code: /*
   * 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.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>
   *
   * @author Frank W. Zammetti
   * @author Stephen Colebourne
   * @author Thomas Ledoux
   * @author James Urie
   * @author Magnus Grimsell
   * @author Thomas Ledoux
   * @version $Id: FileSystemUtils.java 1003647 2010-10-01 20:53:59Z niallp $
   * @since Commons IO 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 (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 Commons IO 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(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 Commons IO 1.2, enhanced OS support in 1.3
       */
      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.
       * <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 Commons IO 2.0
       */
      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.
       * <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 Commons IO 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 Commons IO 2.0
       */
      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.
       * <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(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) / 1024 : 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 = FilenameUtils.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 /-c " + path};
          
          // read in the output of the command to an ArrayList
          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--) {
              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<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);
          }
          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 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 parsed data
       * @throws IOException if an error occurs
       */
      List<String> 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<String> lines = new ArrayList<String>(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.size() == 0) {
                  // 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 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(String[] cmdAttribs) throws IOException {
          return Runtime.getRuntime().exec(cmdAttribs);
      }
  
  }
  