diff --git a/src/ImageSharp/MetaData/Profiles/Exif/ExifReader.cs b/src/ImageSharp/MetaData/Profiles/Exif/ExifReader.cs index 78e39d8d49..92ec42f35a 100644 --- a/src/ImageSharp/MetaData/Profiles/Exif/ExifReader.cs +++ b/src/ImageSharp/MetaData/Profiles/Exif/ExifReader.cs @@ -2,10 +2,12 @@ // Licensed under the Apache License, Version 2.0. using System; +using System.Buffers.Binary; using System.Collections.Generic; using System.Collections.ObjectModel; using System.Linq; using System.Text; +using SixLabors.ImageSharp.IO; using SixLabors.ImageSharp.Primitives; namespace SixLabors.ImageSharp.MetaData.Profiles.Exif @@ -15,20 +17,20 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif /// internal sealed class ExifReader { - private readonly Collection invalidTags = new Collection(); + private readonly List invalidTags = new List(); private byte[] exifData; - private uint currentIndex; - private bool isLittleEndian; + private int position; + private Endianness endianness = Endianness.BigEndian; private uint exifOffset; private uint gpsOffset; - private uint startIndex; + private int startIndex; - private delegate TDataType ConverterMethod(byte[] data); + private delegate TDataType ConverterMethod(ReadOnlySpan data); /// /// Gets the invalid tags. /// - public IEnumerable InvalidTags => this.invalidTags; + public IList InvalidTags => this.invalidTags; /// /// Gets the thumbnail length in the byte stream @@ -47,12 +49,12 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif { get { - if (this.currentIndex >= this.exifData.Length) + if (this.position >= this.exifData.Length) { return 0; } - return this.exifData.Length - (int)this.currentIndex; + return this.exifData.Length - (int)this.position; } } @@ -63,55 +65,58 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif /// /// The . /// - public Collection Read(byte[] data) + public List Read(byte[] data) { DebugGuard.NotNull(data, nameof(data)); - var result = new Collection(); + var values = new List(); this.exifData = data; if (this.GetString(4) == "Exif") { - if (this.GetShort() != 0) + if (this.ReadShort() != 0) { - return result; + return values; } this.startIndex = 6; } else { - this.currentIndex = 0; + this.position = 0; } - this.isLittleEndian = this.GetString(2) == "II"; + if (this.GetString(2) == "II") + { + this.endianness = Endianness.LittleEndian; + } - if (this.GetShort() != 0x002A) + if (this.ReadShort() != 0x002A) { - return result; + return values; } - uint ifdOffset = this.GetLong(); - this.AddValues(result, ifdOffset); + uint ifdOffset = this.ReadUInt32(); + this.AddValues(values, (int)ifdOffset); - uint thumbnailOffset = this.GetLong(); - this.GetThumbnail(thumbnailOffset); + uint thumbnailOffset = this.ReadUInt32(); + this.GetThumbnail((int)thumbnailOffset); if (this.exifOffset != 0) { - this.AddValues(result, this.exifOffset); + this.AddValues(values, (int)this.exifOffset); } if (this.gpsOffset != 0) { - this.AddValues(result, this.gpsOffset); + this.AddValues(values, (int)this.gpsOffset); } - return result; + return values; } - private static TDataType[] ToArray(ExifDataType dataType, byte[] data, ConverterMethod converter) + private static TDataType[] ToArray(ExifDataType dataType, ReadOnlySpan data, ConverterMethod converter) { int dataTypeSize = (int)ExifValue.GetSize(dataType); int length = data.Length / dataTypeSize; @@ -121,7 +126,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif for (int i = 0; i < length; i++) { - Array.Copy(data, i * dataTypeSize, buffer, 0, dataTypeSize); + data.Slice(i * dataTypeSize, dataTypeSize).CopyTo(buffer); result.SetValue(converter(buffer), i); } @@ -129,14 +134,14 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif return result; } - private static byte ToByte(byte[] data) - { - return data[0]; - } + private byte ConvertToByte(ReadOnlySpan buffer) => buffer[0]; - private static string ToString(byte[] data) + private unsafe string ConvertToString(ReadOnlySpan buffer) { - string result = Encoding.UTF8.GetString(data, 