CHDStudio/PBPSharp/PbpFile.cs at master · purelogiccode/CHDStudio · GitHub

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using System.Buffers.Binary;

using System.Text;

using PBPSharp.Models;

namespace PBPSharp;

/// <summary>

/// Provides functionality to open and read PBP (EBOOT.PBP) files.

/// Supports single-disc and multi-disc PlayStation PBP files.

/// </summary>

/// <remarks>

/// Missing files are reported through the returned <see cref="PbpError" />

/// (<see cref="PbpError.FileNotFound" />) rather than exceptions, following the CSOSharp

/// convention for the compressed-image family.

/// </remarks>

public sealed class PbpFile : IDisposable

{

private readonly bool _ownsStream;

private bool _disposed;

private Stream _stream;

/// <summary>

/// Initializes a new instance of the <see cref="PbpFile" /> class. Instances are created by

/// the static <see cref="Open(string, out PbpFile?)" /> and

/// <see cref="Open(Stream, bool, out PbpFile?)" /> factory methods.

/// </summary>

/// <param name="stream">The seekable stream containing the PBP data.</param>

/// <param name="ownsStream">Whether disposing this instance disposes <paramref name="stream" />.</param>

/// <param name="header">The parsed PBP header.</param>

/// <param name="sfoData">The parsed PARAM.SFO metadata.</param>

/// <param name="discs">The disc entries discovered in the PSAR section.</param>

private PbpFile(

Stream stream,

bool ownsStream,

PbpHeader header,

SfoData sfoData,

IReadOnlyList<PbpDiscInfo> discs

)

{

_stream = stream;

_ownsStream = ownsStream;

Header = header;

SfoData = sfoData;

Discs = discs;

}

/// <summary>

/// The parsed PBP header containing resource offsets.

/// </summary>

public PbpHeader Header { get; }

/// <summary>

/// The SFO (PARAM.SFO) metadata parsed from the PBP.

/// </summary>

public SfoData SfoData { get; }

/// <summary>

/// The list of disc entries found in the PBP.

/// </summary>

public IReadOnlyList<PbpDiscInfo> Discs { get; }

/// <summary>

/// Whether this is a multi-disc PBP.

/// </summary>

public bool IsMultiDisc => Discs.Count > 1;

/// <summary>

/// The game title from SFO metadata.

/// </summary>

public string? Title => SfoData.GetString(SfoData.Keys.Title);

/// <summary>

/// The disc ID from SFO metadata (first disc).

/// </summary>

public string? DiscId => SfoData.GetString(SfoData.Keys.DiscId);

/// <summary>

/// The game category (e.g., "ME" for PS1 EBOOT).

/// </summary>

public string? Category => SfoData.GetString(SfoData.Keys.Category);

/// <summary>

/// Disposes of the PBP file and releases associated resources.

/// </summary>

public void Dispose()

{

if (_disposed)

return;

_disposed = true;

if (_ownsStream)

_stream.Dispose();

_stream = null!;

}

/// <summary>

/// Opens a PBP file from the specified file path.

/// </summary>

/// <param name="path">The full path to the PBP file.</param>

/// <param name="pbp">

/// When this method returns, contains the opened <see cref="PbpFile" /> instance if successful;

/// otherwise, null.

/// </param>

/// <returns>A <see cref="PbpError" /> indicating the result of the operation.</returns>

public static PbpError Open(string path, out PbpFile? pbp)

{

pbp = null;

if (!File.Exists(path))

return PbpError.FileNotFound;

try

{

var stream = File.OpenRead(path);

var error = Open(stream, true, out pbp);

if (error != PbpError.None)

stream.Dispose();

return error;

}

catch (IOException ex)

{

PbpDiagnostics.SetDetail($"Failed to open '{path}': {ex.Message}");

return PbpError.IoError;

}

/// <summary>

/// Opens a PBP from an existing stream.

/// </summary>

/// <param name="stream">The stream containing PBP data. Must be seekable and readable.</param>

/// <param name="ownsStream">Whether this instance should dispose the stream when disposed.</param>

/// <param name="pbp">

/// When this method returns, contains the opened <see cref="PbpFile" /> instance if successful;

/// otherwise, null.

