ZIPFile Type

The Zip file in the archive.

Remarks

This type contains information about the Zip file that either exists in the archive or is being added to the archive.

Fields

Attributes
Integer

The attributes of the files to be compressed or decompressed. It will then be written to the archive during compression and to the file system during extraction.

If desired, you may change the value of Attributes before compressing or decompressing.

The property is a bitmask of flags, corresponding to the MS-DOS directory byte:

Readonly1
Hidden2
System4
Directory16
Archive32

In the Java Edition, due to limitations of the JRE, the effect of this property is limited. When including files, only the Hidden and Readonly bits will be read from the file system, and during extraction only the Readonly attribute will be written.

Comment
String

Specifies a comment for the entry in the zip file. Before compression, set This field to include comments in this zip file. After an archive has been scanned, This field will contain any comments the zip file contains.

CompressedDate
Long

The date and time of the entry, as stored within the archive.

FileCompressedDate contains the last modified date of the file, as stored within the archive (it does not generally correspond to when the file was compressed).

FileCompressedDate is returned in a platform-specific format. The Java,C++, and most other Editions will return the number of milliseconds since January 1, 1970, 00:00:00. This value may be passed directly to the java.util.Date constructor to create a java.util.Date object representing this date.

The .NET Edition will return the number of ticks, or 100-nanosecond intervals, since January 1, 0001, 00:00:00. This value may be passed directly to the System.DateTime constructor to create a System.DateTime object representing this date.

Reading the value of this property will return a meaningful value only after the archive has been successfully scanned or decompressed, and only if the values of ArchiveFile, Files collection, and CompressedName have not been changed since. If a meaningful value is not available this property will return a value of 0.

NOTE: This may be set accordingly when the InputStream field is set to a valid stream to input the data for the current file. If not set, the default, 0, is used. Otherwise the value is read from disk.

CompressedName
String

The file name of the current file, as stored inside of the archive. This may be the same as in DecompressedName, but is not required to be.

All paths are stored in the archive in standard (UNIX) format. Pathnames specified in the host operating system's format will be immediately converted.

This field should generally be set with a relative path or with no path at all. The exact interpretation of the path is left to the decompression software; generally, pathnames will be interpreted as relative to a base directory, and these subdirectories will be created as needed. Absolute pathnames will not be interpreted correctly by the component, and may or may not be interpreted correctly by other decompression software.

Paths should be specified in standard (UNIX) format. They may also be specified in the format native to the host operating system, in which case they will be immediately converted.

Example


ZipControl.ArchiveFile = "c:\test.zip"
ZipControl.Files.Add(new ZIPFile())
ZipControl.Files[0].DecompressedName = "c:\test\ipworkszip\temp\test.txt"
ZipControl.Files[0].CompressedName = "readme.txt"
ZipControl.Compress()

CompressedSize
Long

The size of the compressed data, as compressed within the archive. Headers, footers, etc., are not included in the size.

Reading the value of this property will return a meaningful value only after the archive has been compressed, scanned, or decompressed, and only if the values of ArchiveFile, or Files have not been changed since. If a meaningful value is not available this property will return a value of -1.

CompressionLevel
Integer

The compression level to use for the file. This property specifies the level of compression to be used, between 0 and 6. Higher values will cause the component to compress better; lower values will cause the component to compress faster. A value of 0 will store the file without compression.

CRC
Long

The CRC value for the specified file found in the archive. This value is populated after compression or decompression.

DecompressedName
String

The name of the file in the archive, as stored on the file system, outside the archive.

When compressing files, This field should be specified with a path, if necessary, to allow the file to be found by the component. If the file cannot be found during compression, a trappable error will be generated, and the archive will not be correctly written.

When decompressing files, the field indicates where the file should be written. After the archive is scanned, the values of CompressedName and DecompressedName will be set to the exact filenames found in the archive. The value of DecompressedName may then be changed if desired.

If DecompressedName is set to an empty string before extraction, the file will not be written to disk at all. It will still be written to the Progress event if WriteToProgressEvent is set to true.

If DecompressedName is set to an empty string before compression, the file will be skipped, and not written to the archive.

A base path for decompression may be specified by setting the ExtractToPath property. If ExtractToPath is set to a non-empty string, the files will be decompressed to the directory specified in ExtractToPath. If the value of DecompressedName contains a pathname it will be regarded as relative to ExtractToPath.

Paths on the local file system should be specified in the format native to the host operating system. They may also be specified in standard (UNIX) format, in which case they will be immediately converted.

