/* * Copyright (C) 2008 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.providers.downloads; import android.content.ContentUris; import android.content.Context; import android.content.Intent; import android.content.pm.PackageManager; import android.content.pm.ResolveInfo; import android.database.Cursor; import android.drm.mobile1.DrmRawContent; import android.net.Uri; import android.os.Environment; import android.os.StatFs; import android.os.SystemClock; import android.provider.Downloads; import android.util.Config; import android.util.Log; import android.webkit.MimeTypeMap; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.util.Random; import java.util.Set; import java.util.regex.Matcher; import java.util.regex.Pattern; /** * Some helper functions for the download manager */ public class Helpers { public static Random sRandom = new Random(SystemClock.uptimeMillis()); /** Regex used to parse content-disposition headers */ private static final Pattern CONTENT_DISPOSITION_PATTERN = Pattern.compile("attachment;\\s*filename\\s*=\\s*\"([^\"]*)\""); private Helpers() { } /* * Parse the Content-Disposition HTTP Header. The format of the header * is defined here: http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html * This header provides a filename for content that is going to be * downloaded to the file system. We only support the attachment type. */ private static String parseContentDisposition(String contentDisposition) { try { Matcher m = CONTENT_DISPOSITION_PATTERN.matcher(contentDisposition); if (m.find()) { return m.group(1); } } catch (IllegalStateException ex) { // This function is defined as returning null when it can't parse the header } return null; } /** * Exception thrown from methods called by generateSaveFile() for any fatal error. */ private static class GenerateSaveFileError extends Exception { int mStatus; public GenerateSaveFileError(int status) { mStatus = status; } } /** * Creates a filename (where the file should be saved) from a uri. */ public static DownloadFileInfo generateSaveFile( Context context, String url, String hint, String contentDisposition, String contentLocation, String mimeType, int destination, long contentLength, boolean isPublicApi) throws FileNotFoundException { if (!canHandleDownload(context, mimeType, destination, isPublicApi)) { return new DownloadFileInfo(null, null, Downloads.Impl.STATUS_NOT_ACCEPTABLE); } String fullFilename; try { if (destination == Downloads.Impl.DESTINATION_FILE_URI) { fullFilename = getPathForFileUri(hint); } else { fullFilename = chooseFullPath(context, url, hint, contentDisposition, contentLocation, mimeType, destination, contentLength); } } catch (GenerateSaveFileError exc) { return new DownloadFileInfo(null, null, exc.mStatus); } return new DownloadFileInfo(fullFilename, new FileOutputStream(fullFilename), 0); } private static String getPathForFileUri(String hint) throws GenerateSaveFileError { String path = Uri.parse(hint).getSchemeSpecificPart(); if (new File(path).exists()) { Log.d(Constants.TAG, "File already exists: " + path); throw new GenerateSaveFileError(Downloads.Impl.STATUS_FILE_ERROR); } return path; } private static String chooseFullPath(Context context, String url, String hint, String contentDisposition, String contentLocation, String mimeType, int destination, long contentLength) throws GenerateSaveFileError { File base = locateDestinationDirectory(context, mimeType, destination, contentLength); String filename = chooseFilename(url, hint, contentDisposition, contentLocation, destination); // Split filename between base and extension // Add an extension if filename does not have one String extension = null; int dotIndex = filename.indexOf('.'); if (dotIndex < 0) { extension = chooseExtensionFromMimeType(mimeType, true); } else { extension = chooseExtensionFromFilename(mimeType, destination, filename, dotIndex); filename = filename.substring(0, dotIndex); } boolean recoveryDir = Constants.RECOVERY_DIRECTORY.equalsIgnoreCase(filename + extension); filename = base.getPath() + File.separator + filename; if (Constants.LOGVV) { Log.v(Constants.TAG, "target file: " + filename + extension); } return chooseUniqueFilename(destination, filename, extension, recoveryDir); } private static boolean canHandleDownload(Context context, String mimeType, int destination, boolean isPublicApi) { if (isPublicApi) { return true; } if (destination == Downloads.Impl.DESTINATION_EXTERNAL || destination == Downloads.Impl.DESTINATION_CACHE_PARTITION_PURGEABLE) { if (mimeType == null) { if (Config.LOGD) { Log.d(Constants.TAG, "external download with no mime type not allowed"); } return false; } if (!DrmRawContent.DRM_MIMETYPE_MESSAGE_STRING.equalsIgnoreCase(mimeType)) { // Check to see if we are allowed to download this file. Only files // that can be handled by the platform can be downloaded. // special case DRM files, which we should always allow downloading. Intent intent = new Intent(Intent.ACTION_VIEW); // We can provide data as either content: or file: URIs, // so allow both. (I think it would be nice if we just did // everything as content: URIs) // Actually, right now the download manager's UId restrictions // prevent use from using content: so it's got to be file: or // nothing PackageManager pm = context.getPackageManager(); intent.setDataAndType(Uri.fromParts("file", "", null), mimeType); ResolveInfo ri = pm.resolveActivity(intent, PackageManager.MATCH_DEFAULT_ONLY); //Log.i(Constants.TAG, "*** FILENAME QUERY " + intent + ": " + list); if (ri == null) { if (Config.LOGD) { Log.d(Constants.TAG, "no handler found for type " + mimeType); } return false; } } } return true; } private static File locateDestinationDirectory(Context context, String mimeType, int destination, long contentLength) throws GenerateSaveFileError { File base = null; StatFs stat = null; // DRM messages should be temporarily stored internally and then passed to // the DRM content provider if (destination == Downloads.Impl.DESTINATION_CACHE_PARTITION || destination == Downloads.Impl.DESTINATION_CACHE_PARTITION_PURGEABLE || destination == Downloads.Impl.DESTINATION_CACHE_PARTITION_NOROAMING || DrmRawContent.DRM_MIMETYPE_MESSAGE_STRING.equalsIgnoreCase(mimeType)) { // Saving to internal storage. base = Environment.getDownloadCacheDirectory(); stat = new StatFs(base.getPath()); /* * Check whether there's enough space on the target filesystem to save the file. * Put a bit of margin (in case creating the file grows the system by a few blocks). */ int blockSize = stat.getBlockSize(); long bytesAvailable = blockSize * ((long) stat.getAvailableBlocks() - 4); while (bytesAvailable < contentLength) { // Insufficient space; try discarding purgeable files. if (!discardPurgeableFiles(context, contentLength - bytesAvailable)) { // No files to purge, give up. if (Config.LOGD) { Log.d(Constants.TAG, "download aborted - not enough free space in internal storage"); } throw new GenerateSaveFileError(Downloads.Impl.STATUS_INSUFFICIENT_SPACE_ERROR); } else { // Recalculate available space and try again. stat.restat(base.getPath()); bytesAvailable = blockSize * ((long) stat.getAvailableBlocks() - 4); } } } else if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) { // Saving to external storage (SD card). String root = Environment.getExternalStorageDirectory().getPath(); stat = new StatFs(root); /* * Check whether there's enough space on the target filesystem to save the file. * Put a bit of margin (in case creating the file grows the system by a few blocks). */ if (stat.getBlockSize() * ((long) stat.getAvailableBlocks() - 4) < contentLength) { // Insufficient space. if (Config.LOGD) { Log.d(Constants.TAG, "download aborted - not enough free space"); } throw new GenerateSaveFileError(Downloads.Impl.STATUS_INSUFFICIENT_SPACE_ERROR); } base = new File(root + Constants.DEFAULT_DL_SUBDIR); if (!base.isDirectory() && !base.mkdir()) { // Can't create download directory, e.g. because a file called "download" // already exists at the root level, or the SD card filesystem is read-only. if (Config.LOGD) { Log.d(Constants.TAG, "download aborted - can't create base directory " + base.getPath()); } throw new GenerateSaveFileError(Downloads.Impl.STATUS_FILE_ERROR); } } else { // No SD card found. if (Config.LOGD) { Log.d(Constants.TAG, "download aborted - no external storage"); } throw new GenerateSaveFileError(Downloads.Impl.STATUS_DEVICE_NOT_FOUND_ERROR); } return base; } private static String chooseFilename(String url, String hint, String contentDisposition, String contentLocation, int destination) { String filename = null; // First, try to use the hint from the application, if there's one if (filename == null && hint != null && !hint.endsWith("/")) { if (Constants.LOGVV) { Log.v(Constants.TAG, "getting filename from hint"); } int index = hint.lastIndexOf('/') + 1; if (index > 