Add support for virtual files to Clank.

base/android/java/src/org/chromium/base/ContentUriUtils.java

Index: base/android/java/src/org/chromium/base/ContentUriUtils.java
diff --git a/base/android/java/src/org/chromium/base/ContentUriUtils.java b/base/android/java/src/org/chromium/base/ContentUriUtils.java
index 5448aa0e9ebf4b30cbf138bbb77aa0705e817ef0..f1d0ac586c6a86332dc54b672ffea0606056cf58 100644
--- a/base/android/java/src/org/chromium/base/ContentUriUtils.java
+++ b/base/android/java/src/org/chromium/base/ContentUriUtils.java
@@ -4,17 +4,22 @@
 
 package org.chromium.base;
 
+import android.annotation.SuppressLint;
 import android.content.ContentResolver;
 import android.content.Context;
+import android.content.res.AssetFileDescriptor;
 import android.database.Cursor;
 import android.net.Uri;
 import android.os.ParcelFileDescriptor;
+import android.provider.DocumentsContract;
 import android.util.Log;
+import android.webkit.MimeTypeMap;
 
 import org.chromium.base.annotations.CalledByNative;
 
 import java.io.File;
 import java.io.FileNotFoundException;
+import java.io.IOException;
 
 /**
  * This class provides methods to access content URI schemes.
@@ -67,9 +72,9 @@ public abstract class ContentUriUtils {
      */
     @CalledByNative
     public static int openContentUriForRead(Context context, String uriString) {
-        ParcelFileDescriptor pfd = getParcelFileDescriptor(context, uriString);
-        if (pfd != null) {
-            return pfd.detachFd();
+        AssetFileDescriptor afd = getAssetFileDescriptor(context, uriString);
+        if (afd != null) {
+            return afd.getParcelFileDescriptor().detachFd();
         }
         return -1;
     }
@@ -83,7 +88,19 @@ public abstract class ContentUriUtils {
      */
     @CalledByNative
     public static boolean contentUriExists(Context context, String uriString) {
-        return getParcelFileDescriptor(context, uriString) != null;
+        AssetFileDescriptor asf = null;
+        try {
+            asf = getAssetFileDescriptor(context, uriString);
+            return asf != null;
+        } finally {
+            if (asf != null) {

[agrieve, 2016/12/07 16:44:54]

nit: Use StreamUtil.closeQuietly(asf)

[mtomasz, 2016/12/08 06:36:37]

Done.

+                try {
+                    asf.close();
+                } catch (IOException e) {
+                    // Closing quietly.
+                }
+            }
+        }
     }
 
     /**
@@ -96,8 +113,11 @@ public abstract class ContentUriUtils {
     @CalledByNative
     public static String getMimeType(Context context, String uriString) {
         ContentResolver resolver = context.getContentResolver();
-        if (resolver == null) return null;
         Uri uri = Uri.parse(uriString);
+        if (isVirtualDocument(uri, context)) {
+            String[] streamTypes = resolver.getStreamTypes(uri, "*/*");
+            return streamTypes != null ? streamTypes[0] : null;
+        }
         return resolver.getType(uri);
     }
 
@@ -106,15 +126,35 @@ public abstract class ContentUriUtils {
      *
      * @param context {@link Context} in interest.
      * @param uriString the content URI to open.
-     * @return ParcelFileDescriptor of the content URI, or NULL if the file does not exist.
+     * @return AssetFileDescriptor of the content URI, or NULL if the file does not exist.
      */
-    private static ParcelFileDescriptor getParcelFileDescriptor(Context context, String uriString) {
+    @SuppressLint("NewApi")
+    private static AssetFileDescriptor getAssetFileDescriptor(Context context, String uriString) {
         ContentResolver resolver = context.getContentResolver();
         Uri uri = Uri.parse(uriString);
 
-        ParcelFileDescriptor pfd = null;
         try {
-            pfd = resolver.openFileDescriptor(uri, "r");
+            if (isVirtualDocument(uri, context)) {
+                String[] streamTypes = resolver.getStreamTypes(uri, "*/*");
+                if (streamTypes != null) {

[agrieve, 2016/12/07 16:44:53]

should we check for empty array here as well?

[mtomasz, 2016/12/08 06:36:37]

Done.

+                    AssetFileDescriptor afd =
+                            resolver.openTypedAssetFileDescriptor(uri, streamTypes[0], null, null);
+                    if (afd.getStartOffset() != 0) {
+                        try {
+                            afd.close();
+                        } catch (IOException e) {
+                            // Closing quietly.

[agrieve, 2016/12/07 16:44:54]

StreamUtil.closeQuietly()

[mtomasz, 2016/12/08 06:36:37]

Done.

