Add rar file pattern as requested in WerWolv#258

README.md

@@ -124,6 +124,7 @@ Everything will immediately show up in ImHex's Content Store and gets bundled wi
 | QBCL | | [`patterns/qbcl.hexpat`](patterns/qbcl.hexpat) | Qubicle voxel scene project file |
 | QOI  | `image/qoi` | [`patterns/qoi.hexpat`](patterns/qoi.hexpat) | QOI image files |
 | quantized-mesh | | [`patterns/quantized-mesh.hexpat`](patterns/quantized-mesh.hexpat) | Cesium quantized-mesh terrain |
+| RAR | `application/x-rar` | [`patterns/rar.hexpat`](patterns/rar.hexpat) | RAR archive file format |
 | RAS  | `image/x-sun-raster` | [`patterns/ras.hexpat`](patterns/ras.hexpat) | RAS image files |
 | ReFS | | [`patterns/refs.hexpat`](patterns/refs.hexpat) | Microsoft Resilient File System |
 | RGBDS | | [`patterns/rgbds.hexpat`](patterns/rgbds.hexpat) | [RGBDS](https://rgbds.gbdev.io) object file format |

patterns/rar.hexpat

@@ -0,0 +1,364 @@
+#pragma author targodan
+#pragma description RAR archive file format
+#pragma MIME application/x-rar
+
+import type.magic;
+import type.byte;
+import std.mem;
+import std.math;
+import std.string;
+import std.time;
+
+// Source: https://www.rarlab.com/technote.htm
+
+#define RARv5_MAGIC "Rar!\x1a\x07\x01\x00"
+
+using FILETIME = u64 [[format("format_windows_time")]];
+using time_t = std::time::EpochTime [[format("format_unix_time")]];
+using nanotime_t = u64 [[format("format_unix_time")]];
+
+fn format_unix_time(time_t t) {
+    return std::time::format(std::time::to_local(t), "%c");
+};
+
+fn format_windows_time(FILETIME t) {
+    return format_unix_time(std::time::filetime_to_unix(t));
+};
+
+struct vint {
+    u8 data[while(std::mem::read_unsigned($, 1) & 0x80 != 0)];
+    u8 last;
+} [[sealed, transform("vint_value"), format("vint_value")]];
+
+fn vint_value(vint vi) {
+    u64 value = 0;
+    u8 i = 0;
+    for(i = 0, i < sizeof(vi.data), i = i + 1) {
+        value |= (vi.data[i] & 0x7F) << (i * 7);
+    }
+    value |= vi.last << (i * 7);
+    return value;
+};
+
+bitfield LocatorRecordFlags {
+    bool quickOpenRecordOffsetIsPresent : 1;
+    bool recoveryRecordOffsetIsPresent : 1;
+};
+
+struct LocatorRecord {
+    LocatorRecordFlags flags;  // should be vint but not compatible with bitfield
+    if (flags.quickOpenRecordOffsetIsPresent) {
+        vint quickOpenRecordOffset;
+    }
+    if (flags.recoveryRecordOffsetIsPresent) {
+        vint recoveryRecordOffset;
+    }
+};
+
+bitfield MetadataRecordFlags {
+    bool archiveNameIsPresent : 1;
+    bool archiveOriginalCreationTimeIsPresent : 1;
+    bool timeIsUnixTime : 1;
+    bool unixTimeIsNanosecondPrecision : 1;
+};
+
+struct MetadataRecord {
+    MetadataRecordFlags flags;  // should be vint but not compatible with bitfield
+    if (flags.archiveNameIsPresent) {
+        vint nameLength;
+        char name[nameLength];
+    }
+    if (flags.archiveOriginalCreationTimeIsPresent) {
+        match (flags.timeIsUnixTime, flags.unixTimeIsNanosecondPrecision) {
+            (true, true): nanotime_t originalCreationTime;
+            (true, false): time_t originalCreationTime;
+            (false, _): FILETIME originalCreationTime;
+        }
+    }
+};
+
+enum MainHeaderExtraRecordType : vint {
+    Locator = 1,
+    Metadata = 2
+};
+
+struct MainHeaderExtraRecord {
+    vint size;
+    MainHeaderExtraRecordType type;
+    match(type) {
+        (MainHeaderExtraRecordType::Locator): LocatorRecord record [[inline]];
+        (MainHeaderExtraRecordType::Metadata): MetadataRecord record [[inline]];
+    }
+};
+
+bitfield HeaderFlags {
+    bool extraAreaIsPresent : 1;
+    bool dataAreaIsPresent : 1;
+};
+
+bitfield ArchiveFlags {
+    bool archiveIsPartOfMultiVolumeSet : 1;
+    bool volumeNumberFieldIsPresent : 1;
+    bool isSolidArchive : 1;
+    bool recoveryRecordIsPresent : 1;
+    bool isLockedArchive : 1;
