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MBR is short for Master Boot Record. It is the legacy method of booting, the code area is limited to 446 bytes, and it's all 16-bit x86 opcodes. Old BIOS code knows how to call into it and execute the instructions there. MBR also has a 64-byte partition table that can store up to 4 partitions. The GPT partitioning scheme obsoletes this, and allows for more partitions, but that requires UEFI to work. For more information on MBR, see: https://thestarman.pcministry.com/asm/mbr/PartTables.htm#mbr
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|---|---|---|
| @@ -1,3 +1,4 @@ | ||
| .DS_Store | ||
| testfiles/ | ||
| fq | ||
| *.swp |
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| @@ -0,0 +1,66 @@ | ||
| package mbr | ||
|
|
||
| import ( | ||
| "fmt" | ||
|
|
||
| "github.com/wader/fq/format" | ||
| "github.com/wader/fq/format/registry" | ||
| "github.com/wader/fq/pkg/decode" | ||
| "github.com/wader/fq/pkg/scalar" | ||
| ) | ||
|
|
||
| func init() { | ||
| registry.MustRegister(decode.Format{ | ||
| Name: format.MBR, | ||
| Description: "Master Boot Record", | ||
| DecodeFn: mbrDecode, | ||
| }) | ||
| } | ||
|
|
||
| func decodePartitionTableEntry(d *decode.D) { | ||
| d.FieldU8("boot_indicator", scalar.UToDescription{ | ||
| 0x80: "active", | ||
| 0x00: "inactive", | ||
| }) | ||
| d.FieldStrScalarFn("starting_chs_vals", decodeCHSBytes) | ||
| d.FieldU8("partition_type", partitionTypes) | ||
| d.FieldStrScalarFn("ending_chs_vals", decodeCHSBytes) | ||
| d.FieldStrScalarFn("starting_sector", decodeCHSBytes) | ||
| d.U8() // extra byte | ||
| d.FieldScalarU32("partition_size") | ||
| } | ||
|
|
||
| // Because this is a fixed-sized table, I am opting to use a | ||
| // FieldStruct instead of a FieldArray | ||
| func decodePartitionTable(d *decode.D) { | ||
| d.FieldStruct("entry_1", decodePartitionTableEntry) | ||
| d.FieldStruct("entry_2", decodePartitionTableEntry) | ||
| d.FieldStruct("entry_3", decodePartitionTableEntry) | ||
| d.FieldStruct("entry_4", decodePartitionTableEntry) | ||
| } | ||
|
|
||
| // Source: https://thestarman.pcministry.com/asm/mbr/PartTables.htm#Decoding | ||
| func decodeCHSBytes(d *decode.D) scalar.S { | ||
| head, _ := d.Bits(8) | ||
| sectorHighBits, err := d.Bits(2) | ||
| if err != nil { | ||
| d.IOPanic(err, "chs") | ||
| } | ||
| sector, _ := d.Bits(6) | ||
| cylinderLowerBits, err := d.Bits(8) | ||
| if err != nil { | ||
| d.IOPanic(err, "chs") | ||
| } | ||
| cylinder := (sectorHighBits << 2) | cylinderLowerBits | ||
| return scalar.S{Actual: fmt.Sprintf("CHS(%x, %x, %x)", cylinder, head, sector)} | ||
| } | ||
|
|
||
| func mbrDecode(d *decode.D, in interface{}) interface{} { | ||
