Merge pull request #19803 from Snuffleupagus/issue-19800

Catch circular references in /Form XObjects (issue 19800)

Author: Snuffleupagus

src/core/annotation.js

@@ -49,6 +49,8 @@ import {
   lookupNormalRect,
   lookupRect,
   numberToString,
+  RESOURCES_KEYS_OPERATOR_LIST,
+  RESOURCES_KEYS_TEXT_CONTENT,
   stringToAsciiOrUTF16BE,
   stringToUTF16String,
 } from "./core_utils.js";
@@ -1196,7 +1198,7 @@ class Annotation {
 
     const appearanceDict = appearance.dict;
     const resources = await this.loadResources(
-      ["ExtGState", "ColorSpace", "Pattern", "Shading", "XObject", "Font"],
+      RESOURCES_KEYS_OPERATOR_LIST,
       appearance
     );
     const bbox = lookupRect(appearanceDict.getArray("BBox"), [0, 0, 1, 1]);
@@ -1257,7 +1259,7 @@ class Annotation {
     }
 
     const resources = await this.loadResources(
-      ["ExtGState", "Font", "Properties", "XObject"],
+      RESOURCES_KEYS_TEXT_CONTENT,
       this.appearance
     );
 

src/core/core_utils.js

@@ -32,6 +32,23 @@ const MIN_INT_32 = -(2 ** 31);
 
 const IDENTITY_MATRIX = [1, 0, 0, 1, 0, 0];
 
+const RESOURCES_KEYS_OPERATOR_LIST = [
+  "ColorSpace",
+  "ExtGState",
+  "Font",
+  "Pattern",
+  "Properties",
+  "Shading",
+  "XObject",
+];
+
+const RESOURCES_KEYS_TEXT_CONTENT = [
+  "ExtGState",
+  "Font",
+  "Properties",
+  "XObject",
+];
+
 function getLookupTableFactory(initializer) {
   let lookup;
   return function () {
@@ -745,6 +762,8 @@ export {
   readUint16,
   readUint32,
   recoverJsURL,
+  RESOURCES_KEYS_OPERATOR_LIST,
+  RESOURCES_KEYS_TEXT_CONTENT,
   stringToAsciiOrUTF16BE,
   stringToUTF16HexString,
   stringToUTF16String,

src/core/document.js

@@ -45,6 +45,8 @@ import {
   lookupNormalRect,
   MissingDataException,
   PDF_VERSION_REGEXP,
+  RESOURCES_KEYS_OPERATOR_LIST,
+  RESOURCES_KEYS_TEXT_CONTENT,
   validateCSSFont,
   XRefEntryException,
   XRefParseException,
@@ -419,6 +421,25 @@ class Page {
     await objectLoader.load();
   }
 
+  async #getMergedResources(streamDict, keys) {
+    // In rare cases /Resources are also found in the /Contents stream-dict,
+    // in addition to in the /Page dict, hence we need to prefer those when
+    // available (see issue18894.pdf).
+    const localResources = streamDict?.get("Resources");
+
+    if (!(localResources instanceof Dict)) {
+      return this.resources;
+    }
+    const objectLoader = new ObjectLoader(localResources, keys, this.xref);
+    await objectLoader.load();
+
+    return Dict.merge({
+      xref: this.xref,
+      dictArray: [localResources, this.resources],
+      mergeSubDicts: true,
+    });
+  }
+
   async getOperatorList({
     handler,
     sink,
@@ -429,15 +450,7 @@ class Page {
     modifiedIds = null,
   }) {
     const contentStreamPromise = this.getContentStream();
-    const resourcesPromise = this.loadResources([
-      "ColorSpace",
-      "ExtGState",
-      "Font",
-      "Pattern",
-      "Properties",
-      "Shading",
-      "XObject",
-    ]);
+    const resourcesPromise = this.loadResources(RESOURCES_KEYS_OPERATOR_LIST);
 
     const partialEvaluator = new PartialEvaluator({
       xref: this.xref,
@@ -525,11 +538,15 @@ class Page {
       contentStreamPromise,
       resourcesPromise,
     ]).then(async ([contentStream]) => {
+      const resources = await this.#getMergedResources(
+        contentStream.dict,
+        RESOURCES_KEYS_OPERATOR_LIST
+      );
       const opList = new OperatorList(intent, sink);
 
       handler.send("StartRenderPage", {
         transparency: partialEvaluator.hasBlendModes(
-          this.resources,
+          resources,
           this.nonBlendModesSet
         ),
         pageIndex: this.pageIndex,
@@ -539,7 +556,7 @@ class Page {
       await partialEvaluator.getOperatorList({
         stream: contentStream,
         task,
-        resources: this.resources,
+        resources,
         operatorList: opList,
       });
       return opList;
@@ -642,19 +659,19 @@ class Page {
     sink,
   }) {
     const contentStreamPromise = this.getContentStream();
-    const resourcesPromise = this.loadResources([
-      "ExtGState",
-      "Font",
-      "Properties",
-      "XObject",
-    ]);
+    const resourcesPromise = this.loadResources(RESOURCES_KEYS_TEXT_CONTENT);
     const langPromise = this.pdfManager.ensureCatalog("lang");
 
