/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.hadoop.fs;
import java.io.*;
import java.nio.channels.FileChannel;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.util.IOThrottler;
import org.apache.hadoop.util.InjectionEventCore;
import org.apache.hadoop.util.InjectionHandler;
import org.apache.hadoop.util.StringUtils;
import org.apache.hadoop.util.Shell;
import org.apache.hadoop.util.Shell.ShellCommandExecutor;
/**
* A collection of file-processing util methods
*/
public class FileUtil {
static final Log LOG = LogFactory.getLog(FileUtil.class.getName());
/**
* convert an array of FileStatus to an array of Path
*
* @param stats
* an array of FileStatus objects
* @return an array of paths corresponding to the input
*/
public static Path[] stat2Paths(FileStatus[] stats) {
if (stats == null)
return null;
Path[] ret = new Path[stats.length];
for (int i = 0; i < stats.length; ++i) {
ret[i] = stats[i].getPath();
}
return ret;
}
/**
* convert an array of FileStatus to an array of Path.
* If stats if null, return path
* @param stats
* an array of FileStatus objects
* @param path
* default path to return in stats is null
* @return an array of paths corresponding to the input
*/
public static Path[] stat2Paths(FileStatus[] stats, Path path) {
if (stats == null)
return new Path[]{path};
else
return stat2Paths(stats);
}
/**
* Delete a directory and all its contents. If
* we return false, the directory may be partially-deleted.
*/
public static boolean fullyDelete(File dir) throws IOException {
boolean deleted = true;
File contents[] = dir.listFiles();
if (contents != null) {
for (int i = 0; i < contents.length; i++) {
if (contents[i].isFile()) {
if (!contents[i].delete()) {
deleted = false;
}
} else {
//try deleting the directory
// this might be a symlink
boolean b = false;
b = contents[i].delete();
if (b){
//this was indeed a symlink or an empty directory
continue;
}
// if not an empty directory or symlink let
// fullydelete handle it.
if (!fullyDelete(contents[i])) {
deleted = false;
}
}
}
}
return dir.delete() && deleted;
}
/**
* Recursively delete a directory.
*
* @param fs {@link FileSystem} on which the path is present
* @param dir directory to recursively delete
* @throws IOException
* @deprecated Use {@link FileSystem#delete(Path, boolean)}
*/
@Deprecated
public static void fullyDelete(FileSystem fs, Path dir)
throws IOException {
fs.delete(dir, true);
}
//
// If the destination is a subdirectory of the source, then
// generate exception
//
private static void checkDependencies(FileSystem srcFS,
Path src,
FileSystem dstFS,
Path dst)
throws IOException {
if (srcFS == dstFS) {
String srcq = src.makeQualified(srcFS).toString() + Path.SEPARATOR;
String dstq = dst.makeQualified(dstFS).toString() + Path.SEPARATOR;
if (dstq.startsWith(srcq)) {
if (srcq.length() == dstq.length()) {
throw new IOException("Cannot copy " + src + " to itself.");
} else {
throw new IOException("Cannot copy " + src + " to its subdirectory " +
dst);
}
}
}
}
/** Copy files between FileSystems. */
public static boolean copy(FileSystem srcFS, Path src,
FileSystem dstFS, Path dst,
boolean deleteSource,
Configuration conf) throws IOException {
return copy(srcFS, src, dstFS, dst, deleteSource, true, conf);
}
public static boolean copy(FileSystem srcFS, Path[] srcs,
FileSystem dstFS, Path dst,
boolean deleteSource,
boolean overwrite, Configuration conf)
throws IOException {
return copy(srcFS, srcs, dstFS, dst, deleteSource, overwrite, false, conf);
}
/**
* copy a list of files from a source file system to a directory dst
* in a destination file system
*
* @param srcFS source file system
* @param srcs a list of source files
* @param dstFS destination file system
* @param dst destination directory