| d.Endian = decode.LittleEndian | ||
|
|
||
| d.FieldRawLen("code_area", 446*8) | ||
| d.FieldStruct("partition_table", decodePartitionTable) | ||
| d.FieldU16("boot_record_sig", scalar.ActualHex) | ||
| //d.AssertU(0xaa55) | ||
| return nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,151 @@ | ||
| package mbr | ||
|
|
||
| import ( | ||
| "github.com/wader/fq/pkg/scalar" | ||
| ) | ||
|
|
||
| // Source: https://thestarman.pcministry.com/asm/mbr/PartTypes.htm | ||
| var partitionTypes scalar.UToDescription = scalar.UToDescription{ | ||
| 0x00: "empty", | ||
| 0x01: "12-bit FAT", | ||
| 0x02: "XENIX root", | ||
| 0x03: "XENIX /usr (obsolete)", | ||
| 0x04: "16-bit FAT", | ||
| 0x05: "Extended Partition", | ||
| 0x06: "16-bit FAT, partition", | ||
| 0x07: "Installable file systems: HPFS or NTFS. Also, QNX and Advanced Unix.", | ||
| 0x08: "AIX bootable partition", | ||
| 0x09: "AIX data partition", | ||
| 0x0A: "Coherent swap partition, OPUS or OS/2 Boot Manager.", | ||
| 0x0B: "32-bit FAT", | ||
| 0x0C: "32-bit FAT, using INT 13 Extensions.", | ||
| 0x0E: "16-bit FAT >= 32 MB, using INT 13 Extensions.", | ||
| 0x0F: "Extended Partition, using INT 13 Extensions", | ||
| 0x10: "OPUS", | ||
| 0x11: "Hidden 12-bit FAT.", | ||
| 0x12: "Compaq diagnostics.", | ||
| 0x14: "Hidden 16-bit FAT", | ||
| 0x16: "Hidden 16-bit FAT, partition >= 32 MB", | ||
| 0x17: "Hidden IFS (HPFS, NTFS).", | ||
| 0x18: "AST Windows swap file", | ||
| 0x19: "Willowtech Photon coS", | ||
| 0x1B: "Hidden 32-bit FAT", | ||
| 0x1C: "Hidden 32-bit FAT, Ext INT 13", | ||
| 0x1E: "Hidden 16-bit FAT >32 MB, Ext. INT 13 (PowerQuest specific)", | ||
| 0x20: "Willowsoft Overture File System (OFS1)", | ||
| 0x21: "reserved (HP Volume Expansion, SpeedStor variant)", | ||
| 0x22: "Oxygen Extended", | ||
| 0x23: "reserved (HP Volume Expansion, SpeedStor variant?)", | ||
| 0x24: "NEC MS-DOS 3.x", | ||
| 0x26: "reserved (HP Volume Expansion, SpeedStor variant?)", | ||
| 0x31: "reserved (HP Volume Expansion, SpeedStor variant?)", | ||
| 0x33: "reserved (HP Volume Expansion, SpeedStor variant?)", | ||
| 0x34: "reserved (HP Volume Expansion, SpeedStor variant?)", | ||
| 0x36: "reserved (HP Volume Expansion, SpeedStor variant?)", | ||
| 0x38: "Theos", | ||
| 0x3C: "PowerQuest Files Partition Format", | ||
| 0x3D: "Hidden NetWare", | ||
| 0x40: "VENIX 80286", | ||
| 0x41: "Personal RISC Boot, PowerPC boot partition", | ||
| 0x42: "Secure File System, Windows 2000/XP (NT 5)", | ||
| 0x43: "Alternative Linux native file system (EXT2fs) PTS-DOS 6.70 & BootWizard: DR-DOS", | ||
| 0x45: "Priam, EUMEL/Elan. ", | ||
| 0x46: "EUMEL/Elan", | ||
| 0x47: "EUMEL/Elan", | ||
