Category : Utilities for DOS and Windows Machines
Archive   : SQZ1083E.ZIP
Filename : TECH.ENG

The information in this document may, or may not, be correct, but is given
as a bonus. Someone might find it useful. 1993/01/11
-------------------------------------------------------------------------------

DOSversion: 3.3 and onwards,
2.0 to 3.2 will work as long as you use UPPERCASE in all
filenames and don't use SFX/SFXjr.


Memory: For packing; ÷400 kB, but more than 380 kB
Decoding; ÷96 kB

These figures does not include SQZ itself which requires
÷50 kB and filenames which call for their length + 5 bytes
in overhead (450/420 : 150).

These figures can be shrinked at cost of speed.

It's a real memory eater, ain't it;-)


Others: Given filespec may result in a maximum of 4096 filenames
per run. The archive in itself will handle any number
of files.

A maximum of 64 filespec's for files to skip.

A maximum of 16 extension's for files to copy.


-------------------------------------------------------------------------------
Archive header:
offset 0..4: Id: HLSQZ (072d 076d 083d 081d 090d)
5: Version: 1 (049d)
6: OS: 76543210
xxxxx000 0 PC-DOS
xxxxx001 1 OS/2
xxxxx010 2 MVS
xxxxx011 3 HPSF(OS/2)
xxxxx100 4 Amiga
xxxxx101 5 Macintosh
xxxxx110 6 *nix
xxxxx111 7 Future use
XXXXXxxx Future use
7: Flag 76543210
xxxxxxxX byte order
0 Little Endian, Motorola order
1 Big Endian, Intel order
xxxxxxXx Format for Data and time
0 UNIX format. Number of seconds
since 1:st of january 1970.
1 DOS format for Date and Time
in file: E8631E19.
Decoded: 1992/08/30 12.31.32
MSB LSB
19 1E 63 E8
76543210765432107654321076543210
00011001000111100110001111101000
YYYYYYYMMMMDDDDDHHHHHMMMMMM22222
12 8 30 12 31 16
+=1980 *=2
1992 08 30 12 31 32
xxxxx1xx Security Envelope
No modifications allowed!
If you do any thing, you'll ruin it
xxxx1xxx Whole archive encrypted! Keep OUT
When I say whole, I mean WHOLE.
There's nothing that you can do,
just stay out of trouble.
This archive can't be used until
it's decrypted.
xxx1xxxx Unified data
XXXxxxxx Future use


-------------------------------------------------------------------------------
File header:

offset Size Comment
0 1 Header size and type
0 -> End of archive
1..18 Se below (Extra data)
19.. -> normal file header
if normal file
1 1 Header algebraic sum & 0FFh
0 1:76543210
xxxxXXXX Method 0..4(15)
XXXXxxxx Future use
1 4 Compressed size
5 4 Original size
9 4 Last DateTime
13 1 Attributes
14 4 CRC
18.. (size-18) filename, w/o \0.


-------------------------------------------------------------------------------
How to read a SQZ-archive

Do
If > 18. Normal file
Read HeaderSum(1 byte)
Read size bytes
Calculate headersum
{short i; unsigned short s = 0U;
for(i = 0; i < size; i++)
s += header[i];
if(headersum != (unsigned char)s) WRONG HEADERSUM
header[size] = '\0'; // just to makes things easier to handle, ie.
// zero terminate filename

If == 0. End of archive. Terminate

If <= 18. Extra data, se below
switch
case 1: COMMENT
case 2: PASSWORD
case 3: POSTFIX
case 4: SECURITY ENVELOPE
case 5: VOLUME LABEL
case 6: DIRECTORY
case 7: COMMENT, version 2
else Read one word and then skip that many bytes.
end
Read one word (size)
skip that many bytes, if you don't know how to handle it.

while not End of archive


-------------------------------------------------------------------------------
Extra data

00d END_OF_ARC: Well, what's there to say?