* @param deleteSource if source should be deleted
* @param overwrite if destination should be overwritten
* @param validate if destination file should be validated
* @param conf configuration
* @return true if copy succeeds
* @throws IOException if error occurs
*/
public static boolean copy(FileSystem srcFS, Path[] srcs,
FileSystem dstFS, Path dst,
boolean deleteSource,
boolean overwrite, boolean validate, Configuration conf)
throws IOException {
return copy(srcFS, srcs, dstFS, dst, deleteSource,
overwrite, validate, conf, null);
}
/**
* copy a list of files from a source file system to a directory dst
* in a destination file system
*
* @param srcFS source file system
* @param srcs a list of source files
* @param dstFS destination file system
* @param dst destination directory
* @param deleteSource if source should be deleted
* @param overwrite if destination should be overwritten
* @param validate if destination file should be validated
* @param conf configuration
* @param throttler IOThrottler for copy
* @return true if copy succeeds
* @throws IOException if error occurs
*/
public static boolean copy(FileSystem srcFS, Path[] srcs,
FileSystem dstFS, Path dst,
boolean deleteSource,
boolean overwrite, boolean validate,
Configuration conf,
IOThrottler throttler)
throws IOException {
boolean gotException = false;
boolean returnVal = true;
StringBuffer exceptions = new StringBuffer();
if (srcs.length == 1)
return copy(srcFS, srcs[0], dstFS, dst, deleteSource, overwrite,
validate, conf, throttler);
// Check if dest is directory
if (!dstFS.exists(dst)) {
throw new IOException("`" + dst +"': specified destination directory " +
"doest not exist");
} else {
FileStatus sdst = dstFS.getFileStatus(dst);
if (!sdst.isDir())
throw new IOException("copying multiple files, but last argument `" +
dst + "' is not a directory");
}
for (Path src : srcs) {
try {
if (!copy(srcFS, src, dstFS, dst, deleteSource, overwrite,
validate, conf, throttler))
returnVal = false;
} catch (IOException e) {
gotException = true;
exceptions.append(e.getMessage());
exceptions.append("\n");
}
}
if (gotException) {
throw new IOException(exceptions.toString());
}
return returnVal;
}
/** Copy files between FileSystems. */
public static boolean copy(FileSystem srcFS, Path src,
FileSystem dstFS, Path dst,
boolean deleteSource,
boolean overwrite,
Configuration conf) throws IOException {
return copy(srcFS, src, dstFS, dst, deleteSource, overwrite, false, conf);
}
/**
* Copy files between file systems
* @param srcFS source file system
* @param src source file
* @param dstFS destination file system
* @param dst destination file
* @param deleteSource if source should be deleted
* @param overwrite if destination could be overwritten if exists
* @param validate if source and destination should be validated
* @param conf configuration
* @return true if succeed
* @throws IOException if error occurs
*/
public static boolean copy(FileSystem srcFS, Path src,
FileSystem dstFS, Path dst,
boolean deleteSource,
boolean overwrite, boolean validate,
Configuration conf) throws IOException {
return copy(srcFS, src, dstFS, dst, deleteSource,
overwrite, validate, conf, null);
}
/**
* Copy files between file systems
* @param srcFS source file system
* @param src source file
* @param dstFS destination file system
* @param dst destination file
* @param deleteSource if source should be deleted
* @param overwrite if destination could be overwritten if exists
* @param validate if source and destination should be validated
* @param conf configuration
* @param throttler IOThrottler for copy
* @return true if succeed
* @throws IOException if error occurs
*/
public static boolean copy(FileSystem srcFS, Path src,
FileSystem dstFS, Path dst,
