pkg/native_stack_traces/lib/src/reader.dart - sdk.git - Git at Google

 // Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

 import 'dart:io';
 import 'dart:math';
 import 'dart:typed_data';

 String paddedHex(int value, [int bytes = 0]) =>
     value.toRadixString(16).padLeft(2 * bytes, '0');

 class Reader {
   final ByteData bdata;
   // These are mutable so we can update them, in case the endianness and
   // wordSize are read using the reader (e.g., ELF files).
   Endian? _endian;
   int? _wordSize;

   int _offset = 0;

   Endian get endian => _endian as Endian;
   set endian(Endian value) => _endian = value;
   int get wordSize => _wordSize as int;
   set wordSize(int value) => _wordSize = value;

   /// Unless provided, [wordSize] and [endian] are initialized to values that
   /// ensure no reads are made that depend on their value (e.g., readBytes).
   Reader.fromTypedData(TypedData data, {int? wordSize, Endian? endian})
       : _wordSize = wordSize,
         _endian = endian,
         bdata = ByteData.sublistView(data);

   Reader.fromFile(String path, {int? wordSize, Endian? endian})
       : _wordSize = wordSize,
         _endian = endian,
         bdata = ByteData.sublistView(File(path).readAsBytesSync());

   /// Returns a reader focused on a different portion of the underlying buffer.
   /// If size is not provided, then the new reader extends to the end of the
   /// buffer.
   Reader refocusedCopy(int pos, [int? size]) {
     assert(pos >= 0 && pos < bdata.buffer.lengthInBytes);
     if (size != null) {
       assert(size >= 0 && (pos + size) <= bdata.buffer.lengthInBytes);
     } else {
       size = bdata.buffer.lengthInBytes - pos;
     }
     return Reader.fromTypedData(ByteData.view(bdata.buffer, pos, size),
         wordSize: _wordSize, endian: _endian);
   }

   int get start => bdata.offsetInBytes;
   int get offset => _offset;
   int get length => bdata.lengthInBytes;
   bool get done => _offset >= length;

   Uint8List get bytes => Uint8List.sublistView(bdata);

   void seek(int offset, {bool absolute = false}) {
     final newOffset = (absolute ? 0 : _offset) + offset;
     assert(newOffset >= 0 && newOffset <= bdata.lengthInBytes);
     _offset = newOffset;
   }

   int readBytes(int size, {bool signed = false}) {
     if (_offset + size > length) {
       throw ArgumentError('attempt to read $size bytes with only '
           '${length - _offset} bytes remaining in the reader');
     }
     final start = _offset;
     _offset += size;
     switch (size) {
       case 1:
         return signed ? bdata.getInt8(start) : bdata.getUint8(start);
       case 2:
         return signed
             ? bdata.getInt16(start, endian)
             : bdata.getUint16(start, endian);
       case 4:
         return signed
             ? bdata.getInt32(start, endian)
             : bdata.getUint32(start, endian);
       case 8:
         return signed
             ? bdata.getInt64(start, endian)
             : bdata.getUint64(start, endian);
       default:
         _offset -= size;
         throw ArgumentError('invalid request to read $size bytes');
     }
   }

   ByteData readRawBytes(int size) {
     if (offset + size > length) {
       throw ArgumentError('attempt to read $size bytes with only '
           '${length - _offset} bytes remaining in the reader');
     }
     final start = _offset;
     _offset += size;
     return ByteData.sublistView(bdata, start, start + size);
   }

   int readByte({bool signed = false}) => readBytes(1, signed: signed);
   int readWord() => readBytes(wordSize);
   String readNullTerminatedString({int? maxSize}) {
     final start = _offset;
     int end = maxSize != null ? _offset + maxSize : bdata.lengthInBytes;
     for (; _offset < end; _offset++) {
       if (bdata.getUint8(_offset) == 0) {
         end = _offset;
         _offset++; // Move reader past null terminator.
         break;
       }
     }
     return String.fromCharCodes(
         bdata.buffer.asUint8List(bdata.offsetInBytes + start, end - start));
   }

