$ wc -l *.c
  91 epub-zip.c
  59 epub-zip-mimetype-fix.c
 150 total

Set EPUB_ZIP_DEBUG=1 env var for verbose mode.

Makes a proper EPUB 3 OCF ZIP Container:

• automatically adds mimetype file entry as a 1st file without compression & extra fields;
• doesn't compress already compressed files like jpegs;
• won't allow adding non-supported file types like symlinks.

Usage:

$ epub-zip out.epub `find src`

Corrects a botched EPUB 3 OCF ZIP Container in-place:

• moves mimetype file to the 1st position in an archive;
• removes compression & extra fileds from mimetype file.

Usage:

$ epub-zip-mimetype-fix file.epub

$ sudo dnf install libzip-devel     # tested with 1.9.2
$ make

MIT.