zip_set_archive_comment —
set zip archive comment
#include <zip.h>
int
  
  zip_set_archive_comment(zip_t
    *archive, const char
    *comment, zip_uint16_t
    len);
The zip_set_archive_comment() function sets the comment
  for the entire zip archive. If comment is
  NULL and len is 0, the archive
  comment will be removed. comment must be encoded in
  ASCII or UTF-8.
Upon successful completion 0 is returned. Otherwise, -1 is returned and the
  error information in archive is set to indicate the
  error.
zip_set_archive_comment() fails if:
  - [ZIP_ER_INVAL]
- len is less than 0 or longer than the maximum
      comment length in a zip file (65535), or comment is
      not a valid UTF-8 encoded string.
- [ZIP_ER_MEMORY]
- Required memory could not be allocated.
zip_set_archive_comment() was added in libzip 0.7. In
  libzip 0.11 the type of len was changed from
  int to zip_uint16_t.