Initial checkin of AOSP Messaging app.

b/23110861

Change-Id: I9aa980d7569247d6b2ca78f5dcb4502e1eaadb8a

src/com/android/messaging/datamodel/FileProvider.java

@@ -0,0 +1,151 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.messaging.datamodel;
+
+import android.content.ContentProvider;
+import android.content.ContentResolver;
+import android.content.ContentValues;
+import android.database.Cursor;
+import android.net.Uri;
+import android.os.ParcelFileDescriptor;
+import android.text.TextUtils;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.Random;
+
+/**
+ * A very simple content provider that can serve files.
+ */
+public abstract class FileProvider extends ContentProvider {
+    // Object to generate random id for temp images.
+    private static final Random RANDOM_ID = new Random();
+
+    abstract File getFile(final String path, final String extension);
+
+    private static final String FILE_EXTENSION_PARAM_KEY = "ext";
+
+    /**
+     * Check if filename conforms to requirement for our provider
+     * @param fileId filename (optionally starting with path character
+     * @return true if filename consists only of digits
+     */
+    protected static boolean isValidFileId(final String fileId) {
+        // Ignore initial "/"
+        for (int index = (fileId.startsWith("/") ? 1 : 0); index < fileId.length(); index++) {
+            final Character c = fileId.charAt(index);
+            if (!Character.isDigit(c)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Create a temp file (to allow writing to that one particular file)
+     * @param file the file to create
+     * @return true if file successfully created
+     */
+    protected static boolean ensureFileExists(final File file) {
+        try {
+            final File parentDir = file.getParentFile();
+            if (parentDir.exists() || parentDir.mkdirs()) {
+                return file.createNewFile();
+            }
+        } catch (final IOException e) {
+            // fail on exceptions creating the file
+        }
+        return false;
+    }
+
+    /**
+     * Build uri for a new temporary file (creating file)
+     * @param authority authority with which to populate uri
+     * @param extension optional file extension
+     * @return unique uri that can be used to write temporary files
+     */
+    protected static Uri buildFileUri(final String authority, final String extension) {
+        final long fileId = Math.abs(RANDOM_ID.nextLong());
+        final Uri.Builder builder = (new Uri.Builder()).authority(authority).scheme(
+                ContentResolver.SCHEME_CONTENT);
+        builder.appendPath(String.valueOf(fileId));
+        if (!TextUtils.isEmpty(extension)) {
+            builder.appendQueryParameter(FILE_EXTENSION_PARAM_KEY, extension);
+        }
+        return builder.build();
+    }
+
+    @Override
+    public boolean onCreate() {
+        return true;
+    }
+
+    @Override
+    public int delete(final Uri uri, final String selection, final String[] selectionArgs) {
+        final String fileId = uri.getPath();
+        if (isValidFileId(fileId)) {
+            final File file = getFile(fileId, getExtensionFromUri(uri));
+            return file.delete() ? 1 : 0;
+        }
+        return 0;
+    }
+
+    @Override
+    public ParcelFileDescriptor openFile(final Uri uri, final String fileMode)
+            throws FileNotFoundException {
+        final String fileId = uri.getPath();
+        if (isValidFileId(fileId)) {
+            final File file = getFile(fileId, getExtensionFromUri(uri));
+            final int mode =
+                    (TextUtils.equals(fileMode, "r") ? ParcelFileDescriptor.MODE_READ_ONLY :
+                        ParcelFileDescriptor.MODE_WRITE_ONLY | ParcelFileDescriptor.MODE_TRUNCATE);
+            return ParcelFileDescriptor.open(file, mode);
+        }
+        return null;
+    }
+
+    protected static String getExtensionFromUri(final Uri uri) {
+        return uri.getQueryParameter(FILE_EXTENSION_PARAM_KEY);
+    }
+
+    @Override
+    public Cursor query(final Uri uri, final String[] projection, final String selection,
+            final String[] selectionArgs, final String sortOrder) {
+        // Don't support queries.
+        return null;
+    }
+
+    @Override
+    public Uri insert(final Uri uri, final ContentValues values) {
+        // Don't support inserts.
+        return null;
+    }
+
+    @Override
+    public int update(final Uri uri, final ContentValues values, final String selection,
+            final String[] selectionArgs) {
+        // Don't support updates.
+        return 0;
+    }
+
+    @Override
+    public String getType(final Uri uri) {
+        // No need for mime types.
+        return null;
+    }
+}