Recompute all patches on every new tagged version

Related discussion:
AdguardTeam/FiltersCompiler#192 (comment)

tools/make-diffpatch.sh

@@ -40,6 +40,7 @@ for FILE in "${FILES[@]}"; do
         sed -Ei "1,10s;^! Version: .+$;! Version: $VERSION;" $FILE
     fi
 
+    # Patches are for filter lists supporting differential updates
     if [[ -n $(grep '^! Diff-Path: ' <(head $FILE)) ]]; then
 
         # Extract patch name

tools/update-diffpatches.sh

@@ -0,0 +1,95 @@
+#!/usr/bin/env bash
+#
+# This script assumes a linux environment
+
+set -e
+
+# To be executed at the root of uAssetsCDN repo
+#
+# It's not being hosted at uAssetsCDN because that
+# repo is also used as a website
+
+
+# Keep only the most recent (7-day x 4-per-day) patches
+OBSOLETE_PATCHES=( $(ls -1v patches/*.patch | head -n -28) )
+for FILE in "${OBSOLETE_PATCHES[@]}"; do
+    echo "Removing obsolete patch $FILE"
+    git rm $FILE
+done
+
+
+# Revisit all patch files except the most recent one
+PATCH_FILES=( $(ls -1v patches/*.patch | head -n -1) )
+
+NEW_PATCH_FILE=$(mktemp)
+DIFF_FILE=$(mktemp)
+
+for PATCH_FILE in "${PATCH_FILES[@]}"; do
+
+    # Extract tag from patch file name
+    [[ ${PATCH_FILE} =~ ^patches/([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)\.patch$ ]] && \
+        PREVIOUS_VERSION=${BASH_REMATCH[1]}
+
+    # This will receive a clone of an old version of the current repo
+    echo "Fetching repo at $PREVIOUS_VERSION version"
+    OLD_REPO=$(mktemp -d)
+    git clone -q --single-branch --branch $PREVIOUS_VERSION --depth=1 https://github.com/uBlockOrigin/uAssetsCDN.git "$OLD_REPO" 2>/dev/null
+
+    > "$NEW_PATCH_FILE"
+
+    FILTER_LISTS=( $(ls -1 filters/*.min.txt) $(ls -1 thirdparties/*) )
+    for FILTER_LIST in "${FILTER_LISTS[@]}"; do
+
+        if [ ! -f $OLD_REPO/$FILTER_LIST ]; then continue; fi
+
+        # Patches are for filter lists supporting differential updates
+        if [[ -z $(grep '^! Diff-Path: ' <(head $OLD_REPO/$FILTER_LIST)) ]]; then
+            continue
+        fi
+
+        # Skip if the only changes are the Diff-Path and/or Version fields
+        if [[ -z $(diff -I '^! (Diff-Path|Version): ' $OLD_REPO/$FILTER_LIST $FILTER_LIST) ]]; then
+            continue
+        fi
+
+        # Reference:
+        # https://github.com/ameshkov/diffupdates
+
+        # Extract patch name
+        DIFF_NAME=$(grep -m 1 -oP '^! Diff-Name: \K.+' $OLD_REPO/$FILTER_LIST)
+
+        # We need a patch name to generate a valid patch
+        if [[ -z $DIFF_NAME ]]; then
+            echo "Info: $FILTER_LIST was missing a patch name, skipping"
+            continue
+        fi
+
+        # Compute the RCS diff between current version and new version
+        diff -n $OLD_REPO/$FILTER_LIST $FILTER_LIST > "$DIFF_FILE" || true
+
+        FILE_CHECKSUM=$(sha1sum $FILTER_LIST)
+        FILE_CHECKSUM=${FILE_CHECKSUM:0:10}
+
+        DIFF_LINE_COUNT=$(cat "$DIFF_FILE" | wc -l)
+
+        # Patch header
+        DIFF_HEAD="diff name:$DIFF_NAME lines:$DIFF_LINE_COUNT checksum:$FILE_CHECKSUM"
+        echo "\tAdding diff: $DIFF_HEAD"
+        echo "$DIFF_HEAD" >> "$NEW_PATCH_FILE"
+        # Patch data
+        cat "$DIFF_FILE" >> "$NEW_PATCH_FILE"
+
+    done
+
+    rm -rf "$OLD_REPO"
+
+    # Stage changed patch file
+    mv -f "$NEW_PATCH_FILE" "$PATCH_FILE"
+    ls -l "$PATCH_FILE"
+    echo "Info: Staging ${PATCH_FILE}"
+    git add -u $PATCH_FILE
+
+done
+
+rm -f "$DIFF_FILE"
+rm -f "$NEW_PATCH_FILE"