Remove the os.user dependency and manually lookup /etc/passwd instead

Upstream-commit: eb38750d99d4f9706cb2abcb861c84e1d309bd40
Component: engine

components/engine/sysinit.go

@@ -3,10 +3,10 @@ package docker
 import (
 	"flag"
 	"fmt"
+	"github.com/dotcloud/docker/utils"
 	"log"
 	"os"
 	"os/exec"
-	"os/user"
 	"strconv"
 	"strings"
 	"syscall"
@@ -27,10 +27,7 @@ func changeUser(u string) {
 	if u == "" {
 		return
 	}
-	userent, err := user.LookupId(u)
-	if err != nil {
-		userent, err = user.Lookup(u)
-	}
+	userent, err := utils.UserLookup(u)
 	if err != nil {
 		log.Fatalf("Unable to find user %v: %v", u, err)
 	}

components/engine/utils/utils.go

@@ -14,6 +14,7 @@ import (
 	"net/http"
 	"os"
 	"os/exec"
+	"os/user"
 	"path/filepath"
 	"runtime"
 	"strconv"
@@ -700,3 +701,23 @@ func ParseRepositoryTag(repos string) (string, string) {
 	}
 	return repos, ""
 }
+
+func UserLookup(uid string) (*user.User, error) {
+	file, err := ioutil.ReadFile("/etc/passwd")
+	if err != nil {
+		return nil, err
+	}
+	for _, line := range strings.Split(string(file), "\n") {
+		data := strings.Split(line, ":")
+		if len(data) > 5 && (data[0] == uid || data[2] == uid) {
+			return &user.User{
+				Uid:      data[2],
+				Gid:      data[3],
+				Username: data[0],
+				Name:     data[4],
+				HomeDir:  data[5],
+			}, nil
+		}
+	}
+	return nil, fmt.Errorf("User not found in /etc/passwd")
+}