Example


ZipControl.ArchiveFile = "c:\test.tar"
ZipControl.Scan()
ZipControl.ExtractToPath = "c:\temp\"
ZipControl.Files[1].DecompressedName = "test\temp.out"
ZipControl.Extract(ZipControl.Files[1].CompressedName)
Incorrect Example
ZipControl.ExtractToPath = "c:\temp\"
ZipControl.Files[1].DecompressedName = "c:\temp\test\temp.out"
'The file would be extracted to c:\temp\c:\temp\test\temp.out

DecompressedSize
Long

The size of the file, as decompressed outside the archive. If an archive is open for read (i.e. has been scanned or decompressed), this information will be read from the archive headers. If an archive is not open for read, the component will retrieve the information for the corresponding value of DecompressedName from the local file system.

A value of -1 will be returned in case of an I/O error.

EncryptionAlgorithm
EncryptionAlgorithms

The algorithm used to encrypt the specified file written to the archive.

Note that the file will only be encrypted if Password is set. By default the component will use standard zip encryption if Password is set, and will not encrypt data otherwise.

The component supports the use of AES, the Advanced Encryption Standard, as well as standard Zip encryption. The default encryption algorithm is the algorithm introduced in version 2.0 of the Zip specification, and is compatible with virtually all other zip utilities. However, this algorithm is considered weak and should not be used to protect sensitive data.

AES is a U.S. government standard cleared to protect even the most sensitive data. The file format used to create AES-encrypted files is designed to be compatible with WinZip 9.0. AES-encrypted files created by the component may or may not be compatible with other Zip utilities.

The component supports the use of AES with key lengths of 128, 192, or 256 bits. Note that even with the weakest (128-bit) keys AES is much more secure than standard Zip encryption.

If you use strong or maximum AES encryption the component will generate a unique salt value and cryptographic key for each file encrypted. If you use weak encryption the component will use the same salt for each file in the archive. If you are encrypting a large number of files this will have a substantial effect on performance. Set the AESGenerateUniqueKeys configuration setting to configure the salt generation independent of the key length.

If using AES encryption it is important to choose a good Password. For 128-bit keys it is recommended that your password be 32 characters long, and for 256-bit keys, 64 characters.

Important: Note that AES encryption only encrypts the contents of encrypted files within the Zip archive; it does not prevent an attacker from reading the names of files in the archive, or from adding or deleting files to or from the archive. To prevent this consider first storing your files in an unencrypted zip file, and then storing this zip file in another, AES-encrypted zip file.

To set the EncryptionAlgorithm or Password fields for the entire archive, use the EncryptionAlgorithm or Password properties.

Property values:

eaDefault0
eaAESWeak1
eaAESStrong2
etAESMaximum3

Hash
String

The computed hash for the specified File.

This field is populated with the hash value computed for the specified file after calling Compress. This field is only applicable if the FileHashAlgorithm configuration setting is set.

InputData
String

When This field is set, the component will read in the data from This field instead of reading from the file contained in the DecompressedName field.

InputDataB
Byte[]

When This field is set, the component will read in the data from This field instead of reading from the file contained in the DecompressedName field.

InputStream
System.IO.Stream

When This field is set to a valid stream, the component will read in the data from the stream as the current file instead of reading from the file contained in the DecompressedName field.

Password
String

This field specifies the case-sensitive password used to encrypt or decrypt the current file. If set to an empty string, no password is used.

For archives that have multiple files with the same password, you may use the Password property instead of the Password field of the Files collection. You may also use PasswordRequired field to see if a file requires a password after an archive has been scanned.

In this release, streaming out of encrypted archives is not supported. When compressing, WriteToProgressEvent must be set to false if Password is set.

Example (Compressing an Archive)


ZipControl.ArchiveFile = "c:\test.zip"
ZipControl.RecurseSubdirectories = true
ZipControl.IncludeFiles("c:\foo\*")
ZipControl.Password = "nsoftware"
ZipControl.Compress()

PasswordRequired
Boolean

This field describes whether or not the current file has been encrypted or not and requires a password to decompress. It is populated after the archive has been scanned.

Constructors

public ZIPFile();
Public ZIPFile()
public ZIPFile(string decompressedName);
Public ZIPFile(ByVal DecompressedName As String)
public ZIPFile(string compressedName, string decompressedName);
Public ZIPFile(ByVal CompressedName As String, ByVal DecompressedName As String)
public ZIPFile(string compressedName, System.IO.Stream inputStream);
Public ZIPFile(ByVal CompressedName As String, ByVal InputStream As System.IO.Stream)

 
 
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IPWorks ZIP 2020 .NET Edition - Version 20.0 [Build 7720]