An extra field that stores additional file and directory timestamp data * for zip entries. Each zip entry can include up to three timestamps * (modify, access, create*). The timestamps are stored as 32 bit signed * integers representing seconds since UNIX epoch (Jan 1st, 1970, UTC). * This field improves on zip's default timestamp granularity, since it * allows one to store additional timestamps, and, in addition, the timestamps * are stored using per-second granularity (zip's default behaviour can only store * timestamps to the nearest even second). *
* Unfortunately, 32 (signed) bits can only store dates up to the year 2037, * and so this extra field will eventually be obsolete. Enjoy it while it lasts! *
** We're using the field definition given in Info-Zip's source archive: * zip-3.0.tar.gz/proginfo/extrafld.txt *
*
* Value Size Description
* ----- ---- -----------
* 0x5455 Short tag for this extra block type ("UT")
* TSize Short total data size for this block
* Flags Byte info bits
* (ModTime) Long time of last modification (UTC/GMT)
* (AcTime) Long time of last access (UTC/GMT)
* (CrTime) Long time of original creation (UTC/GMT)
*
* Central-header version:
*
* Value Size Description
* ----- ---- -----------
* 0x5455 Short tag for this extra block type ("UT")
* TSize Short total data size for this block
* Flags Byte info bits (refers to local header!)
* (ModTime) Long time of last modification (UTC/GMT)
*
* @since 1.5
*/
public class X5455_ExtendedTimestamp implements ZipExtraField, Cloneable, Serializable {
private static final ZipShort HEADER_ID = new ZipShort(0x5455);
private static final long serialVersionUID = 1L;
/**
* The bit set inside the flags by when the last modification time
* is present in this extra field.
*/
public static final byte MODIFY_TIME_BIT = 1;
/**
* The bit set inside the flags by when the lasr access time is
* present in this extra field.
*/
public static final byte ACCESS_TIME_BIT = 2;
/**
* The bit set inside the flags by when the original creation time
* is present in this extra field.
*/
public static final byte CREATE_TIME_BIT = 4;
// The 3 boolean fields (below) come from this flags byte. The remaining 5 bits
// are ignored according to the current version of the spec (December 2012).
private byte flags;
// Note: even if bit1 and bit2 are set, the Central data will still not contain
// access/create fields: only local data ever holds those! This causes
// some of our implementation to look a little odd, with seemingly spurious
// != null and length checks.
private boolean bit0_modifyTimePresent;
private boolean bit1_accessTimePresent;
private boolean bit2_createTimePresent;
private ZipLong modifyTime;
private ZipLong accessTime;
private ZipLong createTime;
/**
* Constructor for X5455_ExtendedTimestamp.
*/
public X5455_ExtendedTimestamp() {}
/**
* The Header-ID.
*
* @return the value for the header id for this extrafield
*/
@Override
public ZipShort getHeaderId() {
return HEADER_ID;
}
/**
* Length of the extra field in the local file data - without
* Header-ID or length specifier.
*
* @return a ZipShort for the length of the data of this extra field
*/
@Override
public ZipShort getLocalFileDataLength() {
return new ZipShort(1 +
(bit0_modifyTimePresent ? 4 : 0) +
(bit1_accessTimePresent && accessTime != null ? 4 : 0) +
(bit2_createTimePresent && createTime != null ? 4 : 0)
);
}
/**
* Length of the extra field in the local file data - without
* Header-ID or length specifier.
*
* For X5455 the central length is often smaller than the * local length, because central cannot contain access or create * timestamps.
* * @return aZipShort for the length of the data of this extra field
*/
@Override
public ZipShort getCentralDirectoryLength() {
return new ZipShort(1 +
(bit0_modifyTimePresent ? 4 : 0)
);
}
/**
* The actual data to put into local file data - without Header-ID
* or length specifier.
