zip_fdopen man page
zip_fdopen — open zip archive using open file descriptor
zip_fdopen(int fd, int flags, int *errorp);
The zip archive specified by the open file descriptor fd is opened and a pointer to a struct zip, used to manipulate the archive, is returned. In contrast to zip_open(3), using zip_fdopen the archive can only be opened in read-only mode. The fd argument may not be used any longer after calling zip_fdopen. The flags are specified by or'ing the following values, or 0 for none of them.
Perform additional stricter consistency checks on the archive, and error if they fail.
If an error occurs and errorp is non-NULL, it will be set to the corresponding error code.
Upon successful completion zip_fdopen() returns a struct zip pointer, and fd should not be used any longer, nor passed to close(2). Otherwise, NULL is returned and *errorp is set to indicate the error. In the error case, fd remains unchanged.
The file specified by fd is prepared for use by libzip(3) unless:
Inconsistencies were found in the file specified by path. This error is often caused by specifying ZIP_CHECKCONS but can also happen without it.
The flags argument is invalid. Not all zip_open(3) flags are allowed for zip_fdopen, see Description.
Required memory could not be allocated.
The file specified by fd is not a zip archive.
The file specified by fd could not be prepared for use by libzip(3).
A read error occurred; see errno for details.
The file specified by fd does not allow seeks.
libzip(3), zip_close(3), zip_error_to_str(3), zip_open(3)
Dieter Baron <firstname.lastname@example.org> and Thomas Klausner <email@example.com>
libzip(3), zip_close(3), zip_open(3).