Save form data in XFA datasets when pdf is a mix of acroforms and xfa (#12344)

* Move display/xml_parser.js in shared to use it in worker

* Save form data in XFA datasets when pdf is a mix of acroforms and xfa

Co-authored-by: Brendan Dahl <brendan.dahl@gmail.com>

src/core/annotation.js

@@ -1073,6 +1073,7 @@ class WidgetAnnotation extends Annotation {
       return null;
     }
 
+    const value = annotationStorage[this.data.id];
     const bbox = [
       0,
       0,
@@ -1080,11 +1081,15 @@ class WidgetAnnotation extends Annotation {
       this.data.rect[3] - this.data.rect[1],
     ];
 
+    const xfa = {
+      path: stringToPDFString(dict.get("T") || ""),
+      value,
+    };
+
     const newRef = evaluator.xref.getNewRef();
     const AP = new Dict(evaluator.xref);
     AP.set("N", newRef);
 
-    const value = annotationStorage[this.data.id];
     const encrypt = evaluator.xref.encrypt;
     let originalTransform = null;
     let newTransform = null;
@@ -1120,9 +1125,9 @@ class WidgetAnnotation extends Annotation {
     return [
       // data for the original object
       // V field changed + reference for new AP
-      { ref: this.ref, data: bufferOriginal.join("") },
+      { ref: this.ref, data: bufferOriginal.join(""), xfa },
       // data for the new AP
-      { ref: newRef, data: bufferNew.join("") },
+      { ref: newRef, data: bufferNew.join(""), xfa: null },
     ];
   }
 
@@ -1521,6 +1526,11 @@ class ButtonWidgetAnnotation extends WidgetAnnotation {
       return null;
     }
 
+    const xfa = {
+      path: stringToPDFString(dict.get("T") || ""),
+      value: value ? this.data.exportValue : "",
+    };
+
     const name = Name.get(value ? this.data.exportValue : "Off");
     dict.set("V", name);
     dict.set("AS", name);
@@ -1539,7 +1549,7 @@ class ButtonWidgetAnnotation extends WidgetAnnotation {
     writeDict(dict, buffer, originalTransform);
     buffer.push("\nendobj\n");
 
-    return [{ ref: this.ref, data: buffer.join("") }];
+    return [{ ref: this.ref, data: buffer.join(""), xfa }];
   }
 
   async _saveRadioButton(evaluator, task, annotationStorage) {
@@ -1555,6 +1565,11 @@ class ButtonWidgetAnnotation extends WidgetAnnotation {
       return null;
     }
 
+    const xfa = {
+      path: stringToPDFString(dict.get("T") || ""),
+      value: value ? this.data.buttonValue : "",
+    };
+
     const name = Name.get(value ? this.data.buttonValue : "Off");
     let parentBuffer = null;
     const encrypt = evaluator.xref.encrypt;
@@ -1593,9 +1608,13 @@ class ButtonWidgetAnnotation extends WidgetAnnotation {
     writeDict(dict, buffer, originalTransform);
     buffer.push("\nendobj\n");
 
-    const newRefs = [{ ref: this.ref, data: buffer.join("") }];
+    const newRefs = [{ ref: this.ref, data: buffer.join(""), xfa }];
     if (parentBuffer !== null) {
-      newRefs.push({ ref: this.parent, data: parentBuffer.join("") });
+      newRefs.push({
+        ref: this.parent,
+        data: parentBuffer.join(""),
+        xfa: null,
+      });
     }
 
     return newRefs;

src/core/worker.js

@@ -32,7 +32,7 @@ import {
   VerbosityLevel,
   warn,
 } from "../shared/util.js";
-import { clearPrimitiveCaches, Ref } from "./primitives.js";
+import { clearPrimitiveCaches, Dict, isDict, Ref } from "./primitives.js";
 import { LocalPdfManager, NetworkPdfManager } from "./pdf_manager.js";
 import { incrementalUpdate } from "./writer.js";
 import { isNodeJS } from "../shared/is_node.js";
@@ -521,7 +521,10 @@ class WorkerMessageHandler {
       filename,
     }) {
       pdfManager.requestLoadedStream();
-      const promises = [pdfManager.onLoadedStream()];
+      const promises = [
+        pdfManager.onLoadedStream(),
+        pdfManager.ensureCatalog("acroForm"),
+      ];
       const document = pdfManager.pdfDocument;
       for (let pageIndex = 0; pageIndex < numPages; pageIndex++) {
         promises.push(
@@ -532,7 +535,7 @@ class WorkerMessageHandler {
         );
       }
 