*
* @return get the data
*/
@Override
public byte[] getLocalFileDataData() {
final byte[] data = new byte[getLocalFileDataLength().getValue()];
int pos = 0;
data[pos++] = 0;
if (bit0_modifyTimePresent) {
data[0] |= MODIFY_TIME_BIT;
System.arraycopy(modifyTime.getBytes(), 0, data, pos, 4);
pos += 4;
}
if (bit1_accessTimePresent && accessTime != null) {
data[0] |= ACCESS_TIME_BIT;
System.arraycopy(accessTime.getBytes(), 0, data, pos, 4);
pos += 4;
}
if (bit2_createTimePresent && createTime != null) {
data[0] |= CREATE_TIME_BIT;
System.arraycopy(createTime.getBytes(), 0, data, pos, 4);
pos += 4; // NOSONAR - assignment as documentation
}
return data;
}
/**
* The actual data to put into central directory data - without Header-ID
* or length specifier.
*
* @return the central directory data
*/
@Override
public byte[] getCentralDirectoryData() {
final byte[] centralData = new byte[getCentralDirectoryLength().getValue()];
final byte[] localData = getLocalFileDataData();
// Truncate out create & access time (last 8 bytes) from
// the copy of the local data we obtained:
System.arraycopy(localData, 0, centralData, 0, centralData.length);
return centralData;
}
/**
* Populate data from this array as if it was in local file data.
*
* @param data an array of bytes
* @param offset the start offset
* @param length the number of bytes in the array from offset
* @throws java.util.zip.ZipException on error
*/
@Override
public void parseFromLocalFileData(
final byte[] data, int offset, final int length
) throws ZipException {
reset();
final int len = offset + length;
setFlags(data[offset++]);
if (bit0_modifyTimePresent) {
modifyTime = new ZipLong(data, offset);
offset += 4;
}
// Notice the extra length check in case we are parsing the shorter
// central data field (for both access and create timestamps).
if (bit1_accessTimePresent && offset + 4 <= len) {
accessTime = new ZipLong(data, offset);
offset += 4;
}
if (bit2_createTimePresent && offset + 4 <= len) {
createTime = new ZipLong(data, offset);
offset += 4; // NOSONAR - assignment as documentation
}
}
/**
* Doesn't do anything special since this class always uses the
* same parsing logic for both central directory and local file data.
*/
@Override
public void parseFromCentralDirectoryData(
final byte[] buffer, final int offset, final int length
) throws ZipException {
reset();
parseFromLocalFileData(buffer, offset, length);
}
/**
* Reset state back to newly constructed state. Helps us make sure
* parse() calls always generate clean results.
*/
private void reset() {
setFlags((byte) 0);
this.modifyTime = null;
this.accessTime = null;
this.createTime = null;
}
/**
* Sets flags byte. The flags byte tells us which of the
* three datestamp fields are present in the data:
*
* bit0 - modify time
* bit1 - access time
* bit2 - create time
*
* Only first 3 bits of flags are used according to the
* latest version of the spec (December 2012).
*
* @param flags flags byte indicating which of the
* three datestamp fields are present.
*/
public void setFlags(final byte flags) {
this.flags = flags;
this.bit0_modifyTimePresent = (flags & MODIFY_TIME_BIT) == MODIFY_TIME_BIT;
this.bit1_accessTimePresent = (flags & ACCESS_TIME_BIT) == ACCESS_TIME_BIT;
this.bit2_createTimePresent = (flags & CREATE_TIME_BIT) == CREATE_TIME_BIT;
}
/**
* Gets flags byte. The flags byte tells us which of the
* three datestamp fields are present in the data:
*
* bit0 - modify time
* bit1 - access time
* bit2 - create time
*
* Only first 3 bits of flags are used according to the
* latest version of the spec (December 2012).
*
* @return flags byte indicating which of the
* three datestamp fields are present.
*/
public byte getFlags() { return flags; }
/**
* Returns whether bit0 of the flags byte is set or not,
* which should correspond to the presence or absence of
* a modify timestamp in this particular zip entry.
*
* @return true if bit0 of the flags byte is set.
*/
public boolean isBit0_modifyTimePresent() { return bit0_modifyTimePresent; }
/**
* Returns whether bit1 of the flags byte is set or not,
* which should correspond to the presence or absence of
* a "last access" timestamp in this particular zip entry.
*
* @return true if bit1 of the flags byte is set.
