boot over nfs with netns

    /system/bin/ip link add eth_slave type veth peer name slave

    ifconfig eth0 down
    ip link set eth0 name nfsif
    ifconfig nfsif up

    #We're changing ip routes/interfaces while nfs is mounted... sounds very safe.
    ifconfig nfsif 0.0.0.0 up
    brctl addbr br0
    #Add nfsif first to get the same MAC, and, hopefully, same IP
    brctl addif br0 nfsif
    mac="$(cat /sys/class/net/nfsif/address)"
    macPrefix="$(echo "$mac" |cut -d : -f 1-5)"
    macEnd="$(echo "$mac" |cut -d : -f 6)"
    macEndAdd="$(printf '%02x' $((0x$macEnd+3)))"
    newMac="${macPrefix}:${macEndAdd}"
    ip link set dev eth_slave address $newMac
    brctl addif br0 android
    ifconfig br0 up
    ifconfig android up
    exec /netns
    
    netns.c
    #define _GNU_SOURCE
#include <sched.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>

int createNetns(void* arg) {
    while(1) sleep(1);
}

void register_interface(char *const iface, char *const ns) {
    if(fork() == 0) {
        char *const args[] = {
            "/system/bin/ip",
            "link",
            "set",
            iface,
            "netns",
            ns,
            NULL
        };
        execve("/system/bin/ip", args, environ);
        return;
    }
    int status;
    wait(&status);
    printf("ip link set returned %d\n", status);
}

int main() {
    void* stack = malloc(16*1024);
    long pid = clone(createNetns, stack, CLONE_NEWNET | SIGCHLD, NULL);
    char *path = NULL;
    asprintf(&path, "/proc/%ld/ns/net", pid);
    int ns = -1;
    while(ns == -1) {
        ns = open(path, O_RDONLY);
        printf("open ns %s %d\n", path, ns);
        sleep(1);
    }

    register_interface("eth0", path);

    int res = setns(ns, 0);
    close(ns);

    printf("setns returned %d %d\n", res, errno);
    char *args[] = {
        "/sbin/switch_root",
        NULL
    };

    execve("/sbin/init", args, environ);
    return 0;
}


    /system/bin/ip link set eth_slave name eth0
    ifconfig eth0 up
    
    exec /netns