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Panda Core is the core module of Panda Framework, it contains commonly used utility classes similar to apache-commons.
package panda.io;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Locale;
import java.util.StringTokenizer;
import panda.lang.Numbers;
import panda.lang.ThreadMonitor;
/**
* General File System utilities.
*
* This class provides static utility methods for general file system functions not provided via the
* JDK {@link java.io.File File} class.
*
* The current functions provided are:
*
* - Get the free space on a drive
*
*/
public class FileSystems {
/** Singleton instance, used mainly for testing. */
private static final FileSystems INSTANCE = new FileSystems();
/** Operating system state flag for error. */
private static final int INIT_PROBLEM = -1;
/** Operating system state flag for neither Unix nor Windows. */
private static final int OTHER = 0;
/** Operating system state flag for Windows. */
private static final int WINDOWS = 1;
/** Operating system state flag for Unix. */
private static final int UNIX = 2;
/** Operating system state flag for Posix flavour Unix. */
private static final int POSIX_UNIX = 3;
/** The operating system flag. */
private static final int OS;
/** The path to df */
private static final String DF;
static {
int os = OTHER;
String dfPath = "df";
try {
String osName = System.getProperty("os.name");
if (osName == null) {
throw new IOException("os.name not found");
}
osName = osName.toLowerCase(Locale.ENGLISH);
// match
if (osName.indexOf("windows") != -1) {
os = WINDOWS;
}
else if (osName.indexOf("linux") != -1 || osName.indexOf("mpe/ix") != -1 || osName.indexOf("freebsd") != -1
|| osName.indexOf("irix") != -1 || osName.indexOf("digital unix") != -1
|| osName.indexOf("unix") != -1 || osName.indexOf("mac os x") != -1) {
os = UNIX;
}
else if (osName.indexOf("sun os") != -1 || osName.indexOf("sunos") != -1 || osName.indexOf("solaris") != -1) {
os = POSIX_UNIX;
dfPath = "/usr/xpg4/bin/df";
}
else if (osName.indexOf("hp-ux") != -1 || osName.indexOf("aix") != -1) {
os = POSIX_UNIX;
}
else {
os = OTHER;
}
}
catch (Exception ex) {
os = INIT_PROBLEM;
}
OS = os;
DF = dfPath;
}
// -----------------------------------------------------------------------
/**
* Returns the free space on a drive or volume in kilobytes by invoking the command line.
*
*
* FileSystemUtils.freeSpaceKb("C:"); // Windows
* FileSystemUtils.freeSpaceKb("/volume"); // *nix
*
*
* The free space is calculated via the command line. It uses 'dir /-c' on Windows, 'df -kP' on
* AIX/HP-UX and 'df -k' on other Unix.
*
* In order to work, you must be running Windows, or have a implementation of Unix df that
* supports GNU format when passed -k (or -kP). If you are going to rely on this code, please
* check that it works on your OS by running some simple tests to compare the command line with
* the output from this class. If your operating system isn't supported, please raise a JIRA
* call detailing the exact result from df -k and as much other detail as possible, thanks.
*
* @param path the path to get free space for, not null, not empty on Unix
* @return the amount of free drive space on the drive or volume in kilobytes
* @throws IllegalArgumentException if the path is invalid
* @throws IllegalStateException if an error occurred in initialisation
* @throws IOException if an error occurs when finding the free space
*/
public static long freeSpaceKb(String path) throws IOException {
return freeSpaceKb(path, -1);
}
/**
* Returns the free space on a drive or volume in kilobytes by invoking the command line.
*
*
* FileSystemUtils.freeSpaceKb("C:"); // Windows
* FileSystemUtils.freeSpaceKb("/volume"); // *nix
*
*
* The free space is calculated via the command line. It uses 'dir /-c' on Windows, 'df -kP' on
* AIX/HP-UX and 'df -k' on other Unix.
*
* In order to work, you must be running Windows, or have a implementation of Unix df that
* supports GNU format when passed -k (or -kP). If you are going to rely on this code, please
* check that it works on your OS by running some simple tests to compare the command line with
* the output from this class. If your operating system isn't supported, please raise a JIRA
* call detailing the exact result from df -k and as much other detail as possible, thanks.
*
* @param path the path to get free space for, not null, not empty on Unix
* @param timeout The timout amount in milliseconds or no timeout if the value is zero or less
* @return the amount of free drive space on the drive or volume in kilobytes
* @throws IllegalArgumentException if the path is invalid
* @throws IllegalStateException if an error occurred in initialisation
* @throws IOException if an error occurs when finding the free space
*/
public static long freeSpaceKb(String path, long timeout) throws IOException {
return INSTANCE.freeSpaceOS(path, OS, true, timeout);
}
/**
* Returns the disk size of the volume which holds the working directory.
*
* Identical to:
*
*
* freeSpaceKb(new File(".").getAbsolutePath())
*
*
* @return the amount of free drive space on the drive or volume in kilobytes
* @throws IllegalStateException if an error occurred in initialisation
* @throws IOException if an error occurs when finding the free space
*/
public static long freeSpaceKb() throws IOException {
return freeSpaceKb(-1);
}
/**
* Returns the disk size of the volume which holds the working directory.
