From ae34659b26fd96c63cf0c390ddfee72ec6edfa32 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=AE=8B=E9=A1=B5?= <a1364259@163.com>
Date: Sat, 18 Feb 2023 07:00:14 +0800
Subject: [PATCH] No kernel repack if it isn't patched at all
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

It turns out that decompressing and recompressing the kernel is enough to break booting on many devices that use MT6763.
Fix #5124, fix #6204, fix #6566

Co-authored-by: LoveSy <shana@zju.edu.cn>
Co-authored-by: 南宫雪珊 <vvb2060@gmail.com>
---
 native/src/boot/bootimg.cpp |  3 +++
 scripts/boot_patch.sh       | 20 ++++++++++++++------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/native/src/boot/bootimg.cpp b/native/src/boot/bootimg.cpp
index 0faf119d2..5b84e23ed 100644
--- a/native/src/boot/bootimg.cpp
+++ b/native/src/boot/bootimg.cpp
@@ -601,6 +601,9 @@ void repack(const char *src_img, const char *out_img, bool skip_comp) {
             // zImage size shall remain the same
             hdr->kernel_size() = boot.hdr->kernel_size();
         }
+    } else if (boot.hdr->kernel_size() != 0) {
+        xwrite(fd, boot.kernel, boot.hdr->kernel_size());
+        hdr->kernel_size() = boot.hdr->kernel_size();
     }
     if (boot.flags[ZIMAGE_KERNEL]) {
         // Copy zImage tail and adjust size accordingly
diff --git a/scripts/boot_patch.sh b/scripts/boot_patch.sh
index 07e286f13..966a7c127 100644
--- a/scripts/boot_patch.sh
+++ b/scripts/boot_patch.sh
@@ -6,7 +6,7 @@
 # Usage: boot_patch.sh <bootimage>
 #
 # The following flags can be set in environment variables:
-# KEEPVERITY, KEEPFORCEENCRYPT, PATCHVBMETAFLAG, RECOVERYMODE
+# KEEPVERITY, KEEPFORCEENCRYPT, PATCHVBMETAFLAG, RECOVERYMODE, SYSTEM_ROOT
 #
 # This script should be placed in a directory with the following files:
 #
@@ -73,6 +73,7 @@ fi
 [ -z $KEEPFORCEENCRYPT ] && KEEPFORCEENCRYPT=false
 [ -z $PATCHVBMETAFLAG ] && PATCHVBMETAFLAG=false
 [ -z $RECOVERYMODE ] && RECOVERYMODE=false
+[ -z $SYSTEM_ROOT ] && SYSTEM_ROOT=false
 [ -z $ISENCRYPTED ] && ISENCRYPTED=false
 export KEEPVERITY
 export KEEPFORCEENCRYPT
@@ -203,21 +204,28 @@ for dt in dtb kernel_dtb extra; do
 done
 
 if [ -f kernel ]; then
+  PATCHEDKERNEL=false
   # Remove Samsung RKP
   ./magiskboot hexpatch kernel \
   49010054011440B93FA00F71E9000054010840B93FA00F7189000054001840B91FA00F7188010054 \
-  A1020054011440B93FA00F7140020054010840B93FA00F71E0010054001840B91FA00F7181010054
+  A1020054011440B93FA00F7140020054010840B93FA00F71E0010054001840B91FA00F7181010054 \
+  && PATCHEDKERNEL=true
 
   # Remove Samsung defex
   # Before: [mov w2, #-221]   (-__NR_execve)
   # After:  [mov w2, #-32768]
-  ./magiskboot hexpatch kernel 821B8012 E2FF8F12
+  ./magiskboot hexpatch kernel 821B8012 E2FF8F12 && PATCHEDKERNEL=true
 
-  # Force kernel to load rootfs
+  # Force kernel to load rootfs for legacy SAR devices
   # skip_initramfs -> want_initramfs
-  ./magiskboot hexpatch kernel \
+  $SYSTEM_ROOT && ./magiskboot hexpatch kernel \
   736B69705F696E697472616D667300 \
-  77616E745F696E697472616D667300
+  77616E745F696E697472616D667300 \
+  && PATCHEDKERNEL=true
+
+  # If the kernel doesn't need to be patched at all,
+  # keep raw kernel to avoid bootloops on some weird devices
+  $PATCHEDKERNEL || rm -f kernel
 fi
 
 #################