294 lines
10 KiB
Python
294 lines
10 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 time
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from typing import List, Tuple
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import pyte
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from pyte.screens import HistoryScreen
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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 render_line(line, columns: int) -> str:
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"""Render a single screen line from the pyte buffer (a mapping of column to Char)."""
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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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return "".join(line[x].data for x in range(columns) if x in line)
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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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screen = HistoryScreen(cols, rows, history=2000, ratio=0.5)
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stream = pyte.Stream(screen)
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# Open a new pseudo-tty.
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master_fd, slave_fd = os.openpty()
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# Set master_fd to non-blocking to avoid indefinite blocking.
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os.set_blocking(master_fd, False)
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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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# Set up environment variables for the subprocess using detected terminal size.
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env = os.environ.copy()
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env.update(
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{
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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(cols),
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"LINES": str(rows),
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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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)
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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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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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elapsed = time.time() - start_time
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if elapsed > 3 * expected_runtime_seconds:
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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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os.killpg(os.getpgid(proc.pid), signal.SIGTERM)
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return True
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return False
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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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os.write(1, data)
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except KeyboardInterrupt:
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proc.terminate()
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os.close(master_fd)
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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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# 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 = [render_line(line, cols) for line in screen.history.top]
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display_lines = [render_line(line, cols) for line in screen.display]
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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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trimmed_lines = [line for line in all_lines if line and line.strip()]
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final_output = "\n".join(trimmed_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
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if isinstance(final_output, str):
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final_output = final_output[-8000:]
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final_output = final_output.encode("utf-8")
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elif isinstance(final_output, bytes):
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final_output = final_output[-8000:]
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else:
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# Handle any unexpected type
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final_output = str(final_output)[-8000:].encode("utf-8")
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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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