Only have a single call into pdfium at a time.

Pdfium is not thread safe and uses global variables, hence no
parallel call pdfium is safe

Fixes: 28705066
Change-Id: I04309ee691bd9cea37587e0af5be2c07ce8c9f2c
(cherry picked from commit 0768a7dc450caf4c873c5b0883a75135536e1546)
diff --git a/core/jni/android/graphics/pdf/PdfEditor.cpp b/core/jni/android/graphics/pdf/PdfEditor.cpp
index d2d39cd..0468b64 100644
--- a/core/jni/android/graphics/pdf/PdfEditor.cpp
+++ b/core/jni/android/graphics/pdf/PdfEditor.cpp
@@ -52,11 +52,9 @@
 } gRectClassInfo;
 
 // Also used in PdfRenderer.cpp
-Mutex sPdfiumLock;
 int sUnmatchedPdfiumInitRequestCount = 0;
 
 static void initializeLibraryIfNeeded() {
-    Mutex::Autolock _l(sPdfiumLock);
     if (sUnmatchedPdfiumInitRequestCount == 0) {
         FPDF_InitLibrary();
     }
@@ -64,7 +62,6 @@
 }
 
 static void destroyLibraryIfNeeded() {
-    Mutex::Autolock _l(sPdfiumLock);
     sUnmatchedPdfiumInitRequestCount--;
     if (sUnmatchedPdfiumInitRequestCount == 0) {
        FPDF_DestroyLibrary();
diff --git a/core/jni/android/graphics/pdf/PdfRenderer.cpp b/core/jni/android/graphics/pdf/PdfRenderer.cpp
index 71bec78..43550ac 100644
--- a/core/jni/android/graphics/pdf/PdfRenderer.cpp
+++ b/core/jni/android/graphics/pdf/PdfRenderer.cpp
@@ -44,11 +44,9 @@
 } gPointClassInfo;
 
 // See PdfEditor.cpp
-extern Mutex sPdfiumLock;
 extern int sUnmatchedPdfiumInitRequestCount;
 
 static void initializeLibraryIfNeeded() {
-    Mutex::Autolock _l(sPdfiumLock);
     if (sUnmatchedPdfiumInitRequestCount == 0) {
         FPDF_InitLibrary();
     }
@@ -56,7 +54,6 @@
 }
 
 static void destroyLibraryIfNeeded() {
-    Mutex::Autolock _l(sPdfiumLock);
     sUnmatchedPdfiumInitRequestCount--;
     if (sUnmatchedPdfiumInitRequestCount == 0) {
        FPDF_DestroyLibrary();
diff --git a/graphics/java/android/graphics/pdf/PdfEditor.java b/graphics/java/android/graphics/pdf/PdfEditor.java
index 2b70b6a..cd1f8de 100644
--- a/graphics/java/android/graphics/pdf/PdfEditor.java
+++ b/graphics/java/android/graphics/pdf/PdfEditor.java
@@ -79,8 +79,12 @@
         }
 
         mInput = input;
-        mNativeDocument = nativeOpen(mInput.getFd(), size);
-        mPageCount = nativeGetPageCount(mNativeDocument);
+
+        synchronized (PdfRenderer.sPdfiumLock) {
+            mNativeDocument = nativeOpen(mInput.getFd(), size);
+            mPageCount = nativeGetPageCount(mNativeDocument);
+        }
+
         mCloseGuard.open("close");
     }
 
@@ -102,7 +106,10 @@
     public void removePage(int pageIndex) {
         throwIfClosed();
         throwIfPageNotInDocument(pageIndex);
-        mPageCount = nativeRemovePage(mNativeDocument, pageIndex);
+
+        synchronized (PdfRenderer.sPdfiumLock) {
+            mPageCount = nativeRemovePage(mNativeDocument, pageIndex);
+        }
     }
 
     /**
@@ -125,11 +132,16 @@
         if (clip == null) {
             Point size = new Point();
             getPageSize(pageIndex, size);
-            nativeSetTransformAndClip(mNativeDocument, pageIndex, transform.native_instance,
-                    0, 0, size.x, size.y);
+
+            synchronized (PdfRenderer.sPdfiumLock) {
+                nativeSetTransformAndClip(mNativeDocument, pageIndex, transform.native_instance,
+                        0, 0, size.x, size.y);
+            }
         } else {
-            nativeSetTransformAndClip(mNativeDocument, pageIndex, transform.native_instance,
-                    clip.left, clip.top, clip.right, clip.bottom);
+            synchronized (PdfRenderer.sPdfiumLock) {
+                nativeSetTransformAndClip(mNativeDocument, pageIndex, transform.native_instance,
+                        clip.left, clip.top, clip.right, clip.bottom);
+            }
         }
     }
 
@@ -143,7 +155,10 @@
         throwIfClosed();
         throwIfOutSizeNull(outSize);
         throwIfPageNotInDocument(pageIndex);
-        nativeGetPageSize(mNativeDocument, pageIndex, outSize);
+
+        synchronized (PdfRenderer.sPdfiumLock) {
+            nativeGetPageSize(mNativeDocument, pageIndex, outSize);
+        }
     }
 
     /**
@@ -156,7 +171,10 @@
         throwIfClosed();
         throwIfOutMediaBoxNull(outMediaBox);
         throwIfPageNotInDocument(pageIndex);
-        return nativeGetPageMediaBox(mNativeDocument, pageIndex, outMediaBox);
+
+        synchronized (PdfRenderer.sPdfiumLock) {
+            return nativeGetPageMediaBox(mNativeDocument, pageIndex, outMediaBox);
+        }
     }
 
