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The source code

/*
** Authored by Timothy Gerard Endres
**   
** 
** This work has been placed into the public domain.
** You may use this work in any way and for any purpose you wish.
**
** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
** REDISTRIBUTION OF THIS SOFTWARE. 
** 
*/

package installer;

import java.io.*;
import java.util.Date;


/**
 *
 * This class represents an entry in a Tar archive. It consists
 * of the entry's header, as well as the entry's File. Entries
 * can be instantiated in one of three ways, depending on how
 * they are to be used.
 * 

* TarEntries that are created from the header bytes read from * an archive are instantiated with the TarEntry( byte[] ) * constructor. These entries will be used when extracting from * or listing the contents of an archive. These entries have their * header filled in using the header bytes. They also set the File * to null, since they reference an archive entry not a file. *

* TarEntries that are created from Files that are to be written * into an archive are instantiated with the TarEntry( File ) * constructor. These entries have their header filled in using * the File's information. They also keep a reference to the File * for convenience when writing entries. *

* Finally, TarEntries can be constructed from nothing but a name. * This allows the programmer to construct the entry by hand, for * instance when only an InputStream is available for writing to * the archive, and the header information is constructed from * other information. In this case the header fields are set to * defaults and the File is set to null. * *

* The C structure for a Tar Entry's header is: *

 * struct header {
 *		char	name[NAMSIZ];
 *		char	mode[8];
 *		char	uid[8];
 *		char	gid[8];
 *		char	size[12];
 *		char	mtime[12];
 *		char	chksum[8];
 *		char	linkflag;
 *		char	linkname[NAMSIZ];
 *		char	magic[8];
 *		char	uname[TUNMLEN];
 *		char	gname[TGNMLEN];
 *		char	devmajor[8];
 *		char	devminor[8];
 *	} header;
 * 
* * @see TarHeader * */ public class TarEntry extends Object { /** * If this entry represents a File, this references it. */ protected File file; /** * This is the entry's header information. */ protected TarHeader header; /** * Construct an entry with only a name. This allows the programmer * to construct the entry's header "by hand". File is set to null. */ public TarEntry( String name ) { this.initialize(); this.nameTarHeader( this.header, name ); } /** * Construct an entry for a file. File is set to file, and the * header is constructed from information from the file. * * @param file The file that the entry represents. */ public TarEntry( File file ) throws InvalidHeaderException { this.initialize(); this.getFileTarHeader( this.header, file ); } /** * Construct an entry from an archive's header bytes. File is set * to null. * * @param headerBuf The header bytes from a tar archive entry. */ public TarEntry( byte[] headerBuf ) throws InvalidHeaderException { this.initialize(); this.parseTarHeader( this.header, headerBuf ); } /** * Initialization code common to all constructors. */ private void initialize() { this.file = null; this.header = new TarHeader(); } /** * Determine if the two entries are equal. Equality is determined * by the header names being equal. * * @return it Entry to be checked for equality. * @return True if the entries are equal. */ public boolean equals( TarEntry it ) { return this.header.name.toString().equals ( it.header.name.toString() ); } /** * Determine if the given entry is a descendant of this entry. * Descendancy is determined by the name of the descendant * starting with this entry's name. * * @param desc Entry to be checked as a descendent of this. * @return True if entry is a descendant of this. */ public boolean isDescendent( TarEntry desc ) { return desc.header.name.toString().startsWith ( this.header.name.toString() ); } /** * Get this entry's header. * * @return This entry's TarHeader. */ public TarHeader getHeader() { return this.header; } /** * Get this entry's name. * * @return This entry's name. */ public String getName() { return this.header.name.toString(); } /** * Set this entry's name. * * @param name This entry's new name. */ public void setName( String name ) { this.header.name = new StringBuffer( name ); } /** * Get this entry's user id. * * @return This entry's user id. */ public int getUserId() { return this.header.userId; } /** * Set this entry's user id. * * @param userId This entry's new user id. */ public void setUserId( int userId ) { this.header.userId = userId; } /** * Get this entry's group id. * * @return This entry's group id. */ public int getGroupId() { return this.header.groupId; } /** * Set this entry's group id. * * @param groupId This entry's new group id. */ public void setGroupId( int groupId ) { this.header.groupId = groupId; } /** * Get this entry's user name. * * @return This entry's user name. */ public String getUserName() { return this.header.userName.toString(); } /** * Set this entry's user name. * * @param userName This entry's new user name. */ public void setUserName( String userName ) { this.header.userName = new StringBuffer( userName ); } /** * Get this entry's group name. * * @return This entry's group name. */ public String getGroupName() { return this.header.groupName.toString(); } /** * Set this entry's group name. * * @param groupName This entry's new group name. */ public void setGroupName( String groupName ) { this.header.groupName = new StringBuffer( groupName ); } /** * Convenience method to set this entry's group and user ids. * * @param userId This entry's new user id. * @param groupId This entry's new group id. */ public void setIds( int userId, int groupId ) { this.setUserId( userId ); this.setGroupId( groupId ); } /** * Convenience method to set this entry's group and user names. * * @param userName This entry's new user name. * @param groupName This entry's new group name. */ public void setNames( String userName, String groupName ) { this.setUserName( userName ); this.setGroupName( groupName ); } /** * Set this entry's modification time. The parameter passed * to this method is in "Java time". * * @param time This entry's new modification time. */ public void setModTime( long time ) { this.header.modTime = time / 1000; } /** * Set this entry's modification time. * * @param time This entry's new modification time. */ public void setModTime( Date time ) { this.header.modTime = time.getTime() / 1000; } /** * Set this entry's modification time. * * @param time This entry's new modification time. */ public Date getModTime() { return new Date( this.header.modTime * 1000 ); } /** * Get this entry's file. * * @return This entry's file. */ public File getFile() { return this.file; } /** * Get this entry's file size. * * @return This entry's file size. */ public long getSize() { return this.header.size; } /** * Set this entry's file size. * * @param size This entry's new file size. */ public void setSize( long size ) { this.header.size = size; } /** * Convenience method that will modify an entry's name directly * in place in an entry header buffer byte array. * * @param outbuf The buffer containing the entry header to modify. * @param newName The new name to place into the header buffer. */ public void adjustEntryName( byte[] outbuf, String newName ) { int offset = 0; offset = TarHeader.getNameBytes ( new StringBuffer( newName ), outbuf, offset, TarHeader.NAMELEN ); } /** * Return whether or not this entry represents a directory. * * @return True if this entry is a directory. */ public boolean isDirectory() { if ( this.file != null ) return this.file.isDirectory(); if ( this.header != null ) { if ( this.header.linkFlag == TarHeader.LF_DIR ) return true; if ( this.header.name.toString().endsWith( "/" ) ) return true; } return false; } /** * Fill in a TarHeader with information from a File. * * @param hdr The TarHeader to fill in. * @param file The file from which to get the header information. */ public void getFileTarHeader( TarHeader hdr, File file ) throws InvalidHeaderException { this.file = file; String name = file.getPath(); String osname = System.getProperty( "os.name" ); if ( osname != null ) { // Strip off drive letters! // REVIEW Would a better check be "(File.separator == '\')"? // String Win32Prefix = "Windows"; // String prefix = osname.substring( 0, Win32Prefix.length() ); // if ( prefix.equalsIgnoreCase( Win32Prefix ) ) // if ( File.separatorChar == '\\' ) // Per Patrick Beard: String Win32Prefix = "windows"; if ( osname.toLowerCase().startsWith( Win32Prefix ) ) { if ( name.length() > 2 ) { char ch1 = name.charAt(0); char ch2 = name.charAt(1); if ( ch2 == ':' && ( (ch1 >= 'a' && ch1 <= 'z') || (ch1 >= 'A' && ch1 <= 'Z') ) ) { name = name.substring( 2 ); } } } } name = name.replace( File.separatorChar, '/' ); // No absolute pathnames // Windows (and Posix?) paths can start with "\\NetworkDrive\", // so we loop on starting /'s. for ( ; name.startsWith( "/" ) ; ) name = name.substring( 1 ); hdr.linkName = new StringBuffer( "" ); hdr.name = new StringBuffer( name ); if ( file.isDirectory() ) { hdr.mode = 040755; hdr.linkFlag = TarHeader.LF_DIR; if ( hdr.name.charAt( hdr.name.length() - 1 ) != '/' ) hdr.name.append( "/" ); } else { hdr.mode = 0100644; hdr.linkFlag = TarHeader.LF_NORMAL; } // UNDONE When File lets us get the userName, use it! hdr.size = file.length(); hdr.modTime = file.lastModified() / 1000; hdr.checkSum = 0; hdr.devMajor = 0; hdr.devMinor = 0; } /** * If this entry represents a file, and the file is a directory, return * an array of TarEntries