From a3f8e49a0dc6d613a93bde9ed9173c2760e8599d Mon Sep 17 00:00:00 2001
From: NiLuJe <ninuje@gmail.com>
Date: Sun, 17 Feb 2019 22:57:05 +0100
Subject: [PATCH] Use a temporary copy of our tar binary during OTA updating,
 to avoid the potential for a SIGBUS error...

Fix #4602
---
 platform/kindle/koreader.sh | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/platform/kindle/koreader.sh b/platform/kindle/koreader.sh
index 50d2a86b0..b45a144ad 100755
--- a/platform/kindle/koreader.sh
+++ b/platform/kindle/koreader.sh
@@ -107,9 +107,14 @@ ko_update_check() {
         FILESIZE="$(stat -c %b "${NEWUPDATE}")"
         BLOCKS="$((FILESIZE / 20))"
         export CPOINTS="$((BLOCKS / 100))"
+        # NOTE: To avoid blowing up when tar truncates itself during an update, copy our GNU tar binary to the system's tmpfs,
+        #       and run that one (c.f., #4602)...
+        cp -pf ./tar /var/tmp/gnutar
         # shellcheck disable=SC2016
-        ./tar --no-same-permissions --no-same-owner --checkpoint="${CPOINTS}" --checkpoint-action=exec='./fbink -q -y -6 -P $(($TAR_CHECKPOINT/$CPOINTS))' -C "/mnt/us" -xf "${NEWUPDATE}"
+        /var/tmp/gnutar --no-same-permissions --no-same-owner --checkpoint="${CPOINTS}" --checkpoint-action=exec='./fbink -q -y -6 -P $(($TAR_CHECKPOINT/$CPOINTS))' -C "/mnt/us" -xf "${NEWUPDATE}"
         fail=$?
+        # And remove our temporary tar binary...
+        rm -f /var/tmp/gnutar
         # Cleanup behind us...
         if [ "${fail}" -eq 0 ]; then
             mv "${NEWUPDATE}" "${INSTALLED}"