boolean deleteSource,
boolean overwrite, boolean validate,
Configuration conf,
IOThrottler throttler) throws IOException {
dst = checkDest(src.getName(), dstFS, dst, overwrite);
FileStatus srcFileStatus = srcFS.getFileStatus(src);
if (srcFileStatus == null) {
throw new FileNotFoundException("File not found: " + src);
}
if (srcFileStatus.isDir()) {
checkDependencies(srcFS, src, dstFS, dst);
if (!dstFS.mkdirs(dst)) {
return false;
}
FileStatus contents[] = srcFS.listStatus(src);
for (int i = 0; i < contents.length; i++) {
copy(srcFS, contents[i].getPath(), dstFS,
new Path(dst, contents[i].getPath().getName()),
deleteSource, overwrite, validate, conf, throttler);
}
} else {
InputStream in=null;
OutputStream out = null;
try {
in = srcFS.open(src);
out = dstFS.create(dst, overwrite);
IOUtils.copyBytes(in, out, conf.getInt("io.file.buffer.size", 4096),
true, throttler);
// validate file size
if (validate) {
InjectionHandler.processEventIO(
InjectionEventCore.FILE_TRUNCATION, dstFS, dst);
FileStatus dstFileStatus = dstFS.getFileStatus(dst);
if (dstFileStatus == null ||
dstFileStatus.getLen() != srcFileStatus.getLen()) {
throw new IOException("Mismatched file length: src=" + src +
" dst=" + dst);
}
}
} catch (IOException e) {
IOUtils.closeStream(out);
IOUtils.closeStream(in);
dstFS.delete(dst, true);
throw e;
}
}
if (deleteSource) {
return srcFS.delete(src, true);
} else {
return true;
}
}
/** Copy all files in a directory to one output file (merge). */
public static boolean copyMerge(FileSystem srcFS, Path srcDir,
FileSystem dstFS, Path dstFile,
boolean deleteSource,
Configuration conf, String addString) throws IOException {
dstFile = checkDest(srcDir.getName(), dstFS, dstFile, false);
if (!srcFS.getFileStatus(srcDir).isDir())
return false;
OutputStream out = dstFS.create(dstFile);
try {
FileStatus contents[] = srcFS.listStatus(srcDir);
for (int i = 0; i < contents.length; i++) {
if (!contents[i].isDir()) {
InputStream in = srcFS.open(contents[i].getPath());
try {
IOUtils.copyBytes(in, out, conf, false);
if (addString!=null)
out.write(addString.getBytes("UTF-8"));
} finally {
in.close();
}
}
}
} finally {
out.close();
}
if (deleteSource) {
return srcFS.delete(srcDir, true);
} else {
return true;
}
}
public static boolean copy(File src, FileSystem dstFS, File dst,
boolean deleteSource, Configuration conf) throws IOException {
return copy(src, dstFS, new Path(dst.getAbsolutePath()), deleteSource, conf);
}
/** Copy local files to a FileSystem. */
public static boolean copy(File src,
FileSystem dstFS, Path dst,
boolean deleteSource,
Configuration conf) throws IOException {
dst = checkDest(src.getName(), dstFS, dst, false);
if (src.isDirectory()) {
if (!dstFS.mkdirs(dst)) {
return false;
}
File contents[] = src.listFiles();
for (int i = 0; i < contents.length; i++) {
copy(contents[i], dstFS, new Path(dst, contents[i].getName()),
deleteSource, conf);
}
} else if (src.isFile()) {
InputStream in = null;
OutputStream out =null;
try {
in = new FileInputStream(src);
out = dstFS.create(dst);
IOUtils.copyBytes(in, out, conf);
} catch (IOException e) {
IOUtils.closeStream( out );
IOUtils.closeStream( in );
throw e;
}
} else {
throw new IOException(src.toString() +
": No such file or directory");
}
if (deleteSource) {
return FileUtil.fullyDelete(src);
} else {
return true;
}
}
/** Copy FileSystem files to local files. */
public static boolean copy(FileSystem srcFS, Path src,
File dst, boolean deleteSource,
Configuration conf) throws IOException {
return copy(srcFS, src, dst, deleteSource, conf, false, 0L);
}
public static void printChecksumToStderr(long checksum, Path file) {
System.err.println(Long.toHexString(checksum) + " " + file);
}
/** Copy FileSystem files to local files.
