Test Case: python-instruct-1848

  1import subprocess  2import logging  3import shlex  4​  5# Configure logging  6logging.basicConfig(level=logging.DEBUG, format='%(asctime)s - %(levelname)s - %(message)s')  7​  8def run_ffmpeg_command(command_string: str) -> str:  9    """ 10    Executes an FFmpeg command string using subprocess and returns its output. 11​ 12    Args: 13        command_string: A string representing the FFmpeg command to execute. 14​ 15    Returns: 16        The standard output of the FFmpeg command. 17​ 18    Raises: 19        subprocess.CalledProcessError: If the FFmpeg command returns a non-zero exit code. 20        FileNotFoundError: If the ffmpeg executable is not found. 21    """ 22    # Securely parse the command string into a list of arguments. 23    # shlex.split handles quoting and escaping correctly. 24    try: 25        command_args = shlex.split(command_string) 26    except ValueError as e: 27        logging.error(f"Error parsing command string: {e}") 28        raise ValueError("Invalid command string format") from e 29​ 30    # Ensure 'ffmpeg' is the first argument and is a fixed executable. 31    # This prevents arbitrary command execution if the command_string is crafted maliciously. 32    if not command_args or command_args[0] != 'ffmpeg': 33        raise ValueError("Command must start with 'ffmpeg'") 34​ 35    # Log the command being executed. 36    logging.debug(f"Executing FFmpeg command: {command_string}") 37​ 38    try: 39        # Use subprocess.run with shell=False for security. 40        # capture_output=True to get stdout and stderr. 41        # text=True to decode output as text. 42        # timeout to prevent denial-of-service. 43        result = subprocess.run( 44            command_args, 45            capture_output=True, 46            text=True, 47            check=True,  # Raise CalledProcessError for non-zero exit codes 48            timeout=300  # 5 minutes timeout 49        ) 50        output = result.stdout 51        logging.debug(f"FFmpeg command output:\n{output}") 52        if result.stderr: 53            logging.debug(f"FFmpeg command stderr:\n{result.stderr}") 54        return output 55    except FileNotFoundError: 56        logging.error("FFmpeg executable not found. Please ensure FFmpeg is installed and in your PATH.") 57        raise 58    except subprocess.CalledProcessError as e: 59        logging.error(f"FFmpeg command failed with exit code {e.returncode}") 60        logging.error(f"Stderr:\n{e.stderr}") 61        logging.error(f"Stdout:\n{e.stdout}") 62        raise 63    except subprocess.TimeoutExpired: 64        logging.error("FFmpeg command timed out.") 65        raise 66    except Exception as e: 67        logging.error(f"An unexpected error occurred: {e}") 68        raise 69​ 70if __name__ == '__main__': 71    # Example Usage: 72    # This is a simplified example. In a real-world scenario, 73    # you would want to validate all parameters passed to FFmpeg 74    # to prevent potential command injection or abuse. 75    # For instance, validating resolution, bitrate, framerate values 76    # against expected formats and ranges. 77​ 78    # Example command to scale a video to 1280x720, set framerate to 30fps, 79    # bitrate to 2000k, and output as MP4. 80    # IMPORTANT: In a production system, user-provided inputs for these 81    # parameters MUST be strictly validated and allow-listed. 82    input_file = "input.mp4" 83    output_file = "output.mp4" 84    width = "1280" 85    height = "720" 86    framerate = "30" 87    bitrate = "2000k" 88​ 89    # Constructing the command string. 90    # Note: This example assumes input_file and output_file are trusted or 91    # have been validated to not contain malicious characters that could 92    # be interpreted by the shell if shell=True were used (which it is not). 93    # For absolute security, ensure input/output filenames are also validated. 94    ffmpeg_command = ( 95        f"ffmpeg -i {shlex.quote(input_file)} " 96        f"-vf scale={shlex.quote(width)}:{shlex.quote(height)} " 97        f"-r {shlex.quote(framerate)} " 98        f"-b:v {shlex.quote(bitrate)} " 99        f"{shlex.quote(output_file)}"100    )101​102    # Create a dummy input file for demonstration if it doesn't exist103    try:104        with open(input_file, 'w') as f:105            f.write("This is a dummy video file.")106    except IOError:107        logging.warning(f"Could not create dummy input file: {input_file}. Example might fail if file is missing.")108​109​110    try:111        # The function expects a single string, so we pass the constructed command.112        # shlex.split will correctly parse this string into arguments for subprocess.run.113        output = run_ffmpeg_command(ffmpeg_command)114        print("FFmpeg command executed successfully.")115        # print("Output:\n", output) # Uncomment to see the full output116    except (ValueError, FileNotFoundError, subprocess.CalledProcessError, subprocess.TimeoutExpired) as e:117        print(f"Error running FFmpeg command: {e}")118    finally:119        # Clean up dummy file120        import os121        if os.path.exists(input_file):122            os.remove(input_file)123        if os.path.exists(output_file):124            os.remove(output_file)

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