-      return Promise.all(promises).then(([stream, ...refs]) => {
+      return Promise.all(promises).then(([stream, acroForm, ...refs]) => {
         let newRefs = [];
         for (const ref of refs) {
           newRefs = ref
@@ -545,6 +548,20 @@ class WorkerMessageHandler {
           return stream.bytes;
         }
 
+        acroForm = isDict(acroForm) ? acroForm : Dict.empty;
+        const xfa = acroForm.get("XFA") || [];
+        let xfaDatasets = null;
+        if (Array.isArray(xfa)) {
+          for (let i = 0, ii = xfa.length; i < ii; i += 2) {
+            if (xfa[i] === "datasets") {
+              xfaDatasets = xfa[i + 1];
+            }
+          }
+        } else {
+          // TODO: Support XFA streams.
+          warn("Unsupported XFA type.");
+        }
+
         const xref = document.xref;
         let newXrefInfo = Object.create(null);
         if (xref.trailer) {
@@ -572,7 +589,13 @@ class WorkerMessageHandler {
         }
         xref.resetNewRef();
 
-        return incrementalUpdate(stream.bytes, newXrefInfo, newRefs);
+        return incrementalUpdate(
+          stream.bytes,
+          newXrefInfo,
+          newRefs,
+          xref,
+          xfaDatasets
+        );
       });
     });
 

src/core/writer.js

@@ -14,8 +14,14 @@
  */
 /* eslint no-var: error */
 
-import { bytesToString, escapeString } from "../shared/util.js";
+import {
+  bytesToString,
+  escapeString,
+  parseXFAPath,
+  warn,
+} from "../shared/util.js";
 import { Dict, isDict, isName, isRef, isStream, Name } from "./primitives.js";
+import { SimpleDOMNode, SimpleXMLParser } from "../shared/xml_parser.js";
 import { calculateMD5 } from "./crypto.js";
 
 function writeDict(dict, buffer, transform) {
@@ -123,7 +129,55 @@ function computeMD5(filesize, xrefInfo) {
   return bytesToString(calculateMD5(array));
 }
 
-function incrementalUpdate(originalData, xrefInfo, newRefs) {
+function updateXFA(datasetsRef, newRefs, xref) {
+  if (datasetsRef === null || xref === null) {
+    return;
+  }
+  const datasets = xref.fetchIfRef(datasetsRef);
+  const str = bytesToString(datasets.getBytes());
+  const xml = new SimpleXMLParser(/* hasAttributes */ true).parseFromString(
+    str
+  );
+
+  for (const { xfa } of newRefs) {
+    if (!xfa) {
+      continue;
+    }
+    const { path, value } = xfa;
+    if (!path) {
+      continue;
+    }
+    const node = xml.documentElement.searchNode(parseXFAPath(path), 0);
+    if (node) {
+      node.childNodes = [new SimpleDOMNode("#text", value)];
+    } else {
+      warn(`Node not found for path: ${path}`);
+    }
+  }
+  const buffer = [];
+  xml.documentElement.dump(buffer);
+  let updatedXml = buffer.join("");
+
+  const encrypt = xref.encrypt;
+  if (encrypt) {
+    const transform = encrypt.createCipherTransform(
+      datasetsRef.num,
+      datasetsRef.gen
+    );
+    updatedXml = transform.encryptString(updatedXml);
+  }
+  const data =
+    `${datasetsRef.num} ${datasetsRef.gen} obj\n` +
+    `<< /Type /EmbeddedFile /Length ${updatedXml.length}>>\nstream\n` +
+    updatedXml +
+    "\nendstream\nendobj\n";
+
+  newRefs.push({ ref: datasetsRef, data });
+}
+
+function incrementalUpdate(originalData, xrefInfo, newRefs, xref, datasetsRef) {
+  updateXFA(datasetsRef, newRefs, xref);
+
   const newXref = new Dict(null);
   const refForXrefTable = xrefInfo.newRef;
 

