zip_file_set_comment —
set comment for file in zip
#include <zip.h>
int
  
  zip_file_set_comment(zip_t
    *archive, zip_uint64_t
    index, const char
    *comment, zip_uint16_t
    len, zip_flags_t
    flags);
The zip_file_set_comment() function sets the comment for
  the file at position index in the zip archive to
  comment of length len. If
  comment is NULL and
  len is 0, the file comment will be removed. The
  flags argument can be any of:
  - ZIP_FL_ENC_GUESS
- Guess encoding of comment (default).
- ZIP_FL_ENC_UTF_8
- Interpret comment as UTF-8.
- ZIP_FL_ENC_CP437
- Interpret comment as code page 437 (CP-437).
Upon successful completion 0 is returned. Otherwise, -1 is returned and the
  error information in archive is set to indicate the
  error.zip_file_set_comment() fails if:
  - [ZIP_ER_INVAL]
- index is not a valid file index in
      archive, or 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_ER_RDONLY]
- The archive was opened in read-only mode.
zip_file_set_comment() was added in libzip 0.11.