* If src is a file:
* genCrc = true: print the CRC checksum of file to stderr
* offset >=0 : copy starts from offset
* offset < 0 : copy starts from fileLen + offset (throw exception if
* file is still under-construction)
*/
public static boolean copy(FileSystem srcFS, Path src,
File dst, boolean deleteSource,
Configuration conf, boolean genCrc,
long offset) throws IOException {
return copy(srcFS, src, dst, deleteSource, false, conf, genCrc, offset);
}
public static boolean copy(FileSystem srcFS, Path src, File dst,
boolean deleteSource, boolean validate,
Configuration conf, boolean genCrc, long offset) throws IOException {
return copy(srcFS, src, dst, deleteSource, validate,
conf, genCrc, offset, null);
}
public static boolean copy(FileSystem srcFS, Path src, File dst,
boolean deleteSource, boolean validate,
Configuration conf, boolean genCrc, long offset,
IOThrottler throttler) throws IOException {
FileStatus fStat = srcFS.getFileStatus(src);
if (fStat == null) {
throw new FileNotFoundException(src.toString());
}
if (fStat.isDir()) {
if (!dst.mkdirs()) {
return false;
}
FileStatus contents[] = srcFS.listStatus(src);
for (int i = 0; i < contents.length; i++) {
copy(srcFS, contents[i].getPath(),
new File(dst, contents[i].getPath().getName()),
deleteSource, validate, conf, genCrc, offset, throttler);
}
} else {
FSDataInputStream in = srcFS.open(src);
if (offset < 0) {
if (in.isUnderConstruction()) {
throw new IOException("Couldn't copy under-construction file with " +
"negative offset " + offset);
}
offset += fStat.getLen();
}
in.seek(offset);
if (!genCrc) {
IOUtils.copyBytes(in, new FileOutputStream(dst),
conf.getInt("io.file.buffer.size", 4096), true, throttler);
} else {
long checksum = IOUtils.copyBytesAndGenerateCRC(in,
new FileOutputStream(dst), conf.getInt("io.file.buffer.size", 4096),
true, throttler);
printChecksumToStderr(checksum, src);
}
if (validate) {
InjectionHandler.processEventIO(
InjectionEventCore.FILE_TRUNCATION, FileSystem.getLocal(conf), dst);
if (fStat.getLen() - offset != dst.length()) {
throw new IOException("Mismatched file length: src=" + src +
" dst=" + dst);
}
}
}
if (deleteSource) {
return srcFS.delete(src, true);
} else {
return true;
}
}
private static Path checkDest(String srcName, FileSystem dstFS, Path dst,
boolean overwrite) throws IOException {
if (dstFS.exists(dst)) {
FileStatus sdst = dstFS.getFileStatus(dst);
if (sdst.isDir()) {
if (null == srcName) {
throw new IOException("Target " + dst + " is a directory");
}
return checkDest(null, dstFS, new Path(dst, srcName), overwrite);
} else if (!overwrite) {
throw new IOException("Target " + dst + " already exists");
}
}
return dst;
}
/**
* This class is only used on windows to invoke the cygpath command.
*/
private static class CygPathCommand extends Shell {
String[] command;
String result;
CygPathCommand(String path) throws IOException {
command = new String[]{"cygpath", "-u", path};
run();
}
String getResult() throws IOException {
return result;
}
protected String[] getExecString() {
return command;
}
protected void parseExecResult(BufferedReader lines) throws IOException {
String line = lines.readLine();
if (line == null) {
throw new IOException("Can't convert '" + command[2] +
" to a cygwin path");
}
result = line;
}
}
/**
* Convert a os-native filename to a path that works for the shell.
* @param filename The filename to convert
* @return The unix pathname
* @throws IOException on windows, there can be problems with the subprocess
*/
public static String makeShellPath(String filename) throws IOException {
if (Path.WINDOWS) {
return new CygPathCommand(filename).getResult();
} else {
return filename;
}
}
/**
* Convert a os-native filename to a path that works for the shell.
* @param file The filename to convert
* @return The unix pathname
* @throws IOException on windows, there can be problems with the subprocess
*/
public static String makeShellPath(File file) throws IOException {
return makeShellPath(file, false);
}
/**
* Convert a os-native filename to a path that works for the shell.
* @param file The filename to convert
* @param makeCanonicalPath
* Whether to make canonical path for the file passed
* @return The unix pathname
* @throws IOException on windows, there can be problems with the subprocess
*/
public static String makeShellPath(File file, boolean makeCanonicalPath)
throws IOException {
if (makeCanonicalPath) {
return makeShellPath(file.getCanonicalPath());
} else {
return makeShellPath(file.toString());
}
}
/**
* Takes an input dir and returns the du on that local directory. Very basic
* implementation.
*
* @param dir
* The input dir to get the disk space of this local dir
* @return The total disk space of the input local directory
*/
public static long getDU(File dir) {
long size = 0;
if (!dir.exists())
return 0;
if (!dir.isDirectory()) {
return dir.length();
} else {
size = dir.length();
File[] allFiles = dir.listFiles();
for (int i = 0; i < allFiles.length; i++) {
size = size + getDU(allFiles[i]);
}
return size;
}
}
/**
* Given a File input it will unzip the file in a the unzip directory
* passed as the second parameter
* @param inFile The zip file as input
* @param unzipDir The unzip directory where to unzip the zip file.