for this entry's children. * * @return An array of TarEntry's for this entry's children. */ public TarEntry[] getDirectoryEntries() throws InvalidHeaderException { if ( this.file == null || ! this.file.isDirectory() ) { return new TarEntry[0]; } String[] list = this.file.list(); TarEntry[] result = new TarEntry[ list.length ]; for ( int i = 0 ; i < list.length ; ++i ) { result[i] = new TarEntry ( new File( this.file, list[i] ) ); } return result; } /** * Compute the checksum of a tar entry header. * * @param buf The tar entry's header buffer. * @return The computed checksum. */ public long computeCheckSum( byte[] buf ) { long sum = 0; for ( int i = 0 ; i < buf.length ; ++i ) { sum += 255 & buf[ i ]; } return sum; } /** * Write an entry's header information to a header buffer. * * @param outbuf The tar entry header buffer to fill in. */ public void writeEntryHeader( byte[] outbuf ) { int offset = 0; offset = TarHeader.getNameBytes ( this.header.name, outbuf, offset, TarHeader.NAMELEN ); offset = TarHeader.getOctalBytes ( this.header.mode, outbuf, offset, TarHeader.MODELEN ); offset = TarHeader.getOctalBytes ( this.header.userId, outbuf, offset, TarHeader.UIDLEN ); offset = TarHeader.getOctalBytes ( this.header.groupId, outbuf, offset, TarHeader.GIDLEN ); long size = this.header.size; offset = TarHeader.getLongOctalBytes ( size, outbuf, offset, TarHeader.SIZELEN ); offset = TarHeader.getLongOctalBytes ( this.header.modTime, outbuf, offset, TarHeader.MODTIMELEN ); int csOffset = offset; for ( int c = 0 ; c < TarHeader.CHKSUMLEN ; ++c ) outbuf[ offset++ ] = (byte) ' '; outbuf[ offset++ ] = this.header.linkFlag; offset = TarHeader.getNameBytes ( this.header.linkName, outbuf, offset, TarHeader.NAMELEN ); offset = TarHeader.getNameBytes ( this.header.magic, outbuf, offset, TarHeader.MAGICLEN ); offset = TarHeader.getNameBytes ( this.header.userName, outbuf, offset, TarHeader.UNAMELEN ); offset = TarHeader.getNameBytes ( this.header.groupName, outbuf, offset, TarHeader.GNAMELEN ); offset = TarHeader.getOctalBytes ( this.header.devMajor, outbuf, offset, TarHeader.DEVLEN ); offset = TarHeader.getOctalBytes ( this.header.devMinor, outbuf, offset, TarHeader.DEVLEN ); for ( ; offset < outbuf.length ; ) outbuf[ offset++ ] = 0; long checkSum = this.computeCheckSum( outbuf ); TarHeader.getCheckSumOctalBytes ( checkSum, outbuf, csOffset, TarHeader.CHKSUMLEN ); } /** * Parse an entry's TarHeader information from a header buffer. * * @param hdr The TarHeader to fill in from the buffer information. * @param header The tar entry header buffer to get information from. */ public void parseTarHeader( TarHeader hdr, byte[] header ) throws InvalidHeaderException { int offset = 0; hdr.name = TarHeader.parseName( header, offset, TarHeader.NAMELEN ); offset += TarHeader.NAMELEN; hdr.mode = (int) TarHeader.parseOctal( header, offset, TarHeader.MODELEN ); offset += TarHeader.MODELEN; hdr.userId = (int) TarHeader.parseOctal( header, offset, TarHeader.UIDLEN ); offset += TarHeader.UIDLEN; hdr.groupId = (int) TarHeader.parseOctal( header, offset, TarHeader.GIDLEN ); offset += TarHeader.GIDLEN; hdr.size = TarHeader.parseOctal( header, offset, TarHeader.SIZELEN ); offset += TarHeader.SIZELEN; hdr.modTime = TarHeader.parseOctal( header, offset, TarHeader.MODTIMELEN ); offset += TarHeader.MODTIMELEN; hdr.checkSum = (int) TarHeader.parseOctal( header, offset, TarHeader.CHKSUMLEN ); offset += TarHeader.CHKSUMLEN; hdr.linkFlag = header[ offset++ ]; hdr.linkName = TarHeader.parseName( header, offset, TarHeader.NAMELEN ); offset += TarHeader.NAMELEN; hdr.magic = TarHeader.parseName( header, offset, TarHeader.MAGICLEN ); offset += TarHeader.MAGICLEN; hdr.userName = TarHeader.parseName( header, offset, TarHeader.UNAMELEN ); offset += TarHeader.UNAMELEN; hdr.groupName = TarHeader.parseName( header, offset, TarHeader.GNAMELEN ); offset += TarHeader.GNAMELEN; hdr.devMajor = (int) TarHeader.parseOctal( header, offset, TarHeader.DEVLEN ); offset += TarHeader.DEVLEN; hdr.devMinor = (int) TarHeader.parseOctal( header, offset, TarHeader.DEVLEN ); } /** * Fill in a TarHeader given only the entry's name. * * @param hdr The TarHeader to fill in. * @param name The tar entry name. */ public void nameTarHeader( TarHeader hdr, String name ) { boolean isDir = name.endsWith( "/" ); hdr.checkSum = 0; hdr.devMajor = 0; hdr.devMinor = 0; hdr.name = new StringBuffer( name ); hdr.mode = isDir ? 040755 : 0100644; hdr.userId = 0; hdr.groupId = 0; hdr.size = 0; hdr.checkSum = 0; hdr.modTime = (new java.util.Date()).getTime() / 1000; hdr.linkFlag = isDir ? TarHeader.LF_DIR : TarHeader.LF_NORMAL; hdr.linkName = new StringBuffer( "" ); hdr.userName = new StringBuffer( "" ); hdr.groupName = new StringBuffer( "" ); hdr.devMajor = 0; hdr.devMinor = 0; } }
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