to simulate
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a terminal and capture the final scrollback history (non-blank lines).
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The interface remains compatible with external callers expecting a tuple (output, return_code),
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where output is a bytes object (UTF-8 encoded).
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"""
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import errno
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import io
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import os
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import select
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import shutil
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import signal
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import subprocess
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import sys
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import threading
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import time
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from typing import List, Tuple, Optional, Any
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import pyte
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from pyte.screens import HistoryScreen
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# Import platform-specific modules
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if sys.platform == "win32":
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import msvcrt
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else:
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import termios
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import tty
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def get_terminal_size() -> Tuple[int, int]:
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"""
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Get the current terminal size in a cross-platform way.
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This function works on both Unix and Windows systems, using shutil.get_terminal_size()
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which is available in Python 3.3+. If the terminal size cannot be determined
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(e.g., when running in a non-interactive environment), it falls back to default values.
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Returns:
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A tuple of (columns, rows) representing the terminal dimensions.
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"""
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try:
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size = shutil.get_terminal_size()
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return size.columns, size.lines
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except OSError:
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# Default fallback values
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return 80, 24
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def create_process(cmd: List[str]) -> Tuple[subprocess.Popen, Any]:
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"""
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Create a subprocess with appropriate platform-specific settings.
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This function handles the platform-specific differences between Windows and Unix:
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On Windows:
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- Creates a process with pipes for stdin/stdout
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- Uses STARTF_USESHOWWINDOW to prevent console windows from appearing
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- Returns the process and None (no PTY on Windows)
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On Unix:
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- Creates a pseudo-terminal (PTY) for full terminal emulation
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- Sets up non-blocking I/O on the master file descriptor
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- Configures environment variables for consistent behavior
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- Creates a new process group for proper signal handling
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Args:
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cmd: A list containing the command and its arguments.
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Returns:
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A tuple of (process, master_fd) where:
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- process is the subprocess.Popen object
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- master_fd is the master file descriptor (on Unix) or None (on Windows)
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"""
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if sys.platform == "win32":
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# Windows-specific process creation
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startupinfo = subprocess.STARTUPINFO()
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startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
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proc = subprocess.Popen(
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cmd,
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stdin=subprocess.PIPE,
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stdout=subprocess.PIPE,
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stderr=subprocess.STDOUT,
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bufsize=0,
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startupinfo=startupinfo
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)
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return proc, None
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else:
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# Unix-specific process creation with pty
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master_fd, slave_fd = os.openpty()
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os.set_blocking(master_fd, False)
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env = os.environ.copy()
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env.update({
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"DEBIAN_FRONTEND": "noninteractive",
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"GIT_PAGER": "",
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"PYTHONUNBUFFERED": "1",
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"CI": "true",
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"LANG": "C.UTF-8",
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"LC_ALL": "C.UTF-8",
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"COLUMNS": str(get_terminal_size()[0]),
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"LINES": str(get_terminal_size()[1]),
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"FORCE_COLOR": "1",
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"GIT_TERMINAL_PROMPT": "0",
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"PYTHONDONTWRITEBYTECODE": "1",
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"NODE_OPTIONS": "--unhandled-rejections=strict",
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})
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proc = subprocess.Popen(
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cmd,
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stdin=slave_fd,
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stdout=slave_fd,
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stderr=slave_fd,
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bufsize=0,
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close_fds=True,
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env=env,
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preexec_fn=os.setsid, # Create new process group for proper signal handling.
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)
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os.close(slave_fd) # Close slave end in the parent process.
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return proc, master_fd
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def render_line(line, columns: int) -> str:
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"""
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Render a single screen line from the pyte buffer.