* @throws IOException
*/
public static void unZip(File inFile, File unzipDir) throws IOException {
Enumeration<? extends ZipEntry> entries;
ZipFile zipFile = new ZipFile(inFile);
try {
entries = zipFile.entries();
while (entries.hasMoreElements()) {
ZipEntry entry = entries.nextElement();
if (!entry.isDirectory()) {
InputStream in = zipFile.getInputStream(entry);
try {
File file = new File(unzipDir, entry.getName());
if (!file.getParentFile().mkdirs()) {
if (!file.getParentFile().isDirectory()) {
throw new IOException("Mkdirs failed to create " +
file.getParentFile().toString());
}
}
OutputStream out = new FileOutputStream(file);
try {
byte[] buffer = new byte[8192];
int i;
while ((i = in.read(buffer)) != -1) {
out.write(buffer, 0, i);
}
} finally {
out.close();
}
} finally {
in.close();
}
}
}
} finally {
zipFile.close();
}
}
/**
* Given a Tar File as input it will untar the file in a the untar directory
* passed as the second parameter
*
* This utility will untar ".tar" files and ".tar.gz","tgz" files.
*
* @param inFile The tar file as input.
* @param untarDir The untar directory where to untar the tar file.
* @throws IOException
*/
public static void unTar(File inFile, File untarDir) throws IOException {
if (!untarDir.mkdirs()) {
if (!untarDir.isDirectory()) {
throw new IOException("Mkdirs failed to create " + untarDir);
}
}
StringBuffer untarCommand = new StringBuffer();
boolean gzipped = inFile.toString().endsWith("gz");
if (gzipped) {
untarCommand.append(" gzip -dc '");
untarCommand.append(FileUtil.makeShellPath(inFile));
untarCommand.append("' | (");
}
untarCommand.append("cd '");
untarCommand.append(FileUtil.makeShellPath(untarDir));
untarCommand.append("' ; ");
untarCommand.append("tar -xf ");
if (gzipped) {
untarCommand.append(" -)");
} else {
untarCommand.append(FileUtil.makeShellPath(inFile));
}
String[] shellCmd = { "bash", "-c", untarCommand.toString() };
ShellCommandExecutor shexec = new ShellCommandExecutor(shellCmd);
shexec.execute();
int exitcode = shexec.getExitCode();
if (exitcode != 0) {
throw new IOException("Error untarring file " + inFile +
". Tar process exited with exit code " + exitcode);
}
}
/**
* Create a soft link between a src and destination
* only on a local disk. HDFS does not support this
* @param target the target for symlink
* @param linkname the symlink
* @return value returned by the command
*/
public static int symLink(String target, String linkname) throws IOException{
String cmd = "ln -s " + target + " " + linkname;
Process p = Runtime.getRuntime().exec(cmd, null);
int returnVal = -1;
try{
returnVal = p.waitFor();
} catch(InterruptedException e){
//do nothing as of yet
}
return returnVal;
}
/**
* Change the permissions on a filename.
* @param filename the name of the file to change
* @param perm the permission string
* @return the exit code from the command
* @throws IOException
* @throws InterruptedException
*/
public static int chmod(String filename, String perm
) throws IOException, InterruptedException {
return chmod(filename, perm, false);
}
/**
* Change the permissions on a file / directory, recursively, if
* needed.
* @param filename name of the file whose permissions are to change
* @param perm permission string
* @param recursive true, if permissions should be changed recursively
* @return the exit code from the command.
* @throws IOException
* @throws InterruptedException
*/
public static int chmod(String filename, String perm, boolean recursive)
throws IOException, InterruptedException {
StringBuffer cmdBuf = new StringBuffer();
cmdBuf.append("chmod ");
if (recursive) {
cmdBuf.append("-R ");
}
cmdBuf.append(perm).append(" ");
cmdBuf.append(filename);
String[] shellCmd = {"bash", "-c" ,cmdBuf.toString()};
ShellCommandExecutor shExec = new ShellCommandExecutor(shellCmd);
try {
shExec.execute();
}catch(IOException e) {
if(LOG.isDebugEnabled()) {
LOG.debug("Error while changing permission : " + filename
+" Exception: " + StringUtils.stringifyException(e));
}
}
return shExec.getExitCode();
}
/**
* Create a tmp file for a base file.
