Web restrictions component.

components/web_restrictions/java/src/org/chromium/components/webrestrictions/WebRestrictionsContentProvider.java

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package org.chromium.components.webrestrictions;
-
-import android.content.ContentProvider;
-import android.content.ContentValues;
-import android.content.Context;
-import android.content.UriMatcher;
-import android.content.pm.ProviderInfo;
-import android.database.AbstractCursor;
-import android.database.Cursor;
-import android.net.Uri;
-import android.util.Pair;
-
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-
-/**
- * Abstract content provider for providing web restrictions, i.e. for providing a filter for URLs so
- * that they can be blocked or permitted, and a means of requesting permission for new URLs. It
- * provides two (virtual) tables; an 'authorized' table listing the the status of every URL, and a
- * 'requested' table containing the requests for access to new URLs. The 'authorized' table is read
- * only and the 'requested' table is write only.
- */
-public abstract class WebRestrictionsContentProvider extends ContentProvider {
-    public static final int BLOCKED = 0;
-    public static final int PROCEED = 1;
-    private static final int WEB_RESTRICTIONS = 1;
-    private static final int AUTHORIZED = 2;
-    private static final int REQUESTED = 3;
-
-    private final Pattern mSelectionPattern;
-    private UriMatcher mContentUriMatcher;
-    private Uri mContentUri;
-
-    protected WebRestrictionsContentProvider() {
-        // Pattern to extract the URL from the selection.
-        // Matches patterns of the form "url = '<url>'" with arbitrary spacing around the "=" etc.
-        mSelectionPattern = Pattern.compile("\\s*url\\s*=\\s*'([^']*)'");
-    }
-
-    @Override
-    public boolean onCreate() {
-        return true;
-    }
-
-    @Override
-    public void attachInfo(Context context, ProviderInfo info) {
-        super.attachInfo(context, info);
-        mContentUri = new Uri.Builder().scheme("content").authority(info.authority).build();
-        mContentUriMatcher = new UriMatcher(WEB_RESTRICTIONS);
-        mContentUriMatcher.addURI(info.authority, "authorized", AUTHORIZED);
-        mContentUriMatcher.addURI(info.authority, "requested", REQUESTED);
-    }
-
-    @Override
-    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
-            String sortOrder) {
-        if (!contentProviderEnabled()) return null;
-        // Check that this is the a query on the 'authorized' table
-        // TODO(aberent): Provide useful queries on the 'requested' table.
-        if (mContentUriMatcher.match(uri) != AUTHORIZED) return null;
-        // If the selection is of the right form get the url we are querying.
-        Matcher matcher = mSelectionPattern.matcher(selection);
-        if (!matcher.find()) return null;
-        final String url = matcher.group(1);
-        final Pair<Boolean, String> result = shouldProceed(url);
-
-        return new AbstractCursor() {
-
-            @Override
-            public int getCount() {
-                return 1;
-            }
-
-            @Override
-            public String[] getColumnNames() {
-                return new String[] {
-                        "Should Proceed", "Error message"
-                };
-            }
-
-            @Override
-            public String getString(int column) {
-                if (column == 1) return result.second;
-                return null;
-            }
-
-            @Override
-            public short getShort(int column) {
-                return 0;
-            }
-
-            @Override
-            public int getInt(int column) {
-                if (column == 0) return result.first ? PROCEED : BLOCKED;
-                return 0;
-            }
-
-            @Override
-            public long getLong(int column) {
-                return 0;
-            }
-
-            @Override
-            public float getFloat(int column) {
-                return 0;
-            }
-
-            @Override
-            public double getDouble(int column) {
-                return 0;
-            }
-
-            @Override
-            public boolean isNull(int column) {
-                return false;
-            }
-        };
-    }
-
-    @Override
-    public String getType(Uri uri) {
-        // Abused to return whether we can insert
-        if (!contentProviderEnabled()) return null;
-        if (mContentUriMatcher.match(uri) != REQUESTED) return null;
-        return canInsert() ? "text/plain" : null;
-    }
-
-    @Override
-    public Uri insert(Uri uri, ContentValues values) {
-        if (!contentProviderEnabled()) return null;
-        if (mContentUriMatcher.match(uri) != REQUESTED) return null;
-        String url = values.getAsString("url");
-        if (requestInsert(url)) {
-            // TODO(aberent): If we ever make the 'requested' table readable then we might want to
-            // change this to a more conventional content URI (with a row number).
-            return uri.buildUpon().appendPath(url).build();
-        } else {
-            return null;
-        }
-    }
-
-    @Override
-    public int delete(Uri uri, String selection, String[] selectionArgs) {
-        return 0;
-    }
-
-    @Override
-    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
-        return 0;
-    }
-
-    /**
-     * @param url the URL that is wanted.
-     * @return a pair containing the Result and the HTML Error Message. result is true if safe to
-     *         proceed, false otherwise. error message is only meaningful if result is false, a null
-     *         error message means use application default.
-     */
-    protected abstract Pair<Boolean, String> shouldProceed(final String url);
-
-    /**
-     * @return whether the content provider allows insertions.
-     */
-    protected abstract boolean canInsert();
-
-    /**
-     * Start a request that a URL should be permitted
-     *
-     * @param url the URL that is wanted.
-     */
-    protected abstract boolean requestInsert(final String url);
-
-    /**
-     * @return true if the content provider is enabled, false if not
-     */
-    protected abstract boolean contentProviderEnabled();
-
-    /**
-     * Call to tell observers that the filter has changed.
-     */
-    protected void onFilterChanged() {
-        getContext().getContentResolver().notifyChange(
-                mContentUri.buildUpon().appendPath("authorized").build(), null);
-    }
-}