From f74220efeade1dcc2461a5f36819a398f2f003b5 Mon Sep 17 00:00:00 2001
From: Deterous <138427222+Deterous@users.noreply.github.com>
Date: Sun, 18 Feb 2024 16:59:04 +0900
Subject: [PATCH] Read ISO in larger chunks
---
LibIRD/IRD.cs | 130 +++++++++++++++++++++++++++++++-------------------
1 file changed, 82 insertions(+), 48 deletions(-)
diff --git a/LibIRD/IRD.cs b/LibIRD/IRD.cs
index 593d5e5..68fe858 100644
--- a/LibIRD/IRD.cs
+++ b/LibIRD/IRD.cs
@@ -715,7 +715,6 @@ namespace LibIRD
HashFiles(fs, reader, rootDir);
if (FileCount != fileCount)
{
- //Console.WriteLine($"{isoPath} contains split files: detected {FileCount} out of {fileCount} expected files");
long[] tempFileKeys = FileKeys;
Array.Resize(ref tempFileKeys, (int)FileCount);
FileKeys = tempFileKeys;
@@ -891,8 +890,8 @@ namespace LibIRD
RegionEnd[^1] = (UpdateEnd / SectorSize) - 1;
// Determine MD5 hashes for each region
- using MD5 md5 = MD5.Create();
- byte[] buf = new byte[SectorSize];
+ int bufSectors = 1024;
+ byte[] buf = new byte[bufSectors * SectorSize];
for (int i = 0; i < RegionCount; i++)
{
// Start reading data from first sector of region
@@ -900,19 +899,32 @@ namespace LibIRD
// Compute MD5 hash for just the region portion of the ISO file
int numBytes;
- for (long j = RegionStart[i]; j <= RegionEnd[i]; j++)
+ using MD5 md5 = MD5.Create();
+ int regionSectors = (int)(RegionEnd[i] - RegionStart[i]) + 1;
+ for (int j = bufSectors; j <= regionSectors; j += bufSectors)
{
- // Read one sector at a time
+ // Read into buffer
numBytes = fs.Read(buf, 0, buf.Length);
- // Check that an entire sector was read
+ // TODO: Process partial buffer if non-zero is returned
if (numBytes < buf.Length)
throw new InvalidFileSystemException("Disc region ended unexpectedly");
- // Process MD5 sum one sector at a time
+
+ // Process MD5 sum
md5.TransformBlock(buf, 0, buf.Length, null, 0);
}
+ // Read any remaining sectors
+ int bufRemainder = (int)(SectorSize * (regionSectors % bufSectors));
+ if (bufRemainder != 0)
+ {
+ numBytes = fs.Read(buf, 0, bufRemainder);
+ // TODO: Process partial buffer if non-zero is returned
+ if (numBytes < bufRemainder)
+ throw new InvalidFileSystemException("Disc region ended unexpectedly");
+ }
+
// Compute and store MD5 hash of region
- md5.TransformFinalBlock(buf, 0, 0);
+ md5.TransformFinalBlock(buf, 0, bufRemainder);
RegionHashes[i] = md5.Hash;
}
}
@@ -938,13 +950,14 @@ namespace LibIRD
// Determine smallest file offset as first sector
long smallestOffset = fileClusters[0].Offset;
+ bool nonContiguous = false;
for (int i = 1; i < fileClusters.Length; i++)
{
if (fileClusters[i] == null)
throw new InvalidFileSystemException($"Unexpected file extents for {filePath}");
if (fileClusters[i].Offset * SectorSize != fileClusters[i - 1].Offset * SectorSize + fileClusters[i - 1].Count)
- Console.WriteLine($"Non-contiguous file found: {filePath}");
+ nonContiguous = true;
if (fileClusters[i].Offset < smallestOffset)
smallestOffset = fileClusters[i].Offset;
@@ -953,6 +966,8 @@ namespace LibIRD
// If already encountered file offset, skip this file
if (Array.Exists(FileKeys, element => element == smallestOffset))
continue;
+ else if (nonContiguous)
+ Console.WriteLine($"Non-contiguous file found: {filePath}");
// Add file offset to keys
FileKeys[FileCount] = smallestOffset;
@@ -968,39 +983,47 @@ namespace LibIRD
}
}
- // Hash each non-contiguous portion of the ISO file
- byte[] buf = new byte[SectorSize];
- MD5 md5 = MD5.Create();
+ // Read one sector at a time for small files
+ int bufSectors = (fileClusters[0].Count < 1024 * SectorSize) ? 1 : 1024;
+ byte[] buf = new byte[bufSectors * SectorSize];
+
+ // Hash each non-contiguous portion of the file
+ using MD5 md5 = MD5.Create();
for (int i = 0; i < fileClusters.Length; i++)
{
- // Start reading data from the beginning of the ISO file
+ // Start reading data from the beginning of the current extent
