org.apache.commons.compress.archivers.zip

Class X5455_ExtendedTimestamp

java.lang.Object

org.apache.commons.compress.archivers.zip.X5455_ExtendedTimestamp

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, ZipExtraField

public class X5455_ExtendedTimestamp
extends java.lang.Object
implements ZipExtraField, java.lang.Cloneable, java.io.Serializable

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!

• modifyTime: most recent time of file/directory modification (or file/dir creation if the entry has not been modified since it was created).
• accessTime: most recent time file/directory was opened (e.g., read from disk). Many people disable their operating systems from updating this value using the NOATIME mount option to optimize disk behaviour, and thus it's not always reliable. In those cases it's always equal to modifyTime.
• *createTime: modern linux file systems (e.g., ext2 and newer) do not appear to store a value like this, and so it's usually omitted altogether in the zip extra field. Perhaps other unix systems track this.

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

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static byte	ACCESS_TIME_BIT The bit set inside the flags by when the lasr access time is present in this extra field.
static byte	CREATE_TIME_BIT The bit set inside the flags by when the original creation time is present in this extra field.
static byte	MODIFY_TIME_BIT The bit set inside the flags by when the last modification time is present in this extra field.

Fields inherited from interface org.apache.commons.compress.archivers.zip.ZipExtraField

EXTRAFIELD_HEADER_SIZE

Constructor Summary

Constructors

Constructor and Description
X5455_ExtendedTimestamp() Constructor for X5455_ExtendedTimestamp.

Method Summary

Modifier and Type	Method and Description
java.lang.Object	clone()
boolean	equals(java.lang.Object o)
java.util.Date	getAccessJavaTime() Returns the access time as a java.util.Date of this zip entry, or null if no such timestamp exists in the zip entry.
ZipLong	getAccessTime() 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.
byte[]	getCentralDirectoryData() The actual data to put into central directory data - without Header-ID or length specifier.
ZipShort	getCentralDirectoryLength() Length of the extra field in the local file data - without Header-ID or length specifier.
java.util.Date	getCreateJavaTime() 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.
ZipLong	getCreateTime() 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.
byte	getFlags() Gets flags byte.
ZipShort	getHeaderId() The Header-ID.
byte[]	getLocalFileDataData() The actual data to put into local file data - without Header-ID or length specifier.
ZipShort	getLocalFileDataLength() Length of the extra field in the local file data - without Header-ID or length specifier.
java.util.Date	getModifyJavaTime() Returns the modify time as a java.util.Date of this zip entry, or null if no such timestamp exists in the zip entry.
ZipLong	getModifyTime() 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.
int	hashCode()
boolean	isBit0_modifyTimePresent() 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.
boolean	isBit1_accessTimePresent() 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.
boolean	isBit2_createTimePresent() 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.
void	parseFromCentralDirectoryData(byte[] buffer, int offset, int length) Doesn't do anything special since this class always uses the same parsing logic for both central directory and local file data.
void	parseFromLocalFileData(byte[] data, int offset, int length) Populate data from this array as if it was in local file data.
void	setAccessJavaTime(java.util.Date d) Sets the access time as a java.util.Date of this zip entry.
void	setAccessTime(ZipLong l) Sets the access time (seconds since epoch) of this zip entry using a ZipLong object
void	setCreateJavaTime(java.util.Date d) Sets the create time as a java.util.Date of this zip entry.
void	setCreateTime(ZipLong l) Sets the create time (seconds since epoch) of this zip entry using a ZipLong object
void	setFlags(byte flags) Sets flags byte.
void	setModifyJavaTime(java.util.Date d) Sets the modify time as a java.util.Date of this zip entry.
void	setModifyTime(ZipLong l) Sets the modify time (seconds since epoch) of this zip entry using a ZipLong object.
java.lang.String	toString() Returns a String representation of this class useful for debugging purposes.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

MODIFY_TIME_BIT

public static final byte MODIFY_TIME_BIT

The bit set inside the flags by when the last modification time is present in this extra field.

See Also:

Constant Field Values

ACCESS_TIME_BIT

public static final byte ACCESS_TIME_BIT

The bit set inside the flags by when the lasr access time is present in this extra field.

See Also:

Constant Field Values

CREATE_TIME_BIT

public static final byte CREATE_TIME_BIT

The bit set inside the flags by when the original creation time is present in this extra field.

See Also:

Constant Field Values

Constructor Detail

X5455_ExtendedTimestamp

public X5455_ExtendedTimestamp()

Constructor for X5455_ExtendedTimestamp.

