From 84e433fbbe01a288f1a82e73c28ede1cdc30db00 Mon Sep 17 00:00:00 2001
From: guihkx <626206+guihkx@users.noreply.github.com>
Date: Mon, 26 Jun 2023 19:18:06 -0300
Subject: [PATCH] linux: ensure bytes are valid before patching

We use sed to replace original bytes by patched ones, but unfortunately
sed doesn't report any errors when this substitution fails.

Now, before actually running sed, we check if these bytes that are soon
to be replaced, actually exist in the driver file.
---
 patch-fbc.sh | 15 +++++++++++++++
 patch.sh     | 15 +++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/patch-fbc.sh b/patch-fbc.sh
index abf7c37..6c66118 100755
--- a/patch-fbc.sh
+++ b/patch-fbc.sh
@@ -381,6 +381,20 @@ patch_common () {
 
 }
 
+ensure_bytes_are_valid () {
+    driver_file="$driver_dir/$object.$driver_version"
+    original_bytes=$(awk -F / '$2 { print $2 }' <<< "$patch")
+    patched_bytes=$(awk -F / '$3 { print $3 }' <<< "$patch")
+    if LC_ALL=C grep -qaP "$original_bytes" "$driver_file"; then
+        return 0 # file is ready to be patched
+    fi
+    if LC_ALL=C grep -qaP "$patched_bytes" "$driver_file"; then
+        return 0 # file is likely patched already
+    fi
+    echo "Error: Could not find bytes '$original_bytes' to patch in '$driver_file'."
+    exit 1
+}
+
 rollback () {
     patch_common
     if [[ -f "$backup_path/$object.$driver_version$backup_suffix" ]]; then
@@ -395,6 +409,7 @@ rollback () {
 
 patch () {
     patch_common
+    ensure_bytes_are_valid
     if [[ -f "$backup_path/$object.$driver_version$backup_suffix" ]]; then
         bkp_hash="$(sha1sum "$backup_path/$object.$driver_version$backup_suffix" | cut -f1 -d\ )"
         drv_hash="$(sha1sum "$driver_dir/$object.$driver_version" | cut -f1 -d\ )"
diff --git a/patch.sh b/patch.sh
index fe70eec..18527a3 100755
--- a/patch.sh
+++ b/patch.sh
@@ -457,6 +457,20 @@ patch_common () {
 
 }
 
+ensure_bytes_are_valid () {
+    driver_file="$driver_dir/$object.$driver_version"
+    original_bytes=$(awk -F / '$2 { print $2 }' <<< "$patch")
+    patched_bytes=$(awk -F / '$3 { print $3 }' <<< "$patch")
+    if LC_ALL=C grep -qaP "$original_bytes" "$driver_file"; then
+        return 0 # file is ready to be patched
+    fi
+    if LC_ALL=C grep -qaP "$patched_bytes" "$driver_file"; then
+        return 0 # file is likely patched already
+    fi
+    echo "Error: Could not find bytes '$original_bytes' to patch in '$driver_file'."
+    exit 1
+}
+
 rollback () {
     patch_common
     if [[ -f "$backup_path/$object.$driver_version$backup_suffix" ]]; then
@@ -471,6 +485,7 @@ rollback () {
 
 patch () {
     patch_common
+    ensure_bytes_are_valid
     if [[ -f "$backup_path/$object.$driver_version$backup_suffix" ]]; then
         bkp_hash="$(sha1sum "$backup_path/$object.$driver_version$backup_suffix" | cut -f1 -d\ )"
         drv_hash="$(sha1sum "$driver_dir/$object.$driver_version" | cut -f1 -d\ )"