repo_description: Process execution for humans
repo_topics: binary child-process exec execute javascript nodejs shell spawn spawned-processes streams
code: import {MaxBufferError} from 'get-stream';
  import {getStreamName} from '../utils/standard-stream.js';
  import {getFdSpecificValue} from '../arguments/specific.js';
  
  // When the `maxBuffer` option is hit, a MaxBufferError is thrown.
  // The stream is aborted, then specific information is kept for the error message.
  export const handleMaxBuffer = ({error, stream, readableObjectMode, lines, encoding, fdNumber}) => {
  	if (!(error instanceof MaxBufferError)) {
  		throw error;
  	}
  
  	if (fdNumber === 'all') {
  		return error;
  	}
  
  	const unit = getMaxBufferUnit(readableObjectMode, lines, encoding);
  	error.maxBufferInfo = {fdNumber, unit};
  	stream.destroy();
  	throw error;
  };
  
  const getMaxBufferUnit = (readableObjectMode, lines, encoding) => {
  	if (readableObjectMode) {
  		return 'objects';
  	}
  
  	if (lines) {
  		return 'lines';
  	}
  
  	if (encoding === 'buffer') {
  		return 'bytes';
  	}
  
  	return 'characters';
  };
  
  // Check the `maxBuffer` option with `result.ipcOutput`
  export const checkIpcMaxBuffer = (subprocess, ipcOutput, maxBuffer) => {
  	if (ipcOutput.length !== maxBuffer) {
  		return;
  	}
  
  	const error = new MaxBufferError();
  	error.maxBufferInfo = {fdNumber: 'ipc'};
  	throw error;
  };
  
  // Error message when `maxBuffer` is hit
  export const getMaxBufferMessage = (error, maxBuffer) => {
  	const {streamName, threshold, unit} = getMaxBufferInfo(error, maxBuffer);
  	return `Command's ${streamName} was larger than ${threshold} ${unit}`;
  };
  
  const getMaxBufferInfo = (error, maxBuffer) => {
  	if (error?.maxBufferInfo === undefined) {
  		return {streamName: 'output', threshold: maxBuffer[1], unit: 'bytes'};
  	}
  
  	const {maxBufferInfo: {fdNumber, unit}} = error;
  	delete error.maxBufferInfo;
  
  	const threshold = getFdSpecificValue(maxBuffer, fdNumber);
  	if (fdNumber === 'ipc') {
  		return {streamName: 'IPC output', threshold, unit: 'messages'};
  	}
  
  	return {streamName: getStreamName(fdNumber), threshold, unit};
  };
  
  // The only way to apply `maxBuffer` with `spawnSync()` is to use the native `maxBuffer` option Node.js provides.
  // However, this has multiple limitations, and cannot behave the exact same way as the async behavior.
  // When the `maxBuffer` is hit, a `ENOBUFS` error is thrown.
  export const isMaxBufferSync = (resultError, output, maxBuffer) => resultError?.code === 'ENOBUFS'
  	&& output !== null
  	&& output.some(result => result !== null && result.length > getMaxBufferSync(maxBuffer));
  
  // When `maxBuffer` is hit, ensure the result is truncated
  export const truncateMaxBufferSync = (result, isMaxBuffer, maxBuffer) => {
  	if (!isMaxBuffer) {
  		return result;
  	}
  
  	const maxBufferValue = getMaxBufferSync(maxBuffer);
  	return result.length > maxBufferValue ? result.slice(0, maxBufferValue) : result;
  };
  
  // `spawnSync()` does not allow differentiating `maxBuffer` per file descriptor, so we always use `stdout`
  export const getMaxBufferSync = ([, stdoutMaxBuffer]) => stdoutMaxBuffer;
  