CP Shrink
From Just Solve the File Format Problem
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0 8 Archive Header segment | 0 8 Archive Header segment | ||
8 32×nmembers Member File Headers segment | 8 32×nmembers Member File Headers segment | ||
| − | 8 | + | 8 32×nmembers File Data area |
Archive Header segment | Archive Header segment | ||
| Line 44: | Line 44: | ||
Offset Size Description | Offset Size Description | ||
------ ---- ----------- | ------ ---- ----------- | ||
| − | + | 0 4 CRC of *compressed* file data | |
| − | + | 4 15 Filename, NUL terminated | |
| − | + | 19 1 Compression method: | |
0 = [[PKWARE DCL Implode]], Binary | 0 = [[PKWARE DCL Implode]], Binary | ||
1 = PKWARE DCL Implode, ASCII | 1 = PKWARE DCL Implode, ASCII | ||
2 = not compressed | 2 = not compressed | ||
| − | + | 20 4 Original size | |
| − | + | 24 4 Compressed size | |
| − | + | 28 4 Timestamp ([[MS-DOS date/time|DOS date, time]]) | |
File Data area | File Data area | ||
| − | The first file's compressed data starts at 8 | + | The first file's compressed data starts at 8 32×nmembers. |
Location of other files' data is implied by the sum of the compressed | Location of other files' data is implied by the sum of the compressed | ||
| Line 71: | Line 71: | ||
== Sample files == | == Sample files == | ||
| − | * | + | * {{DexvertSamples|archive/cpShrink}} |
Latest revision as of 02:55, 28 December 2023
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
- Central Point More PC Tools 2.0 for DOS and Windows (German) → disk1.img → CPSHRINK.EXE (English)
- PC Tools Pro v9.0 (German) → disk1.img → CPSHRINK.EXE (German)
- CP Shrink, from the SAC collection (German)
- Deark
