*: ignore errorlint warnings about unix.* errors

Errors from unix.* are always bare and thus can be used directly.

Add //nolint:errorlint annotation to ignore errors such as these:

libcontainer/system/xattrs_linux.go:18:7: comparing with == will fail on wrapped errors. Use errors.Is to check for a specific error (errorlint)
	case errno == unix.ERANGE:
	     ^
libcontainer/container_linux.go:1259:9: comparing with != will fail on wrapped errors. Use errors.Is to check for a specific error (errorlint)
					if e != unix.EINVAL {
					   ^
libcontainer/rootfs_linux.go:919:7: comparing with != will fail on wrapped errors. Use errors.Is to check for a specific error (errorlint)
			if err != unix.EINVAL && err != unix.EPERM {
			   ^
libcontainer/rootfs_linux.go:1002:4: switch on an error will fail on wrapped errors. Use errors.Is to check for specific errors (errorlint)
			switch err {
			^

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/cgroups/file.go

@@ -81,7 +81,7 @@ func prepareOpenat2() error {
 		})
 		if err != nil {
 			prepErr = &os.PathError{Op: "openat2", Path: cgroupfsDir, Err: err}
-			if err != unix.ENOSYS {
+			if err != unix.ENOSYS { //nolint:errorlint // unix errors are bare
 				logrus.Warnf("falling back to securejoin: %s", prepErr)
 			} else {
 				logrus.Debug("openat2 not available, falling back to securejoin")

libcontainer/cgroups/fs/cpuset.go

@@ -197,7 +197,7 @@ func cpusetEnsureParent(current string) error {
 	}
 	// Treat non-existing directory as cgroupfs as it will be created,
 	// and the root cpuset directory obviously exists.
-	if err != nil && err != unix.ENOENT {
+	if err != nil && err != unix.ENOENT { //nolint:errorlint // unix errors are bare
 		return &os.PathError{Op: "statfs", Path: parent, Err: err}
 	}
 

libcontainer/cgroups/utils.go

@@ -210,7 +210,7 @@ func EnterPid(cgroupPaths map[string]string, pid int) error {
 
 func rmdir(path string) error {
 	err := unix.Rmdir(path)
-	if err == nil || err == unix.ENOENT {
+	if err == nil || err == unix.ENOENT { //nolint:errorlint // unix errors are bare
 		return nil
 	}
 	return &os.PathError{Op: "rmdir", Path: path, Err: err}

libcontainer/container_linux.go

@@ -1256,7 +1256,7 @@ func (c *linuxContainer) prepareCriuRestoreMounts(mounts []*configs.Mount) error
 		for _, u := range umounts {
 			_ = utils.WithProcfd(c.config.Rootfs, u, func(procfd string) error {
 				if e := unix.Unmount(procfd, unix.MNT_DETACH); e != nil {
-					if e != unix.EINVAL {
+					if e != unix.EINVAL { //nolint:errorlint // unix errors are bare
 						// Ignore EINVAL as it means 'target is not a mount point.'
 						// It probably has already been unmounted.
 						logrus.Warnf("Error during cleanup unmounting of %s (%s): %v", procfd, u, e)

libcontainer/init_linux.go

@@ -399,6 +399,8 @@ func fixStdioPermissions(config *initConfig, u *user.ExecUser) error {
 			// privileged_wrt_inode_uidgid() has failed). In either case, we
 			// are in a configuration where it's better for us to just not
 			// touch the stdio rather than bail at this point.
+
+			// nolint:errorlint // unix errors are bare
 			if err == unix.EINVAL || err == unix.EPERM {
 				continue
 			}

libcontainer/system/xattrs_linux.go

@@ -10,6 +10,7 @@ func Lgetxattr(path string, attr string) ([]byte, error) {
 	dest := make([]byte, 128)
 	sz, errno := unix.Lgetxattr(path, attr, dest)
 
+	//nolint:errorlint // unix errors are bare
 	switch {
 	case errno == unix.ENODATA:
 		return nil, errno

signals.go

@@ -120,7 +120,7 @@ func (h *signalHandler) reap() (exits []exit, err error) {
 	for {
 		pid, err := unix.Wait4(-1, &ws, unix.WNOHANG, &rus)
 		if err != nil {
-			if err == unix.ECHILD {
+			if err == unix.ECHILD { //nolint:errorlint // unix errors are bare
 				return exits, nil
 			}
 			return nil, err