zip_dir_add —
add directory to zip archive
#include <zip.h>
zip_int64_t
  
  zip_dir_add(zip_t
    *archive, const char
    *name, zip_flags_t
    flags);
The function zip_dir_add() adds a directory to a zip
  archive. The argument archive specifies the zip archive
  to which the directory should be added. name is the
  directory's name in the zip archive. The flags argument
  can be any of:
  - ZIP_FL_ENC_GUESS
- Guess encoding of name (default).
- ZIP_FL_ENC_UTF_8
- Interpret name as UTF-8.
- ZIP_FL_ENC_CP437
- Interpret name as code page 437 (CP-437).
Upon successful completion, the index of the new entry in the archive is
  returned. Otherwise, -1 is returned and the error code in
  archive is set to indicate the error.zip_dir_add() fails if:
  - [ZIP_ER_EXISTS]
- There is already an entry called name in the
      archive.
- [ZIP_ER_INVAL]
- archive or name are
      NULL, or invalid UTF-8 encoded file names.
- [ZIP_ER_MEMORY]
- Required memory could not be allocated.
zip_dir_add() was added in libzip 0.11.
zip_dir_add() does not look in the file system, it just
  creates one entry in the archive for the provided name.