/// </param>

/// <returns>A <see cref="PbpError" /> indicating the result of the operation.</returns>

public static PbpError Open(Stream stream, bool ownsStream, out PbpFile? pbp)

{

pbp = null;

if (stream is not { CanRead: true } || !stream.CanSeek)

return PbpError.IoError;

try

{

stream.Seek(0, SeekOrigin.Begin);

var headerError = ReadHeader(stream, out var header);

if (headerError != PbpError.None)

return headerError;

var sfoError = ReadSfo(stream, header, out var sfoData);

if (sfoError != PbpError.None)

return sfoError;

var discError = ReadDiscs(stream, header, out var discs);

if (discError != PbpError.None)

return discError;

pbp = new PbpFile(stream, ownsStream, header, sfoData, discs);

return PbpError.None;

}

catch (EndOfStreamException)

{

// The stream ended before the structure it declares: the download is truncated or

// incomplete, which is a different condition from a failing device or permission.

return PbpError.TruncatedPsar;

}

catch (IOException ex)

{

PbpDiagnostics.SetDetail($"Failed to read the PBP stream: {ex.Message}");

return PbpError.IoError;

}

catch (NoIsoIndexException)

{

// The PSAR header parsed correctly but no ISO index entries followed: the file ends

// before its data area, which is the signature of a truncated or incomplete download.

return PbpError.TruncatedPsar;

}

catch (InvalidDataException)

{

return PbpError.CorruptFile;

}

catch (Exception)

{

return PbpError.CorruptFile;

}

/// <summary>

/// Reads and validates the 40-byte PBP header at the start of the stream.

/// </summary>

/// <param name="stream">The seekable PBP stream, positioned at the start of the file.</param>

/// <param name="header">

/// When this method returns, contains the parsed header when the magic is valid; otherwise,

/// the default value.

/// </param>

/// <returns>

/// <see cref="PbpError.None" /> on success; <see cref="PbpError.InvalidHeader" /> when the

/// stream is too short or the PBP magic does not match.

/// </returns>

private static PbpError ReadHeader(Stream stream, out PbpHeader header)

{

header = default;

Span<byte> headerBytes = stackalloc byte[PbpHeader.HeaderSize];

try

{

stream.ReadExactly(headerBytes);

}

catch (EndOfStreamException)

{

return PbpError.InvalidHeader;

}

var magic = BinaryPrimitives.ReadUInt32LittleEndian(headerBytes[..4]);

if (magic != PbpHeader.MagicValue)

return PbpError.InvalidHeader;

var version = BinaryPrimitives.ReadUInt32LittleEndian(headerBytes[4..8]);

var sfoOffset = BinaryPrimitives.ReadInt32LittleEndian(headerBytes[8..12]);

var icon0Offset = BinaryPrimitives.ReadInt32LittleEndian(headerBytes[12..16]);

var icon1Offset = BinaryPrimitives.ReadInt32LittleEndian(headerBytes[16..20]);

var pic0Offset = BinaryPrimitives.ReadInt32LittleEndian(headerBytes[20..24]);

var pic1Offset = BinaryPrimitives.ReadInt32LittleEndian(headerBytes[24..28]);

var snd0Offset = BinaryPrimitives.ReadInt32LittleEndian(headerBytes[28..32]);

var dataPspOffset = BinaryPrimitives.ReadInt32LittleEndian(headerBytes[32..36]);

var dataPsarOffset = BinaryPrimitives.ReadInt32LittleEndian(headerBytes[36..40]);

header = new PbpHeader(

version,

sfoOffset,

icon0Offset,

icon1Offset,

pic0Offset,

pic1Offset,

snd0Offset,

dataPspOffset,

dataPsarOffset

);

return PbpError.None;

}

/// <summary>

/// Reads the PARAM.SFO metadata section pointed to by the PBP header. Parsing is best

/// effort: a missing or malformed SFO leaves the returned data empty instead of failing the

/// open, because disc extraction does not depend on the metadata.

/// </summary>

/// <param name="stream">The seekable PBP stream.</param>

/// <param name="header">The parsed PBP header providing the SFO offset.</param>

/// <param name="sfoData">

/// When this method returns, contains the parsed SFO entries, or an empty instance when the

/// SFO is absent or corrupt.

