How do I go from io.ReadCloser to io.ReadSeeker? -
i'm trying download file s3 , upload file bucket in s3. copy api won't work here because i've been told not use it. getting object s3 has response.body that's io.readcloser , upload file, payload takes body that's io.readseeker . the way can figure out saving response.body file passing file io.readseeker . require writing entire file disk first reading entire file disk sounds pretty wrong. what is: resp, _ := conn.getobject(&s3.getobjectinput{key: "bla"}) conn.putobject(&s3.putobjectinput{body: resp.body}) // resp.body io.readcloser , field type expects io.readseeker question is, how go io.readcloser io.readseeker in efficient way possible? io.readseeker interface groups basic read() , seek() methods. definition of seek() method: seek(offset int64, whence int) (int64, error) an implementation of seek() method requires able seek anywhere in source, requires all source available or reproducible. file perfect ...