From db8e6c8434f48c67dd57e95e539c72dc838fabe5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20K=C4=85dzio=C5=82ka?= <kuba@kadziolka.net>
Date: Wed, 15 Jan 2020 00:01:59 +0100
Subject: [PATCH] Initial commit

---
 LICENSE     | 13 +++++++++++++
 README.md   | 25 +++++++++++++++++++++++++
 mkfs.cursed | 13 +++++++++++++
 3 files changed, 51 insertions(+)
 create mode 100644 LICENSE
 create mode 100644 README.md
 create mode 100755 mkfs.cursed

diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..5c93f45
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,13 @@
+            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+                    Version 2, December 2004
+
+ Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
+
+ Everyone is permitted to copy and distribute verbatim or modified
+ copies of this license document, and changing it is allowed as long
+ as the name is changed.
+
+            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. You just DO WHAT THE FUCK YOU WANT TO.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..a1c9742
--- /dev/null
+++ b/README.md
@@ -0,0 +1,25 @@
+# cursedfs
+
+Make a disk image formatted with both ext2 and FAT, at once.
+
+```bash
+~/cursedfs% wget 'https://github.com/NieDzejkob/cursedfs/releases/download/v1.0/cursed.img'
+~/cursedfs% sudo mount -o loop -t ext2 cursed.img mountpoint/
+~/cursedfs% ls mountpoint/
+mkfs.cursed
+~/cursedfs% sudo umount mountpoint/
+~/cursedfs% sudo mount -o loop -t msdos cursed.img mountpoint/
+~/cursedfs% ls mountpoint/
+gudnuse.ogg
+```
+
+# Why?
+
+[I got nerd-sniped](https://twitter.com/Foone/status/1217162186130198529?s=20)
+
+# How?
+
+It turns out this is surprisingly simple to do: just create a FAT volume with a
+lot of reserved sectors and put the ext2 into the reserved sectors. This works
+because the filesystems choose different places to put their superblock: FAT
+uses the very first sector, while ext2 leaves the first kilobyte unused.
diff --git a/mkfs.cursed b/mkfs.cursed
new file mode 100755
index 0000000..bc0def7
--- /dev/null
+++ b/mkfs.cursed
@@ -0,0 +1,13 @@
+#!/bin/sh
+
+SIZE_EXT2=128 # sectors, max is 65535
+
+set -euxo pipefail
+EXT2_TMP="$(mktemp)"
+trap "rm $EXT2_TMP" EXIT
+
+truncate -s 4M cursed.img
+truncate -s "$((512*$SIZE_EXT2))" $EXT2_TMP
+mkfs.ext2 $EXT2_TMP
+mkfs.fat -R $SIZE_EXT2 cursed.img
+dd if=$EXT2_TMP of=cursed.img bs=512 skip=1 seek=1 conv=notrunc