*/
public boolean isBit1_accessTimePresent() { return bit1_accessTimePresent; }
/**
* Returns whether bit2 of the flags byte is set or not,
* which should correspond to the presence or absence of
* a create timestamp in this particular zip entry.
*
* @return true if bit2 of the flags byte is set.
*/
public boolean isBit2_createTimePresent() { return bit2_createTimePresent; }
/**
* Returns the modify time (seconds since epoch) of this zip entry
* as a ZipLong object, or null if no such timestamp exists in the
* zip entry.
*
* @return modify time (seconds since epoch) or null.
*/
public ZipLong getModifyTime() { return modifyTime; }
/**
* Returns the access time (seconds since epoch) of this zip entry
* as a ZipLong object, or null if no such timestamp exists in the
* zip entry.
*
* @return access time (seconds since epoch) or null.
*/
public ZipLong getAccessTime() { return accessTime; }
/**
* * Returns the create time (seconds since epoch) of this zip entry * as a ZipLong object, or null if no such timestamp exists in the * zip entry. *
* Note: modern linux file systems (e.g., ext2) * do not appear to store a "create time" value, and so * it's usually omitted altogether in the zip extra * field. Perhaps other unix systems track this. * * @return create time (seconds since epoch) or null. */ public ZipLong getCreateTime() { return createTime; } /** * Returns the modify time as a java.util.Date * of this zip entry, or null if no such timestamp exists in the zip entry. * The milliseconds are always zeroed out, since the underlying data * offers only per-second precision. * * @return modify time as java.util.Date or null. */ public Date getModifyJavaTime() { return zipLongToDate(modifyTime); } /** * Returns the access time as a java.util.Date * of this zip entry, or null if no such timestamp exists in the zip entry. * The milliseconds are always zeroed out, since the underlying data * offers only per-second precision. * * @return access time as java.util.Date or null. */ public Date getAccessJavaTime() { return zipLongToDate(accessTime); } /** *
* Returns the create time as a a java.util.Date * of this zip entry, or null if no such timestamp exists in the zip entry. * The milliseconds are always zeroed out, since the underlying data * offers only per-second precision. *
* Note: modern linux file systems (e.g., ext2) * do not appear to store a "create time" value, and so * it's usually omitted altogether in the zip extra * field. Perhaps other unix systems track this. * * @return create time as java.util.Date or null. */ public Date getCreateJavaTime() { return zipLongToDate(createTime); } /** *
* Sets the modify time (seconds since epoch) of this zip entry * using a ZipLong object. *
* Note: the setters for flags and timestamps are decoupled. * Even if the timestamp is not-null, it will only be written * out if the corresponding bit in the flags is also set. *
* * @param l ZipLong of the modify time (seconds per epoch) */ public void setModifyTime(final ZipLong l) { bit0_modifyTimePresent = l != null; flags = (byte) (l != null ? (flags | MODIFY_TIME_BIT) : (flags & ~MODIFY_TIME_BIT)); this.modifyTime = l; } /** ** Sets the access time (seconds since epoch) of this zip entry * using a ZipLong object *
* Note: the setters for flags and timestamps are decoupled. * Even if the timestamp is not-null, it will only be written * out if the corresponding bit in the flags is also set. *
* * @param l ZipLong of the access time (seconds per epoch) */ public void setAccessTime(final ZipLong l) { bit1_accessTimePresent = l != null; flags = (byte) (l != null ? (flags | ACCESS_TIME_BIT) : (flags & ~ACCESS_TIME_BIT)); this.accessTime = l; } /** ** Sets the create time (seconds since epoch) of this zip entry * using a ZipLong object *
* Note: the setters for flags and timestamps are decoupled. * Even if the timestamp is not-null, it will only be written * out if the corresponding bit in the flags is also set. *