src/display/metadata.js

@@ -14,7 +14,7 @@
  */
 
 import { assert } from "../shared/util.js";
-import { SimpleXMLParser } from "./xml_parser.js";
+import { SimpleXMLParser } from "../shared/xml_parser.js";
 
 class Metadata {
   constructor(data) {

src/shared/util.js

@@ -910,6 +910,73 @@ const createObjectURL = (function createObjectURLClosure() {
   };
 })();
 
+/**
+ * AcroForm field names use an array like notation to refer to
+ * repeated XFA elements e.g. foo.bar[nnn].
+ * see: XFA Spec Chapter 3 - Repeated Elements
+ *
+ * @param {string} path - XFA path name.
+ * @returns {Array} - Array of Objects with the name and pos of
+ * each part of the path.
+ */
+function parseXFAPath(path) {
+  const positionPattern = /(.+)\[([0-9]+)\]$/;
+  return path.split(".").map(component => {
+    const m = component.match(positionPattern);
+    if (m) {
+      return { name: m[1], pos: parseInt(m[2], 10) };
+    }
+    return { name: component, pos: 0 };
+  });
+}
+
+const XMLEntities = {
+  /* < */ 0x3c: "&lt;",
+  /* > */ 0x3e: "&gt;",
+  /* & */ 0x26: "&amp;",
+  /* " */ 0x22: "&quot;",
+  /* ' */ 0x27: "&apos;",
+};
+
+function encodeToXmlString(str) {
+  const buffer = [];
+  let start = 0;
+  for (let i = 0, ii = str.length; i < ii; i++) {
+    const char = str.codePointAt(i);
+    if (0x20 <= char && char <= 0x7e) {
+      // ascii
+      const entity = XMLEntities[char];
+      if (entity) {
+        if (start < i) {
+          buffer.push(str.substring(start, i));
+        }
+        buffer.push(entity);
+        start = i + 1;
+      }
+    } else {
+      if (start < i) {
+        buffer.push(str.substring(start, i));
+      }
+      buffer.push(`&#x${char.toString(16).toUpperCase()};`);
+      if (char > 0xd7ff && (char < 0xe000 || char > 0xfffd)) {
+        // char is represented by two u16
+        i++;
+      }
+      start = i + 1;
+    }
+  }
+
+  if (buffer.length === 0) {
+    return str;
+  }
+
+  if (start < str.length) {
+    buffer.push(str.substring(start, str.length));
+  }
+
+  return buffer.join("");
+}
+
 export {
   BaseException,
   FONT_IDENTITY_MATRIX,
@@ -947,6 +1014,7 @@ export {
   createPromiseCapability,
   createObjectURL,
   escapeString,
+  encodeToXmlString,
   getModificationDate,
   getVerbosityLevel,
   info,
@@ -959,6 +1027,7 @@ export {
   createValidAbsoluteUrl,
   IsLittleEndianCached,
   IsEvalSupportedCached,
+  parseXFAPath,
   removeNullCharacters,
   setVerbosityLevel,
   shadow,

src/shared/xml_parser.js

@@ -16,6 +16,8 @@
 // The code for XMLParserBase copied from
 // https://github.com/mozilla/shumway/blob/16451d8836fa85f4b16eeda8b4bda2fa9e2b22b0/src/avm2/natives/xml.ts
 