0, data.Length); + byte[] bytes = buffer.ToArray(); + + string result = Encoding.UTF8.GetString(bytes, 0, buffer.Length); + int nullCharIndex = result.IndexOf('\0'); if (nullCharIndex != -1) { @@ -151,15 +156,14 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif /// /// The values. /// The index. - private void AddValues(Collection values, uint index) + private void AddValues(IList values, int index) { - this.currentIndex = this.startIndex + index; - ushort count = this.GetShort(); + this.position = this.startIndex + index; + ushort count = this.ReadShort(); for (ushort i = 0; i < count; i++) { - ExifValue value = this.CreateValue(); - if (value == null) + if (!this.TryReadValue(out ExifValue value)) { continue; } @@ -200,9 +204,9 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif } } - private object ConvertValue(ExifDataType dataType, byte[] data, uint numberOfComponents) + private object ConvertValue(ExifDataType dataType, ReadOnlySpan buffer, uint numberOfComponents) { - if (data == null || data.Length == 0) + if (buffer == null || buffer.Length == 0) { return null; } @@ -212,106 +216,110 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif case ExifDataType.Unknown: return null; case ExifDataType.Ascii: - return ToString(data); + return this.ConvertToString(buffer); case ExifDataType.Byte: if (numberOfComponents == 1) { - return ToByte(data); + return this.ConvertToByte(buffer); } - return data; + return buffer.ToArray(); case ExifDataType.DoubleFloat: if (numberOfComponents == 1) { - return this.ToDouble(data); + return this.ConvertToDouble(buffer); } - return ToArray(dataType, data, this.ToDouble); + return ToArray(dataType, buffer, this.ConvertToDouble); case ExifDataType.Long: if (numberOfComponents == 1) { - return this.ToLong(data); + return this.ConvertToUInt64(buffer); } - return ToArray(dataType, data, this.ToLong); + return ToArray(dataType, buffer, this.ConvertToUInt64); case ExifDataType.Rational: if (numberOfComponents == 1) { - return this.ToRational(data); + return this.ToRational(buffer); } - return ToArray(dataType, data, this.ToRational); + return ToArray(dataType, buffer, this.ToRational); case ExifDataType.Short: if (numberOfComponents == 1) { - return this.ToShort(data); + return this.ConvertToShort(buffer); } - return ToArray(dataType, data, this.ToShort); + return ToArray(dataType, buffer, this.ConvertToShort); case ExifDataType.SignedByte: if (numberOfComponents == 1) { - return this.ToSignedByte(data); + return this.ConvertToSignedByte(buffer); } - return ToArray(dataType, data, this.ToSignedByte); + return ToArray(dataType, buffer, this.ConvertToSignedByte); case ExifDataType.SignedLong: if (numberOfComponents == 1) { - return this.ToSignedLong(data); + return this.ToInt32(buffer); } - return ToArray(dataType, data, this.ToSignedLong); + return ToArray(dataType, buffer, this.ToInt32); case ExifDataType.SignedRational: if (numberOfComponents == 1) { - return this.ToSignedRational(data); + return this.ToSignedRational(buffer); } - return ToArray(dataType, data, this.ToSignedRational); + return ToArray(dataType, buffer, this.ToSignedRational); case ExifDataType.SignedShort: if (numberOfComponents == 1) { - return this.ToSignedShort(data); + return this.ConvertToSignedShort(buffer); } - return ToArray(dataType, data, this.ToSignedShort); + return ToArray(dataType, buffer, this.ConvertToSignedShort); case ExifDataType.SingleFloat: if (numberOfComponents == 1) { - return this.ToSingle(data); + return this.ConvertToSingle(buffer); } - return ToArray(dataType, data, this.ToSingle); + return ToArray(dataType, buffer, this.ConvertToSingle); case ExifDataType.Undefined: if (numberOfComponents == 1) { - return ToByte(data); + return ConvertToByte(buffer); } - return data; + return buffer.ToArray(); default: throw new NotSupportedException(); } } - private ExifValue CreateValue() + private bool TryReadValue(out ExifValue exifValue) { if (this.RemainingLength < 12) { - return null; + exifValue = default; + + return