#47 Incorrect group/component handling

[Anonymous]

Encountered in
http://downloads.bioware.com/baldursgate1/bgintl114315.exe
(just unzip it...); unshield attributes every file to
every group, resulting in overwritten files, if each
group contains files of the same name ('dialog.tlk' in
this case).

[David Eriksson]

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Very interesting bug!

[David Eriksson]

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If I implement support for extract-by-component it might be
possible to workaround this... hmm...

[Hugh Allen]

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The problem is unshield incorrectly handling CABs with a version of 0x01000004, which snoopy81's Winpack auto-detects as version 5.0.

unshield extracts the 4th-least-significant nybble from the version and uses that as the major version number, in this case giving 0. There used to be code in libunshield.c which checked for a major version less than 5 and changed it to 5, but it's been #ifed out (line 275). Most of the places which check for version 5 were changed to also check for "version 0" but not the code in file_group.c which reads the first_file and last_file members of each group in the header. Consequently it is filling those values with garbage when reading version 0x01000004 CABs. The obvious fix is to change line 20 from

if (header->major_version == 5)
to
if (header->major_version == 0 || header->major_version == 5)

This fixes the file groups for bgintl114315.exe, and also a couple of examples I've found:
http://www.frontechonline.com/driver/pctv.zip (16 MB)
ftp://ftp.sceptre.com/pub/U2000/VGAWin2K&XP13.zip (46 MB)

twogood: you might want to review other places in the code which check the major version number.