fs.Seek(fileClusters[i].Offset * SectorSize, SeekOrigin.Begin);
int numBytes;
- // Read all data before the first data sector
- for (int j = 0; j < (fileClusters[i].Count / SectorSize); j++)
+ // Read file in buffers
+ long fileSectors = fileClusters[i].Count / SectorSize;
+ for (int j = 0; j <= fileSectors - bufSectors; j += bufSectors)
{
numBytes = fs.Read(buf, 0, buf.Length);
- // Check that an entire sector was read
- if (numBytes < buf.Length)
+ // TODO: Process partial buffer if non-zero is returned
+ if (numBytes != buf.Length)
throw new InvalidFileSystemException("Disc region ended unexpectedly");
- // Decrypt sector if necessary
+
+ // Decrypt buffer if necessary
if (encrypted)
- buf = DecryptSector(buf, (int)fileClusters[i].Offset + j);
+ DecryptSectors(ref buf, (int)fileClusters[i].Offset + j);
+
// Hash sector
- md5.TransformBlock(buf, 0, numBytes, null, 0);
+ md5.TransformBlock(buf, 0, buf.Length, null, 0);
}
- // Read remaining partial sector
- if (fileClusters[i].Count % SectorSize != 0)
+ // Read remaining partial buffer
+ if ((fileClusters[i].Count % buf.Length) > 0)
{
numBytes = fs.Read(buf, 0, buf.Length);
- // Check that an entire sector was read
- if (numBytes < buf.Length)
+ // TODO: Process partial buffer if non-zero is returned
+ if (numBytes != buf.Length)
throw new InvalidFileSystemException("Disc region ended unexpectedly");
- // Decrypt partial sector if necessary
+
+ // Decrypt buffer if necessary
if (encrypted)
- buf = DecryptSector(buf, (int)fileClusters[i].Offset + (int)(fileClusters[i].Count / SectorSize));
- // Hash partial sector
- md5.TransformBlock(buf, 0, (int)(fileClusters[i].Count % SectorSize), null, 0);
+ DecryptSectors(ref buf, (int)fileClusters[i].Offset + bufSectors * (int)(fileClusters[i].Count / buf.Length));
+
+ // Hash partial buffer
+ md5.TransformBlock(buf, 0, (int)(fileClusters[i].Count % buf.Length), null, 0);
}
}
@@ -1018,38 +1041,49 @@ namespace LibIRD
}
///
- /// Decrypts a given sector byte array
+ /// Decrypts a given byte array of sector(s)
///
- /// Byte array to be decrypted
+ /// Byte array to be decrypted
+ /// Number of bytes to decrypt
///
- private protected byte[] DecryptSector(byte[] sector, int sectorNumber)
+ private protected void DecryptSectors(ref byte[] buffer, int sectorNumber)
{
+ ArgumentNullException.ThrowIfNull(buffer);
+
+ if (buffer.Length == 0 || buffer.Length % SectorSize != 0)
+ throw new ArgumentException("Encrypted buffer must be multiple of SectorSize");
+
// Setup AES decryption
using Aes aes = Aes.Create() ?? throw new InvalidOperationException("AES not available. Change your system settings");
-
// Set AES settings
aes.Key = DiscKey;
aes.Padding = PaddingMode.None;
aes.Mode = CipherMode.CBC;
- // Determine Initial Value based on sector number
- byte[] iv = new byte[16];
- for (int i = 0; i < 16; i++)
+ // Decrypt buffer one sector at a time
+ for (int i = 0; i < buffer.Length; i += (int)SectorSize)
{
- byte a = (byte)(sectorNumber & 0xFF);
- iv[16 - i - 1] = (byte)(sectorNumber & 0xFF);
- sectorNumber >>= 8;
+ // Determine AES Initial Value based on sector number
+ byte[] iv = new byte[16];
+ int tempNum = sectorNumber;
+ for (int j = 0; j < 16; j++)
+ {
+ iv[16 - j - 1] = (byte)(tempNum & 0xFF);
+ tempNum >>= 8;
+ }
+ aes.IV = iv;
+
+ // Perform AES decryption
+ using MemoryStream stream = new();
+ using CryptoStream cs = new(stream, aes.CreateDecryptor(), CryptoStreamMode.Write);
+ cs.Write(buffer, i, (int)SectorSize);
+ cs.FlushFinalBlock();
+
+ // Write decrypted sector to output
+ stream.ToArray().CopyTo(buffer, i);
+ sectorNumber++;
}
- aes.IV = iv;
-
- // Perform AES decryption
- using MemoryStream stream = new();
- using ICryptoTransform dec = aes.CreateDecryptor();
- using CryptoStream cs = new(stream, dec, CryptoStreamMode.Write);
- cs.Write(sector, 0, sector.Length);
- cs.FlushFinalBlock();
-
- return stream.ToArray();
+ return;
}
///