     const [contentStream, , lang] = await Promise.all([
       contentStreamPromise,
       resourcesPromise,
       langPromise,
     ]);
+    const resources = await this.#getMergedResources(
+      contentStream.dict,
+      RESOURCES_KEYS_TEXT_CONTENT
+    );
+
     const partialEvaluator = new PartialEvaluator({
       xref: this.xref,
       handler,
@@ -672,7 +689,7 @@ class Page {
     return partialEvaluator.getTextContent({
       stream: contentStream,
       task,
-      resources: this.resources,
+      resources,
       includeMarkedContent,
       disableNormalization,
       sink,

src/core/evaluator.js

@@ -462,7 +462,8 @@ class PartialEvaluator {
     operatorList,
     task,
     initialState,
-    localColorSpaceCache
+    localColorSpaceCache,
+    seenRefs
   ) {
     const dict = xobj.dict;
     const matrix = lookupMatrix(dict.getArray("Matrix"), null);
@@ -526,6 +527,7 @@ class PartialEvaluator {
       resources: dict.get("Resources") || resources,
       operatorList,
       initialState,
+      prevRefs: seenRefs,
     });
     operatorList.addOp(OPS.paintFormXObjectEnd, []);
 
@@ -850,7 +852,8 @@ class PartialEvaluator {
     operatorList,
     task,
     stateManager,
-    localColorSpaceCache
+    localColorSpaceCache,
+    seenRefs
   ) {
     const smaskContent = smask.get("G");
     const smaskOptions = {
@@ -880,7 +883,8 @@ class PartialEvaluator {
       operatorList,
       task,
       stateManager.state.clone({ newPath: true }),
-      localColorSpaceCache
+      localColorSpaceCache,
+      seenRefs
     );
   }
 
@@ -1065,6 +1069,7 @@ class PartialEvaluator {
     stateManager,
     localGStateCache,
     localColorSpaceCache,
+    seenRefs,
   }) {
     const gStateRef = gState.objId;
     let isSimpleGState = true;
@@ -1127,7 +1132,8 @@ class PartialEvaluator {
                 operatorList,
                 task,
                 stateManager,
-                localColorSpaceCache
+                localColorSpaceCache,
+                seenRefs
               )
             );
             gStateObj.push([key, true]);
@@ -1696,7 +1702,19 @@ class PartialEvaluator {
     operatorList,
     initialState = null,
     fallbackFontDict = null,
+    prevRefs = null,
   }) {
+    const objId = stream.dict?.objId;
+    const seenRefs = new RefSet(prevRefs);
+
+    if (objId) {
+      if (prevRefs?.has(objId)) {
+        throw new Error(
+          `getOperatorList - ignoring circular reference: ${objId}`
+        );
+      }
+      seenRefs.put(objId);
+    }
     // Ensure that `resources`/`initialState` is correctly initialized,
     // even if the provided parameter is e.g. `null`.
     resources ||= Dict.empty;
@@ -1808,7 +1826,8 @@ class PartialEvaluator {
                       operatorList,
                       task,
                       stateManager.state.clone({ newPath: true }),
-                      localColorSpaceCache
+                      localColorSpaceCache,
+                      seenRefs
                     )
                     .then(function () {
                       stateManager.restore();
@@ -2158,6 +2177,7 @@ class PartialEvaluator {
                     stateManager,
                     localGStateCache,
                     localColorSpaceCache,
+                    seenRefs,
                   })
                   .then(resolveGState, rejectGState);
               }).catch(function (reason) {
@@ -2339,7 +2359,19 @@ class PartialEvaluator {
     markedContentData = null,
     disableNormalization = false,
     keepWhiteSpace = false,
+    prevRefs = null,
   }) {
+    const objId = stream.dict?.objId;
+    const seenRefs = new RefSet(prevRefs);
+
+    if (objId) {
+      if (prevRefs?.has(objId)) {
+        throw new Error(
+          `getTextContent - ignoring circular reference: ${objId}`
+        );
+      }
+      seenRefs.put(objId);
+    }
     // Ensure that `resources`/`stateManager` is correctly initialized,
     // even if the provided parameter is e.g. `null`.
     resources ||= Dict.empty;
@@ -3326,6 +3358,7 @@ class PartialEvaluator {
                     markedContentData,
                     disableNormalization,
                     keepWhiteSpace,
+                    prevRefs: seenRefs,
                   })
                   .then(function () {
                     if (!sinkWrapper.enqueueInvoked) {

test/pdfs/.gitignore

@@ -206,6 +206,7 @@
 !issue3928.pdf
 !issue8565.pdf
 !clippath.pdf
+!issue19800.pdf
 !issue8795_reduced.pdf
 !bug1755507.pdf
 !close-path-bug.pdf

test/pdfs/issue19800.pdf

@@ -6897,6 +6897,20 @@
     "lastPage": 2,
     "type": "eq"
   },
+  {
+    "id": "issue19800-eq",
+    "file": "pdfs/issue19800.pdf",
+    "md5": "92825d3178196bdd01096c4081609efd",
+    "rounds": 1,
+    "type": "eq"
+  },
+  {
+    "id": "issue19800-text",
+    "file": "pdfs/issue19800.pdf",
+    "md5": "92825d3178196bdd01096c4081609efd",
+    "rounds": 1,
+    "type": "text"
+  },
   {
     "id": "issue3438",
     "file": "pdfs/issue3438.pdf",