0) { filename = hint.substring(index); } else { filename = hint; } } // If we couldn't do anything with the hint, move toward the content disposition if (filename == null && contentDisposition != null) { filename = parseContentDisposition(contentDisposition); if (filename != null) { if (Constants.LOGVV) { Log.v(Constants.TAG, "getting filename from content-disposition"); } int index = filename.lastIndexOf('/') + 1; if (index > 0) { filename = filename.substring(index); } } } // If we still have nothing at this point, try the content location if (filename == null && contentLocation != null) { String decodedContentLocation = Uri.decode(contentLocation); if (decodedContentLocation != null && !decodedContentLocation.endsWith("/") && decodedContentLocation.indexOf('?') < 0) { if (Constants.LOGVV) { Log.v(Constants.TAG, "getting filename from content-location"); } int index = decodedContentLocation.lastIndexOf('/') + 1; if (index > 0) { filename = decodedContentLocation.substring(index); } else { filename = decodedContentLocation; } } } // If all the other http-related approaches failed, use the plain uri if (filename == null) { String decodedUrl = Uri.decode(url); if (decodedUrl != null && !decodedUrl.endsWith("/") && decodedUrl.indexOf('?') < 0) { int index = decodedUrl.lastIndexOf('/') + 1; if (index > 0) { if (Constants.LOGVV) { Log.v(Constants.TAG, "getting filename from uri"); } filename = decodedUrl.substring(index); } } } // Finally, if couldn't get filename from URI, get a generic filename if (filename == null) { if (Constants.LOGVV) { Log.v(Constants.TAG, "using default filename"); } filename = Constants.DEFAULT_DL_FILENAME; } filename = filename.replaceAll("[^a-zA-Z0-9\\.\\-_]+", "_"); return filename; } private static String chooseExtensionFromMimeType(String mimeType, boolean useDefaults) { String extension = null; if (mimeType != null) { extension = MimeTypeMap.getSingleton().getExtensionFromMimeType(mimeType); if (extension != null) { if (Constants.LOGVV) { Log.v(Constants.TAG, "adding extension from type"); } extension = "." + extension; } else { if (Constants.LOGVV) { Log.v(Constants.TAG, "couldn't find extension for " + mimeType); } } } if (extension == null) { if (mimeType != null && mimeType.toLowerCase().startsWith("text/")) { if (mimeType.equalsIgnoreCase("text/html")) { if (Constants.LOGVV) { Log.v(Constants.TAG, "adding default html extension"); } extension = Constants.DEFAULT_DL_HTML_EXTENSION; } else if (useDefaults) { if (Constants.LOGVV) { Log.v(Constants.TAG, "adding default text extension"); } extension = Constants.DEFAULT_DL_TEXT_EXTENSION; } } else if (useDefaults) { if (Constants.LOGVV) { Log.v(Constants.TAG, "adding default binary extension"); } extension = Constants.DEFAULT_DL_BINARY_EXTENSION; } } return extension; } private static String chooseExtensionFromFilename(String mimeType, int destination, String filename, int dotIndex) { String extension = null; if (mimeType != null) { // Compare the last segment of the extension against the mime type. // If there's a mismatch, discard the entire extension. int lastDotIndex = filename.lastIndexOf('.'); String typeFromExt = MimeTypeMap.getSingleton().getMimeTypeFromExtension( filename.substring(lastDotIndex + 1)); if (typeFromExt == null || !typeFromExt.equalsIgnoreCase(mimeType)) { extension = chooseExtensionFromMimeType(mimeType, false); if (extension != null) { if (Constants.LOGVV) { Log.v(Constants.TAG, "substituting extension from type"); } } else { if (Constants.LOGVV) { Log.v(Constants.TAG, "couldn't find extension for " + mimeType); } } } } if (extension == null) { if (Constants.LOGVV) { Log.v(Constants.TAG, "keeping extension"); } extension = filename.substring(dotIndex); } return extension; } private static String chooseUniqueFilename(int destination, String filename, String extension, boolean recoveryDir) throws GenerateSaveFileError { String fullFilename = filename + extension; if (!new File(fullFilename).exists() && (!recoveryDir || (destination != Downloads.Impl.DESTINATION_CACHE_PARTITION && destination != Downloads.Impl.DESTINATION_CACHE_PARTITION_PURGEABLE && destination != Downloads.Impl.DESTINATION_CACHE_PARTITION_NOROAMING))) { return fullFilename; } filename = filename + Constants.FILENAME_SEQUENCE_SEPARATOR; /* * This number is used to generate partially randomized filenames to avoid * collisions. * It starts at 1. * The next 9 iterations increment it by 1 at a time (up to 10). * The next 9 iterations increment it by 1 to 10 (random) at a time. * The next 9 iterations increment it by 1 to 100 (random) at a time. * ... Up to the point where it increases by 100000000 at a time. * (the maximum value that can be reached is 1000000000) * As soon as a number is reached that generates a filename that doesn't exist, * that filename is used. * If the filename coming in is [base].