This class uses the ASi extra field in the format: *
* Value Size Description * ----- ---- ----------- * (Unix3) 0x756e Short tag for this extra block type * TSize Short total data size for this block * CRC Long CRC-32 of the remaining data * Mode Short file permissions * SizDev Long symlink'd size OR major/minor dev num * UID Short user ID * GID Short group ID * (var.) variable symbolic link filename ** taken from appnote.iz (Info-ZIP note, 981119) found at ftp://ftp.uu.net/pub/archiving/zip/doc/ * *
Short is two bytes and Long is four bytes in big endian byte and * word order, device numbers are currently not supported.
* * @author Stefan Bodewig * @version $Revision: 1.1 $ */ public class AsiExtraField implements ZipExtraField, UnixStat, Cloneable { private final static ZipShort HEADER_ID = new ZipShort(0x756E); /** * Standard Unix stat(2) file mode. * * @since 1.1 */ private int mode = 0; /** * User ID. * * @since 1.1 */ private int uid = 0; /** * Group ID. * * @since 1.1 */ private int gid = 0; /** * File this entry points to, if it is a symbolic link. * *empty string - if entry is not a symbolic link.
* * @since 1.1 */ private String link = ""; /** * Is this an entry for a directory? * * @since 1.1 */ private boolean dirFlag = false; /** * Instance used to calculate checksums. * * @since 1.1 */ private CRC32 crc = new CRC32(); public AsiExtraField() { } /** * The Header-ID. * * @since 1.1 */ public ZipShort getHeaderId() { return HEADER_ID; } /** * Length of the extra field in the local file data - without * Header-ID or length specifier. * * @since 1.1 */ public ZipShort getLocalFileDataLength() { return new ZipShort( 4 // CRC + 2 // Mode + 4 // SizDev + 2 // UID + 2 // GID + getLinkedFile().getBytes().length); } /** * Delegate to local file data. * * @since 1.1 */ public ZipShort getCentralDirectoryLength() { return getLocalFileDataLength(); } /** * The actual data to put into local file data - without Header-ID * or length specifier. * * @since 1.1 */ public byte[] getLocalFileDataData() { // CRC will be added later byte[] data = new byte[getLocalFileDataLength().getValue() - 4]; System.arraycopy((new ZipShort(getMode())).getBytes(), 0, data, 0, 2); byte[] linkArray = getLinkedFile().getBytes(); System.arraycopy((new ZipLong(linkArray.length)).getBytes(), 0, data, 2, 4); System.arraycopy((new ZipShort(getUserId())).getBytes(), 0, data, 6, 2); System.arraycopy((new ZipShort(getGroupId())).getBytes(), 0, data, 8, 2); System.arraycopy(linkArray, 0, data, 10, linkArray.length); crc.reset(); crc.update(data); long checksum = crc.getValue(); byte[] result = new byte[data.length + 4]; System.arraycopy((new ZipLong(checksum)).getBytes(), 0, result, 0, 4); System.arraycopy(data, 0, result, 4, data.length); return result; } /** * Delegate to local file data. * * @since 1.1 */ public byte[] getCentralDirectoryData() { return getLocalFileDataData(); } /** * Set the user id. * * @since 1.1 */ public void setUserId(int uid) { this.uid = uid; } /** * Get the user id. * * @since 1.1 */ public int getUserId() { return uid; } /** * Set the group id. * * @since 1.1 */ public void setGroupId(int gid) { this.gid = gid; } /** * Get the group id. * * @since 1.1 */ public int getGroupId() { return gid; } /** * Indicate that this entry is a symbolic link to the given filename. * * @param name Name of the file this entry links to, empty String * if it is not a symbolic link. * * @since 1.1 */ public void setLinkedFile(String name) { link = name; mode = getMode(mode); } /** * Name of linked file * * @return name of the file this entry links to if it is a * symbolic link, the empty string otherwise. * * @since 1.1 */ public String getLinkedFile() { return link; } /** * Is this entry a symbolic link? * * @since 1.1 */ public boolean isLink() { return getLinkedFile().length() != 0; } /** * File mode of this file. * * @since 1.1 */ public void setMode(int mode) { this.mode = getMode(mode); } /** * File mode of this file. * * @since 1.1 */ public int getMode() { return mode; } /** * Indicate whether this entry is a directory. * * @since 1.1 */ public void setDirectory(boolean dirFlag) { this.dirFlag = dirFlag; mode = getMode(mode); } /** * Is this entry a directory? * * @since 1.1 */ public boolean isDirectory() { return dirFlag && !isLink(); } /** * Populate data from this array as if it was in local file data. * * @since 1.1 */ public void parseFromLocalFileData(byte[] data, int offset, int length) throws ZipException { long givenChecksum = (new ZipLong(data, offset)).getValue(); byte[] tmp = new byte[length-4]; System.arraycopy(data, offset+4, tmp, 0, length-4); crc.reset(); crc.update(tmp); long realChecksum = crc.getValue(); if (givenChecksum != realChecksum) { throw new ZipException("bad CRC checksum " + Long.toHexString(givenChecksum) + " instead of " + Long.toHexString(realChecksum)); } int newMode = (new ZipShort(tmp, 0)).getValue(); byte[] linkArray = new byte[(int) (new ZipLong(tmp, 2)).getValue()]; uid = (new ZipShort(tmp, 6)).getValue(); gid = (new ZipShort(tmp, 8)).getValue(); if (linkArray.length == 0) { link = ""; } else { System.arraycopy(tmp, 10, linkArray, 0, linkArray.length); link = new String(linkArray); } setDirectory((newMode & DIR_FLAG) != 0); setMode(newMode); } /** * Get the file mode for given permissions with the correct file type. * * @since 1.1 */ protected int getMode(int mode) { int type = FILE_FLAG; if (isLink()) { type = LINK_FLAG; } else if (isDirectory()) { type = DIR_FLAG; } return type | (mode & PERM_MASK); } }