| 0x48: "EUMEL/Elan", | ||
| 0x4A: "ALFS/THIN lightweight filesystem for DOS", | ||
| 0x4D: "QNX", | ||
| 0x4E: "QNX", | ||
| 0x4F: "QNX, Oberon boot/data partition.", | ||
| 0x50: "Ontrack Disk Manager, read-only partition, FAT partition (Logical sector size varies)", | ||
| 0x51: "Ontrack Disk Manager, read/write partition, FAT partition (Logical sector size varies) Novell?", | ||
| 0x52: "CP/M, Microport System V/386.", | ||
| 0x53: "Ontrack Disk Manager, write-only", | ||
| 0x54: "Ontrack Disk Manager 6.0 (DDO)", | ||
| 0x55: "EZ-Drive 3.05", | ||
| 0x56: "Golden Bow VFeature", | ||
| 0x5C: "Priam EDISK", | ||
| 0x61: "Storage Dimensions SpeedStor", | ||
| 0x63: "GNU HURD, Mach, MtXinu BSD 4.2 on Mach, Unix Sys V/386, 386/ix.", | ||
| 0x64: "Novell NetWare 286, SpeedStore.", | ||
| 0x65: "Novell NetWare (3.11 and 4.1)", | ||
| 0x66: "Novell NetWare 386", | ||
| 0x67: "Novell NetWare", | ||
| 0x68: "Novell NetWare", | ||
| 0x69: "Novell NetWare 5+", | ||
| 0x70: "DiskSecure Multi-Boot", | ||
| 0x75: "IBM PC/IX", | ||
| 0x80: "Minix v1.1 - 1.4a, Old MINIX (Linux).", | ||
| 0x81: "Linux/Minix v1.4b+, Mitac Advanced Disk Manager.", | ||
| 0x82: "Linux Swap partition, Prime or Solaris (Unix).", | ||
| 0x83: "Linux native file systems (ext2/3/4, JFS, Reiser, xiafs, and others).", | ||
| 0x84: "OS/2 hiding type 04h partition", | ||
| 0x86: "NT Stripe Set, Volume Set?", | ||
| 0x87: "NT Stripe Set, Volume Set?, HPFS FT mirrored partition.", | ||
| 0x93: "Amoeba file system, Hidden Linux EXT2 partition (PowerQuest).", | ||
| 0x94: "Amoeba bad block table", | ||
| 0x99: "Mylex EISA SCSI", | ||
| 0x9F: "BSDI", | ||
| 0xA0: "Phoenix NoteBios Power Management 'Save to Disk', IBM hibernation.", | ||
| 0xA1: "HP Volume Expansion (SpeedStor variant)", | ||
| 0xA3: "HP Volume Expansion (SpeedStor variant)", | ||
| 0xA4: "HP Volume Expansion (SpeedStor variant)", | ||
| 0xA5: "FreeBSD/386", | ||
| 0xA6: "OpenBSD", | ||
| 0xA7: "NextStep Partition", | ||
| 0xA9: "NetBSD", | ||
| 0xAA: "Olivetti DOS with FAT12", | ||
| 0xB0: "Bootmanager BootStar by Star-Tools GmbH", | ||
| 0xB1: "HP Volume Expansion (SpeedStor variant)", | ||
| 0xB3: "HP Volume Expansion (SpeedStor variant)", | ||
| 0xB4: "HP Volume Expansion (SpeedStor variant)", | ||
| 0xB6: "HP Volume Expansion (SpeedStor variant)", | ||
| 0xB7: "BSDI file system or secondarily swap", | ||
| 0xB8: "BSDI swap partition or secondarily file system", | ||
| 0xBB: "PTS BootWizard (hidden) 4.0", | ||
| 0xBC: "May be an Acronis 'Backup' or 'Secure Zone' partition, when labeled 'ACRONIS SZ' (FAT32, LBA mapped, primary).", | ||
| 0xBE: "Solaris boot partition", | ||
| 0xC0: "Novell DOS/OpenDOS/DR-OpenDOS/DR-DOS secured partition, or CTOS (reported by a client).", | ||