[ext], the generated filenames are * [base]-[sequence].[ext]. */ int sequence = 1; for (int magnitude = 1; magnitude < 1000000000; magnitude *= 10) { for (int iteration = 0; iteration < 9; ++iteration) { fullFilename = filename + sequence + extension; if (!new File(fullFilename).exists()) { return fullFilename; } if (Constants.LOGVV) { Log.v(Constants.TAG, "file with sequence number " + sequence + " exists"); } sequence += sRandom.nextInt(magnitude) + 1; } } throw new GenerateSaveFileError(Downloads.Impl.STATUS_FILE_ERROR); } /** * Deletes purgeable files from the cache partition. This also deletes * the matching database entries. Files are deleted in LRU order until * the total byte size is greater than targetBytes. */ public static final boolean discardPurgeableFiles(Context context, long targetBytes) { Cursor cursor = context.getContentResolver().query( Downloads.Impl.CONTENT_URI, null, "( " + Downloads.Impl.COLUMN_STATUS + " = '" + Downloads.Impl.STATUS_SUCCESS + "' AND " + Downloads.Impl.COLUMN_DESTINATION + " = '" + Downloads.Impl.DESTINATION_CACHE_PARTITION_PURGEABLE + "' )", null, Downloads.Impl.COLUMN_LAST_MODIFICATION); if (cursor == null) { return false; } long totalFreed = 0; try { cursor.moveToFirst(); while (!cursor.isAfterLast() && totalFreed < targetBytes) { File file = new File(cursor.getString(cursor.getColumnIndex(Downloads.Impl._DATA))); if (Constants.LOGVV) { Log.v(Constants.TAG, "purging " + file.getAbsolutePath() + " for " + file.length() + " bytes"); } totalFreed += file.length(); file.delete(); long id = cursor.getLong(cursor.getColumnIndex(Downloads.Impl._ID)); context.getContentResolver().delete( ContentUris.withAppendedId(Downloads.Impl.CONTENT_URI, id), null, null); cursor.moveToNext(); } } finally { cursor.close(); } if (Constants.LOGV) { if (totalFreed > 0) { Log.v(Constants.TAG, "Purged files, freed " + totalFreed + " for " + targetBytes + " requested"); } } return totalFreed > 0; } /** * Returns whether the network is available */ public static boolean isNetworkAvailable(SystemFacade system) { return system.getActiveNetworkType() != null; } /** * Checks whether the filename looks legitimate */ public static boolean isFilenameValid(String filename) { filename = filename.replaceFirst("/+", "/"); // normalize leading slashes return filename.startsWith(Environment.getDownloadCacheDirectory().toString()) || filename.startsWith(Environment.getExternalStorageDirectory().toString()); } /** * Checks whether this looks like a legitimate selection parameter */ public static void validateSelection(String selection, Set allowedColumns) { try { if (selection == null || selection.isEmpty()) { return; } Lexer lexer = new Lexer(selection, allowedColumns); parseExpression(lexer); if (lexer.currentToken() != Lexer.TOKEN_END) { throw new IllegalArgumentException("syntax error"); } } catch (RuntimeException ex) { if (Constants.LOGV) { Log.d(Constants.TAG, "invalid selection [" + selection + "] triggered " + ex); } else if (Config.LOGD) { Log.d(Constants.TAG, "invalid selection triggered " + ex); } throw ex; } } // expression <- ( expression ) | statement [AND_OR ( expression ) | statement] * // | statement [AND_OR expression]* private static void parseExpression(Lexer lexer) { for (;;) { // ( expression ) if (lexer.currentToken() == Lexer.TOKEN_OPEN_PAREN) { lexer.advance(); parseExpression(lexer); if (lexer.currentToken() != Lexer.TOKEN_CLOSE_PAREN) { throw new IllegalArgumentException("syntax error, unmatched parenthese"); } lexer.advance(); } else { // statement parseStatement(lexer); } if (lexer.currentToken() != Lexer.TOKEN_AND_OR) { break; } lexer.advance(); } } // statement <- COLUMN COMPARE VALUE // | COLUMN IS NULL private static void parseStatement(Lexer lexer) { // both possibilities start with COLUMN if (lexer.currentToken() != Lexer.TOKEN_COLUMN) { throw new IllegalArgumentException("syntax error, expected column name"); } lexer.advance(); // statement <- COLUMN COMPARE VALUE if (lexer.currentToken() == Lexer.TOKEN_COMPARE) { lexer.advance(); if (lexer.currentToken() != Lexer.TOKEN_VALUE) { throw new IllegalArgumentException("syntax error, expected quoted string"); } lexer.advance(); return; } // statement <- COLUMN IS NULL if (lexer.currentToken() == Lexer.TOKEN_IS) { lexer.advance(); if (lexer.currentToken() != Lexer.TOKEN_NULL) { throw new IllegalArgumentException("syntax error, expected NULL"); } lexer.advance(); return; } // didn't get anything good after COLUMN throw new IllegalArgumentException("syntax error after column name"); } /** * A simple lexer that recognizes the words of our restricted subset of SQL where clauses */ private static class Lexer { public static final int TOKEN_START = 0; public static final int TOKEN_OPEN_PAREN = 1; public static final int TOKEN_CLOSE_PAREN = 2; public static final int TOKEN_AND_OR = 3; public static final int TOKEN_COLUMN = 4; public static final int TOKEN_COMPARE = 5; public static final int TOKEN_VALUE = 6; public static final int TOKEN_IS = 7; public static final int TOKEN_NULL = 8; public static final int TOKEN_END = 9; private final String mSelection; private final Set mAllowedColumns; private int mOffset = 0; private int mCurrentToken = TOKEN_START; private final char[] mChars; public Lexer(String selection, Set allowedColumns) { mSelection = selection; mAllowedColumns = allowedColumns; mChars = new char[mSelection.length()]; mSelection.getChars(0, mChars.length, mChars, 0); advance(); } public int currentToken() { return mCurrentToken; } public void advance() { char[] chars = mChars; // consume whitespace while (mOffset < chars.length && chars[mOffset] == ' ') { ++mOffset; } // end of input if (mOffset == chars.length) { mCurrentToken = TOKEN_END; return; } // "(" if (chars[mOffset] == '(') { ++mOffset; mCurrentToken = TOKEN_OPEN_PAREN; return; } // ")" if (chars[mOffset] == ')') { ++mOffset; mCurrentToken = TOKEN_CLOSE_PAREN; return; } // "?" if (chars[mOffset] == '?') { ++mOffset; mCurrentToken = TOKEN_VALUE; return; } // "=" and "==" if (chars[mOffset] == '=') { ++mOffset; mCurrentToken = TOKEN_COMPARE; if (mOffset < chars.length && chars[mOffset] == '=') { ++mOffset; } return; } // ">" and ">=" if (chars[mOffset] == '>') { ++mOffset; mCurrentToken = TOKEN_COMPARE; if (mOffset < chars.length && chars[mOffset] == '=') { ++mOffset; } return; } // "<", "<=" and "<>" if (chars[mOffset] == '<') { ++mOffset; mCurrentToken = TOKEN_COMPARE; if (mOffset < chars.length && (chars[mOffset] == '=' || chars[mOffset] == '>')) { ++mOffset; } return; } // "!=" if (chars[mOffset] == '!') { ++mOffset; mCurrentToken = TOKEN_COMPARE; if (mOffset < chars.length && chars[mOffset] == '=') { ++mOffset; return; } throw new IllegalArgumentException("Unexpected character after !"); } // columns and keywords // first look for anything that looks like an identifier or a keyword // and then recognize the individual words. // no attempt is made at discarding sequences of underscores with no alphanumeric // characters, even though it's not clear that they'd be legal column names. if (isIdentifierStart(chars[mOffset])) { int startOffset = mOffset; ++mOffset; while (mOffset < chars.length && isIdentifierChar(chars[mOffset])) { ++mOffset; } String word = mSelection.substring(startOffset, mOffset); if (mOffset - startOffset <= 4) { if (word.equals("IS")) { mCurrentToken = TOKEN_IS; return; } if (word.equals("OR") || word.equals("AND")) { mCurrentToken = TOKEN_AND_OR; return; } if (word.equals("NULL")) { mCurrentToken = TOKEN_NULL; return; } } if (mAllowedColumns.contains(word)) { mCurrentToken = TOKEN_COLUMN; return; } throw new IllegalArgumentException("unrecognized column or keyword"); } // quoted strings if (chars[mOffset] == '\'') { ++mOffset; while (mOffset < chars.length) { if (chars[mOffset] == '\'') { if (mOffset + 1 < chars.length && chars[mOffset + 1] == '\'') { ++mOffset; } else { break; } } ++mOffset; } if (mOffset == chars.length) { throw new IllegalArgumentException("unterminated string"); } ++mOffset; mCurrentToken = TOKEN_VALUE; return; } // anything we don't recognize throw new IllegalArgumentException("illegal character: " + chars[mOffset]); } private static final boolean isIdentifierStart(char c) { return c == '_' || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'); } private static final boolean isIdentifierChar(char c) { return c == '_' || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9'); } } }