*
* Identical to:
*
*
* freeSpaceKb(new File(".").getAbsolutePath())
*
*
* @param timeout The timout amount in milliseconds or no timeout if the value is zero or less
* @return the amount of free drive space on the drive or volume in kilobytes
* @throws IllegalStateException if an error occurred in initialisation
* @throws IOException if an error occurs when finding the free space
*/
public static long freeSpaceKb(long timeout) throws IOException {
return freeSpaceKb(new File(".").getAbsolutePath(), timeout);
}
// -----------------------------------------------------------------------
/**
* Returns the free space on a drive or volume in a cross-platform manner. Note that some OS's
* are NOT currently supported, including OS/390.
*
*
* FileSystemUtils.freeSpace("C:"); // Windows
* FileSystemUtils.freeSpace("/volume"); // *nix
*
*
* The free space is calculated via the command line. It uses 'dir /-c' on Windows and 'df' on
* *nix.
*
* @param path the path to get free space for, not null, not empty on Unix
* @param os the operating system code
* @param kb whether to normalize to kilobytes
* @param timeout The timout amount in milliseconds or no timeout if the value is zero or less
* @return the amount of free drive space on the drive or volume
* @throws IllegalArgumentException if the path is invalid
* @throws IllegalStateException if an error occurred in initialisation
* @throws IOException if an error occurs when finding the free space
*/
long freeSpaceOS(String path, int os, boolean kb, long timeout) throws IOException {
if (path == null) {
throw new IllegalArgumentException("Path must not be empty");
}
switch (os) {
case WINDOWS:
return kb ? freeSpaceWindows(path, timeout) / Numbers.KB : freeSpaceWindows(path, timeout);
case UNIX:
return freeSpaceUnix(path, kb, false, timeout);
case POSIX_UNIX:
return freeSpaceUnix(path, kb, true, timeout);
case OTHER:
throw new IllegalStateException("Unsupported operating system");
default:
throw new IllegalStateException("Exception caught when determining operating system");
}
}
// -----------------------------------------------------------------------
/**
* Find free space on the Windows platform using the 'dir' command.
*
* @param path the path to get free space for, including the colon
* @param timeout The timout amount in milliseconds or no timeout if the value is zero or less
* @return the amount of free drive space on the drive
* @throws IOException if an error occurs
*/
long freeSpaceWindows(String path, long timeout) throws IOException {
path = FileNames.normalize(path, false);
if (path.length() > 0 && path.charAt(0) != '"') {
path = "\"" + path + "\"";
}
// build and run the 'dir' command
String[] cmdAttribs = new String[] { "cmd.exe", "/C", "dir /a /-c " + path };
// read in the output of the command to an ArrayList
List lines = performCommand(cmdAttribs, Integer.MAX_VALUE, timeout);
// now iterate over the lines we just read and find the LAST
// non-empty line (the free space bytes should be in the last element
// of the ArrayList anyway, but this will ensure it works even if it's
// not, still assuming it is on the last non-blank line)
for (int i = lines.size() - 1; i >= 0; i--) {
String line = lines.get(i);
if (line.length() > 0) {
return parseDir(line, path);
}
}
// all lines are blank
throw new IOException("Command line 'dir /-c' did not return any info " + "for path '" + path + "'");
}
/**
* Parses the Windows dir response last line
*
* @param line the line to parse
* @param path the path that was sent
* @return the number of bytes
* @throws IOException if an error occurs
*/
long parseDir(String line, String path) throws IOException {
// read from the end of the line to find the last numeric
// character on the line, then continue until we find the first
// non-numeric character, and everything between that and the last
// numeric character inclusive is our free space bytes count
int bytesStart = 0;
int bytesEnd = 0;
int j = line.length() - 1;
innerLoop1: while (j >= 0) {
char c = line.charAt(j);
if (Character.isDigit(c)) {
// found the last numeric character, this is the end of
// the free space bytes count
bytesEnd = j + 1;
break innerLoop1;
}
j--;
}
innerLoop2: while (j >= 0) {
char c = line.charAt(j);
if (!Character.isDigit(c) && c != ',' && c != '.') {
// found the next non-numeric character, this is the
// beginning of the free space bytes count
bytesStart = j + 1;
break innerLoop2;
}
j--;
}
if (j < 0) {
throw new IOException("Command line 'dir /-c' did not return valid info " + "for path '" + path + "'");
}
// remove commas and dots in the bytes count
StringBuilder buf = new StringBuilder(line.substring(bytesStart, bytesEnd));
for (int k = 0; k < buf.length(); k++) {
if (buf.charAt(k) == ',' || buf.charAt(k) == '.') {
buf.deleteCharAt(k--);
}
}
return parseBytes(buf.toString(), path);
}
// -----------------------------------------------------------------------
/**
* Find free space on the *nix platform using the 'df' command.