   String readFixedLengthNullTerminatedString(int maxSize) {
     final start = _offset;
     final str = readNullTerminatedString(maxSize: maxSize);
     // Ensure reader points past fixed space, not at end of string within it.
     _offset = start + maxSize;
     return str;
   }

   int readLEB128EncodedInteger({bool signed = false}) {
     var ret = 0;
     var shift = 0;
     for (var byte = readByte(); !done; byte = readByte()) {
       ret |= (byte & 0x7f) << shift;
       shift += 7;
       if (byte & 0x80 == 0) {
         if (signed && byte & 0x40 != 0) {
           ret |= -(1 << shift);
         }
         break;
       }
     }
     return ret;
   }

   /// Repeatedly calls [callback] with this reader to retrieve items.
   ///
   /// The key of the returned [MapEntry]s are the offsets of the items. If
   /// absolute is false, the offsets are from the reader position when
   /// [readRepeated] was invoked, otherwise they are absolute offsets from
   /// the start of the reader.
   ///
   /// Stops either when the reader is empty or when a null item is returned
   /// from the callback.
   Iterable<MapEntry<int, S>> readRepeatedWithOffsets<S>(
       S? Function(Reader) callback,
       {bool absolute = false}) sync* {
     final start = offset;
     while (!done) {
       final itemStart = offset;
       final item = callback(this);
       if (item == null) break;
       yield MapEntry(absolute ? itemStart : itemStart - start, item);
     }
   }

   Iterable<S> readRepeated<S>(S? Function(Reader) callback) =>
       readRepeatedWithOffsets(callback).map((kv) => kv.value);

   void writeCurrentReaderPosition(StringBuffer buffer,
       {int maxSize = 0, int bytesPerLine = 16}) {
     var baseData = ByteData.view(bdata.buffer, 0, bdata.buffer.lengthInBytes);
     var startOffset = 0;
     var endOffset = baseData.lengthInBytes;
     final currentOffset = start + _offset;
     if (maxSize != 0 && maxSize < baseData.lengthInBytes) {
       var lowerWindow = currentOffset - (maxSize >> 1);
       // Adjust so that we always start at the beginning of a line.
       lowerWindow -= lowerWindow % bytesPerLine;
       final upperWindow = lowerWindow + maxSize;
       startOffset = max(startOffset, lowerWindow);
       endOffset = min(endOffset, upperWindow);
     }
     for (var i = startOffset; i < endOffset; i += bytesPerLine) {
       buffer
         ..write('0x')
         ..write(paddedHex(i, 8))
         ..write(' ');
       for (var j = 0; j < bytesPerLine && i + j < endOffset; j++) {
         var byte = baseData.getUint8(i + j);
         buffer
           ..write(i + j == currentOffset ? '|' : ' ')
           ..write(paddedHex(byte, 1));
       }
       buffer.writeln();
     }
   }

   @override
   String toString() {
     final buffer = StringBuffer();
     buffer
       ..write('Word size: ')
       ..write(_wordSize)
       ..writeln();
     buffer
       ..write('Endianness: ')
       ..write(_endian)
       ..writeln();
     buffer
       ..write('Start:  0x')
       ..write(paddedHex(start, _wordSize ?? 0))
       ..write(' (')
       ..write(start)
       ..writeln(')');
     buffer
       ..write('Offset: 0x')
       ..write(paddedHex(offset, _wordSize ?? 0))
       ..write(' (')
       ..write(offset)
       ..writeln(')');
     buffer
       ..write('Length: 0x')
       ..write(paddedHex(length, _wordSize ?? 0))
       ..write(' (')
       ..write(length)
       ..writeln(')');
     buffer.writeln('Bytes around current position:');
     writeCurrentReaderPosition(buffer, maxSize: 256);
     return buffer.toString();
   }
 }
	// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
	// for details. All rights reserved. Use of this source code is governed by a
	// BSD-style license that can be found in the LICENSE file.

