/*

  * 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.commons.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.nio.charset.Charset;

 import java.util.ArrayList;

 import java.util.Arrays;

 import java.util.List;

 import java.util.Locale;

 import java.util.StringTokenizer;

 /**

  * General File System utilities.

  * <p>

  * This class provides static utility methods for general file system

  * functions not provided via the JDK {@link java.io.File File} class.

  * <p>

  * The current functions provided are:

  * <ul>

  * <li>Get the free space on a drive

  * </ul>

  *

  * @version $Id: FileSystemUtils.java 1471767 2013-04-24 23:24:19Z sebb $

  * @since 1.1

  */

 public class FileSystemUtils {

     /** Singleton instance, used mainly for testing. */

     private static final FileSystemUtils INSTANCE = new FileSystemUtils();

     /** 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 (final Exception ex) {

             os = INIT_PROBLEM;

         }

         OS = os;

         DF = dfPath;

     }

     /**

      * Instances should NOT be constructed in standard programming.

      */

     public FileSystemUtils() {

         super();

     }

     //-----------------------------------------------------------------------

     /**

      * Returns the free space on a drive or volume by invoking

      * the command line.

      * This method does not normalize the result, and typically returns

      * bytes on Windows, 512 byte units on OS X and kilobytes on Unix.

      * As this is not very useful, this method is deprecated in favour

      * of {@link #freeSpaceKb(String)} which returns a result in kilobytes.

      * <p>

      * Note that some OS's are NOT currently supported, including OS/390,

      * OpenVMS.

      * <pre>

      * FileSystemUtils.freeSpace("C:");       // Windows

      * FileSystemUtils.freeSpace("/volume");  // *nix

      * </pre>

      * 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

      * @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

      * @since 1.1, enhanced OS support in 1.2 and 1.3

      * @deprecated Use freeSpaceKb(String)

      *  Deprecated from 1.3, may be removed in 2.0

      */

     @Deprecated

     public static long freeSpace(final String path) throws IOException {

         return INSTANCE.freeSpaceOS(path, OS, false, -1);

     }

     //-----------------------------------------------------------------------

     /**

      * Returns the free space on a drive or volume in kilobytes by invoking

      * the command line.

      * <pre>

      * FileSystemUtils.freeSpaceKb("C:");       // Windows

      * FileSystemUtils.freeSpaceKb("/volume");  // *nix

      * </pre>

      * 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.

      * <p>

      * 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

      * @since 1.2, enhanced OS support in 1.3

      */

     public static long freeSpaceKb(final String path) throws IOException {

         return freeSpaceKb(path, -1);

     }

     /**

      * Returns the free space on a drive or volume in kilobytes by invoking

      * the command line.

      * <pre>

      * FileSystemUtils.freeSpaceKb("C:");       // Windows

      * FileSystemUtils.freeSpaceKb("/volume");  // *nix

      * </pre>

      * 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.

      * <p>

      * 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

      * @since 2.0

      */

     public static long freeSpaceKb(final String path, final long timeout) throws IOException {

         return INSTANCE.freeSpaceOS(path, OS, true, timeout);

     }

     /**

      * Returns the disk size of the volume which holds the working directory.

      * <p>

      * Identical to:

      * <pre>

      * freeSpaceKb(new File(".").getAbsolutePath())

      * </pre>

      * @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

      * @since 2.0

      */

     public static long freeSpaceKb() throws IOException {

         return freeSpaceKb(-1);

     }

     /**

      * Returns the disk size of the volume which holds the working directory.

      * <p>

      * Identical to:

      * <pre>

      * freeSpaceKb(new File(".").getAbsolutePath())

      * </pre>

      * @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

      * @since 2.0

      */

     public static long freeSpaceKb(final 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.

      * <pre>

      * FileSystemUtils.freeSpace("C:");  // Windows

      * FileSystemUtils.freeSpace("/volume");  // *nix

      * </pre>

      * 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(final String path, final int os, final boolean kb, final long timeout) throws IOException {

         if (path == null) {

             throw new IllegalArgumentException("Path must not be empty");

         }

         switch (os) {

             case WINDOWS:

                 return kb ? freeSpaceWindows(path, timeout) / FileUtils.ONE_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, final long timeout) throws IOException {

         path = FilenameUtils.normalize(path, false);

         if (path.length() > 0 && path.charAt(0) != '"') {

             path = "\"" + path + "\"";

         }

         // build and run the 'dir' command

         final String[] cmdAttribs = new String[] {"cmd.exe", "/C", "dir /a /-c " + path};

         // read in the output of the command to an ArrayList

         final List<String> 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--) {

             final 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(final String line, final 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) {

             final 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) {

             final 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

         final 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(final String path, final boolean kb, final boolean posix, final 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";

         }

         final 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)

         final List<String> 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);

         }

         final 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) {

                 final 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

         final 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(final String freeSpace, final String path) throws IOException {

         try {

             final 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 (final NumberFormatException ex) {

             throw new IOExceptionWithCause(

                     "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 lines returned by the command, converted to lower-case

      * @throws IOException if an error occurs

      */

     List<String> performCommand(final String[] cmdAttribs, final int max, final 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 commons-exec or Ant for a better multi-threaded multi-os solution)

         final List<String> lines = new ArrayList<String>(20);

         Process proc = null;

         InputStream in = null;

         OutputStream out = null;

         InputStream err = null;

         BufferedReader inr = null;

         try {

             final Thread monitor = ThreadMonitor.start(timeout);

             proc = openProcess(cmdAttribs);

             in = proc.getInputStream();

             out = proc.getOutputStream();

             err = proc.getErrorStream();

             // default charset is most likely appropriate here

             inr = new BufferedReader(new InputStreamReader(in, Charset.defaultCharset()));

             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 (final InterruptedException ex) {

             throw new IOExceptionWithCause(

                     "Command line threw an InterruptedException " +

                     "for command " + Arrays.asList(cmdAttribs) + " timeout=" + timeout, ex);

         } finally {

             IOUtils.closeQuietly(in);

             IOUtils.closeQuietly(out);

             IOUtils.closeQuietly(err);

             IOUtils.closeQuietly(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(final String[] cmdAttribs) throws IOException {

         return Runtime.getRuntime().exec(cmdAttribs);

     }

 }