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This function handles different types of line representations from pyte:
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- String lines (from screen.display)
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- Dictionary-style lines (from history, mapping column indices to Char objects)
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Args:
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line: A line from pyte's screen buffer (string or dict mapping column to Char)
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columns: Maximum number of columns to render
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Returns:
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A string representation of the line with proper character data
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"""
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if not line:
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return ""
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# Handle string lines directly (from screen.display)
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if isinstance(line, str):
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return line
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# Handle dictionary-style lines (from history)
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try:
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max_col = max(line.keys()) if line else -1
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result = ""
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for x in range(min(columns, max_col + 1)):
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if x in line:
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result += line[x].data
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return result
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except (AttributeError, TypeError):
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# Fallback for any unexpected types
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return str(line)
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def run_interactive_command(
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cmd: List[str], expected_runtime_seconds: int = 30
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) -> Tuple[bytes, int]:
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"""
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Runs an interactive command with output capture, capturing final scrollback history.
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This function provides a cross-platform way to run interactive commands with:
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- Full terminal emulation using pyte's HistoryScreen
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- Real-time display of command output
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- Input forwarding when running in an interactive terminal
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- Timeout handling to prevent runaway processes
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- Comprehensive output capture including ANSI escape sequences
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The implementation differs significantly between Windows and Unix:
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On Windows:
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- Uses threading to handle I/O operations
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- Relies on msvcrt for keyboard input detection
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- Uses pipes for process communication
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On Unix:
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- Uses pseudo-terminals (PTY) for full terminal emulation
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- Uses select() for non-blocking I/O
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- Handles raw terminal mode for proper input forwarding
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- Uses process groups for proper signal handling
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Args:
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cmd: A list containing the command and its arguments.
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expected_runtime_seconds: Expected runtime in seconds, defaults to 30.
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If process exceeds 2x this value, it will be terminated gracefully.
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If process exceeds 3x this value, it will be killed forcefully.
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Must be between 1 and 1800 seconds (30 minutes).
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Returns:
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A tuple of (captured_output, return_code), where captured_output is a UTF-8 encoded
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bytes object containing the trimmed non-empty history lines from the terminal session.
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Raises:
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ValueError: If no command is provided.
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FileNotFoundError: If the command is not found in PATH.
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ValueError: If expected_runtime_seconds is less than or equal to 0 or greater than 1800.
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RuntimeError: If an error occurs during execution.
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"""
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if not cmd:
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raise ValueError("No command provided.")
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if shutil.which(cmd[0]) is None:
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raise FileNotFoundError(f"Command '{cmd[0]}' not found in PATH.")
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if expected_runtime_seconds <= 0 or expected_runtime_seconds > 1800:
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raise ValueError(
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"expected_runtime_seconds must be between 1 and 1800 seconds (30 minutes)"
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)
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cols, rows = get_terminal_size()
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# Set up pyte screen and stream to capture terminal output.
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# Increase history size to capture more lines (from 2000 to 5000)
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screen = HistoryScreen(cols, rows, history=5000, ratio=0.8)
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stream = pyte.Stream(screen)
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# Create process with platform-specific settings
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proc, master_fd = create_process(cmd)
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captured_data = []
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start_time = time.time()
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was_terminated = False
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def check_timeout():
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"""
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Check if the process has exceeded its timeout limits and terminate if necessary.
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Returns:
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True if the process was terminated due to timeout, False otherwise.
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"""
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elapsed = time.time() - start_time
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if sys.platform == "win32":
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# Windows process termination
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if elapsed > 3 * expected_runtime_seconds:
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# Hard kill after 3x the expected time
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proc.kill()
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return True
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elif elapsed > 2 * expected_runtime_seconds:
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# Graceful termination after 2x the expected time
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proc.terminate()
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return True
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else:
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# Unix process termination (using process groups)
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if elapsed > 3 * expected_runtime_seconds:
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# Hard kill with SIGKILL after 3x the expected time
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os.killpg(os.getpgid(proc.pid), signal.SIGKILL)
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return True
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elif elapsed > 2 * expected_runtime_seconds:
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# Graceful termination with SIGTERM after 2x the expected time
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os.killpg(os.getpgid(proc.pid), signal.SIGTERM)
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return True
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return False
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# Windows implementation
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if sys.platform == "win32":
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try:
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stdin_fd = None
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if sys.stdin and sys.stdin.isatty():
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try:
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stdin_fd = sys.stdin.fileno()
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except (AttributeError, io.UnsupportedOperation):
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stdin_fd = None
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# Function to read output from the process
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def read_output():
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"""
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Thread function to continuously read and process output from the subprocess.
