c++ - How to return a pointer char from v8 to javascript -

i return char pointer v8 javascript, not work. in js length of result not good. example outlength 43529bytes in v8, in js have 4 bytes. correct in using return string::new((char *)img);

javascript:

var result = module.encode(); console.log(result.length); 

v8

handle<value> encode(const arguments& args) {    file *pinputfile = fopen ( "images/file.rgb" , "rb" );     if (!pinputfile ) {     fprintf(stderr, "could not open %s\n", "vr.rgb");     exit(1);    }    fseek (pinputfile , 0 , seek_end);    long lsizeinput = ftell (pinputfile );    rewind (pinputfile );    char *img=(char*) malloc(lsizeinput*sizeof( char ));    fread (img,1,lsizeinput,pinputfile);     cout<<"length = "<< lsizeinput<<endl;    return  string::new((char *)img);  }