Fix https://github.com/uBlockOrigin/uBlock-issues/issues/461

uBO will fallback using a JSON string when trying to encode an array
buffer in Chromium version 59 and earlier.

src/js/hntrie.js

@@ -372,11 +372,13 @@ HNTrieContainer.prototype = {
     },
 
     unserialize: function(selfie, decoder) {
+        this.needle = '';
         const shouldDecode = typeof selfie === 'string';
         let byteLength = shouldDecode
             ? decoder.decodeSize(selfie)
             : selfie.length << 2;
         byteLength = byteLength + HNTRIE_PAGE_SIZE-1 & ~(HNTRIE_PAGE_SIZE-1);
+        if ( byteLength === 0 ) { return; }
         if ( this.wasmMemory !== null ) {
             const pageCountBefore = this.buf.length >>> 16;
             const pageCountAfter = byteLength >>> 16;
@@ -394,7 +396,6 @@ HNTrieContainer.prototype = {
         } else {
             this.buf32.set(selfie);
         }
-        this.needle = '';
     },
 
     //--------------------------------------------------------------------------

src/js/storage.js

@@ -935,17 +935,17 @@
 // https://github.com/AdguardTeam/AdguardBrowserExtension/issues/917
 
 µBlock.processDirectives = function(content) {
-    var reIf = /^!#(if|endif)\b([^\n]*)/gm,
-        parts = [],
-        beg = 0, depth = 0, discard = false;
+    const reIf = /^!#(if|endif)\b([^\n]*)/gm;
+    const parts = [];
+    let  beg = 0, depth = 0, discard = false;
     while ( beg < content.length ) {
-        var match = reIf.exec(content);
+        const match = reIf.exec(content);
         if ( match === null ) { break; }
         if ( match[1] === 'if' ) {
-            var expr = match[2].trim();
-            var target = expr.startsWith('!');
+            let expr = match[2].trim();
+            const target = expr.startsWith('!');
             if ( target ) { expr = expr.slice(1); }
-            var token = this.processDirectives.tokens.get(expr);
+            const token = this.processDirectives.tokens.get(expr);
             if (
                 depth === 0 &&
                 discard === false &&
@@ -1034,8 +1034,11 @@
         'compiled/' + this.pslAssetKey
     ).then(details =>
         publicSuffixList.fromSelfie(details.content, µBlock.base128)
-    ).then(valid => {
-        if ( valid === true ) { return; }
+    ).catch(reason => {
+        console.info(reason);
+        return false;
+    }).then(success => {
+        if ( success ) { return; }
         return this.assets.get(this.pslAssetKey, details => {
             if ( details.content !== '' ) {
                 this.compilePublicSuffixList(details.content);

src/js/utils.js

@@ -505,9 +505,22 @@
 //   Could expand the LZ4 codec API to be able to return UTF8-safe string
 //   representation of a compressed buffer, and thus the code below could be
 //   moved LZ4 codec-side.
+// https://github.com/uBlockOrigin/uBlock-issues/issues/461
+//   Provide a fallback encoding for Chromium 59 and less by issuing a plain
+//   JSON string. The fallback can be removed once min supported version is
+//   above 59.
 
 µBlock.base128 = {
     encode: function(arrbuf, arrlen) {
+        if (
+            vAPI.webextFlavor.soup.has('chromium') &&
+            vAPI.webextFlavor.major < 60
+        ) {
+            return this.encodeJSON(arrbuf);
+        }
+        return this.encodeBase128(arrbuf, arrlen);
+    },
+    encodeBase128: function(arrbuf, arrlen) {
         const inbuf = new Uint8Array(arrbuf, 0, arrlen);
         const inputLength = arrlen;
         let _7cnt = Math.floor(inputLength / 7);
@@ -556,6 +569,9 @@
         const textDecoder = new TextDecoder();
         return textDecoder.decode(outbuf);
     },
+    encodeJSON: function(arrbuf) {
+        return JSON.stringify(Array.from(new Uint32Array(arrbuf)));
+    },
     // TODO:
     //   Surprisingly, there does not seem to be any performance gain when
     //   first converting the input string into a Uint8Array through
@@ -568,6 +584,22 @@
     //   const inbuf = textEncoder.encode(instr);
     //   const inputLength = inbuf.byteLength;
     decode: function(instr, arrbuf) {
+        if ( instr.length === 0 ) { return; }
+        if ( instr.charCodeAt(0) === 0x5B /* '[' */ ) {
+            const outbuf = this.decodeJSON(instr, arrbuf);
+            if ( outbuf !== undefined ) {
+                return outbuf;
+            }
+        }
+        if (
+            vAPI.webextFlavor.soup.has('chromium') &&
+            vAPI.webextFlavor.major < 60
+        ) {
+            throw new Error('Unexpected µBlock.base128 encoding');
+        }
+        return this.decodeBase128(instr, arrbuf);
+    },
+    decodeBase128: function(instr, arrbuf) {
         const inputLength = instr.length;
         let _8cnt = inputLength >>> 3;
         let outputLength = _8cnt * 7;
@@ -599,7 +631,37 @@
         }
         return outbuf;
     },
+    decodeJSON: function(instr, arrbuf) {
+        let buf;
+        try {
+            buf = JSON.parse(instr);
+        } catch (ex) {
+        }
+        if ( Array.isArray(buf) === false ) { return; }
+        const outbuf = arrbuf instanceof ArrayBuffer === false
+            ? new Uint32Array(buf.length << 2)
+            : new Uint32Array(arrbuf);
+        outbuf.set(buf);
+        return new Uint8Array(outbuf.buffer);
+    },
     decodeSize: function(instr) {
+        if ( instr.length === 0 ) { return 0; }
+        if ( instr.charCodeAt(0) === 0x5B /* '[' */ ) {
+            let buf;
+            try {
+                buf = JSON.parse(instr);
+            } catch (ex) {
+            }
+            if ( Array.isArray(buf) ) {
+                return buf.length << 2;
+            }
+        }
+        if (
+            vAPI.webextFlavor.soup.has('chromium') &&
+            vAPI.webextFlavor.major < 60
+        ) {
+            throw new Error('Unexpected µBlock.base128 encoding');
+        }
         const size = (instr.length >>> 3) * 7;
         const rem = instr.length & 7;
         return rem === 0 ? size : size + rem - 1;

src/lib/publicsuffixlist/publicsuffixlist.js

@@ -500,6 +500,7 @@ const fromSelfie = function(selfie, decoder) {
         }
         const bufferStr = selfie.slice(pos + 1);
         byteLength = decoder.decodeSize(bufferStr);
+        if ( byteLength === 0 ) { return false; }
         allocateBuffers(byteLength);
         decoder.decode(bufferStr, pslBuffer8.buffer);
     } else if (