From 01d24ef22778337ed04cf9d6444b1be57b6a1e1a Mon Sep 17 00:00:00 2001
From: Stefan Becker <stefanb2@users.noreply.github.com>
Date: Tue, 9 May 2023 16:24:49 +0300
Subject: [PATCH 1/2] Skip binfmt_misc register when unnecessary (#693)

This improves commit 6dc45a80e764eacd6e311c32164b623bbe7f8e08

Check if interpreter is already registered before running the register
step. This avoids unnecessary "sudo" execution which may require user
interaction for the password.

Improves on #685
---
 build-docker.sh | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/build-docker.sh b/build-docker.sh
index 7d0b5ad..4fdd89c 100755
--- a/build-docker.sh
+++ b/build-docker.sh
@@ -132,13 +132,15 @@ if [[ "${binfmt_misc_required}" == "1" ]]; then
     fi
     echo "binfmt_misc mounted"
   fi
-  # Register qemu-arm for binfmt_misc (binfmt_misc won't care duplicate entries unless they have common names)
-  reg="echo ':qemu-arm-rpi:M::"\
+  if ! grep -q "^interpreter ${qemu_arm}" /proc/sys/fs/binfmt_misc/qemu-arm* ; then
+    # Register qemu-arm for binfmt_misc
+    reg="echo ':qemu-arm-rpi:M::"\
 "\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00:"\
 "\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:"\
-"$qemu_arm:F' > /proc/sys/fs/binfmt_misc/register"
-  echo "Registering qemu-arm for binfmt_misc..."
-  sudo bash -c "$reg" 2>/dev/null || true
+"${qemu_arm}:F' > /proc/sys/fs/binfmt_misc/register"
+    echo "Registering qemu-arm for binfmt_misc..."
+    sudo bash -c "${reg}" 2>/dev/null || true
+  fi
 fi
 
 trap 'echo "got CTRL+C... please wait 5s" && ${DOCKER} stop -t 5 ${DOCKER_CMDLINE_NAME}' SIGINT SIGTERM

From 446f3e34c8ceb33dfe7bd38578f1cd6b6afe19da Mon Sep 17 00:00:00 2001
From: bamartin125 <bamartin125@gmail.com>
Date: Thu, 17 Aug 2023 10:24:47 -0500
Subject: [PATCH 2/2] Adds call to mknod if loop dev does not exist after call
 to `losetup -f` (#483)

---
 export-image/prerun.sh | 2 +-
 export-noobs/prerun.sh | 2 +-
 scripts/common         | 8 ++++++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/export-image/prerun.sh b/export-image/prerun.sh
index 2d8e1bb..267bbe0 100755
--- a/export-image/prerun.sh
+++ b/export-image/prerun.sh
@@ -35,7 +35,7 @@ if [ "${NO_PRERUN_QCOW2}" = "0" ]; then
 
 	echo "Creating loop device..."
 	cnt=0
-	until LOOP_DEV="$(losetup --show --find --partscan "$IMG_FILE")"; do
+	until ensure_next_loopdev && LOOP_DEV="$(losetup --show --find --partscan "$IMG_FILE")"; do
 		if [ $cnt -lt 5 ]; then
 			cnt=$((cnt + 1))
 			echo "Error in losetup.  Retrying..."
diff --git a/export-noobs/prerun.sh b/export-noobs/prerun.sh
index 3858c66..6282836 100755
--- a/export-noobs/prerun.sh
+++ b/export-noobs/prerun.sh
@@ -11,7 +11,7 @@ rm -rf "${NOOBS_DIR}"
 
 echo "Creating loop device..."
 cnt=0
-until LOOP_DEV="$(losetup --show --find --partscan "$IMG_FILE")"; do
+until ensure_next_loopdev && LOOP_DEV="$(losetup --show --find --partscan "$IMG_FILE")"; do
 	if [ $cnt -lt 5 ]; then
 		cnt=$((cnt + 1))
 		echo "Error in losetup.  Retrying..."
diff --git a/scripts/common b/scripts/common
index 5731b72..c94b0f0 100644
--- a/scripts/common
+++ b/scripts/common
@@ -102,3 +102,11 @@ update_issue() {
 	echo -e "Raspberry Pi reference ${IMG_DATE}\nGenerated using ${PI_GEN}, ${PI_GEN_REPO}, ${GIT_HASH}, ${1}" > "${ROOTFS_DIR}/etc/rpi-issue"
 }
 export -f update_issue
+
+ensure_next_loopdev() {
+	local loopdev
+	loopdev="$(losetup -f)"
+	loopmaj="$(echo "$loopdev" | sed -E 's/.*[^0-9]*?([0-9]+)$/\1/')"
+	[[ -b "$loopdev" ]] || mknod "$loopdev" b 7 "$loopmaj"
+}
+export -f ensure_next_loopdev