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using System.IO.Compression;
namespace LibGit.Extensions;
public static class StreamExtensions
{
private const bool _debug = false;
public static long Remaining(this Stream stream)
{
//if (_debug) Console.WriteLine($"stream pos: {stream.Position}, stream len: {stream.Length}, stream rem: {stream.Length - stream.Position}");
return stream.Length - stream.Position;
}
public static int Peek(this Stream stream)
{
if (!stream.CanRead)
throw new InvalidOperationException("Can't peek a non-readable stream");
if (!stream.CanSeek)
throw new InvalidOperationException("Can't peek a non-seekable stream");
int peek = stream.ReadByte();
if (peek != -1)
stream.Seek(-1, SeekOrigin.Current);
return peek;
}
public static IEnumerable<byte> Peek(this Stream stream, long count)
{
if (!stream.CanRead)
throw new InvalidOperationException("Can't peek a non-readable stream");
if (!stream.CanSeek)
throw new InvalidOperationException("Can't peek a non-seekable stream");
long i;
for (i = 0; i < count; i++)
{
int peek = stream.ReadByte();
if (peek == -1)
{
if(_debug) Console.WriteLine($"Can't peek {count} bytes, only {i} bytes remaining");
stream.Seek(-i, SeekOrigin.Current);
yield break;
}
yield return (byte)peek;
}
stream.Seek(-i, SeekOrigin.Current);
}
public static IEnumerable<byte> ReadBytes(this Stream stream, long count)
{
if (!stream.CanRead)
throw new InvalidOperationException("Can't read a non-readable stream");
if (!stream.CanSeek)
throw new InvalidOperationException("Can't read a non-seekable stream");
for (long i = 0; i < count; i++)
{
int read = stream.ReadByte();
if (read == -1)
yield break;
yield return (byte)read;
}
}
public static bool StartsWith(this Stream stream, IEnumerable<byte> sequence)
{
if (!stream.CanRead)
throw new InvalidOperationException("Can't read a non-readable stream");
if (!stream.CanSeek)
throw new InvalidOperationException("Can't read a non-seekable stream");
if (_debug)
{
Console.WriteLine($"Expected: {sequence.AsHexString()} ({sequence.AsString()})");
Console.WriteLine($"Actual: {stream.Peek(sequence.Count()).AsHexString()} ({stream.Peek(sequence.Count()).AsString()})");
}
int readCount = 0;
foreach (int b in sequence)
{
int read = stream.ReadByte();
readCount++;
if (read == -1)
{
stream.Seek(-readCount, SeekOrigin.Current);
return false;
}
if (read != b)
{
if (_debug)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("^^".PadLeft(readCount * 3 + 9));
Console.ResetColor();
}
stream.Seek(-readCount, SeekOrigin.Current);
return false;
}
}
stream.Seek(-readCount, SeekOrigin.Current);
return true;
}
public static bool StartsWith(this Stream stream, string ascii_seq)
{
return stream.StartsWith(ascii_seq.Select(x => (byte)x));
}
public static Stream Skip(this Stream stream, long count = 1)
{
if (!stream.CanSeek)
throw new InvalidOperationException("Can't skip a non-seekable stream");
stream.Seek(count, SeekOrigin.Current);
return stream;
}
public static IEnumerable<byte> ReadNullTerminatedField(this Stream stream, IEnumerable<byte>? binaryPrefix = null, string? asciiPrefix = null) => ReadTerminatedField(stream: stream, terminator: 0x00, binaryPrefix: binaryPrefix, asciiPrefix: asciiPrefix);
public static IEnumerable<byte> ReadSpaceTerminatedField(this Stream stream, IEnumerable<byte>? binaryPrefix = null, string? asciiPrefix = null) => ReadTerminatedField(stream: stream, terminator: 0x20, binaryPrefix: binaryPrefix, asciiPrefix: asciiPrefix);
public static IEnumerable<byte> ReadTerminatedField(this Stream stream, byte terminator, IEnumerable<byte>? binaryPrefix = null, string? asciiPrefix = null)
{
if (!stream.CanRead)
throw new InvalidOperationException("Can't read a non-readable stream");
if (binaryPrefix != null)
if (!stream.StartsWith(binaryPrefix))
throw new InvalidDataException($"Binary prefix {stream.Peek(binaryPrefix.Count()).AsHexString()} does not match expected value of {binaryPrefix.AsHexString()}!");
else stream.Skip(binaryPrefix.Count());
else if (asciiPrefix != null)
if (!stream.StartsWith(asciiPrefix))
throw new InvalidDataException($"Text prefix {stream.Peek(asciiPrefix.Length).AsHexString()} ({stream.Peek(asciiPrefix.Length).AsString()}) does not match expected value of {asciiPrefix.AsBytes().AsHexString()} ({asciiPrefix})!");
else stream.Skip(asciiPrefix.Length);
var read = 0;
while (stream.Peek() != terminator)
{
if (_debug) Console.WriteLine($"ReadTerminatedField -- pos: {stream.Position}/+{stream.Remaining()}/{stream.Length} | next: {(char)stream.Peek()} | Length: {read}");
if (stream.Peek() == -1)
{
Console.WriteLine($"Warning: Reached end of stream while reading null-terminated field");
yield break;
}
read++;
yield return (byte)stream.ReadByte();
}
if (stream.Peek() == terminator) stream.Skip();
}
public static IEnumerable<byte> ReadToEnd(this Stream stream)
{
if (!stream.CanRead)
throw new InvalidOperationException("Can't read a non-readable stream");
while (stream.Peek() != -1)
yield return (byte)stream.ReadByte();
}
public static int ReadInt32BE(this Stream stream)
{
if (!stream.CanRead)
throw new InvalidOperationException("Can't read a non-readable stream");
var bytes = stream.ReadBytes(4).ToArray();
if (BitConverter.IsLittleEndian)
Array.Reverse(bytes);
Console.WriteLine("ReadInt32BE: " + bytes.AsHexString() + " => " + BitConverter.ToInt32(bytes));
return BitConverter.ToInt32(bytes);
}
//read variable length number
public static int ReadVLQ(this Stream stream)
{
if (!stream.CanRead)
throw new InvalidOperationException("Can't read a non-readable stream");
int result = 0;
int shift = 0;
byte b;
do
{
b = (byte)stream.ReadByte();
result |= (b & 0b0111_1111) << shift;
shift += 7;
} while ((b & 0b1000_0000) != 0);
return result;
}
public static int ReadVLQBigEndian(this Stream stream)
{
if (!stream.CanRead)
throw new InvalidOperationException("Can't read a non-readable stream");
int result = 0;
int shift = 0;
byte b;
do
{
b = (byte)stream.ReadByte();
result = (result << 7) | (b & 0b0111_1111);
} while ((b & 0b1000_0000) != 0);
return result;
}
}
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