How to build ZIP compatible with Kaffe ?

[Daniel.Veillard at imag.fr]

 I have tried to build prepackaged ZIP files but unfortunately
it seems that Kaffe is unable to open and read clesses from the
archive. I first tried with  Zip 2.1 (April 27th 1996) coming
standard with my Linux distribution. The command used is :

zip amaya.zip amaya/file1.class ... amaya/filen.class

 I get : 

Bad magic 6d52ed4e in class

at amaya startup.
Since this version introduced some incompatibilies with older
versions of the ZIP format, I tried with Zip 1.1 (29 Aug 1992)

Bad magic f000102 in class

The zip files produced are correct and unzipping them produces
a binary identical classes tree.

----------------------------------------------------------------
open("./amaya/amayaInit.class", O_RDONLY) = -1 ENOENT (No such file or 
directory)
open("/users/veillard/opera/classes/../classes/amaya/amayaInit.class", 
O_RDONLY) = -1 ENOENT (No such file or directory)
open("/users/veillard/opera/classes/../classes/jigsaw.zip", O_RDONLY) = 4
lseek(4, 0, SEEK_END)                   = 336868
mmap(0, 336868, PROT_READ|PROT_WRITE, MAP_PRIVATE, 4, 0) = 0x40506000
mprotect(0x40506000, 339968, PROT_READ) = 0
close(4)                                = 0
open("/users/veillard/opera/classes/../classes/thotlib.zip", O_RDONLY) = 4
lseek(4, 0, SEEK_END)                   = 23290
mmap(0, 23290, PROT_READ|PROT_WRITE, MAP_PRIVATE, 4, 0) = 0x40559000
mprotect(0x40559000, 24576, PROT_READ)  = 0
close(4)                                = 0
open("/users/veillard/opera/classes/../classes/amaya.zip", O_RDONLY) = 4
lseek(4, 0, SEEK_END)                   = 20836
mmap(0, 20836, PROT_READ|PROT_WRITE, MAP_PRIVATE, 4, 0) = 0x4055f000
mprotect(0x4055f000, 24576, PROT_READ)  = 0
close(4)                                = 0
write(2, "Bad magic 6d51ed4e in class\n", 28Bad magic 6d51ed4e in class
) = 28
_exit(1)                                = ?
---------------------------------------------------------------------

   I'm certainly doing something obviously wrong but wasn't abble to
guess what's happening,

   any help is welcome,

Daniel