| 0xC1: "DR-DOS 6.0 LOGIN.EXE-secured 12-bit FAT partition", | ||
| 0xC2: "Reserved for DR-DOS 7+", | ||
| 0xC3: "Reserved for DR-DOS 7+", | ||
| 0xC4: "DR-DOS 6.0 LOGIN.EXE-secured 16-bit FAT partition", | ||
| 0xC6: "DR-DOS 6.0 LOGIN.EXE-secured Huge partition, or: Corrupted FAT16 volume/stripe (V/S) set (Windows NT).", | ||
| 0xC7: "Syrinx, Cyrnix, HPFS FT disabled mirrored partition, or: Corrupted NTFS volume/stripe set.", | ||
| 0xC8: "Reserved for DR-DOS 7+", | ||
| 0xC9: "Reserved for DR-DOS 7+", | ||
| 0xCA: "Reserved for DR-DOS 7+", | ||
| 0xCB: "Reserved for DR-DOS secured FAT32", | ||
| 0xCC: "Reserved for DR-DOS secured FAT32X (LBA)", | ||
| 0xCD: "Reserved for DR-DOS 7+", | ||
| 0xCE: "Reserved for DR-DOS secured FAT16X (LBA)", | ||
| 0xCF: "Reserved for DR-DOS secured Extended partition (LBA)", | ||
| 0xD0: "Multiuser DOS secured (FAT12???)", | ||
| 0xD1: "Old Multiuser DOS secured FAT12", | ||
| 0xD4: "Old Multiuser DOS secured FAT16 (<= 32M)", | ||
| 0xD5: "Old Multiuser DOS secured extended partition", | ||
| 0xD6: "Old Multiuser DOS secured FAT16 (BIGDOS > 32 Mb)", | ||
| 0xD8: "CP/M 86", | ||
| 0xDB: "CP/M, Concurrent CP/M, Concurrent DOS, or CTOS (Convergent Technologies OS).", | ||
| 0xDE: "Dell partition. Normally it contains a FAT16 file system of about 32 MB.", | ||
| 0xDF: "BootIt EMBRM", | ||
| 0xE1: "SpeedStor 12-bit FAT Extended partition, DOS access (Linux).", | ||
| 0xE2: "DOS read-only (Florian Painke's XFDISK 1.0.4)", | ||
| 0xE3: "SpeedStor (Norton, Linux says DOS R/O)", | ||
| 0xE4: "SpeedStor 16-bit FAT Extended partition", | ||
| 0xE5: "Tandy DOS with logical sectored FAT", | ||
| 0xE6: "Storage Dimensions SpeedStor", | ||
| 0xEB: "BeOS file system", | ||
| 0xED: "Reserved for Matthias Paul's Spryt*x", | ||
| 0xEE: "GPT Protective MBR followed by a GPT/EFI Header. Used to define a fake partition covering the entire disk.", | ||
| 0xEF: "EFI/UEFI System Partition (or ESP)", | ||
| 0xF1: "SpeedStor Dimensions (Norton,Landis)", | ||
| 0xF2: "DOS 3.3+ second partition, Unisys DOS with logical sectored FAT.", | ||
| 0xF3: "Storage Dimensions SpeedStor", | ||
| 0xF4: "SpeedStor Storage Dimensions (Norton,Landis)", | ||
| 0xF5: "Prologue", | ||
| 0xF6: "Storage Dimensions SpeedStor", | ||
| 0xFD: "Reserved for FreeDOS (http://www.freedos.org)", | ||
| 0xFE: "LANstep, IBM PS/2 IML (Initial Microcode Load) partition, or...", | ||
| 0xFF: "Xenix bad-block table", | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,41 @@ | ||
| # head -c 512 /dev/sda > mbr.bin | ||
| |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13|0123456789abcdef0123|.{}: format/mbr/testdata/mbr.bin (mbr) 0x0-0x1ff.7 (512) | ||