/// </param>

/// <returns>Always <see cref="PbpError.None" />.</returns>

private static PbpError ReadSfo(Stream stream, PbpHeader header, out SfoData sfoData)

{

sfoData = new SfoData();

try

{

stream.Seek(header.SfoOffset, SeekOrigin.Begin);

var sfoBuffer = new byte[4];

sfoData.Magic = ReadUInt32(stream, sfoBuffer);

sfoData.Version = ReadUInt32(stream, sfoBuffer);

// A real SFO starts with the bytes 00 50 53 46 ("\0PSF"), which as a little-endian

// uint32 is 0x46535000. A missing or corrupt SFO does not stop the run: none of the

// reference tools read the SFO when extracting disc images from the PSAR, so metadata

// is simply absent (Title/DiscId are null) rather than the whole file rejected.

if (sfoData.Magic != 0x46535000)

return PbpError.None;

sfoData.KeyTableOffset = ReadUInt32(stream, sfoBuffer);

sfoData.DataTableOffset = ReadUInt32(stream, sfoBuffer);

var entryCount = ReadUInt32(stream, sfoBuffer);

var entries = new List<SfoEntry>();

var dataTableSize = 0UL;

for (var i = 0; i < entryCount; i++)

{

var dirBuffer = new byte[16];

stream.Seek(header.SfoOffset + 20 + i * 16, SeekOrigin.Begin);

stream.ReadExactly(dirBuffer, 0, 16);

// Layout: KeyOffset(2) + Format(2) + Length(4) + MaxLength(4) + DataOffset(4)

var keyOffset = BinaryPrimitives.ReadUInt16LittleEndian(dirBuffer.AsSpan(0, 2));

var entry = new SfoEntry

{

Format = BinaryPrimitives.ReadUInt16LittleEndian(dirBuffer.AsSpan(2, 2)),

Length = BinaryPrimitives.ReadUInt32LittleEndian(dirBuffer.AsSpan(4, 4)),

MaxLength = BinaryPrimitives.ReadUInt32LittleEndian(dirBuffer.AsSpan(8, 4))

};

var dataOffset = BinaryPrimitives.ReadUInt32LittleEndian(dirBuffer.AsSpan(12, 4));

var entryEnd = (ulong)dataOffset + entry.MaxLength;

if (entryEnd > dataTableSize)

dataTableSize = entryEnd;

stream.Seek(header.SfoOffset + sfoData.KeyTableOffset + keyOffset, SeekOrigin.Begin);

entry.Key = ReadNullTerminatedString(stream, 128);

stream.Seek(header.SfoOffset + sfoData.DataTableOffset + dataOffset, SeekOrigin.Begin);

switch (entry.Format)

{

case 0x0204:

// The declared length is untrusted; it cannot exceed what is left in the

// file, and must fit an int so a corrupt entry cannot drive a multi-gigabyte

// allocation or overflow the cast below.

var remaining = stream.Length - stream.Position;

if (remaining > 0 && entry.Length <= (ulong)remaining && entry.Length <= int.MaxValue)

entry.Value = ReadNullTerminatedString(stream, (int)entry.Length);

break;

case 0x0404:

entry.Value = ReadUInt32(stream, new byte[4]);

break;

}

entries.Add(entry);

}

sfoData.Entries = entries;

sfoData.Size = (uint)Math.Min((ulong)sfoData.DataTableOffset + dataTableSize, uint.MaxValue);

}

catch

{

// Best effort: keep whatever entries parsed before the failure. A malformed SFO

// table must not abort extraction of an otherwise readable PSAR.

}

return PbpError.None;

}

/// <summary>

/// Locates the disc entries inside the PSAR section. A "PSISOIMG0000" PSAR is a single-disc

/// container; a "PSTITLEIMG000000" PSAR is a multi-disc container whose disc positions are

/// read from the table at PSAR+0x200. Each position is then parsed into a

/// <see cref="PbpDiscInfo" />.

/// </summary>

/// <param name="stream">The seekable PBP stream.</param>

/// <param name="header">The parsed PBP header providing the DATA.PSAR offset.</param>

/// <param name="discs">

/// When this method returns, contains the discs discovered in the PSAR, in disc order.