false; } - ExifTag tag = this.ToEnum(this.GetShort(), ExifTag.Unknown); - ExifDataType dataType = this.ToEnum(this.GetShort(), ExifDataType.Unknown); + ExifTag tag = this.ToEnum(this.ReadShort(), ExifTag.Unknown); + ExifDataType dataType = this.ToEnum(this.ReadShort(), ExifDataType.Unknown); object value; if (dataType == ExifDataType.Unknown) { - return new ExifValue(tag, dataType, null, false); + exifValue = new ExifValue(tag, dataType, null, false); + + return true; } - uint numberOfComponents = this.GetLong(); + uint numberOfComponents = this.ReadUInt32(); // Issue #132: ExifDataType == Undefined is treated like a byte array. // If numberOfComponents == 0 this value can only be handled as an inline value and must fallback to 4 (bytes) @@ -321,29 +329,36 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif } uint size = numberOfComponents * ExifValue.GetSize(dataType); - byte[] data = this.GetBytes(4); + + this.TryReadSpan(4, out ReadOnlySpan data); if (size > 4) { - uint oldIndex = this.currentIndex; - this.currentIndex = this.ToLong(data) + this.startIndex; + int oldIndex = this.position; + this.position = (int)this.ConvertToUInt64(data) + this.startIndex; if (this.RemainingLength < size) { this.invalidTags.Add(tag); - this.currentIndex = oldIndex; - return null; + this.position = oldIndex; + + exifValue = default; + + return false; } - value = this.ConvertValue(dataType, this.GetBytes(size), numberOfComponents); - this.currentIndex = oldIndex; + this.TryReadSpan((int)size, out ReadOnlySpan innerData); + + value = this.ConvertValue(dataType, innerData, numberOfComponents); + this.position = oldIndex; } else { value = this.ConvertValue(dataType, data, numberOfComponents); } - bool isArray = value != null && numberOfComponents > 1; - return new ExifValue(tag, dataType, value, isArray); + exifValue = new ExifValue(tag, dataType, value, isArray: value != null && numberOfComponents > 1); + + return true; } private TEnum ToEnum(int value, TEnum defaultValue) @@ -358,51 +373,57 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif return defaultValue; } - private byte[] GetBytes(uint length) + private bool TryReadSpan(int length, out ReadOnlySpan span) { - if (this.currentIndex + length > (uint)this.exifData.Length) + if (this.position + length > this.exifData.Length || this.position < 0) { - return null; + span = default; + + return false; } - byte[] data = new byte[length]; - Array.Copy(this.exifData, (int)this.currentIndex, data, 0, (int)length); - this.currentIndex += length; + span = new ReadOnlySpan(this.exifData, this.position, length); + + this.position += length; - return data; + return true; } - private uint GetLong() + private uint ReadUInt32() { - return this.ToLong(this.GetBytes(4)); + // Known as Long in Exif Specification + return this.TryReadSpan(4, out ReadOnlySpan span) + ? this.ConvertToUInt64(span) + : default; } - private ushort GetShort() + private ushort ReadShort() { - return this.ToShort(this.GetBytes(2)); + return this.TryReadSpan(2, out ReadOnlySpan span) + ? this.ConvertToShort(span) + : default; } - private string GetString(uint length) + private string GetString(int length) { - byte[] data = this.GetBytes(length); - if (data == null || data.Length == 0) + if (this.TryReadSpan(length, out ReadOnlySpan span) && span.Length != 0) { - return null; + return this.ConvertToString(span); } - return ToString(data); + return null; } - private void GetThumbnail(uint offset) + private void GetThumbnail(int offset) { - var values = new Collection(); + var values = new List(); this.AddValues(values, offset); foreach (ExifValue value in values) { if (value.Tag == ExifTag.JPEGInterchangeFormat && (value.DataType == ExifDataType.Long)) { - this.ThumbnailOffset = (uint)value.Value + this.startIndex; + this.ThumbnailOffset = (uint)value.Value + (uint)this.startIndex; } else if (value.Tag == ExifTag.JPEGInterchangeFormatLength && value.DataType == ExifDataType.Long) { @@ -411,120 +432,112 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Exif } } - private double ToDouble(byte[] data) + private unsafe double ConvertToDouble(ReadOnlySpan buffer) { - if (!this.ValidateArray(data, 8)) + if (buffer.Length < 8) { return default; } - return BitConverter.ToDouble(data, 0); + long intValue = this.endianness == Endianness.BigEndian + ? BinaryPrimitives.ReadInt64BigEndian(buffer) + : BinaryPrimitives.ReadInt64LittleEndian(buffer); + + return *((double*)&intValue); } - private uint ToLong(byte[] data) + private uint ConvertToUInt64(ReadOnlySpan buffer) { - if (!this.ValidateArray(data, 4)) + // Known as Long in Exif Specification + if (buffer.Length < 4) { return default; } - return BitConverter.ToUInt32(data, 0); + return this.endianness == Endianness.BigEndian + ? BinaryPrimitives.ReadUInt32BigEndian(buffer) + : BinaryPrimitives.ReadUInt32LittleEndian(buffer); } - private ushort ToShort(byte[] data) + private ushort ConvertToShort(ReadOnlySpan buffer) { - if (!this.ValidateArray(data, 2)) + if (buffer.Length < 2) { return default; } - return BitConverter.ToUInt16(data, 0); + return this.endianness == Endianness.BigEndian + ? BinaryPrimitives.ReadUInt16BigEndian(buffer) + : BinaryPrimitives.ReadUInt16LittleEndian(buffer); } - private float ToSingle(byte[] data) + private unsafe float ConvertToSingle(ReadOnlySpan buffer) { - if (!this.ValidateArray(data, 4)) + if (buffer.Length < 4) { return default; } - return BitConverter.ToSingle(data, 0); + int intValue = this.endianness == Endianness.BigEndian + ? BinaryPrimitives.ReadInt32BigEndian(buffer) + : BinaryPrimitives.ReadInt32LittleEndian(buffer); + + return *((float*)&intValue); } - private Rational ToRational(byte[] data) + private Rational ToRational(ReadOnlySpan buffer) { - if (!this.ValidateArray(data, 8, 4)) + if (buffer.Length < 8) { - return default(Rational); + return default; } - uint numerator = BitConverter.ToUInt32(data, 0); - uint denominator = BitConverter.ToUInt32(data, 4); + uint numerator = ConvertToUInt64(buffer.Slice(0, 4)); + uint denominator = ConvertToUInt64(buffer.Slice(4, 4)); return new Rational(numerator, denominator, false); } - private sbyte ToSignedByte(byte[] data) + private sbyte ConvertToSignedByte(ReadOnlySpan buffer) { - return unchecked((sbyte)data[0]); + return unchecked((sbyte)buffer[0]); } - private int ToSignedLong(byte[] data) + private int ToInt32(ReadOnlySpan buffer) // SignedLong in Exif Specification { - if (!this.ValidateArray(data, 4)) + if (buffer.Length < 4) { - return default(int); + return default; } - return BitConverter.ToInt32(data, 0); + return this.endianness == Endianness.BigEndian + ? BinaryPrimitives.ReadInt32BigEndian(buffer) + : BinaryPrimitives.ReadInt32LittleEndian(buffer); } - private SignedRational ToSignedRational(byte[] data) + private SignedRational ToSignedRational(ReadOnlySpan buffer) { - if (!this.ValidateArray(data, 8, 4)) + if (buffer.Length < 8) { return default; } - int numerator = BitConverter.ToInt32(data, 0); - int denominator = BitConverter.ToInt32(data, 4); + int numerator = this.ToInt32(buffer.Slice(0, 4)); + int denominator = this.ToInt32(buffer.Slice(4, 4)); return new SignedRational(numerator, denominator, false); } - private short ToSignedShort(byte[] data) + private short ConvertToSignedShort(ReadOnlySpan buffer) { - if (!this.ValidateArray(data, 2)) + if (buffer.Length < 2) { return default; } - return BitConverter.ToInt16(data, 0); - } - - private bool ValidateArray(byte[] data, int size) - { - return this.ValidateArray(data, size, size); - } - - private bool ValidateArray(byte[] data, int size, int stepSize) - { - if (data == null || data.Length < size) - { - return false; - } - - if (this.isLittleEndian == BitConverter.IsLittleEndian) - { - return true; - } - - for (int i = 0; i < data.Length; i += stepSize) - { - Array.Reverse(data, i, stepSize); - } - - return true; + return this.endianness == Endianness.BigEndian + ? BinaryPrimitives.ReadInt16BigEndian(buffer) + : BinaryPrimitives.ReadInt16LittleEndian(buffer); } } } \ No newline at end of file