* * @param l ZipLong of the create time (seconds per epoch) */ public void setCreateTime(final ZipLong l) { bit2_createTimePresent = l != null; flags = (byte) (l != null ? (flags | CREATE_TIME_BIT) : (flags & ~CREATE_TIME_BIT)); this.createTime = l; } /** ** Sets the modify time as a java.util.Date * of this zip entry. Supplied value is truncated to per-second * precision (milliseconds zeroed-out). *
* Note: the setters for flags and timestamps are decoupled. * Even if the timestamp is not-null, it will only be written * out if the corresponding bit in the flags is also set. *
* * @param d modify time as java.util.Date */ public void setModifyJavaTime(final Date d) { setModifyTime(dateToZipLong(d)); } /** ** Sets the access time as a java.util.Date * of this zip entry. Supplied value is truncated to per-second * precision (milliseconds zeroed-out). *
* Note: the setters for flags and timestamps are decoupled. * Even if the timestamp is not-null, it will only be written * out if the corresponding bit in the flags is also set. *
* * @param d access time as java.util.Date */ public void setAccessJavaTime(final Date d) { setAccessTime(dateToZipLong(d)); } /** ** Sets the create time as a java.util.Date * of this zip entry. Supplied value is truncated to per-second * precision (milliseconds zeroed-out). *
* Note: the setters for flags and timestamps are decoupled. * Even if the timestamp is not-null, it will only be written * out if the corresponding bit in the flags is also set. *
* * @param d create time as java.util.Date */ public void setCreateJavaTime(final Date d) { setCreateTime(dateToZipLong(d)); } /** * Utility method converts java.util.Date (milliseconds since epoch) * into a ZipLong (seconds since epoch). * * Also makes sure the converted ZipLong is not too big to fit * in 32 unsigned bits. * * @param d java.util.Date to convert to ZipLong * @return ZipLong */ private static ZipLong dateToZipLong(final Date d) { if (d == null) { return null; } return unixTimeToZipLong(d.getTime() / 1000); } /** * Returns a String representation of this class useful for * debugging purposes. * * @return A String representation of this class useful for * debugging purposes. */ @Override public String toString() { final StringBuilder buf = new StringBuilder(); buf.append("0x5455 Zip Extra Field: Flags="); buf.append(Integer.toBinaryString(ZipUtil.unsignedIntToSignedByte(flags))).append(" "); if (bit0_modifyTimePresent && modifyTime != null) { final Date m = getModifyJavaTime(); buf.append(" Modify:[").append(m).append("] "); } if (bit1_accessTimePresent && accessTime != null) { final Date a = getAccessJavaTime(); buf.append(" Access:[").append(a).append("] "); } if (bit2_createTimePresent && createTime != null) { final Date c = getCreateJavaTime(); buf.append(" Create:[").append(c).append("] "); } return buf.toString(); } @Override public Object clone() throws CloneNotSupportedException { return super.clone(); } @Override public boolean equals(final Object o) { if (o instanceof X5455_ExtendedTimestamp) { final X5455_ExtendedTimestamp xf = (X5455_ExtendedTimestamp) o; // The ZipLong==ZipLong clauses handle the cases where both are null. // and only last 3 bits of flags matter. return ((flags & 0x07) == (xf.flags & 0x07)) && (modifyTime == xf.modifyTime || (modifyTime != null && modifyTime.equals(xf.modifyTime))) && (accessTime == xf.accessTime || (accessTime != null && accessTime.equals(xf.accessTime))) && (createTime == xf.createTime || (createTime != null && createTime.equals(xf.createTime))); } return false; } @Override public int hashCode() { int hc = (-123 * (flags & 0x07)); // only last 3 bits of flags matter if (modifyTime != null) { hc ^= modifyTime.hashCode(); } if (accessTime != null) { // Since accessTime is often same as modifyTime, // this prevents them from XOR negating each other. hc ^= Integer.rotateLeft(accessTime.hashCode(), 11); } if (createTime != null) { hc ^= Integer.rotateLeft(createTime.hashCode(), 22); } return hc; } private static Date zipLongToDate(ZipLong unixTime) { return unixTime != null ? new Date(unixTime.getIntValue() * 1000L) : null; } private static ZipLong unixTimeToZipLong(long l) { if (l < Integer.MIN_VALUE || l > Integer.MAX_VALUE) { throw new IllegalArgumentException("X5455 timestamps must fit in a signed 32 bit integer: " + l); } return new ZipLong(l); } }