* @param basefile the base file of the tmp
* @param prefix file name prefix of tmp
* @param isDeleteOnExit if true, the tmp will be deleted when the VM exits
* @return a newly created tmp file
* @exception IOException If a tmp file cannot created
* @see java.io.File#createTempFile(String, String, File)
* @see java.io.File#deleteOnExit()
*/
public static final File createLocalTempFile(final File basefile,
final String prefix,
final boolean isDeleteOnExit)
throws IOException {
File tmp = File.createTempFile(prefix + basefile.getName(),
"", basefile.getParentFile());
if (isDeleteOnExit) {
tmp.deleteOnExit();
}
return tmp;
}
/**
* Return an array of FileStatus objects for each file beneath
* the given path to a specified depth (inclusive). Directories at
* the given depth will be returned, while directories above that
* depth will not.
* @param fs FileSystem on which to operate
* @param f starting path
* @param depth the depth of recursion. If 0 the function will
* return the status of the current file or directory.
* @exception IOException If this operation fails
*/
public static FileStatus[] listStatus(FileSystem fs, Path f, int depth)
throws IOException {
if (null == f) {
throw new IllegalArgumentException("Path cannot be null.");
}
if (null == fs) {
throw new IllegalArgumentException("File system cannot be null.");
}
if (depth < 0) {
throw new IllegalArgumentException("Depth cannot be negative.");
}
if (depth == 0) {
FileStatus[] fileStatus = {fs.getFileStatus(f)};
return fileStatus;
}
List<FileStatus> fileStatuses = listStatusHelper(fs, f, depth,
new ArrayList<FileStatus>());
return fileStatuses.toArray(new FileStatus[fileStatuses.size()]);
}
/**
* Core logic for listStatus
*/
public static List<FileStatus> listStatusHelper(FileSystem fs, Path path,
int depth, List<FileStatus> acc) throws IOException {
FileStatus[] fileStatusResults = fs.listStatus(path);
if (fileStatusResults == null) {
throw new IOException("Path does not exist: " + path);
}
for (FileStatus f : fileStatusResults) {
Path subPath = f.getPath();
if (!f.isDir()) {
acc.add(f); // Accumulate all files
} else {
if (depth > 1) {
listStatusHelper(fs, subPath, depth - 1, acc);
} else {
acc.add(f); // Accumulate all leaves
}
}
}
return acc;
}
/**
* pass in a directory path, get the list of statuses of leaf directories
* @param fs file system
* @param path path to scan
* @param acc the collection of file status of leaf directories
* @throws IOException if any error occurs
*/
public static void listStatusForLeafDir(FileSystem fs,
FileStatus pathStatus,
List<FileStatus> acc) throws IOException {
if (!pathStatus.isDir())
return;
FileStatus[] fileStatusResults = fs.listStatus(pathStatus.getPath());
if (fileStatusResults == null) {
throw new IOException("Path does not exist: " + pathStatus.getPath());
}
boolean leafDir = true;
for (FileStatus f : fileStatusResults) {
if (f.isDir()) {
leafDir = false;
listStatusForLeafDir(fs, f, acc);
}
}
if (leafDir) {
acc.add(pathStatus); // Accumulate leaf dir
}
}
/**
* A wrapper for {@link File#listFiles()}. This java.io API returns null when
* a dir is not a directory or for any I/O error. Instead of having null check
* everywhere File#listFiles() is used, we will add utility API to get around
* this problem. For the majority of cases where we prefer an IOException to
* be thrown.
*
* @param dir directory for which listing should be performed
* @return list of files or empty list
* @exception IOException
* for invalid directory or for a bad disk.
*/
public static File[] listFiles(File dir) throws IOException {
File[] files = dir.listFiles();
if (files == null) {
throw new IOException("Invalid directory or I/O error occurred for dir: "
+ dir.toString());
}
return files;
}
/**
* Move the src file to the name specified by target.
* @param src the source file
* @param target the target file
* @exception IOException If this operation fails
*/
public static void replaceFile(File src, File target) throws IOException {
/* renameTo() has two limitations on Windows platform.
* src.renameTo(target) fails if
* 1) If target already exists OR
* 2) If target is already open for reading/writing.
*/
if (!src.renameTo(target)) {
int retries = 5;
while (target.exists() && !target.delete() && retries-- >= 0) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
throw new IOException("replaceFile interrupted.");
}
}
if (!src.renameTo(target)) {
throw new IOException("Unable to rename " + src +
" to " + target);
}
}
}
}