Add MBR format

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

.gitignore

@@ -1,3 +1,4 @@
 .DS_Store
 testfiles/
 fq
+*.swp

README.md

@@ -86,6 +86,7 @@ jpeg,
 json,
 [macho](doc/formats.md#macho),
 [matroska](doc/formats.md#matroska),
+mbr,
 mp3,
 mp3_frame,
 [mp4](doc/formats.md#mp4),

doc/dev.md

@@ -5,7 +5,7 @@
 - Create a directory  `format/<name>`
 - Copy some similar decoder, `format/format/bson.go` is quite small, to `format/<name>/<name>.go`
 - Cleanup and fill in the register struct, rename `format.BSON` and add it
-to `format/fromat.go` and don't forget to change the string constant.
+to `format/format.go` and don't forget to change the string constant.
 - Add an import to `format/all/all.go`
 
 ### Some general tips

doc/formats.md

@@ -56,6 +56,7 @@
 |`json`                  |JSON                                                                            |<sub></sub>|
 |[`macho`](#macho)       |Mach-O&nbsp;macOS&nbsp;executable                                               |<sub></sub>|
 |[`matroska`](#matroska) |Matroska&nbsp;file                                                              |<sub>`aac_frame` `av1_ccr` `av1_frame` `avc_au` `avc_dcr` `flac_frame` `flac_metadatablocks` `hevc_au` `hevc_dcr` `image` `mp3_frame` `mpeg_asc` `mpeg_pes_packet` `mpeg_spu` `opus_packet` `vorbis_packet` `vp8_frame` `vp9_cfm` `vp9_frame`</sub>|
+|`mbr`                   |Master&nbsp;Boot&nbsp;Record
 |`mp3`                   |MP3&nbsp;file                                                                   |<sub>`id3v2` `id3v1` `id3v11` `apev2` `mp3_frame`</sub>|
 |`mp3_frame`             |MPEG&nbsp;audio&nbsp;layer&nbsp;3&nbsp;frame                                    |<sub>`xing`</sub>|
 |[`mp4`](#mp4)           |MPEG-4&nbsp;file&nbsp;and&nbsp;similar                                          |<sub>`aac_frame` `av1_ccr` `av1_frame` `flac_frame` `flac_metadatablocks` `id3v2` `image` `jpeg` `mp3_frame` `avc_au` `avc_dcr` `mpeg_es` `hevc_au` `hevc_dcr` `mpeg_pes_packet` `opus_packet` `protobuf_widevine` `pssh_playready` `vorbis_packet` `vp9_frame` `vpx_ccr` `icc_profile`</sub>|

format/all/all.go

@@ -24,6 +24,7 @@ import (
 	_ "github.com/wader/fq/format/json"
 	_ "github.com/wader/fq/format/macho"
 	_ "github.com/wader/fq/format/matroska"
+	_ "github.com/wader/fq/format/mbr"
 	_ "github.com/wader/fq/format/mp3"
 	_ "github.com/wader/fq/format/mp4"
 	_ "github.com/wader/fq/format/mpeg"

format/format.go

@@ -63,6 +63,7 @@ const (
 	JSON                = "json"
 	MACHO               = "macho"
 	MATROSKA            = "matroska"
+	MBR                 = "mbr"
 	MP3                 = "mp3"
 	MP3_FRAME           = "mp3_frame"
 	MP4                 = "mp4"

format/mbr/mbr.go

@@ -0,0 +1,22 @@
+package mbr
+
+import (
+	"github.com/wader/fq/format"
+	"github.com/wader/fq/format/registry"
+	"github.com/wader/fq/pkg/decode"
+)
+
+func init() {
+	registry.MustRegister(decode.Format{
+		Name:        format.MBR,
+		Description: "Master Boot Record",
+		DecodeFn:    mbrDecode,
+	})
+}
+
+func mbrDecode(d *decode.D, in interface{}) interface{} {
+	d.FieldRawLen("code_area", 446*8)
+	d.FieldRawLen("partition_table", 64*8)
+	d.FieldRawLen("boot_record_sig", 2*8)
+	return nil
+}

format/mbr/testdata/mbr.fqtest

@@ -0,0 +1,9 @@
+# head -c 512 /dev/sda > mbr.bin
+$ fq . -d mbr mbr.bin
+     |00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f|0123456789abcdef|.{}: mbr.bin (mbr)
+0x000|fa bc 00 7c 31 c0 8e d0 8e c0 8e d8 52 be 00 7c|...|1.......R..||  code_area: raw bits
+*    |until 0x1bd.7 (446)                            |                |
+0x1b0|                                          00 00|              ..|  partition_table: raw bits
+0x1c0|00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00|................|
+*    |until 0x1fd.7 (64)                             |                |
+0x1f0|                                          55 aa|              U.|  boot_record_sig: raw bits

fq.go

@@ -6,7 +6,7 @@ import (
 	"github.com/wader/fq/pkg/cli"
 )
 
-const version = "0.0.6"
+const version = "0.0.7"
 
 func main() {
 	cli.Main(registry.Default, version)

pkg/interp/testdata/args.fqtest

@@ -145,6 +145,7 @@ jpeg                 Joint Photographic Experts Group file
 json                 JSON
 macho                Mach-O macOS executable
 matroska             Matroska file
+mbr                  Master Boot Record
 mp3                  MP3 file
 mp3_frame            MPEG audio layer 3 frame
 mp4                  MPEG-4 file and similar