Merge pull request #16461 from Snuffleupagus/issue-16454

Improve "EI" detection in inline images (PR 12028 follow-up, issue 16454)

src/core/parser.js

@@ -26,6 +26,7 @@ import {
   MissingDataException,
   ParserEOFException,
 } from "./core_utils.js";
+import { NullStream, Stream } from "./stream.js";
 import { Ascii85Stream } from "./ascii_85_stream.js";
 import { AsciiHexStream } from "./ascii_hex_stream.js";
 import { CCITTFaxStream } from "./ccitt_stream.js";
@@ -34,7 +35,6 @@ import { Jbig2Stream } from "./jbig2_stream.js";
 import { JpegStream } from "./jpeg_stream.js";
 import { JpxStream } from "./jpx_stream.js";
 import { LZWStream } from "./lzw_stream.js";
-import { NullStream } from "./stream.js";
 import { PredictorStream } from "./predictor_stream.js";
 import { RunLengthStream } from "./run_length_stream.js";
 
@@ -190,9 +190,9 @@ class Parser {
       LF = 0xa,
       CR = 0xd,
       NUL = 0x0;
-    const lexer = this.lexer,
+    const { knownCommands } = this.lexer,
       startPos = stream.pos,
-      n = 10;
+      n = 15;
     let state = 0,
       ch,
       maybeEIPos;
@@ -209,7 +209,12 @@ class Parser {
           maybeEIPos = stream.pos;
           // Let's check that the next `n` bytes are ASCII... just to be sure.
           const followingBytes = stream.peekBytes(n);
-          for (let i = 0, ii = followingBytes.length; i < ii; i++) {
+
+          const ii = followingBytes.length;
+          if (ii === 0) {
+            break; // The end of the stream was reached, nothing to check.
+          }
+          for (let i = 0; i < ii; i++) {
             ch = followingBytes[i];
             if (ch === NUL && followingBytes[i + 1] !== NUL) {
               // NUL bytes are not supposed to occur *outside* of inline
@@ -235,19 +240,47 @@ class Parser {
           if (state !== 2) {
             continue;
           }
-          // Check that the "EI" sequence isn't part of the image data, since
-          // that would cause the image to be truncated (fixes issue11124.pdf).
-          if (lexer.knownCommands) {
-            const nextObj = lexer.peekObj();
-            if (nextObj instanceof Cmd && !lexer.knownCommands[nextObj.cmd]) {
-              // Not a valid command, i.e. the inline image data *itself*
-              // contains an "EI" sequence. Resetting the state.
-              state = 0;
-            }
-          } else {
+          if (!knownCommands) {
             warn(
               "findDefaultInlineStreamEnd - `lexer.knownCommands` is undefined."
             );
+            continue;
+          }
+          // Check that the "EI" sequence isn't part of the image data, since
+          // that would cause the image to be truncated (fixes issue11124.pdf).
+          const tmpLexer = new Lexer(
+            new Stream(followingBytes.slice()),
+            knownCommands
+          );
+          // Reduce the number of (potential) warning messages.
+          tmpLexer._hexStringWarn = () => {};
+          let numArgs = 0;
+
+          while (true) {
+            const nextObj = tmpLexer.getObj();
+
+            if (nextObj === EOF) {
+              state = 0; // No valid command found, resetting the state.
+              break;
+            }
+            if (nextObj instanceof Cmd) {
+              const knownCommand = knownCommands[nextObj.cmd];
+              if (!knownCommand) {
+                // Not a valid command, i.e. the inline image data *itself*
+                // contains an "EI" sequence. Resetting the state.
+                state = 0;
+                break;
+              } else if (
+                knownCommand.variableArgs
+                  ? numArgs <= knownCommand.numArgs
+                  : numArgs === knownCommand.numArgs
+              ) {
+                break; // Valid command found.
+              }
+              numArgs = 0;
+              continue;
+            }
+            numArgs++;
           }
 
           if (state === 2) {
@@ -1284,28 +1317,6 @@ class Lexer {
     return Cmd.get(str);
   }
 
-  peekObj() {
-    const streamPos = this.stream.pos,
-      currentChar = this.currentChar,
-      beginInlineImagePos = this.beginInlineImagePos;
-
-    let nextObj;
-    try {
-      nextObj = this.getObj();
-    } catch (ex) {
-      if (ex instanceof MissingDataException) {
-        throw ex;
-      }
-      warn(`peekObj: ${ex}`);
-    }
-    // Ensure that we reset *all* relevant `Lexer`-instance state.
-    this.stream.pos = streamPos;
-    this.currentChar = currentChar;
-    this.beginInlineImagePos = beginInlineImagePos;
-
-    return nextObj;
-  }
-
   skipToNextLine() {
     let ch = this.currentChar;
     while (ch >= 0) {

test/pdfs/issue16454.pdf.link

@@ -0,0 +1 @@
+https://github.com/mozilla/pdf.js/files/11537582/Pages.62.73.from.0560-22_WSP.Plan_July.2022_Version.1.pdf

test/test_manifest.json

@@ -5972,6 +5972,14 @@
        "link": true,
        "type": "eq"
     },
+    {  "id": "issue16454",
+       "file": "pdfs/issue16454.pdf",
+       "md5": "82fe0c54a96667472ce999be7a789199",
+       "rounds": 1,
+       "lastPage": 1,
+       "link": true,
+       "type": "eq"
+    },
     {  "id": "decodeACSuccessive",
        "file": "pdfs/decodeACSuccessive.pdf",
        "md5": "7749c032624fe27ab8e8d7d5e9a4a93f",