| 0x000|eb 63 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90|.c..................| code_area: raw bits 0x0-0x1bd.7 (446) | ||
| * |until 0x1bd.7 (446) | | | ||
| | | | partition_table{}: 0x1be-0x1fd.7 (64) | ||
| | | | entry_1{}: 0x1be-0x1cd.7 (16) | ||
| 0x1b8| 80 | . | boot_indicator: 128 (active) 0x1be-0x1be.7 (1) | ||
| 0x1b8| 02 01 00 | ... | starting_chs_vals: "CHS(0, 2, 1)" 0x1bf-0x1c1.7 (3) | ||
| 0x1b8| cd | . | partition_type: 205 (Reserved for DR-DOS 7+) 0x1c2-0x1c2.7 (1) | ||
| 0x1b8| 3f e0 ff | ?.. | ending_chs_vals: "CHS(ff, 3f, 20)" 0x1c3-0x1c5.7 (3) | ||
| 0x1b8| 40 00 00 | @.. | starting_sector: "CHS(0, 40, 0)" 0x1c6-0x1c8.7 (3) | ||
| 0x1b8| ec 26| .&| partition_size: 7939820 0x1ca-0x1cd.7 (4) | ||
| 0x1cc|79 00 |y. | | ||
| | | | entry_2{}: 0x1ce-0x1dd.7 (16) | ||
| 0x1cc| 00 | . | boot_indicator: 0 (inactive) 0x1ce-0x1ce.7 (1) | ||
| 0x1cc| 3f e0 ff | ?.. | starting_chs_vals: "CHS(ff, 3f, 20)" 0x1cf-0x1d1.7 (3) | ||
| 0x1cc| ef | . | partition_type: 239 (EFI/UEFI System Partition (or ESP)) 0x1d2-0x1d2.7 (1) | ||
| 0x1cc| 3f e0 ff | ?.. | ending_chs_vals: "CHS(ff, 3f, 20)" 0x1d3-0x1d5.7 (3) | ||
| 0x1cc| 2c 27 79 | ,'y | starting_sector: "CHS(79, 2c, 27)" 0x1d6-0x1d8.7 (3) | ||
| 0x1cc| 00 20 00 00 | . .. | partition_size: 8192 0x1da-0x1dd.7 (4) | ||
| | | | entry_3{}: 0x1de-0x1ed.7 (16) | ||
| 0x1cc| 00 | . | boot_indicator: 0 (inactive) 0x1de-0x1de.7 (1) | ||
| 0x1cc| 00| .| starting_chs_vals: "CHS(0, 0, 0)" 0x1df-0x1e1.7 (3) | ||
| 0x1e0|00 00 |.. | | ||
| 0x1e0| 00 | . | partition_type: 0 (empty) 0x1e2-0x1e2.7 (1) | ||
| 0x1e0| 00 00 00 | ... | ending_chs_vals: "CHS(0, 0, 0)" 0x1e3-0x1e5.7 (3) | ||
| 0x1e0| 00 00 00 | ... | starting_sector: "CHS(0, 0, 0)" 0x1e6-0x1e8.7 (3) | ||
| 0x1e0| 00 00 00 00 | .... | partition_size: 0 0x1ea-0x1ed.7 (4) | ||
| | | | entry_4{}: 0x1ee-0x1fd.7 (16) | ||
| 0x1e0| 00 | . | boot_indicator: 0 (inactive) 0x1ee-0x1ee.7 (1) | ||
| 0x1e0| 00 00 00 | ... | starting_chs_vals: "CHS(0, 0, 0)" 0x1ef-0x1f1.7 (3) | ||
| 0x1e0| 00 | . | partition_type: 0 (empty) 0x1f2-0x1f2.7 (1) | ||
| 0x1e0| 00| .| ending_chs_vals: "CHS(0, 0, 0)" 0x1f3-0x1f5.7 (3) | ||
| 0x1f4|00 00 |.. | | ||
| 0x1f4| 00 00 00 | ... | starting_sector: "CHS(0, 0, 0)" 0x1f6-0x1f8.7 (3) | ||
| 0x1f4| 00 00 00 00 | .... | partition_size: 0 0x1fa-0x1fd.7 (4) | ||
| 0x1b8| 00 | . | unknown0: raw bits 0x1c9-0x1c9.7 (1) | ||
| 0x1cc| 00 | . | unknown1: raw bits 0x1d9-0x1d9.7 (1) | ||
| 0x1e0| 00 | . | unknown2: raw bits 0x1e9-0x1e9.7 (1) | ||
| 0x1f4| 00 | . | unknown3: raw bits 0x1f9-0x1f9.7 (1) | ||
| 0x1f4| 55 aa| | U.| | boot_record_sig: 0xaa55 0x1fe-0x1ff.7 (2) |
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