search

madler / zlib

A massively spiffy yet delicately unobtrusive compression library.
http://zlib.net/
Other
5.71k stars 2.45k forks source link

64-bit offset is truncated to 32 bits in minizip #776

Closed skalleAnka closed 1 year ago

skalleAnka commented 1 year ago

In commit 2014a993addbc8f1b9785d97f55fd189792c2f78, ioapi.c funcion fseek64_file_func was changed to cast the offset to a long, truncating the 64 bit offset value.

This was changed in commit 9b291c9f013f99ad494ffecf4295cb2f594a18e3 to be a z_off_t.

If you build minizip on Windows with Visual C++ without defining z_off_t yourself, zconf.h will define it as a long, which still causes truncation.

fredgan commented 1 year ago

Maybe you can submit a PR.

skalleAnka commented 1 year ago

If I did submit one, the change I would make is to revert all changes on this line to before these two changes. This is because I have no knowledge of why this casting was added in the first place, seems pretty unnecessary to me.

But I assume it was put there to either silence a warning on some compiler that I don't have or fix some remark by some code analysis tool that I probably also don't have. So I wouldn't know what the proper fix is.

M-DeRosier commented 1 year ago

This issue causes zip files over 2GB created via Minizip to be unreadable by other programs. I have opened a PR to fix it: #790

Neustradamus commented 1 year ago

@gvollant: Can you look?

durs commented 1 year ago

Faced the same problem. Maybe replace z_off_t with z_off64_t in fseek64_file_func? Correctly worked in VC14.3 and GCC9.4

tbeu commented 1 year ago

Already addressed by #749.

madler commented 1 year ago

If I did submit one, the change I would make is to revert all changes on this line to before these two changes. This is because I have no knowledge of why this casting was added in the first place, seems pretty unnecessary to me.

It was to silence a warning for the implicit casting of an unsigned type to a signed type. This is now addressed by https://github.com/madler/zlib/commit/05527a1b1ef39014b44281fbbbec5deabb4be106 .