*
* @param path the path to get free space for
* @param kb whether to normalize to kilobytes
* @param posix whether to use the posix standard format flag
* @param timeout The timout amount in milliseconds or no timeout if the value is zero or less
* @return the amount of free drive space on the volume
* @throws IOException if an error occurs
*/
long freeSpaceUnix(String path, boolean kb, boolean posix, long timeout) throws IOException {
if (path.length() == 0) {
throw new IllegalArgumentException("Path must not be empty");
}
// build and run the 'dir' command
String flags = "-";
if (kb) {
flags += "k";
}
if (posix) {
flags += "P";
}
String[] cmdAttribs = flags.length() > 1 ? new String[] { DF, flags, path } : new String[] { DF, path };
// perform the command, asking for up to 3 lines (header, interesting, overflow)
List lines = performCommand(cmdAttribs, 3, timeout);
if (lines.size() < 2) {
// unknown problem, throw exception
throw new IOException("Command line '" + DF + "' did not return info as expected " + "for path '" + path
+ "'- response was " + lines);
}
String line2 = lines.get(1); // the line we're interested in
// Now, we tokenize the string. The fourth element is what we want.
StringTokenizer tok = new StringTokenizer(line2, " ");
if (tok.countTokens() < 4) {
// could be long Filesystem, thus data on third line
if (tok.countTokens() == 1 && lines.size() >= 3) {
String line3 = lines.get(2); // the line may be interested in
tok = new StringTokenizer(line3, " ");
}
else {
throw new IOException("Command line '" + DF + "' did not return data as expected " + "for path '"
+ path + "'- check path is valid");
}
}
else {
tok.nextToken(); // Ignore Filesystem
}
tok.nextToken(); // Ignore 1K-blocks
tok.nextToken(); // Ignore Used
String freeSpace = tok.nextToken();
return parseBytes(freeSpace, path);
}
// -----------------------------------------------------------------------
/**
* Parses the bytes from a string.
*
* @param freeSpace the free space string
* @param path the path
* @return the number of bytes
* @throws IOException if an error occurs
*/
long parseBytes(String freeSpace, String path) throws IOException {
try {
long bytes = Long.parseLong(freeSpace);
if (bytes < 0) {
throw new IOException("Command line '" + DF + "' did not find free space in response " + "for path '"
+ path + "'- check path is valid");
}
return bytes;
}
catch (NumberFormatException ex) {
throw new IOException("Command line '" + DF + "' did not return numeric data as expected " + "for path '"
+ path + "'- check path is valid", ex);
}
}
// -----------------------------------------------------------------------
/**
* Performs the os command.
*
* @param cmdAttribs the command line parameters
* @param max The maximum limit for the lines returned
* @param timeout The timout amount in milliseconds or no timeout if the value is zero or less
* @return the parsed data
* @throws IOException if an error occurs
*/
List performCommand(String[] cmdAttribs, int max, long timeout) throws IOException {
// this method does what it can to avoid the 'Too many open files' error
// based on trial and error and these links:
// http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4784692
// http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4801027
// http://forum.java.sun.com/thread.jspa?threadID=533029&messageID=2572018
// however, its still not perfect as the JDK support is so poor
// (see commond-exec or ant for a better multi-threaded multi-os solution)
List lines = new ArrayList(20);
Process proc = null;
InputStream in = null;
OutputStream out = null;
InputStream err = null;
BufferedReader inr = null;
try {
Thread monitor = ThreadMonitor.start(timeout);
proc = openProcess(cmdAttribs);
in = proc.getInputStream();
out = proc.getOutputStream();
err = proc.getErrorStream();
inr = new BufferedReader(new InputStreamReader(in));
String line = inr.readLine();
while (line != null && lines.size() < max) {
line = line.toLowerCase(Locale.ENGLISH).trim();
lines.add(line);
line = inr.readLine();
}
proc.waitFor();
ThreadMonitor.stop(monitor);
if (proc.exitValue() != 0) {
// os command problem, throw exception
throw new IOException("Command line returned OS error code '" + proc.exitValue() + "' for command "
+ Arrays.asList(cmdAttribs));
}
if (lines.isEmpty()) {
// unknown problem, throw exception
throw new IOException("Command line did not return any info " + "for command "
+ Arrays.asList(cmdAttribs));
}
return lines;
}
catch (InterruptedException ex) {
throw new IOException("Command line threw an InterruptedException " + "for command "
+ Arrays.asList(cmdAttribs) + " timeout=" + timeout, ex);
}
finally {
Streams.safeClose(in);
Streams.safeClose(out);
Streams.safeClose(err);
Streams.safeClose(inr);
if (proc != null) {
proc.destroy();
}
}
}
/**
* Opens the process to the operating system.
*
* @param cmdAttribs the command line parameters
* @return the process
* @throws IOException if an error occurs
*/
Process openProcess(String[] cmdAttribs) throws IOException {
return Runtime.getRuntime().exec(cmdAttribs);
}
}