From 7270828db756eb9cee80859b3bd3c6954532af20 Mon Sep 17 00:00:00 2001
From: Ben Hoyt <ben.hoyt@canonical.com>
Date: Mon, 10 Jun 2024 20:25:18 +1200
Subject: [PATCH 1/2] fix: work around issue with user.Lookup not returning
 UnknownUserError

Per https://github.com/golang/go/issues/67912, under some circumstances
(on my machine) user.Lookup isn't returning UnknownUserError when it
should.
---
 internals/osutil/user.go | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/internals/osutil/user.go b/internals/osutil/user.go
index 464c5b244..6c6c8e975 100644
--- a/internals/osutil/user.go
+++ b/internals/osutil/user.go
@@ -19,6 +19,7 @@ import (
 	"os"
 	"os/user"
 	"strconv"
+	"strings"
 
 	"github.com/canonical/pebble/internals/osutil/sys"
 )
@@ -56,6 +57,12 @@ func RealUser() (*user.User, error) {
 	if _, ok := err.(user.UnknownUserError); ok {
 		return cur, nil
 	}
+	// Workaround for https://github.com/golang/go/issues/67912, until our
+	// minimum Go version has a fix for that. In short, user.Lookup sometimes
+	// doesn't return UnknownUserError when it should.
+	if err != nil && strings.Contains(err.Error(), "no such file or directory") {
+		return cur, nil
+	}
 	if err != nil {
 		return nil, err
 	}
@@ -90,6 +97,10 @@ func NormalizeUidGid(uid, gid *int, username, group string) (*int, *int, error)
 	if username != "" {
 		u, err := userLookup(username)
 		if err != nil {
+			if strings.Contains(err.Error(), "no such file or directory") {
+				// Better error message to work around https://github.com/golang/go/issues/67912
+				return nil, nil, user.UnknownUserError(username)
+			}
 			return nil, nil, err
 		}
 		n, _ := strconv.Atoi(u.Uid)
@@ -107,6 +118,10 @@ func NormalizeUidGid(uid, gid *int, username, group string) (*int, *int, error)
 	if group != "" {
 		g, err := userLookupGroup(group)
 		if err != nil {
+			if strings.Contains(err.Error(), "no such file or directory") {
+				// Better error message to work around https://github.com/golang/go/issues/67912
+				return nil, nil, user.UnknownGroupError(group)
+			}
 			return nil, nil, err
 		}
 		n, _ := strconv.Atoi(g.Gid)

From d0df08fc22315f04bc11b53b6be7ef3d63b6889c Mon Sep 17 00:00:00 2001
From: Ben Hoyt <ben.hoyt@canonical.com>
Date: Tue, 11 Jun 2024 12:57:19 +1200
Subject: [PATCH 2/2] Use syscall.ENOENT.Error() instead of hard-coded error
 messages

---
 internals/osutil/user.go | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/internals/osutil/user.go b/internals/osutil/user.go
index 6c6c8e975..c2b0879d4 100644
--- a/internals/osutil/user.go
+++ b/internals/osutil/user.go
@@ -20,6 +20,7 @@ import (
 	"os/user"
 	"strconv"
 	"strings"
+	"syscall"
 
 	"github.com/canonical/pebble/internals/osutil/sys"
 )
@@ -28,6 +29,8 @@ var (
 	userCurrent     = user.Current
 	userLookup      = user.Lookup
 	userLookupGroup = user.LookupGroup
+
+	enoentMessage = syscall.ENOENT.Error()
 )
 
 // RealUser finds the user behind a sudo invocation when root, if applicable
@@ -60,7 +63,7 @@ func RealUser() (*user.User, error) {
 	// Workaround for https://github.com/golang/go/issues/67912, until our
 	// minimum Go version has a fix for that. In short, user.Lookup sometimes
 	// doesn't return UnknownUserError when it should.
-	if err != nil && strings.Contains(err.Error(), "no such file or directory") {
+	if err != nil && strings.Contains(err.Error(), enoentMessage) {
 		return cur, nil
 	}
 	if err != nil {
@@ -97,7 +100,7 @@ func NormalizeUidGid(uid, gid *int, username, group string) (*int, *int, error)
 	if username != "" {
 		u, err := userLookup(username)
 		if err != nil {
-			if strings.Contains(err.Error(), "no such file or directory") {
+			if strings.Contains(err.Error(), enoentMessage) {
 				// Better error message to work around https://github.com/golang/go/issues/67912
 				return nil, nil, user.UnknownUserError(username)
 			}
@@ -118,7 +121,7 @@ func NormalizeUidGid(uid, gid *int, username, group string) (*int, *int, error)
 	if group != "" {
 		g, err := userLookupGroup(group)
 		if err != nil {
-			if strings.Contains(err.Error(), "no such file or directory") {
+			if strings.Contains(err.Error(), enoentMessage) {
 				// Better error message to work around https://github.com/golang/go/issues/67912
 				return nil, nil, user.UnknownGroupError(group)
 			}