Add first magic value detector.
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ReMime/ContentResolvers/Image/ImageMagicValues.cs
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58
ReMime/ContentResolvers/Image/ImageMagicValues.cs
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using System.Collections.Generic;
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namespace ReMime.ContentResolvers.Image
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{
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public static class ImageMagicValues
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{
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private static readonly MediaType Tiff = new MediaType("image/tiff", new string[] { "nif", "tif", "tiff"});
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private static readonly MediaType Jpeg = new MediaType("image/jpeg", new string[] { "jpg", "jpeg" });
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public static readonly IReadOnlyList<MagicValueMediaType> List = new List<MagicValueMediaType>() {
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new MagicValueMediaType(new MagicValue("BM"), new MediaType("image/bmp")),
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new MagicValueMediaType(new MagicValue("GIF8"), new MediaType("image/gif")),
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new MagicValueMediaType(new MagicValue("IIN1"), Tiff),
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new MagicValueMediaType(new MagicValue(new byte[] { 0x4d, 0x4d, 0x00, 0x2a }), Tiff),
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new MagicValueMediaType(new MagicValue(new byte[] { 0x49, 0x49, 0x2a, 0x00 }), Tiff),
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new MagicValueMediaType(new MagicValue(new byte[] { 0x89, 0x50, 0x4e, 0x47 }), new MediaType("image/png")),
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/* Yes this is how we are doing JPEG, I don't want to modify my thing to allow for magic values to be defined in terms of bits. */
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xe0 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xe1 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xe2 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xe3 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xe4 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xe5 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xe6 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xe7 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xe8 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xe9 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xea }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xeb }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xec }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xed }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xee }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xef }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xf0 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xf1 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xf2 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xf3 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xf4 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xf5 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xf6 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xf7 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xf8 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xf9 }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xfa }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xfb }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xfc }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xfd }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xfe }), Jpeg),
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new MagicValueMediaType(new MagicValue(new byte[] { 0xff, 0xd8, 0xff, 0xff }), Jpeg),
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}.AsReadOnly();
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public static void AddToMagicResolver(MagicContentResolver resolver)
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{
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resolver.AddMagicValues(List);
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}
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}
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}
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132
ReMime/ContentResolvers/MagicResolver.cs
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132
ReMime/ContentResolvers/MagicResolver.cs
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using System;
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using System.Collections.Generic;
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using System.Diagnostics.CodeAnalysis;
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using System.IO;
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namespace ReMime.ContentResolvers
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{
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public record MagicValueMediaType(MagicValue Magic, MediaType MediaType);
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public class MagicContentResolver : IMediaContentResolver
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{
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private readonly List<MediaType> _mediaTypes = new List<MediaType>();
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private readonly Dictionary<string, MediaType> _extensions = new Dictionary<string, MediaType>();
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private readonly Tree _tree = new Tree();
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private int _maxBytes = 0;
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public MagicContentResolver(IEnumerable<MagicValueMediaType> values) : this()
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{
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AddMagicValues(values);
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}
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public MagicContentResolver()
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{
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Image.ImageMagicValues.AddToMagicResolver(this);
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}
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public IReadOnlyCollection<MediaType> MediaTypes => _mediaTypes.AsReadOnly();
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public void AddMagicValue(MagicValueMediaType value)
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{
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_maxBytes = Math.Max(_maxBytes, value.Magic.Value.Length);
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_mediaTypes.Add(value.MediaType);
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_tree.Add(value);
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foreach (string extension in value.MediaType.Extensions)
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{
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_extensions[extension] = value.MediaType;
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}
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}
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public void AddMagicValues(IEnumerable<MagicValueMediaType> values)
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{
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foreach (MagicValueMediaType value in values)
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{
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AddMagicValue(value);
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}
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}
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public bool TryResolve(Stream str, [NotNullWhen(true)] out MediaType? mediaType)
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{
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Span<byte> bytes = stackalloc byte[_maxBytes];
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str.Read(bytes);
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return TryResolve(bytes, out mediaType);
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}
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public bool TryResolve(ReadOnlySpan<byte> content, [NotNullWhen(true)] out MediaType? mediaType)
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{
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MagicValueMediaType? type = _tree[content];
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if (type == null)
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{
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mediaType = null;
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return false;
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}
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else
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{
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mediaType = type.MediaType;
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return true;
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}
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}
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public bool TryResolve(string extension, out MediaType? mediaType)
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{
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return _extensions.TryGetValue(extension, out mediaType);
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}
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private class Tree
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{
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public MagicValueMediaType? Node { get; private set; }
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public Dictionary<byte, Tree>? Children { get; private set; }
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public MagicValueMediaType? this[ReadOnlySpan<byte> bytes]
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{
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get
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{
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if (bytes.Length == 0)
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return Node;
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if (Children == null)
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return null;
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byte b = bytes[0];
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if (!Children.TryGetValue(b, out Tree? subtree))
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{
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return null;
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}
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return subtree[bytes.Slice(1)];
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}
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}
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private void AddInternal(MagicValueMediaType magic, ReadOnlySpan<byte> bytes)
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{
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if (bytes.Length == 0)
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{
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Node = magic;
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return;
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}
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if (Children == null)
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{
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Children = new Dictionary<byte, Tree>();
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}
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if (!Children.TryGetValue(bytes[0], out Tree? tree))
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{
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tree = new Tree();
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Children[bytes[0]] = tree;
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}
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tree.AddInternal(magic, bytes.Slice(1));
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}
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public void Add(MagicValueMediaType magic)
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{
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ReadOnlySpan<byte> bytes = magic.Magic.Value;
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AddInternal(magic, bytes);
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}
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}
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}
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}
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41
ReMime/ContentResolvers/MagicValue.cs
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41
ReMime/ContentResolvers/MagicValue.cs
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using System;
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using System.Text;
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namespace ReMime.ContentResolvers
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{
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public record struct MagicValue(byte[] Value)
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{
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public MagicValue(int value) : this(BitConverter.GetBytes(value)) { }
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public MagicValue(short value) : this(BitConverter.GetBytes(value)) { }
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public MagicValue(string value, Encoding? encoding = null)
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: this((encoding ?? Encoding.ASCII).GetBytes(value)) { }
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public MagicValue(ReadOnlySpan<byte> bytes) : this(bytes.ToArray()) { }
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public bool Matches(ReadOnlySpan<byte> haystack)
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{
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for (int i = 0; i < haystack.Length && i < Value.Length; i++)
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{
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if (haystack[i] != Value[i])
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return false;
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}
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return true;
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}
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public override int GetHashCode()
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{
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// Uses the FVN-1A algorithm in 32-bit mode.
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const int PRIME = 0x01000193;
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const int BASIS = unchecked((int)0x811c9dc5);
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int hash = BASIS;
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for (int i = 0; i < Value.Length; i++)
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{
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hash ^= Value[i];
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hash *= PRIME;
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}
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return hash;
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}
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}
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}
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@ -3,6 +3,7 @@ using System.Collections.Generic;
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using System.Collections.Immutable;
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using System.IO;
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using System.Linq;
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using ReMime.ContentResolvers;
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using ReMime.Platform;
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namespace ReMime
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@ -40,6 +41,8 @@ namespace ReMime
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static MediaTypeResolver()
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{
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AddResolver(new MagicContentResolver(), 9998);
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if (OperatingSystem.IsWindows())
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{
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AddResolver(new Win32MediaTypeResolver());
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