Buffer overrun when deleting file from archive

[abbeycode]

The overrun occurs on line 1100 of zip.c when running -[UZKArchive deleteFile:error:]:

size_comment = (uInt)strlen(comment);

You can get the exact stack trace by running the DeleteFileTests unit tests with the Address Sanitizer turned on. It looks like this happens for any file in an archive with no comment, because on line 1464 of UZKArchive it's allocating a zero-length buffer when there's no comment:

char *commentBuffer = (char*)malloc(unzipInfo.size_file_comment);

It should instead make the buffer NULL in that case.

Consider, in order to avoid any future errors like this that Xcode's capable of detecting, making a test plan that runs tests with each of the sanitizers turned on.