How can I access unistd write from another scope?

I am trying to use unistd.h write from inside a class where another "write" function has been declared, but I don't know which is the scope resolutor I should use, as unistd is not a library, so unistd::write() won't work.

How can I call it from inside the function?

// this won't compile

#include <stdio.h> // printf
#include <fcntl.h> 
#include <sys/stat.h> 
#include <unistd.h> 


class Fifo {
public:
    void write(const char* msg, int len);
};

void Fifo::write(const char* msg, int len) {
    int fd; 
    const char* filename = "/tmp/fifotest"; 
    mkfifo(filename, 0666); 
    fd = open(filename, O_WRONLY|O_NONBLOCK);
    write(fd, msg, len); 
    close(fd); 
}   

int main() 
{ 
    Fifo fifo;
    fifo.write("hello", 5);
    return 0;
} 

So use the unnamed scope write. The

write(fd, msg, len);

is equal to

this->write(fd, msg, len); 

write resolved to Fifo::write inside Fifo function. Do:

::write(fd, msg, len); 

to use global scope. like:

#include <cstdio> // use cstdio in C++
extern "C" {      // C libraries need to be around extern "C"
#include <fcntl.h> 
#include <sys/stat.h> 
#include <unistd.h> 
}
class Fifo {
public:
    void write(const char* msg, int len);
};
void Fifo::write(const char* msg, int len) {
    int fd; 
    const char* filename = "/tmp/fifotest"; 
    mkfifo(filename, 0666); 
    fd = open(filename, O_WRONLY|O_NONBLOCK);
    ::write(fd, msg, len);  //here
    close(fd); 
}   
int main() { 
    Fifo fifo;
    fifo.write("hello", 5);
    return 0;
}

Research scopes, namespaces and scope resolution operator in C++ for more information.