	import 'dart:io';
	import 'dart:math';
	import 'dart:typed_data';

	String paddedHex(int value, [int bytes = 0]) =>
	value.toRadixString(16).padLeft(2 * bytes, '0');

	class Reader {
	final ByteData bdata;
	// These are mutable so we can update them, in case the endianness and
	// wordSize are read using the reader (e.g., ELF files).
	Endian? _endian;
	int? _wordSize;

	int _offset = 0;

	Endian get endian => _endian as Endian;
	set endian(Endian value) => _endian = value;
	int get wordSize => _wordSize as int;
	set wordSize(int value) => _wordSize = value;

	/// Unless provided, [wordSize] and [endian] are initialized to values that
	/// ensure no reads are made that depend on their value (e.g., readBytes).
	Reader.fromTypedData(TypedData data, {int? wordSize, Endian? endian})
	: _wordSize = wordSize,
	_endian = endian,
	bdata = ByteData.sublistView(data);

	Reader.fromFile(String path, {int? wordSize, Endian? endian})
	: _wordSize = wordSize,
	_endian = endian,
	bdata = ByteData.sublistView(File(path).readAsBytesSync());

	/// Returns a reader focused on a different portion of the underlying buffer.
	/// If size is not provided, then the new reader extends to the end of the
	/// buffer.
	Reader refocusedCopy(int pos, [int? size]) {
	assert(pos >= 0 && pos < bdata.buffer.lengthInBytes);
	if (size != null) {
	assert(size >= 0 && (pos + size) <= bdata.buffer.lengthInBytes);
	} else {
	size = bdata.buffer.lengthInBytes - pos;
	}
	return Reader.fromTypedData(ByteData.view(bdata.buffer, pos, size),
	wordSize: _wordSize, endian: _endian);
	}

	int get start => bdata.offsetInBytes;
	int get offset => _offset;
	int get length => bdata.lengthInBytes;
	bool get done => _offset >= length;

	Uint8List get bytes => Uint8List.sublistView(bdata);

	void seek(int offset, {bool absolute = false}) {
	final newOffset = (absolute ? 0 : _offset) + offset;
	assert(newOffset >= 0 && newOffset <= bdata.lengthInBytes);
	_offset = newOffset;
	}

	int readBytes(int size, {bool signed = false}) {
	if (_offset + size > length) {
	throw ArgumentError('attempt to read $size bytes with only '
	'${length - _offset} bytes remaining in the reader');
	}
	final start = _offset;
	_offset += size;
	switch (size) {
	case 1:
	return signed ? bdata.getInt8(start) : bdata.getUint8(start);
	case 2:
	return signed
	? bdata.getInt16(start, endian)
	: bdata.getUint16(start, endian);
	case 4:
	return signed
	? bdata.getInt32(start, endian)
	: bdata.getUint32(start, endian);
	case 8:
	return signed
	? bdata.getInt64(start, endian)
	: bdata.getUint64(start, endian);
	default:
	_offset -= size;
	throw ArgumentError('invalid request to read $size bytes');
	}
	}

	ByteData readRawBytes(int size) {
	if (offset + size > length) {
	throw ArgumentError('attempt to read $size bytes with only '
	'${length - _offset} bytes remaining in the reader');
	}
	final start = _offset;
	_offset += size;
	return ByteData.sublistView(bdata, start, start + size);
	}

	int readByte({bool signed = false}) => readBytes(1, signed: signed);
	int readWord() => readBytes(wordSize);
	String readNullTerminatedString({int? maxSize}) {
	final start = _offset;
	int end = maxSize != null ? _offset + maxSize : bdata.lengthInBytes;
	for (; _offset < end; _offset++) {
	if (bdata.getUint8(_offset) == 0) {
	end = _offset;
	_offset++; // Move reader past null terminator.
	break;
	}
	}
	return String.fromCharCodes(
	bdata.buffer.asUint8List(bdata.offsetInBytes + start, end - start));
	}

