jpouellet · March 31, 2017 22:51 · Mar 31, 2017
diff --git a/jpo.WriteUSB b/jpo.WriteUSB
@@ -0,0 +1,23 @@
+#!/bin/bash
+
+if [ $# -eq 0 ]; then
+	dev=/dev/sda
+else
+	# Protected by arg-specific qubes-rpc policy.
+	dev=/dev/"$1"
+fi
+
+if ! [ -b "$dev" ]; then
+	echo "${0##*/}: $dev: No such block device" >&2
+	exit 1
+fi
+
+# Keep track of exactly how much we wrote to know where to stop reading later.
+len=$(sudo tee -- "$dev" | wc -c)
+echo "${0##*/}: Done writing $len bytes to $dev. Verifying..." >&2
+
+# Read it back from actual media, only once, passing it to all checksums.
+# Wait for all hashes to be done, and guarantee consistent ordering.
+sudo head -c "$len" -- "$dev" | (
+  tee >(sha1sum --tag) >(sha256sum --tag) > >(sha512sum --tag)
+) | sort