/// </param>

/// <returns>

/// <see cref="PbpError.None" /> on success; <see cref="PbpError.InvalidPsarHeader" /> when the

/// PSAR does not identify itself as a PlayStation disc image.

/// </returns>

private static PbpError ReadDiscs(Stream stream, PbpHeader header, out List<PbpDiscInfo> discs)

{

discs = [];

stream.Seek(header.DataPsarOffset, SeekOrigin.Begin);

var psarHeaderBuffer = new byte[16];

stream.ReadExactly(psarHeaderBuffer, 0, 16);

var psarHeader = Encoding.ASCII.GetString(psarHeaderBuffer, 0, 12);

if (string.Equals(psarHeader, "PSISOIMG0000", StringComparison.Ordinal))

{

discs.Add(new PbpDiscInfo(stream, header.DataPsarOffset, 1));

}

else

{

// Multi-disc: check for PSTITLEIMG000000

var fullHeader = Encoding.ASCII.GetString(psarHeaderBuffer, 0, 16);

if (!string.Equals(fullHeader, "PSTITLEIMG000000", StringComparison.Ordinal))

return PbpError.InvalidPsarHeader;

// Skip past the header structure

var skipBuffer = new byte[4];

stream.ReadExactly(skipBuffer, 0, 4); // padding

// The next 16 bytes are a fixed "random" template in popstation/PSX2PSP/iPoPS

// (0x2CC9C5BC, 0x33B5A90F, 0x06F6B4B3, 0xB25945BA), but pop-fe leaves them zero in

// its multi-disc PBPs and they are still perfectly readable. The disc position

// table at +0x200 is what actually locates the discs, so tolerate any value here

// and let the per-disc parsing validate the real structure.

stream.ReadExactly(skipBuffer, 0, 4);

// The next 16 bytes are a fixed "random" template in popstation/PSX2PSP/iPoPS

// (0x2CC9C5BC, 0x33B5A90F, 0x06F6B4B3, 0xB25945BA), but pop-fe leaves them zero in

// its multi-disc PBPs and they are still perfectly readable. The disc position

// table at +0x200 is what actually locates the discs, so tolerate any value here

// and let the per-disc parsing validate the real structure.

// Skip 0x76 uint32 values

var dummyBuffer = new byte[4];

for (var i = 0; i < 0x76; i++)

stream.ReadExactly(dummyBuffer, 0, 4);

// Read up to 5 disc positions

var posBuffer = new byte[20]; // 5 * 4 bytes

stream.ReadExactly(posBuffer, 0, 20);

for (var i = 0; i < 5; i++)

{

var pos = BitConverter.ToUInt32(posBuffer, i * 4);

if (pos > 0) discs.Add(new PbpDiscInfo(stream, header.DataPsarOffset + (int)pos, i + 1));

}

return PbpError.None;

}

/// <summary>

/// Reads exactly four bytes from the stream and interprets them as a little-endian 32-bit

/// unsigned integer.

/// </summary>

/// <param name="stream">The stream to read from.</param>

/// <param name="buffer">A reusable four-byte buffer used to hold the raw bytes.</param>

/// <returns>The value read from the stream.</returns>

private static uint ReadUInt32(Stream stream, byte[] buffer)

{

stream.ReadExactly(buffer, 0, 4);

return BitConverter.ToUInt32(buffer, 0);

}

/// <summary>

/// Reads an ASCII string from the current stream position up to a null terminator or the

/// specified maximum length, whichever comes first.

/// </summary>

/// <param name="stream">The stream to read from.</param>

/// <param name="maxLength">The maximum number of bytes to read, including the terminator.</param>

/// <returns>The decoded string, without the null terminator.</returns>

private static string ReadNullTerminatedString(Stream stream, int maxLength)

{

var buffer = new byte[maxLength];

var length = 0;

for (var i = 0; i < maxLength; i++)

{

var b = stream.ReadByte();

if (b <= 0)

break;

buffer[length++] = (byte)b;

}

return Encoding.ASCII.GetString(buffer, 0, length);

}

CHDStudio/PBPSharp/PbpFile.cs at master · purelogiccode/CHDStudio · GitHub

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