edifa

Erlang Disk and Image File Abstraction Library

Library to create system images without root privilege on both Linux and MacOS.

Build

$ rebar3 compile

Runtime Dependencies

MacOS

Commands that must be available:

• rm
• mv
• mkdir
• dd
• mktemp
• gzip
• hdiutil
• fdisk
• diskutil
• newfs_msdos

Linux

Commands that must be available:

• rm
• mv
• mkdir
• dd
• mktemp
• gzip
• id
• sfdisk
• fusefat
• fusermount
• mkfs.vfat

Install dependencies:

sudo apt-get install coreutils fdisk fusefat dosfstools gzip

Usage

Create an image file (64 MiB):

{ok, Img} = edifa:create("test.img", 64 * 1024 * 1024).

Write some bootloader (2 MiB):

ok = edifa:write(Img, "bootloader.bin", #{count => 2 * 1024 * 1024}).

Create partitions:

{ok, P1, P2} = edifa:partition(Img, mbr, [
    #{type => fat32, size => 31 * 1024 * 1024, start => 2 * 1024 * 1024},
    #{type => fat32, size => 31 * 1024 * 1024}
]).

Format partition 1:

ok = edifa:format(Img, P1, fat, #{label => "foobar"}).

Mount partition 1:

{ok, MountPoint} = edifa:mount(Img, P1).

Create some files in partition 1 filesystem:

ok = file:write_file(filename:join(MountPoint, "test.txt"), <<"some data\n">>).

Unmount partition 1:

ok = edifa:unmount(Img, P1).

Extract partition 1 into its own file:

ok = edifa:extract(Img, P1, "system.fs").

Generate a tuncated disk image containing the reserved space before the first partition with the bootloader and the partition definition, and partition 1:

ok = edifa:extract(Img, reserved, P1, "disk.img").

Extract into a gziped file:

Close the image:

ok = edifa:close(Img).

ok = edifa:extract(Img, P2, P2, "system.fs.gz").

Limitations

• All partitions involved must be unmounted before extracting data.
• Only support MBR partition tables for now.
• Active/Bootable partition flag is not supported yet.
• Only support FAT filesystem for now.