// concurrency, just threads and synchronization
// and foreign code on multiple pthreads.

package main

import (
	big "."
	"runtime"
)

func fibber(c chan *big.Int, out chan string, n int64) {
	// Keep the fibbers in dedicated operating system
	// threads, so that this program tests coordination
	// between pthreads and not just goroutines.
	runtime.LockOSThread()

	i := big.NewInt(n)
	if n == 0 {
		c <- i
	}

	if flag.NArg() != 1 {
		usage()
	}

	file := flag.Arg(0)
	id, err := buildid.ReadFile(file)
	if err != nil {
		log.Fatal(err)
	}
	if !*wflag {
		fmt.Printf("%s\n", id)
		return
	}

	// Keep in sync with src/cmd/go/internal/work/buildid.go:updateBuildID

	f, err := os.Open(file)
	if err != nil {
		log.Fatal(err)
	}
	matches, hash, err := buildid.FindAndHash(f, id, 0)
	f.Close()
	if err != nil {