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This function:
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1. Reads data from the process stdout in chunks
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2. Adds the data to captured_data for later processing
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3. Feeds the data to the terminal emulator (pyte)
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4. Writes the data to stdout for real-time display
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5. Handles process termination and cleanup
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"""
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while proc.poll() is None:
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try:
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data = proc.stdout.read(1024)
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if not data:
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break
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captured_data.append(data)
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decoded = data.decode("utf-8", errors="ignore")
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stream.feed(decoded)
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# Write to stdout for real-time display
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try:
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sys.stdout.buffer.write(data)
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sys.stdout.buffer.flush()
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except (OSError, IOError):
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pass # Ignore errors writing to stdout
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except (OSError, IOError):
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break
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except Exception as e:
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print(f"Error reading output: {e}", file=sys.stderr)
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break
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# Try to read any remaining data after process ends
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try:
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remaining = proc.stdout.read()
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if remaining:
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captured_data.append(remaining)
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stream.feed(remaining.decode("utf-8", errors="ignore"))
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except Exception:
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pass
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# Start a thread to read output
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output_thread = threading.Thread(target=read_output)
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output_thread.daemon = True
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output_thread.start()
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# Main loop for input and timeout checking
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while proc.poll() is None:
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if check_timeout():
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was_terminated = True
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break
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# Check for input if we have a TTY
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if stdin_fd is not None and msvcrt.kbhit():
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try:
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char = msvcrt.getch()
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proc.stdin.write(char)
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proc.stdin.flush()
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except (OSError, IOError):
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break
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time.sleep(0.1) # Small sleep to prevent CPU hogging
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# Wait for the output thread to finish
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output_thread.join(timeout=1.0)
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except KeyboardInterrupt:
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proc.terminate()
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finally:
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if proc.stdin:
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proc.stdin.close()
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if proc.stdout:
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proc.stdout.close()
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# Unix implementation
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else:
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try:
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stdin_fd = None
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try:
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stdin_fd = sys.stdin.fileno()
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except (AttributeError, io.UnsupportedOperation):
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stdin_fd = None
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# Interactive mode: forward input if running in a TTY.
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if stdin_fd is not None and sys.stdin.isatty():
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old_settings = termios.tcgetattr(stdin_fd)
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tty.setraw(stdin_fd)
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try:
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while True:
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if check_timeout():
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was_terminated = True
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break
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# Use a finite timeout to avoid indefinite blocking.
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rlist, _, _ = select.select([master_fd, stdin_fd], [], [], 1.0)
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if master_fd in rlist:
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try:
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data = os.read(master_fd, 1024)
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except OSError as e:
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if e.errno == errno.EIO:
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break
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else:
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raise
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if not data: # EOF detected.
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break
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captured_data.append(data)
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decoded = data.decode("utf-8", errors="ignore")
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stream.feed(decoded)
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os.write(1, data)
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if stdin_fd in rlist:
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try:
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input_data = os.read(stdin_fd, 1024)
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except OSError:
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input_data = b""
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if input_data:
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os.write(master_fd, input_data)
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except KeyboardInterrupt:
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proc.terminate()
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finally:
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termios.tcsetattr(stdin_fd, termios.TCSADRAIN, old_settings)
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else:
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# Non-interactive mode.
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try:
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while True:
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if check_timeout():
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was_terminated = True
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break
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rlist, _, _ = select.select([master_fd], [], [], 1.0)
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if not rlist:
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continue
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try:
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data = os.read(master_fd, 1024)
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except OSError as e:
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if e.errno == errno.EIO:
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break
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else:
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raise
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if not data: # EOF detected.