01d COMMENT: Created by SQZ 1.08.2
0 2 Number of bytes in comment
Uncompressed size = this field - 7
2 2 Number of bytes compressed
4 1:76543210
xxxxXXXX Method 0..4(15)
XXXXxxxx Future use
5 4 CRC
9 size-7 Comment


02d PASSWORD:
0 2 n
2 1 76543210
xxxxxxx1 Public
xxxxxx1x Not public
xxxxx1xx Signature included
XXXXXxxx Future use
3 n-1
**************************************************************
I'm not done thinking about this one yet, so I'll be in touch.
I've been thinking and... see ya l'ter
**************************************************************

03d POSTFIX: This code are among the last one in the archive (<256)
0 2 5
2 5 HLSQZ
Postfix are automatically added when closing a modified
archive, but, who knows, it might change in the future
so please check the last 256 bytes, just not the last
nine ones, 'cause who knows, someone might have been
using XModem...

04d SECURITY ENVELOPE:
0 2 n
2 2 SE version (major.minor.test.mask)0010
76543210
testmask
majomino
2 2 SE revision.
6 n-2 None of your business

05d VOLUME LABEL
0 2 Number of bytes
2 4 Time for creation of volume
6 1 Attribute, bit 3 always set (if DOS)
7 4 Serial number, if available, otherwise 00000000h
11 n Label
Number of bytes - 9 -> length of label.

06d DIRECTORY
0 2 Number of bytes
2 1 Algebraic sum & 0xFF
3 4 Time for creation of directory
7 1 Attribute
8 n Path
Number of bytes - 6 --> length of path

07d COMMENT: Created by SQZ 1.08.3 and later
0 2 Number of bytes in field
Compressed size = this field - 7
2 2 Number of uncompressed bytes
4 1:76543210
xxxxXXXX Method 0..4(15)
XXXXxxxx Future use
5 4 CRC
9 size-7 Comment

??d OTHERWISE:
0 2 Number of bytes to skip


-------------------------------------------------------------------------------
Errorlevels
#define EC_NO 0 No error
#define EC_NOMEM 1 Out of memory
#define EC_WRITE_ARC 2 Error writing to archive file
#define EC_WRITE_TMP 3 Error writing to temp archive file
#define EC_WRITE_OUT 4 Error writing to extracted file
#define EC_READ_ARC 5 Error reading from archive file
#define EC_READ_INP 6 Error reading from file to archive
#define EC_OPEN_ARC 7 Error opening archive file
#define EC_OPEN_INP 8 Error opening file to archive
#define EC_OPEN_SFX 9 Error opening SFX/SFXjr.exe
#define EC_OPEN_TMP 10 Error opening temp (archive) file
#define EC_CREATE_ARC 11 Error creating archive file
#define EC_CREATE_TMP 12 Error creating temp archive file
#define EC_CREATE_OUT 13 Error creating file to extract
#define EC_CREATE_SFX 14 Error creating archive file EXE
#define EC_CLOSE_ARC 15 Error closing archive file
#define EC_CLOSE_TMP 16 Error closing temp archive file
#define EC_CLOSE_INP 17 Error closing file to archive
#define EC_CLOSE_OUT 18 Error closing extracted file
#define EC_HEADER_SUM 19 Archive corrupted
#define EC_CORRUPT_HDR 20 Archive corrupted
#define EC_2_MANY_EXT 21 Too many extensions to copy (<= 16)
#define EC_UNKNOWN_SWITCH 22 Unknown switch given
#define EC_ILL_COMB_SW 23 Illegal combination of switches, eg.
include subdirectories and strip path
#define EC_CBREAK 24 User C-Break
#define EC_UNKNOWN 25 Unknown type of archive file
#define EC_NOT_ON_SFX 26 Those commands not allowed on SFX
#define EC_NOT_MS_DOS 27 Archive file was not for MS-DOS
#define EC_CRC 28 CRC-errors in Extracting/Testing
#define EC_SQZ_CORRUPT 29 Someone has tangled with SQZ,
look out for virii or a hacker.
#define EC_CORRUPT_ARC 30 Corrupted archive file.
#define EC_OPS_SEC_ARC 31 Can't handle this SECURE ARCHIVE
Mostly due to version/revision
#define EC_SEC_ARC 32 Secured Archive, modifications not allowed
#define EC_NOTHING_2_DO 128 This one are not considered to be an error!
It's given when no files matches, eg.
SQZ E TST *.PCK and there's no *.PCK to
extract.
#define EC_NOT_REMOVED 129 Couldn't MOVE files.

I'm sorry for those of you who check's for != 0, you'll
now have to check for ((ret_code > 0 && ret_code < 0x80))
to catch any errors, again, I'm sorry.