     /**
@@ -169,7 +187,10 @@
         throwIfClosed();
         throwIfMediaBoxNull(mediaBox);
         throwIfPageNotInDocument(pageIndex);
-        nativeSetPageMediaBox(mNativeDocument, pageIndex, mediaBox);
+
+        synchronized (PdfRenderer.sPdfiumLock) {
+            nativeSetPageMediaBox(mNativeDocument, pageIndex, mediaBox);
+        }
     }
 
     /**
@@ -182,7 +203,10 @@
         throwIfClosed();
         throwIfOutCropBoxNull(outCropBox);
         throwIfPageNotInDocument(pageIndex);
-        return nativeGetPageCropBox(mNativeDocument, pageIndex, outCropBox);
+
+        synchronized (PdfRenderer.sPdfiumLock) {
+            return nativeGetPageCropBox(mNativeDocument, pageIndex, outCropBox);
+        }
     }
 
     /**
@@ -195,7 +219,10 @@
         throwIfClosed();
         throwIfCropBoxNull(cropBox);
         throwIfPageNotInDocument(pageIndex);
-        nativeSetPageCropBox(mNativeDocument, pageIndex, cropBox);
+
+        synchronized (PdfRenderer.sPdfiumLock) {
+            nativeSetPageCropBox(mNativeDocument, pageIndex, cropBox);
+        }
     }
 
     /**
@@ -205,7 +232,10 @@
      */
     public boolean shouldScaleForPrinting() {
         throwIfClosed();
-        return nativeScaleForPrinting(mNativeDocument);
+
+        synchronized (PdfRenderer.sPdfiumLock) {
+            return nativeScaleForPrinting(mNativeDocument);
+        }
     }
 
     /**
@@ -219,7 +249,10 @@
     public void write(ParcelFileDescriptor output) throws IOException {
         try {
             throwIfClosed();
-            nativeWrite(mNativeDocument, output.getFd());
+
+            synchronized (PdfRenderer.sPdfiumLock) {
+                nativeWrite(mNativeDocument, output.getFd());
+            }
         } finally {
             IoUtils.closeQuietly(output);
         }
@@ -247,7 +280,9 @@
     }
 
     private void doClose() {
-        nativeClose(mNativeDocument);
+        synchronized (PdfRenderer.sPdfiumLock) {
+            nativeClose(mNativeDocument);
+        }
         IoUtils.closeQuietly(mInput);
         mInput = null;
         mCloseGuard.close();
diff --git a/graphics/java/android/graphics/pdf/PdfRenderer.java b/graphics/java/android/graphics/pdf/PdfRenderer.java
index 520ebe5..cfc1309 100644
--- a/graphics/java/android/graphics/pdf/PdfRenderer.java
+++ b/graphics/java/android/graphics/pdf/PdfRenderer.java
@@ -99,6 +99,12 @@
  * @see #close()
  */
 public final class PdfRenderer implements AutoCloseable {
+    /**
+     * Any call the native pdfium code has to be single threaded as the library does not support
+     * parallel use.
+     */
+    final static Object sPdfiumLock = new Object();
+
     private final CloseGuard mCloseGuard = CloseGuard.get();
 
     private final Point mTempPoint = new Point();
@@ -154,8 +160,12 @@
         }
 
         mInput = input;
-        mNativeDocument = nativeCreate(mInput.getFd(), size);
-        mPageCount = nativeGetPageCount(mNativeDocument);
+
+        synchronized (sPdfiumLock) {
+            mNativeDocument = nativeCreate(mInput.getFd(), size);
+            mPageCount = nativeGetPageCount(mNativeDocument);
+        }
+
         mCloseGuard.open("close");
     }
 
@@ -189,7 +199,10 @@
      */
     public boolean shouldScaleForPrinting() {
         throwIfClosed();
-        return nativeScaleForPrinting(mNativeDocument);
+
+        synchronized (sPdfiumLock) {
+            return nativeScaleForPrinting(mNativeDocument);
+        }
     }
 
     /**
@@ -224,7 +237,9 @@
         if (mCurrentPage != null) {
             mCurrentPage.close();
         }
-        nativeClose(mNativeDocument);
+        synchronized (sPdfiumLock) {
+            nativeClose(mNativeDocument);
+        }
         try {
             mInput.close();
         } catch (IOException ioe) {
@@ -277,7 +292,9 @@
 
         private Page(int index) {
             Point size = mTempPoint;
-            mNativePage = nativeOpenPageAndGetSize(mNativeDocument, index, size);
+            synchronized (sPdfiumLock) {
+                mNativePage = nativeOpenPageAndGetSize(mNativeDocument, index, size);
+            }
             mIndex = index;
             mWidth = size.x;
             mHeight = size.y;
@@ -384,8 +401,10 @@
 
             final long transformPtr = (transform != null) ? transform.native_instance : 0;
 
-            nativeRenderPage(mNativeDocument, mNativePage, destination, contentLeft,
-                    contentTop, contentRight, contentBottom, transformPtr, renderMode);
+            synchronized (sPdfiumLock) {
+                nativeRenderPage(mNativeDocument, mNativePage, destination, contentLeft,
+                        contentTop, contentRight, contentBottom, transformPtr, renderMode);
+            }
         }
 
         /**
@@ -412,7 +431,9 @@
         }
 
         private void doClose() {
-            nativeClosePage(mNativePage);
+            synchronized (sPdfiumLock) {
+                nativeClosePage(mNativePage);
+            }
             mNativePage = 0;
             mCloseGuard.close();
             mCurrentPage = null;