metrics-server/vendor/github.com/onsi/ginkgo/internal/remote/output_interceptor_unix.go

// +build freebsd openbsd netbsd dragonfly darwin linux solaris

package remote

import (
	"errors"
	"io/ioutil"
	"os"
)

func NewOutputInterceptor() OutputInterceptor {
	return &outputInterceptor{}
}

type outputInterceptor struct {
	redirectFile *os.File
	intercepting bool
}

func (interceptor *outputInterceptor) StartInterceptingOutput() error {
	if interceptor.intercepting {
		return errors.New("Already intercepting output!")
	}
	interceptor.intercepting = true

	var err error

	interceptor.redirectFile, err = ioutil.TempFile("", "ginkgo-output")
	if err != nil {
		return err
	}

	// Call a function in ./syscall_dup_*.go
	// If building for everything other than linux_arm64,
	// use a "normal" syscall.Dup2(oldfd, newfd) call. If building for linux_arm64 (which doesn't have syscall.Dup2)
	// call syscall.Dup3(oldfd, newfd, 0). They are nearly identical, see: http://linux.die.net/man/2/dup3
	syscallDup(int(interceptor.redirectFile.Fd()), 1)
	syscallDup(int(interceptor.redirectFile.Fd()), 2)

	return nil
}

func (interceptor *outputInterceptor) StopInterceptingAndReturnOutput() (string, error) {
	if !interceptor.intercepting {
		return "", errors.New("Not intercepting output!")
	}

	interceptor.redirectFile.Close()
	output, err := ioutil.ReadFile(interceptor.redirectFile.Name())
	os.Remove(interceptor.redirectFile.Name())

	interceptor.intercepting = false

	return string(output), err
}