Support for Apple Partition Maps

[vmlemon]

It may be useful to support Apple's legacy Macintosh partition map format, so that we can access Mac OS Classic/Mac OS X disks, and potentially support booting on Apple machines, in the future.

Support on NetBSD, FreeBSD, A/UX, Mac OS X, Mac OS 9 (and older), Linux, ProDOS, and several other OSes exists, the format is well-documented, and TiVo DVRs, and HDD-based iPods also used the APM partitioning scheme.

A typical, small Mac OS 9 disk tends to contain the following partitions:

tyson@tyson-Lenovo-ideapad-120S-14IAP:~$ file MacOS9.img 
MacOS9.img: Apple Driver Map, blocksize 512, blockcount 4194303, devtype 0, devid 0, driver count 2, contains[@0x200]: Apple Partition Map, map block count 7, start block 1, block count 63, name Apple, type Apple_partition_map, contains[@0x400]: Apple Partition Map, map block count 7, start block 64, block count 54, name Macintosh, type Apple_Driver_ATA, processor 68000, boot arguments ptDR, valid, allocated, in use, has boot info, readable, writable, pic boot code, real driver, chain driver, contains[@0x600]: Apple Partition Map, map block count 7, start block 118, block count 74, name Macintosh, type Apple_Driver_ATA, processor 68000, boot arguments wiki, valid, allocated, in use, has boot info, readable, writable, pic boot code, real driver, chain driver, contains[@0x800]: Apple Partition Map, map block count 7, start block 192, block count 512, name Macintosh, type Apple_Driver_IOKit, contains[@0xA00]: Apple Partition Map, map block count 7, start block 704, block count 512, name Patch Partition, type Apple_Patches, contains[@0xC00]: Apple Partition Map, map block count 7, start block 1216, block count 4193078, name untitled, type Apple_HFS, valid, allocated, in use, has boot info, readable, writable, pic boot code, real driver, chain driver, mount at startup, contains[@0xE00]: Apple Partition Map, map block count 7, start block 4194294, block count 10, name Extra, type Apple_Free

tyson@tyson-Lenovo-ideapad-120S-14IAP:~$ sudo partx -l  MacOS9.img
# 1:         1-       63 (       63 sectors,      0 MB)
# 2:        64-      117 (       54 sectors,      0 MB)
# 3:       118-      191 (       74 sectors,      0 MB)
# 4:       192-      703 (      512 sectors,      0 MB)
# 5:       704-     1215 (      512 sectors,      0 MB)
# 6:      1216-  4194293 (  4193078 sectors,   2146 MB)
# 7:   4194294-  4194303 (       10 sectors,      0 MB)