	String readFixedLengthNullTerminatedString(int maxSize) {
	final start = _offset;
	final str = readNullTerminatedString(maxSize: maxSize);
	// Ensure reader points past fixed space, not at end of string within it.
	_offset = start + maxSize;
	return str;
	}

	int readLEB128EncodedInteger({bool signed = false}) {
	var ret = 0;
	var shift = 0;
	for (var byte = readByte(); !done; byte = readByte()) {
	ret \|= (byte & 0x7f) << shift;
	shift += 7;
	if (byte & 0x80 == 0) {
	if (signed && byte & 0x40 != 0) {
	ret \|= -(1 << shift);
	}
	break;
	}
	}
	return ret;
	}

	/// Repeatedly calls [callback] with this reader to retrieve items.
	///
	/// The key of the returned [MapEntry]s are the offsets of the items. If
	/// absolute is false, the offsets are from the reader position when
	/// [readRepeated] was invoked, otherwise they are absolute offsets from
	/// the start of the reader.
	///
	/// Stops either when the reader is empty or when a null item is returned
	/// from the callback.
	Iterable<MapEntry<int, S>> readRepeatedWithOffsets<S>(
	S? Function(Reader) callback,
	{bool absolute = false}) sync* {
	final start = offset;
	while (!done) {
	final itemStart = offset;
	final item = callback(this);
	if (item == null) break;
	yield MapEntry(absolute ? itemStart : itemStart - start, item);
	}
	}

	Iterable<S> readRepeated<S>(S? Function(Reader) callback) =>
	readRepeatedWithOffsets(callback).map((kv) => kv.value);

	void writeCurrentReaderPosition(StringBuffer buffer,
	{int maxSize = 0, int bytesPerLine = 16}) {
	var baseData = ByteData.view(bdata.buffer, 0, bdata.buffer.lengthInBytes);
	var startOffset = 0;
	var endOffset = baseData.lengthInBytes;
	final currentOffset = start + _offset;
	if (maxSize != 0 && maxSize < baseData.lengthInBytes) {
	var lowerWindow = currentOffset - (maxSize >> 1);
	// Adjust so that we always start at the beginning of a line.
	lowerWindow -= lowerWindow % bytesPerLine;
	final upperWindow = lowerWindow + maxSize;
	startOffset = max(startOffset, lowerWindow);
	endOffset = min(endOffset, upperWindow);
	}
	for (var i = startOffset; i < endOffset; i += bytesPerLine) {
	buffer
	..write('0x')
	..write(paddedHex(i, 8))
	..write(' ');
	for (var j = 0; j < bytesPerLine && i + j < endOffset; j++) {
	var byte = baseData.getUint8(i + j);
	buffer
	..write(i + j == currentOffset ? '\|' : ' ')
	..write(paddedHex(byte, 1));
	}
	buffer.writeln();
	}
	}

	@override
	String toString() {
	final buffer = StringBuffer();
	buffer
	..write('Word size: ')
	..write(_wordSize)
	..writeln();
	buffer
	..write('Endianness: ')
	..write(_endian)
	..writeln();
	buffer
	..write('Start: 0x')
	..write(paddedHex(start, _wordSize ?? 0))
	..write(' (')
	..write(start)
	..writeln(')');
	buffer
	..write('Offset: 0x')
	..write(paddedHex(offset, _wordSize ?? 0))
	..write(' (')
	..write(offset)
	..writeln(')');
	buffer
	..write('Length: 0x')
	..write(paddedHex(length, _wordSize ?? 0))
	..write(' (')
	..write(length)
	..writeln(')');
	buffer.writeln('Bytes around current position:');
	writeCurrentReaderPosition(buffer, maxSize: 256);
	return buffer.toString();
	}
	}