Handle ranges that "overflow" the last byte in CMap.mapBfRange (bug 1627427)

src/core/cmap.js

@@ -242,10 +242,17 @@ class CMap {
     const lastByte = dstLow.length - 1;
     while (low <= high) {
       this._map[low++] = dstLow;
-      // Only the last byte has to be incremented.
+      // Only the last byte has to be incremented (in the normal case).
+      const nextCharCode = dstLow.charCodeAt(lastByte) + 1;
+      if (nextCharCode > 0xff) {
+        dstLow =
+          dstLow.substring(0, lastByte - 1) +
+          String.fromCharCode(dstLow.charCodeAt(lastByte - 1) + 1) +
+          "\x00";
+        continue;
+      }
       dstLow =
-        dstLow.substring(0, lastByte) +
-        String.fromCharCode(dstLow.charCodeAt(lastByte) + 1);
+        dstLow.substring(0, lastByte) + String.fromCharCode(nextCharCode);
     }
   }
 

test/pdfs/.gitignore

@@ -338,6 +338,7 @@
 !noembed-jis7.pdf
 !issue12504.pdf
 !noembed-eucjp.pdf
+!bug1627427_reduced.pdf
 !noembed-sjis.pdf
 !vertical.pdf
 !issue13343.pdf

test/test_manifest.json

@@ -3022,6 +3022,13 @@
        "rounds": 1,
        "type": "eq"
     },
+    {  "id": "bug1627427",
+       "file": "pdfs/bug1627427_reduced.pdf",
+       "md5": "3ff75fcf455af49803f0f04eb071bdc3",
+       "link": false,
+       "rounds": 1,
+       "type": "text"
+    },
     {  "id": "issue8586",
        "file": "pdfs/issue8586.pdf",
        "md5": "16b5230364017d3b0d2d65978eb35816",

test/unit/api_spec.js

@@ -1757,6 +1757,22 @@ sources, for full support with Dvips.`)
       await loadingTask.destroy();
     });
 
+    it("gets text content, with beginbfrange operator handled correctly (bug 1627427)", async function () {
+      const loadingTask = getDocument(
+        buildGetDocumentParams("bug1627427_reduced.pdf")
+      );
+      const pdfDoc = await loadingTask.promise;
+      const pdfPage = await pdfDoc.getPage(1);
+      const { items } = await pdfPage.getTextContent();
+      const text = mergeText(items);
+
+      expect(text).toEqual(
+        "침하게 흐린 품이 눈이 올 듯하더니 눈은 아니 오고 얼다가 만 비가 추"
+      );
+
+      await loadingTask.destroy();
+    });
+
     it("gets empty structure tree", async function () {
       const tree = await page.getStructTree();