Method Detail

getHeaderId

public ZipShort getHeaderId()

The Header-ID.

Specified by:

getHeaderId in interface ZipExtraField

Returns:

the value for the header id for this extrafield

getLocalFileDataLength

public ZipShort getLocalFileDataLength()

Length of the extra field in the local file data - without Header-ID or length specifier.

Specified by:

getLocalFileDataLength in interface ZipExtraField

Returns:

a ZipShort for the length of the data of this extra field

getCentralDirectoryLength

public ZipShort getCentralDirectoryLength()

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.

Specified by:

getCentralDirectoryLength in interface ZipExtraField

Returns:

a ZipShort for the length of the data of this extra field

getLocalFileDataData

public byte[] getLocalFileDataData()

The actual data to put into local file data - without Header-ID or length specifier.

Specified by:

getLocalFileDataData in interface ZipExtraField

Returns:

get the data

getCentralDirectoryData

public byte[] getCentralDirectoryData()

The actual data to put into central directory data - without Header-ID or length specifier.

Specified by:

getCentralDirectoryData in interface ZipExtraField

Returns:

the central directory data

parseFromLocalFileData

public void parseFromLocalFileData(byte[] data,
                                   int offset,
                                   int length)
                            throws java.util.zip.ZipException

Populate data from this array as if it was in local file data.

Specified by:

parseFromLocalFileData in interface ZipExtraField

Parameters:

data - an array of bytes

offset - the start offset

length - the number of bytes in the array from offset

Throws:

java.util.zip.ZipException - on error

parseFromCentralDirectoryData

public void parseFromCentralDirectoryData(byte[] buffer,
                                          int offset,
                                          int length)
                                   throws java.util.zip.ZipException

Doesn't do anything special since this class always uses the same parsing logic for both central directory and local file data.

Specified by:

parseFromCentralDirectoryData in interface ZipExtraField

Parameters:

buffer - the buffer to read data from

offset - offset into buffer to read data

length - the length of data

Throws:

java.util.zip.ZipException - on error

setFlags

public void setFlags(byte flags)

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).

Parameters:

flags - flags byte indicating which of the three datestamp fields are present.

getFlags

public byte getFlags()

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).

Returns:

flags byte indicating which of the three datestamp fields are present.

isBit0_modifyTimePresent

public boolean isBit0_modifyTimePresent()

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.

Returns:

true if bit0 of the flags byte is set.

isBit1_accessTimePresent

public boolean isBit1_accessTimePresent()

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.

Returns:

true if bit1 of the flags byte is set.

isBit2_createTimePresent

public boolean isBit2_createTimePresent()

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.

Returns:

true if bit2 of the flags byte is set.

getModifyTime

public ZipLong getModifyTime()

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.

Returns:

modify time (seconds since epoch) or null.

getAccessTime

public ZipLong getAccessTime()

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.

Returns:

access time (seconds since epoch) or null.

getCreateTime

public ZipLong getCreateTime()

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.

Returns:

create time (seconds since epoch) or null.

getModifyJavaTime

public java.util.Date getModifyJavaTime()

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.

Returns:

modify time as java.util.Date or null.

getAccessJavaTime

public java.util.Date getAccessJavaTime()

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.

Returns:

access time as java.util.Date or null.

getCreateJavaTime

public java.util.Date getCreateJavaTime()

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.

Returns:

create time as java.util.Date or null.

setModifyTime

public void setModifyTime(ZipLong l)

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.

Parameters:

l - ZipLong of the modify time (seconds per epoch)

setAccessTime

public void setAccessTime(ZipLong 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.

Parameters:

l - ZipLong of the access time (seconds per epoch)

setCreateTime

public void setCreateTime(ZipLong 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.

Parameters:

l - ZipLong of the create time (seconds per epoch)

setModifyJavaTime

public void setModifyJavaTime(java.util.Date d)

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.

Parameters:

d - modify time as java.util.Date

setAccessJavaTime

public void setAccessJavaTime(java.util.Date 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.

Parameters:

d - access time as java.util.Date

setCreateJavaTime

public void setCreateJavaTime(java.util.Date 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.

Parameters:

d - create time as java.util.Date

toString

public java.lang.String toString()

Returns a String representation of this class useful for debugging purposes.

Overrides:

toString in class java.lang.Object

Returns:

A String representation of this class useful for debugging purposes.

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Overrides:

clone in class java.lang.Object

Throws:

java.lang.CloneNotSupportedException

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object