+                        }
+                        throw new SecurityException("Cannot open files with non-zero offset type.");
+                    }
+                    return afd;
+                }
+            } else {
+                ParcelFileDescriptor pfd = resolver.openFileDescriptor(uri, "r");
+                if (pfd != null) {
+                    return new AssetFileDescriptor(pfd, 0, AssetFileDescriptor.UNKNOWN_LENGTH);
+                }
+            }
         } catch (FileNotFoundException e) {
             Log.w(TAG, "Cannot find content uri: " + uriString, e);
         } catch (SecurityException e) {
@@ -124,29 +164,57 @@ public abstract class ContentUriUtils {
         } catch (IllegalStateException e) {
             Log.w(TAG, "Unknown content uri: " + uriString, e);
         }
-        return pfd;
+
+        return null;
     }
 
     /**
      * Method to resolve the display name of a content URI.
      *
      * @param uri the content URI to be resolved.
-     * @param contentResolver the content resolver to query.
-     * @param columnField the column field to query.
+     * @param context {@link Context} in interest.
      * @return the display name of the @code uri if present in the database
      *  or an empty string otherwise.
      */
-    public static String getDisplayName(
-            Uri uri, ContentResolver contentResolver, String columnField) {
-        if (contentResolver == null || uri == null) return "";
+    @SuppressLint("NewApi")
+    public static String getDisplayName(Uri uri, Context context, String columnField) {
+        if (uri == null) return "";
+        ContentResolver contentResolver = context.getContentResolver();
         Cursor cursor = null;
         try {
             cursor = contentResolver.query(uri, null, null, null, null);
 
             if (cursor != null && cursor.getCount() >= 1) {
                 cursor.moveToFirst();
-                int index = cursor.getColumnIndex(columnField);
-                if (index > -1) return cursor.getString(index);
+                int displayNameIndex = cursor.getColumnIndex(columnField);
+                if (displayNameIndex == -1) {
+                    return "";
+                }
+                String displayName = cursor.getString(displayNameIndex);
+                // For Virtual documents, try to modify the file extension so it's compatible
+                // with the alternative MIME type.
+                if (DocumentsContract.isDocumentUri(context, uri)) {
+                    int flagsIndex = cursor.getColumnIndex(DocumentsContract.Document.COLUMN_FLAGS);
+                    if (flagsIndex > -1) {
+                        boolean isVirtual =
+                                (cursor.getLong(flagsIndex)
+                                        & DocumentsContract.Document.FLAG_VIRTUAL_DOCUMENT)
+                                != 0;
+                        if (isVirtual) {
+                            String[] mimeTypes = contentResolver.getStreamTypes(uri, "*/*");
+                            if (mimeTypes != null) {

[agrieve, 2016/12/07 16:44:54]

check non-empty?

[mtomasz, 2016/12/08 06:36:37]

Done.

+                                String ext = MimeTypeMap.getSingleton().getExtensionFromMimeType(
+                                        mimeTypes[0]);
+                                if (ext != null) {
+                                    // Just append, it's simpler and more secure than altering an
+                                    // existing extension.
+                                    displayName += "." + ext;
+                                }
+                            }
+                        }
+                    }
+                }
+                return displayName;
             }
         } catch (NullPointerException e) {
             // Some android models don't handle the provider call correctly.
@@ -157,4 +225,39 @@ public abstract class ContentUriUtils {
         }
         return "";
     }
+
+    /**
+     * Checks whether the passed Uri represents a virtual document.
+     *
+     * @param uri the content URI to be resolved.
+     * @param contentResolver the content resolver to query.
+     * @return True for virtual file, false for any other file.
+     */
+    @SuppressLint("NewApi")

[agrieve, 2016/12/07 16:44:54]

Do you need to add Build.VERSION check somewhere below?

[mtomasz, 2016/12/08 06:36:37]

I don't think so. All we needed from the newer API is the constant which is
resolved in compile time. So, the entire code will execute correctly on lower
API levels.

[agrieve, 2016/12/09 18:23:14]

Depending on a compiler optimization for correctness is a bad idea I think. If
virtual documents don't exist before the API the constant is added in, it's
probably a good idea to short-circuit anyways.

+    public static boolean isVirtualDocument(Uri uri, Context context) {

[agrieve, 2016/12/07 16:44:53]

Doesn't look like this is used outside of this class. Let's make it private
until it's required.

[mtomasz, 2016/12/08 06:36:37]

Done.

+        if (uri == null) return false;

[agrieve, 2016/12/07 16:44:53]

nit: Make Uri @Nullable and state it can be null in the javadoc. But likely even
better would be to change this to an assert.

[mtomasz, 2016/12/08 06:36:37]

I tried to be consistent with the rest of the file. If you feel strong about it,
I'm happy to fix it everywhere in this file in a follow up CL. Let me know.

[agrieve, 2016/12/09 18:23:14]

Yes please. Only getDisplayName() seems to check it btw, I don't see any other
function check it.

+        if (!DocumentsContract.isDocumentUri(context, uri)) return false;
+        ContentResolver contentResolver = context.getContentResolver();
+        Cursor cursor = null;
+        try {
+            cursor = contentResolver.query(uri, null, null, null, null);
+
+            if (cursor != null && cursor.getCount() >= 1) {
+                cursor.moveToFirst();
+                int index = cursor.getColumnIndex(DocumentsContract.Document.COLUMN_FLAGS);
+                if (index > -1) {
+                    return (cursor.getLong(index)
+                                   & DocumentsContract.Document.FLAG_VIRTUAL_DOCUMENT)
+                            != 0;
+                }
+            }
+        } catch (NullPointerException e) {
+            // Some android models don't handle the provider call correctly.
+            // see crbug.com/345393
+            return false;
+        } finally {
+            if (cursor != null) cursor.close();

[agrieve, 2016/12/07 16:44:53]

StreamUtil.closeQuietly()

[mtomasz, 2016/12/08 06:36:37]

Done.

+        }
+        return false;
+    }
 }