Merge pull request #19692 from Snuffleupagus/writer-improve

Improve the implementation in `src/core/writer.js` a little bit

src/core/writer.js

@@ -168,28 +168,30 @@ function writeInt(number, size, offset, buffer) {
 }
 
 function writeString(string, offset, buffer) {
-  for (let i = 0, len = string.length; i < len; i++) {
+  const ii = string.length;
+  for (let i = 0; i < ii; i++) {
     buffer[offset + i] = string.charCodeAt(i) & 0xff;
   }
+  return offset + ii;
 }
 
 function computeMD5(filesize, xrefInfo) {
   const time = Math.floor(Date.now() / 1000);
   const filename = xrefInfo.filename || "";
-  const md5Buffer = [time.toString(), filename, filesize.toString()];
-  let md5BufferLen = md5Buffer.reduce((a, str) => a + str.length, 0);
-  for (const value of Object.values(xrefInfo.info)) {
-    md5Buffer.push(value);
-    md5BufferLen += value.length;
-  }
+  const md5Buffer = [
+    time.toString(),
+    filename,
+    filesize.toString(),
+    ...Object.values(xrefInfo.info),
+  ];
+  const md5BufferLen = md5Buffer.reduce((a, str) => a + str.length, 0);
 
   const array = new Uint8Array(md5BufferLen);
   let offset = 0;
   for (const str of md5Buffer) {
-    writeString(str, offset, array);
-    offset += str.length;
+    offset = writeString(str, offset, array);
   }
-  return bytesToString(calculateMD5(array));
+  return bytesToString(calculateMD5(array, 0, array.length));
 }
 
 function writeXFADataForAcroform(str, changes) {
@@ -477,8 +479,7 @@ async function incrementalUpdate({
 
   // New data
   for (const str of buffer) {
-    writeString(str, offset, array);
-    offset += str.length;
+    offset = writeString(str, offset, array);
   }
 
   return array;

test/unit/writer_spec.js

@@ -19,6 +19,15 @@ import { bytesToString } from "../../src/shared/util.js";
 import { StringStream } from "../../src/core/stream.js";
 
 describe("Writer", function () {
+  beforeAll(function () {
+    jasmine.clock().install();
+    jasmine.clock().mockDate(new Date(0));
+  });
+
+  afterAll(function () {
+    jasmine.clock().uninstall();
+  });
+
   describe("Incremental update", function () {
     it("should update a file with new objects", async function () {
       const originalData = new Uint8Array();
@@ -50,7 +59,7 @@ describe("Writer", function () {
         "defg\n" +
         "789 0 obj\n" +
         "<< /Prev 314 /Size 790 /Type /XRef /Index [123 1 456 1 789 1] " +
-        "/W [1 1 1] /ID [(id) (\x01#Eg\x89\xab\xcd\xef\xfe\xdc\xba\x98vT2\x10)] " +
+        "/W [1 1 1] /ID [(id) (\xeb\x4b\x2a\xe7\x31\x36\xf0\xcd\x83\x35\x94\x2a\x36\xcf\xaa\xb0)] " +
         "/Length 9>> stream\n" +
         "\x01\x01\x2d" +
         "\x01\x05\x4e" +
@@ -83,7 +92,7 @@ describe("Writer", function () {
         "0000000010 00000 n\r\n" +
         "trailer\n" +
         "<< /Prev 314 /Size 789 " +
-        "/ID [(id) (\x01#Eg\x89\xab\xcd\xef\xfe\xdc\xba\x98vT2\x10)]>>\n" +
+        "/ID [(id) (\xeb\x4b\x2a\xe7\x31\x36\xf0\xcd\x83\x35\x94\x2a\x36\xcf\xaa\xb0)]>>\n" +
         "startxref\n" +
         "10\n" +
         "%%EOF\n";
@@ -279,7 +288,7 @@ describe("Writer", function () {
       "\nabc\n" +
       "789 0 obj\n" +
       "<< /Prev 314 /Size 790 /Type /XRef /Index [123 1 456 1 789 1] " +
-      "/W [1 1 1] /ID [(id) (\x01#Eg\x89\xab\xcd\xef\xfe\xdc\xba\x98vT2\x10)] " +
+      "/W [1 1 1] /ID [(id) (\x5f\xd1\x43\x8e\xf8\x62\x79\x80\xbb\xd6\xf7\xb6\xd2\xb5\x6f\xd8)] " +
       "/Length 9>> stream\n" +
       "\x00\x00\x2e" +
       "\x01\x01\x4e" +
@@ -311,7 +320,7 @@ describe("Writer", function () {
       "0000000005 00000 n\r\n" +
       "trailer\n" +
       "<< /Prev 314 /Size 789 " +
-      "/ID [(id) (\x01#Eg\x89\xab\xcd\xef\xfe\xdc\xba\x98vT2\x10)]>>\n" +
+      "/ID [(id) (\x5f\xd1\x43\x8e\xf8\x62\x79\x80\xbb\xd6\xf7\xb6\xd2\xb5\x6f\xd8)]>>\n" +
       "startxref\n" +
       "5\n" +
       "%%EOF\n";