core/sys/sys.go

package sys

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"os"
	"os/exec"
	"os/signal"
	"syscall"

	"golang.org/x/sys/unix"
)

var TERM_WIDTH = 50

func RunSilentCmd(cmd *exec.Cmd) int {
	err := cmd.Run()
	return ManageStatusCmd(cmd, err)
}

func RunBufferedCmd(cmd *exec.Cmd, out *bytes.Buffer) int {
	rs1, err := cmd.CombinedOutput()
	if err != nil {
		fmt.Println("Error: ", err)
	}
	out.Write(rs1)
	return ManageStatusCmd(cmd, err)
}

func RunCmd(cmd *exec.Cmd) int {
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	return ManageStatusCmd(cmd, cmd.Run())
}

func RunShellCmd(call string) int {
	cmd := exec.Command("sh", "-c", call)
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	return ManageStatusCmd(cmd, cmd.Run())
}

func ManageStatusCmd(cmd *exec.Cmd, err error) int {
	if err == nil {
		return 0
	}
	// Figure out the exit code
	if ws, ok := cmd.ProcessState.Sys().(syscall.WaitStatus); ok {
		if ws.Exited() {
			return ws.ExitStatus()
		}
		if ws.Signaled() {
			return -int(ws.Signal())
		}
	}
	return -1
}

func RunInteractiveCmd(cmd string, withStderr bool, buffers ...*bytes.Buffer) int {
	// fmt.Printf(" == go before command : %s\n", cmd)
	icmd := exec.Command("bash", "-c", cmd)
	icmd.Stdin = os.Stdin
	icmd.Stdout = os.Stdout
	if withStderr {
		if len(buffers) > 0 {
			icmd.Stderr = buffers[0]
		} else {
			icmd.Stderr = os.Stderr
		}
	}
	return ManageStatusCmd(icmd, icmd.Run())
}

func PipeCmd(cmd1 *exec.Cmd, cmd2 *exec.Cmd, buffers ...io.Writer) int {
	status := -1
	// fmt.Println("> Pipe Commands")
	if len(buffers) > 0 {
		errIndex := 0
		pr, pw := io.Pipe()
		cmd1.Stdout = pw
		cmd2.Stdin = pr
		cmd2.Stdout = buffers[errIndex]
		if len(buffers) > 1 {
			errIndex = 1
			cmd2.Stderr = buffers[errIndex]
		}

		cmd1.Start()
		cmd2.Start()

		go func() {
			defer pw.Close()
			err1 := cmd1.Wait()
			if err1 != nil {
				buffers[errIndex].Write([]byte(fmt.Sprintf(" Error pipe in : %v\n", err1)))
			}
		}()

		err2 := cmd2.Wait()
		if err2 != nil {
			buffers[errIndex].Write([]byte(fmt.Sprintf(" Error pipe out : %v\n", err2)))
			status = 1
		} else {
			status = 0
		}
		// fmt.Println("< Pipe Commands")
	}
	return status
}

func UpdateTermSize() error {
	ws, err := unix.IoctlGetWinsize(syscall.Stdout, unix.TIOCGWINSZ)
	if err != nil {
		return err
	}
	TERM_WIDTH = int(ws.Col)
	return nil
}

func HandleTermChange(sigwinch chan os.Signal) {
	// set signal handler
	signal.Notify(sigwinch, syscall.SIGWINCH)
	go func() {
		for {
			if _, ok := <-sigwinch; !ok {
				return
			}
			_ = UpdateTermSize()
		}
	}()
}

func HandleSigKill(done chan os.Signal) {
	signal.Notify(done, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		<-done // Will block here until user hits ctrl+c
		RunCmd(exec.Command("tput", "cnorm"))
		RunCmd(exec.Command("tput", "-x", "clear"))
		os.Exit(0)
	}()
}

func IsRunningOnPod() bool {
	var bufout bytes.Buffer
	return PipeCmd(exec.Command("cat", "/proc/1/cgroup"), exec.Command("grep", "kubepods"), &bufout) == 0
}

func IsFileExists(path string) bool {
	exists := false
	if _, err := os.Open(path); !errors.Is(err, os.ErrNotExist) {
		exists = true
	}
	return exists
}