From 1e8bf20d6b18219c7c1f161eeae79fb0ced0563e Mon Sep 17 00:00:00 2001
From: Kir Kolyshkin <kolyshkin@gmail.com>
Date: Wed, 11 Mar 2020 08:03:43 -0700
Subject: [PATCH] drivers/platformLChown: return early

This is purely aesthetical -- in case we can't get struct stat_t,
return early. This improves readability and decreases the indentation.

No functional change. Please review this with --ignore-space-change.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
---
 drivers/chown_unix.go | 111 +++++++++++++++++++++---------------------
 1 file changed, 56 insertions(+), 55 deletions(-)

diff --git a/drivers/chown_unix.go b/drivers/chown_unix.go
index 94c641536..2fb1cbcdd 100644
--- a/drivers/chown_unix.go
+++ b/drivers/chown_unix.go
@@ -12,66 +12,67 @@ import (
 )
 
 func platformLChown(path string, info os.FileInfo, toHost, toContainer *idtools.IDMappings) error {
-	sysinfo := info.Sys()
-	if st, ok := sysinfo.(*syscall.Stat_t); ok {
-		// Map an on-disk UID/GID pair from host to container
-		// using the first map, then back to the host using the
-		// second map.  Skip that first step if they're 0, to
-		// compensate for cases where a parent layer should
-		// have had a mapped value, but didn't.
-		uid, gid := int(st.Uid), int(st.Gid)
-		if toContainer != nil {
-			pair := idtools.IDPair{
-				UID: uid,
-				GID: gid,
-			}
-			mappedUID, mappedGID, err := toContainer.ToContainer(pair)
-			if err != nil {
-				if (uid != 0) || (gid != 0) {
-					return fmt.Errorf("error mapping host ID pair %#v for %q to container: %v", pair, path, err)
-				}
-				mappedUID, mappedGID = uid, gid
-			}
-			uid, gid = mappedUID, mappedGID
+	st, ok := info.Sys().(*syscall.Stat_t)
+	if !ok {
+		return nil
+	}
+	// Map an on-disk UID/GID pair from host to container
+	// using the first map, then back to the host using the
+	// second map.  Skip that first step if they're 0, to
+	// compensate for cases where a parent layer should
+	// have had a mapped value, but didn't.
+	uid, gid := int(st.Uid), int(st.Gid)
+	if toContainer != nil {
+		pair := idtools.IDPair{
+			UID: uid,
+			GID: gid,
 		}
-		if toHost != nil {
-			pair := idtools.IDPair{
-				UID: uid,
-				GID: gid,
+		mappedUID, mappedGID, err := toContainer.ToContainer(pair)
+		if err != nil {
+			if (uid != 0) || (gid != 0) {
+				return fmt.Errorf("error mapping host ID pair %#v for %q to container: %v", pair, path, err)
 			}
-			mappedPair, err := toHost.ToHost(pair)
-			if err != nil {
-				return fmt.Errorf("error mapping container ID pair %#v for %q to host: %v", pair, path, err)
-			}
-			uid, gid = mappedPair.UID, mappedPair.GID
+			mappedUID, mappedGID = uid, gid
+		}
+		uid, gid = mappedUID, mappedGID
+	}
+	if toHost != nil {
+		pair := idtools.IDPair{
+			UID: uid,
+			GID: gid,
+		}
+		mappedPair, err := toHost.ToHost(pair)
+		if err != nil {
+			return fmt.Errorf("error mapping container ID pair %#v for %q to host: %v", pair, path, err)
+		}
+		uid, gid = mappedPair.UID, mappedPair.GID
+	}
+	if uid != int(st.Uid) || gid != int(st.Gid) {
+		stat, err := os.Lstat(path)
+		if err != nil {
+			return fmt.Errorf("%s: lstat(%q): %v", os.Args[0], path, err)
+		}
+		cap, err := system.Lgetxattr(path, "security.capability")
+		if err != nil && err != system.ErrNotSupportedPlatform {
+			return fmt.Errorf("%s: Lgetxattr(%q): %v", os.Args[0], path, err)
 		}
-		if uid != int(st.Uid) || gid != int(st.Gid) {
-			stat, err := os.Lstat(path)
-			if err != nil {
-				return fmt.Errorf("%s: lstat(%q): %v", os.Args[0], path, err)
-			}
-			cap, err := system.Lgetxattr(path, "security.capability")
-			if err != nil && err != system.ErrNotSupportedPlatform {
-				return fmt.Errorf("%s: Lgetxattr(%q): %v", os.Args[0], path, err)
-			}
-
-			// Make the change.
-			if err := syscall.Lchown(path, uid, gid); err != nil {
-				return fmt.Errorf("%s: chown(%q): %v", os.Args[0], path, err)
-			}
-			// Restore the SUID and SGID bits if they were originally set.
-			if (stat.Mode()&os.ModeSymlink == 0) && stat.Mode()&(os.ModeSetuid|os.ModeSetgid) != 0 {
-				if err := os.Chmod(path, stat.Mode()); err != nil {
-					return fmt.Errorf("%s: chmod(%q): %v", os.Args[0], path, err)
-				}
-			}
-			if cap != nil {
-				if err := system.Lsetxattr(path, "security.capability", cap, 0); err != nil {
-					return fmt.Errorf("%s: Lsetxattr(%q): %v", os.Args[0], path, err)
-				}
-			}
 
+		// Make the change.
+		if err := syscall.Lchown(path, uid, gid); err != nil {
+			return fmt.Errorf("%s: chown(%q): %v", os.Args[0], path, err)
 		}
+		// Restore the SUID and SGID bits if they were originally set.
+		if (stat.Mode()&os.ModeSymlink == 0) && stat.Mode()&(os.ModeSetuid|os.ModeSetgid) != 0 {
+			if err := os.Chmod(path, stat.Mode()); err != nil {
+				return fmt.Errorf("%s: chmod(%q): %v", os.Args[0], path, err)
+			}
+		}
+		if cap != nil {
+			if err := system.Lsetxattr(path, "security.capability", cap, 0); err != nil {
+				return fmt.Errorf("%s: Lsetxattr(%q): %v", os.Args[0], path, err)
+			}
+		}
+
 	}
 	return nil
 }