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Copy pathsysinit.go
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106 lines (93 loc) · 2.17 KB
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package docker
import (
"flag"
"fmt"
"github.com/dotcloud/docker/utils"
"log"
"os"
"os/exec"
"strconv"
"strings"
"syscall"
)
// Setup networking
func setupNetworking(gw string) {
if gw == "" {
return
}
if _, err := ip("route", "add", "default", "via", gw); err != nil {
log.Fatalf("Unable to set up networking: %v", err)
}
}
// Setup working directory
func setupWorkingDirectory(workdir string) {
if workdir == "" {
return
}
syscall.Chdir(workdir)
}
// Takes care of dropping privileges to the desired user
func changeUser(u string) {
if u == "" {
return
}
userent, err := utils.UserLookup(u)
if err != nil {
log.Fatalf("Unable to find user %v: %v", u, err)
}
uid, err := strconv.Atoi(userent.Uid)
if err != nil {
log.Fatalf("Invalid uid: %v", userent.Uid)
}
gid, err := strconv.Atoi(userent.Gid)
if err != nil {
log.Fatalf("Invalid gid: %v", userent.Gid)
}
if err := syscall.Setgid(gid); err != nil {
log.Fatalf("setgid failed: %v", err)
}
if err := syscall.Setuid(uid); err != nil {
log.Fatalf("setuid failed: %v", err)
}
}
// Clear environment pollution introduced by lxc-start
func cleanupEnv(env ListOpts) {
os.Clearenv()
for _, kv := range env {
parts := strings.SplitN(kv, "=", 2)
if len(parts) == 1 {
parts = append(parts, "")
}
os.Setenv(parts[0], parts[1])
}
}
func executeProgram(name string, args []string) {
path, err := exec.LookPath(name)
if err != nil {
log.Printf("Unable to locate %v", name)
os.Exit(127)
}
if err := syscall.Exec(path, args, os.Environ()); err != nil {
panic(err)
}
}
// Sys Init code
// This code is run INSIDE the container and is responsible for setting
// up the environment before running the actual process
func SysInit() {
if len(os.Args) <= 1 {
fmt.Println("You should not invoke docker-init manually")
os.Exit(1)
}
var u = flag.String("u", "", "username or uid")
var gw = flag.String("g", "", "gateway address")
var workdir = flag.String("w", "", "workdir")
var flEnv ListOpts
flag.Var(&flEnv, "e", "Set environment variables")
flag.Parse()
cleanupEnv(flEnv)
setupNetworking(*gw)
setupWorkingDirectory(*workdir)
changeUser(*u)
executeProgram(flag.Arg(0), flag.Args())
}