+};
+
+enum HeaderType : vint {
+    MainHeader = 1,
+    FileHeader,
+    ServiceHeader,
+    EncryptionHeader,
+    EndOfArchive
+};
+
+struct MainArchiveHeader {
+    HeaderFlags flags;  // should be vint but not compatible with bitfield
+    if (flags.extraAreaIsPresent) {
+        vint extraAreaSize;
+    }
+    ArchiveFlags archiveFlags;  // should be vint but not compatible with bitfield
+    if (archiveFlags.volumeNumberFieldIsPresent) {
+        vint volumeNumber;
+    }
+    if (flags.extraAreaIsPresent) {
+        u64 extraEnd = $ + extraAreaSize;
+        MainHeaderExtraRecord extraArea[while($ < extraEnd)];
+    }
+};
+
+bitfield EncryptionHeaderFlags {
+    bool passwordCheckDataIsPresent : 1;
+};
+
+struct EncryptionHeader {
+    HeaderFlags flags;  // should be vint but not compatible with bitfield
+    vint encryptionVersion; // only 0 (AES-256) is supported
+    EncryptionHeaderFlags encryptionFlags;
+    u8 kdfCount;
+    u8 salt[16];
+    if (encryptionFlags.passwordCheckDataIsPresent) {
+        u8 checkValue[12];
+    }
+
+    u8 iv[16];
+    // if this header is present, all following headers are encrypted => gobble up all data
+    u8 encryptedHeaders[while(!std::mem::eof())];
+    // With a bit of guess work, I figured out the exact crypto:
+    // key = PBKDF2(password, salt, keysize=256, iterations=2^kdfCount, hash=sha256)
+    // plainHeaders = AES256Decrypt(key, iv, mode=CBC)
+};
+
+bitfield FileAndServiceHeaderFlags {
+    bool isDirectory : 1;
+    bool timeFieldIsPresent : 1;
+    bool crc32FieldIsPresent : 1;
+    bool unpackedSizeIsUnknown : 1;
+};
+
+enum HostOS : vint {
+    Windows = 0,
+    Unix = 1
+};
+
+bitfield FileEncryptionFlags {
+    bool passwordCheckDataIsPresent : 1;
+    bool useTweakedChecksums : 1;
+};
+
+struct FileEncryptionRecord {
+    vint encryptionVersion; // only 0 (AES-256) is supported
+    FileEncryptionFlags flags;  // should be vint but not compatible with bitfield
+    u8 kdfCount;
+    u8 salt[16];
+    u8 iv[16];
+    u8 checkValue[12];
+};
+
+struct FileHashRecord {
+    vint hashType; // only 0 (BLAKE2sp) hash is documented
+    u8 hashData[32]; // depends on hashType, but only one type is supported
+};
+
+bitfield FileTimeFlags {
+    bool timeIsStoredInUnixTime : 1;
+    bool mtimeIsPresent : 1;
+    bool ctimeIsPresent : 1;
+    bool atimeIsPresent : 1;
+    bool unixTimeIsNanosecondPrecision : 1;
+};
+
+struct FileTimeRecord {
+    FileTimeFlags flags;  // should be vint but not compatible with bitfield
+    if (flags.mtimeIsPresent) {
+        match (flags.timeIsStoredInUnixTime, flags.unixTimeIsNanosecondPrecision) {
+            (true, true): nanotime_t mtime;
+            (true, false): time_t mtime;
+            (false, _): FILETIME mtime;
+        }
+    }
+    if (flags.ctimeIsPresent) {
+        match (flags.timeIsStoredInUnixTime, flags.unixTimeIsNanosecondPrecision) {
+            (true, true): nanotime_t ctime;
+            (true, false): time_t ctime;
+            (false, _): FILETIME ctime;
+        }
+    }
+    if (flags.atimeIsPresent) {
+        match (flags.timeIsStoredInUnixTime, flags.unixTimeIsNanosecondPrecision) {
+            (true, true): nanotime_t atime;
+            (true, false): time_t atime;
+            (false, _): FILETIME atime;
+        }
+    }
+};
+
+struct FileVersionRecord {
+    vint flags;
+    vint versionNumber;
+};
+
+enum RedirectionType : vint {
+    unixSymlink = 1,
+    windowsSymlink,
+    windowsJunktion,
+    hardLink,
+    fileCopy
+};
+
+struct RedirectionRecord {
+    RedirectionType type;
+    vint flags;
+    vint targetLength;
+    char target[targetLength];
+};
+
+bitfield UnixOwnerFlags {
+    bool userNameStringIsPresent : 1;
+    bool groupNameStringIsPresent : 1;
+    bool numericUserIDIsPresent : 1;
+    bool numericGroupIDIsPresent : 1;
