CP Shrink

From Just Solve the File Format Problem
(Difference between revisions)
Jump to: navigation, search
(Created page with "{{FormatInfo |formattype=electronic |subcat=Archiving |extensions={{ext|cpz}} |released=≤1992 }} '''CP Shrink''' (or CPSHRINK) is a compressed archive program for DOS, and i...")
 
m (Change telparia.com samples link to template)
 
(5 intermediate revisions by 2 users not shown)
Line 6: Line 6:
 
}}
 
}}
 
'''CP Shrink''' (or CPSHRINK) is a compressed archive program for DOS, and its native '''.CPZ''' file format. It was developed by Central Point Software. It usually uses [[PKWARE DCL Implode]] compression.
 
'''CP Shrink''' (or CPSHRINK) is a compressed archive program for DOS, and its native '''.CPZ''' file format. It was developed by Central Point Software. It usually uses [[PKWARE DCL Implode]] compression.
 +
 +
== File structure ==
 +
 +
CPSHRINK CPZ archive format overview
 +
 +
  This information is based on reverse engineering. It may be incorrect
 +
  or incomplete.
 +
  Byte order is little-endian.
 +
  CRC algorithm is [[CRC-32#CRC-32/ISO-HDLC|CRC-32-IEEE]].
 +
  Sizes and offsets are in bytes, unless otherwise noted.
 +
 +
File structure
 +
 +
  Offset        Size        Description
 +
  ------        ----        -----------
 +
  0              8            Archive Header segment
 +
  8              32×nmembers  Member File Headers segment
 +
  8 32×nmembers              File Data area
 +
 +
Archive Header segment
 +
 +
  Offset  Size Label    Description
 +
  ------  ---- -----    -----------
 +
  0        4    nmembers  Number of member files
 +
  4        4              CRC of the 32×nmembers bytes following this
 +
                          field
 +
 +
  Note: The nmembers field might actually be a 2-byte field, followed
 +
  by 2 bytes of unknown use.
 +
 +
Member File Headers segment
 +
 +
  Sequence of Member File Headers, each 32 bytes, starts at offset 8.
 +
 +
Member File Header
 +
 +
  Offset  Size  Description
 +
  ------  ----  -----------
 +
  0      4      CRC of *compressed* file data
 +
  4      15    Filename, NUL terminated
 +
  19      1      Compression method:
 +
                  0 = [[PKWARE DCL Implode]], Binary
 +
                  1 = PKWARE DCL Implode, ASCII
 +
                  2 = not compressed
 +
  20      4      Original size
 +
  24      4      Compressed size
 +
  28      4      Timestamp ([[MS-DOS date/time|DOS date, time]])
 +
 +
File Data area
 +
 +
  The first file's compressed data starts at 8 32×nmembers.
 +
 +
  Location of other files' data is implied by the sum of the compressed
 +
  sizes of the preceding files.
  
 
== Identification ==
 
== Identification ==
−
There's no obvious way to identify a CPZ file from its contents. There is probably some sort of checksum field of that could be validated, but more research is needed.
+
There's no quick and easy way to identify a CPZ file from its contents. Validating the CRC of the file headers segment could work, but that segment does not have a fixed size.
  
 
== Software ==
 
== Software ==
−
* [{{SACFTPURL|pack|cpshrink.zip}} CP Shrink] (German language)
+
* [https://archive.org/details/CentralPointMorePCTools2.0ForDOSAndWindows Central Point More PC Tools 2.0 for DOS and Windows (German)] → disk1.img → CPSHRINK.EXE (English)
 +
* [https://archive.org/details/PCToolsProV9.0German PC Tools Pro v9.0 (German)] → disk1.img → CPSHRINK.EXE (German)
 +
* [{{SACFTPURL|pack|cpshrink.zip}} CP Shrink], from the SAC collection (German)
 +
* {{Deark}}
 +
 
 +
== Sample files ==
 +
* {{DexvertSamples|archive/cpShrink}}

Latest revision as of 02:55, 28 December 2023

File Format
Name CP Shrink
Ontology
Extension(s) .cpz
Released ≤1992

CP Shrink (or CPSHRINK) is a compressed archive program for DOS, and its native .CPZ file format. It was developed by Central Point Software. It usually uses PKWARE DCL Implode compression.

Contents

[edit] File structure 

CPSHRINK CPZ archive format overview

 This information is based on reverse engineering. It may be incorrect
  or incomplete.
 Byte order is little-endian.
 CRC algorithm is CRC-32-IEEE.
 Sizes and offsets are in bytes, unless otherwise noted.

File structure

 Offset         Size         Description
 ------         ----         -----------
 0              8            Archive Header segment
 8              32×nmembers  Member File Headers segment
 8 32×nmembers               File Data area

Archive Header segment

 Offset   Size Label     Description
 ------   ---- -----     -----------
 0        4    nmembers  Number of member files
 4        4              CRC of the 32×nmembers bytes following this
                          field

 Note: The nmembers field might actually be a 2-byte field, followed
 by 2 bytes of unknown use.

Member File Headers segment

 Sequence of Member File Headers, each 32 bytes, starts at offset 8.

Member File Header

 Offset   Size   Description
 ------   ----   -----------
  0       4      CRC of *compressed* file data
  4       15     Filename, NUL terminated
  19      1      Compression method:
                  0 = PKWARE DCL Implode, Binary
                  1 = PKWARE DCL Implode, ASCII
                  2 = not compressed
  20      4      Original size
  24      4      Compressed size
  28      4      Timestamp (DOS date, time)

File Data area

 The first file's compressed data starts at 8 32×nmembers.

 Location of other files' data is implied by the sum of the compressed
 sizes of the preceding files.

[edit] Identification

There's no quick and easy way to identify a CPZ file from its contents. Validating the CRC of the file headers segment could work, but that segment does not have a fixed size.

[edit] Software

[edit] Sample files

Retrieved from "http://fileformats.archiveteam.org/index.php?title=CP_Shrink&oldid=46576"
Personal tools
Namespaces

Variants
Actions
Navigation
Toolbox