+import { encodeToXmlString } from "./util.js";
+
 const XMLParserErrorCode = {
   NoError: 0,
   EndOfDocument: -1,
@@ -48,9 +50,9 @@ class XMLParserBase {
   _resolveEntities(s) {
     return s.replace(/&([^;]+);/g, (all, entity) => {
       if (entity.substring(0, 2) === "#x") {
-        return String.fromCharCode(parseInt(entity.substring(2), 16));
+        return String.fromCodePoint(parseInt(entity.substring(2), 16));
       } else if (entity.substring(0, 1) === "#") {
-        return String.fromCharCode(parseInt(entity.substring(1), 10));
+        return String.fromCodePoint(parseInt(entity.substring(1), 10));
       }
       switch (entity) {
         case "lt":
@@ -326,14 +328,99 @@ class SimpleDOMNode {
   hasChildNodes() {
     return this.childNodes && this.childNodes.length > 0;
   }
+
+  searchNode(paths, pos) {
+    if (pos >= paths.length) {
+      return this;
+    }
+
+    const component = paths[pos];
+    const stack = [];
+    let node = this;
+
+    while (true) {
+      if (component.name === node.nodeName) {
+        if (component.pos === 0) {
+          const res = node.searchNode(paths, pos + 1);
+          if (res !== null) {
+            return res;
+          }
+        } else if (stack.length === 0) {
+          return null;
+        } else {
+          const [parent] = stack.pop();
+          let siblingPos = 0;
+          for (const child of parent.childNodes) {
+            if (component.name === child.nodeName) {
+              if (siblingPos === component.pos) {
+                return child.searchNode(paths, pos + 1);
+              }
+              siblingPos++;
+            }
+          }
+          // We didn't find the correct sibling
+          // so just return the first found node
+          return node.searchNode(paths, pos + 1);
+        }
+      }
+
+      if (node.childNodes && node.childNodes.length !== 0) {
+        stack.push([node, 0]);
+        node = node.childNodes[0];
+      } else if (stack.length === 0) {
+        return null;
+      } else {
+        while (stack.length !== 0) {
+          const [parent, currentPos] = stack.pop();
+          const newPos = currentPos + 1;
+          if (newPos < parent.childNodes.length) {
+            stack.push([parent, newPos]);
+            node = parent.childNodes[newPos];
+            break;
+          }
+        }
+        if (stack.length === 0) {
+          return null;
+        }
+      }
+    }
+  }
+
+  dump(buffer) {
+    if (this.nodeName === "#text") {
+      buffer.push(encodeToXmlString(this.nodeValue));
+      return;
+    }
+
+    buffer.push(`<${this.nodeName}`);
+    if (this.attributes) {
+      for (const attribute of this.attributes) {
+        buffer.push(
+          ` ${attribute.name}=\"${encodeToXmlString(attribute.value)}\"`
+        );
+      }
+    }
+    if (this.hasChildNodes()) {
+      buffer.push(">");
+      for (const child of this.childNodes) {
+        child.dump(buffer);
+      }
+      buffer.push(`</${this.nodeName}>`);
+    } else if (this.nodeValue) {
+      buffer.push(`>${encodeToXmlString(this.nodeValue)}</${this.nodeName}>`);
+    } else {
+      buffer.push("/>");
+    }
+  }
 }
 
 class SimpleXMLParser extends XMLParserBase {
-  constructor() {
+  constructor(hasAttributes = false) {
     super();
     this._currentFragment = null;
     this._stack = null;
     this._errorCode = XMLParserErrorCode.NoError;
+    this._hasAttributes = hasAttributes;
   }
 
   parseFromString(data) {
@@ -379,6 +466,9 @@ class SimpleXMLParser extends XMLParserBase {
   onBeginElement(name, attributes, isEmpty) {
     const node = new SimpleDOMNode(name);
     node.childNodes = [];
+    if (this._hasAttributes) {
+      node.attributes = attributes;
+    }
     this._currentFragment.push(node);
     if (isEmpty) {
       return;
@@ -403,4 +493,4 @@ class SimpleXMLParser extends XMLParserBase {
   }
 }
 
-export { SimpleXMLParser };
+export { SimpleDOMNode, SimpleXMLParser };