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break
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captured_data.append(data)
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decoded = data.decode("utf-8", errors="ignore")
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stream.feed(decoded)
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try:
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os.write(1, data)
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except (OSError, IOError):
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pass # Ignore errors writing to stdout
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except KeyboardInterrupt:
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proc.terminate()
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os.close(master_fd)
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except Exception as e:
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print(f"Error in Unix implementation: {e}", file=sys.stderr)
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# Wait for the process to finish
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proc.wait()
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# Ensure we have captured data even if the screen processing failed
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raw_output = b"".join(captured_data)
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# Try to assemble full scrollback from the terminal emulation
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try:
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# Assemble full scrollback: combine history.top, the current display, and history.bottom.
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top_lines = []
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display_lines = []
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bottom_lines = []
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# Safely extract history.top (scrollback buffer above visible area)
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if hasattr(screen, 'history') and hasattr(screen.history, 'top'):
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top_lines = [render_line(line, cols) for line in screen.history.top]
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# Safely extract current display (visible terminal area)
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if hasattr(screen, 'display'):
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display_lines = [render_line(line, cols) for line in screen.display]
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# Safely extract history.bottom (scrollback buffer below visible area)
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if hasattr(screen, 'history') and hasattr(screen.history, 'bottom'):
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bottom_lines = [render_line(line, cols) for line in screen.history.bottom]
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# Combine all lines to get the complete terminal history
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all_lines = top_lines + display_lines + bottom_lines
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# Trim out empty lines to get only meaningful "history" lines
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# This is important for commands that don't fill the entire terminal
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trimmed_lines = [line for line in all_lines if line and line.strip()]
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# IMPORTANT: Always check if we have meaningful content from the screen
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if trimmed_lines and any(line.strip() for line in trimmed_lines):
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final_output = "\n".join(trimmed_lines)
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else:
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# Fall back to raw output if no meaningful lines from screen
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# This is critical for simple commands like "echo hello world"
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raw_decoded = raw_output.decode('utf-8', errors='replace')
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final_output = raw_decoded.strip()
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# If raw output is also empty, try to extract any content from the screen
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if not final_output and display_lines:
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final_output = "\n".join(display_lines)
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except Exception as e:
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# If anything goes wrong with screen processing, fall back to raw output
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print(f"Warning: Error processing terminal output: {e}", file=sys.stderr)
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final_output = raw_output.decode('utf-8', errors='replace').strip()
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# Add timeout message if process was terminated due to timeout.
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if was_terminated:
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timeout_msg = f"\n[Process exceeded timeout ({expected_runtime_seconds} seconds expected)]"
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final_output += timeout_msg
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# Limit output to the last 8000 bytes, but try to keep complete lines
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# This ensures we don't exceed memory limits while preserving readable output
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if len(final_output) > 8000:
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# Find a newline near the 8000-byte cutoff point
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cutoff = max(0, len(final_output) - 8000)
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# Try to find a newline after the cutoff to avoid cutting in the middle of a line
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newline_pos = final_output.find('\n', cutoff)
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if newline_pos != -1 and newline_pos < cutoff + 200: # Don't look too far ahead
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cutoff = newline_pos + 1
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final_output = final_output[cutoff:]
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# Ensure we're returning bytes with consistent encoding
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if isinstance(final_output, str):
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# Make sure we have content in the final output
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if not final_output.strip() and raw_output:
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# Fall back to raw output if processed output is empty
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final_output = raw_output.decode('utf-8', errors='replace').strip()
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final_output = final_output.encode("utf-8")
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elif not isinstance(final_output, bytes):
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# Handle any unexpected type by converting to string and then bytes
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final_output = str(final_output).encode("utf-8")
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# Ensure we have at least some output, even if the command produced none
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# This is important for error reporting and debugging
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if not final_output or final_output.strip() == b"":
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# Last resort: use raw output directly
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if raw_output:
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final_output = raw_output
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else:
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final_output = b"[No output captured]"
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return final_output, proc.returncode
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if __name__ == "__main__":
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import sys
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if len(sys.argv) < 2:
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print("Usage: interactive.py <command> [args...]")
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sys.exit(1)
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output, return_code = run_interactive_command(sys.argv[1:])
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sys.exit(return_code)
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