+};
+
+struct UnixOwnerRecord {
+    UnixOwnerFlags flags;  // should be vint but not compatible with bitfield
+    if (flags.userNameStringIsPresent) {
+        vint userNameLength;
+        char userName[usernameLength];
+    }
+    if (flags.groupNameStringIsPresent) {
+        vint groupNameLength;
+        char groupName[groupNameLength];
+    }
+    if (flags.numericUserIDIsPresent) {
+        vint uid;
+    }
+    if (flags.numericGroupIDIsPresent) {
+        vint gid;
+    }
+};
+
+enum FSHeaderExtraRecordType : vint {
+    FileEncryption = 1,
+    FileHash,
+    FileTime,
+    FileVersion,
+    Redirection,
+    UnixOwner,
+    ServiceData
+};
+
+struct FSHeaderExtraRecord {
+    vint size;
+    FSHeaderExtraRecordType type;
+    match(type) {
+        (FSHeaderExtraRecordType::FileEncryption): FileEncryptionRecord record [[inline]];
+        (FSHeaderExtraRecordType::FileHash): FileHashRecord record [[inline]];
+        (FSHeaderExtraRecordType::FileTime): FileTimeRecord record [[inline]];
+        (FSHeaderExtraRecordType::FileVersion): FileVersionRecord record [[inline]];
+        (FSHeaderExtraRecordType::Redirection): RedirectionRecord record [[inline]];
+        (FSHeaderExtraRecordType::UnixOwner): UnixOwnerRecord record [[inline]];
+        (FSHeaderExtraRecordType::ServiceData): u8 data[size - sizeof(type)]; // couldn't find any info on these records
+    }
+};
+
+bitfield _CompressionInformation {
+    version : 6;
+    bool isSolid : 1;
+    method : 3;
+    minDictionarySizeExponent : 5; // min dict size is `128 KB * 2^minDictionarySizeExponent`
+    additionalDictionarySize : 5;
+    bool compressionAlgorithmIsZeroButSizeIsV1 : 1;
+};
+
+struct CompressionInformation {
+    vint value; // TODO: I'd like to somehow cast the resulting value to _CompressionInformation
+};
+
+fn to_CompressionInformation(vint v) {
+    std::mem::Reinterpreter<u64, _CompressionInformation> conv;
+    conv.from = v;
+    return conv.to;
+};
+
+struct FileOrServiceHeader {
+    HeaderFlags flags;  // should be vint but not compatible with bitfield
+    if (flags.extraAreaIsPresent) {
+        vint extraAreaSize;
+    }
+    if (flags.dataAreaIsPresent) {
+        vint dataAreaSize;
+    }
+    FileAndServiceHeaderFlags fileOrServiceFlags;  // should be vint but not compatible with bitfield
+    vint unpackedSize;
+    vint fileAttributes;
+    if (fileOrServiceFlags.timeFieldIsPresent) {
+        u32 fileModificationUnixTime;
+    }
+    if (fileOrServiceFlags.crc32FieldIsPresent) {
+        u32 unpackedCrc32;
+    }
+    CompressionInformation compressionInformation;
+    try {
+        HostOS hostOS;
+        vint nameLength;
+        char name[nameLength];
+        if (flags.extraAreaIsPresent) {
+            u64 extraEnd = $ + extraAreaSize;
+            FSHeaderExtraRecord extraArea[while($ < extraEnd)];
+        }
+        if (flags.dataAreaIsPresent) {
+            u8 data[dataAreaSize] [[sealed]];
+        }
+    } catch {}
+};
+
+bitfield EOAHeaderFlags {
+    bool archiveIsVolumeAndNotLastInVolumeSet : 1;
+};
+
+struct EndOfArchiveHeader {
+    HeaderFlags flags;
+    EOAHeaderFlags eoaFlags;
+};
+
+struct Header {
+    u32 crc32;
+    vint headerSize;
+    HeaderType type;
+    match (type) {
+        (HeaderType::EncryptionHeader): EncryptionHeader [[inline]];
+        (HeaderType::MainHeader): MainArchiveHeader [[inline]];
+        (HeaderType::FileHeader): FileOrServiceHeader [[inline]];
+        (HeaderType::ServiceHeader): FileOrServiceHeader [[inline]];
+        (HeaderType::EndOfArchive): EndOfArchiveHeader [[inline]];
+    }
+};
+
+struct RARv5 {
+    type::Magic<RARv5_MAGIC> magic;
+    Header headers[while(!std::mem::eof())]; // TODO: would be better to read until EOAHeader
+};
+
+RARv5 archive @ std::mem::find_string(0, RARv5_MAGIC);
+