container/check: return error backed by string type

The struct turned out not necessary during initial implementation but was not unwrapped into its single string field. This change replaces it with the underlying string and removes the indirection.

Signed-off-by: Ophestra <cat@gensokyo.uk>

7 files changed, 30 insertions, 21 deletions

diff --git a/container/check/absolute.go b/container/check/absolute.go
index 26f0def6..d17d5e1a 100644
--- a/container/check/absolute.go
+++ b/container/check/absolute.go
@@ -13,15 +13,18 @@ import (
 )
 
 // AbsoluteError is returned by [NewAbs] and holds the invalid pathname.
-type AbsoluteError struct{ Pathname string }
+type AbsoluteError string
 
-func (e *AbsoluteError) Error() string { return fmt.Sprintf("path %q is not absolute", e.Pathname) }
-func (e *AbsoluteError) Is(target error) bool {
-	var ce *AbsoluteError
+func (e AbsoluteError) Error() string {
+	return fmt.Sprintf("path %q is not absolute", string(e))
+}
+
+func (e AbsoluteError) Is(target error) bool {
+	var ce AbsoluteError
 	if !errors.As(target, &ce) {
 		return errors.Is(target, syscall.EINVAL)
 	}
-	return *e == *ce
+	return e == ce
 }
 
 // Absolute holds a pathname checked to be absolute.
@@ -59,7 +62,7 @@ func (a *Absolute) Is(v *Absolute) bool {
 // NewAbs checks pathname and returns a new [Absolute] if pathname is absolute.
 func NewAbs(pathname string) (*Absolute, error) {
 	if !path.IsAbs(pathname) {
-		return nil, &AbsoluteError{pathname}
+		return nil, AbsoluteError(pathname)
 	}
 	return unsafeAbs(pathname), nil
 }
@@ -90,7 +93,7 @@ func (a *Absolute) GobEncode() ([]byte, error) {
 func (a *Absolute) GobDecode(data []byte) error {
 	pathname := string(data)
 	if !path.IsAbs(pathname) {
-		return &AbsoluteError{pathname}
+		return AbsoluteError(pathname)
 	}
 	a.pathname = unique.Make(pathname)
 	return nil
@@ -108,7 +111,7 @@ func (a *Absolute) UnmarshalJSON(data []byte) error {
 		return err
 	}
 	if !path.IsAbs(pathname) {
-		return &AbsoluteError{pathname}
+		return AbsoluteError(pathname)
 	}
 	a.pathname = unique.Make(pathname)
 	return nil
diff --git a/container/check/absolute_test.go b/container/check/absolute_test.go
index 107407f3..25592a71 100644
--- a/container/check/absolute_test.go
+++ b/container/check/absolute_test.go
@@ -31,8 +31,8 @@ func TestAbsoluteError(t *testing.T) {
 	}{
 		{"EINVAL", new(AbsoluteError), syscall.EINVAL, true},
 		{"not EINVAL", new(AbsoluteError), syscall.EBADE, false},
-		{"ne val", new(AbsoluteError), &AbsoluteError{Pathname: "etc"}, false},
-		{"equals", &AbsoluteError{Pathname: "etc"}, &AbsoluteError{Pathname: "etc"}, true},
+		{"ne val", new(AbsoluteError), AbsoluteError("etc"), false},
+		{"equals", AbsoluteError("etc"), AbsoluteError("etc"), true},
 	}
 
 	for _, tc := range testCases {
@@ -45,7 +45,7 @@ func TestAbsoluteError(t *testing.T) {
 		t.Parallel()
 
 		want := `path "etc" is not absolute`
-		if got := (&AbsoluteError{Pathname: "etc"}).Error(); got != want {
+		if got := (AbsoluteError("etc")).Error(); got != want {
 			t.Errorf("Error: %q, want %q", got, want)
 		}
 	})
@@ -62,8 +62,8 @@ func TestNewAbs(t *testing.T) {
 		wantErr  error
 	}{
 		{"good", "/etc", MustAbs("/etc"), nil},
-		{"not absolute", "etc", nil, &AbsoluteError{Pathname: "etc"}},
-		{"zero", "", nil, &AbsoluteError{Pathname: ""}},
+		{"not absolute", "etc", nil, AbsoluteError("etc")},
+		{"zero", "", nil, AbsoluteError("")},
 	}
 
 	for _, tc := range testCases {
@@ -84,7 +84,7 @@ func TestNewAbs(t *testing.T) {
 		t.Parallel()
 
 		defer func() {
-			wantPanic := &AbsoluteError{Pathname: "etc"}
+			wantPanic := AbsoluteError("etc")
 
 			if r := recover(); !reflect.DeepEqual(r, wantPanic) {
 				t.Errorf("MustAbs: panic = %v; want %v", r, wantPanic)
@@ -175,7 +175,7 @@ func TestCodecAbsolute(t *testing.T) {
 
 			`"/etc"`, `{"val":"/etc","magic":3236757504}`},
 		{"not absolute", nil,
-			&AbsoluteError{Pathname: "etc"},
+			AbsoluteError("etc"),
 			"\t\x7f\x05\x01\x02\xff\x82\x00\x00\x00\a\xff\x80\x00\x03etc",
 			",\xff\x83\x03\x01\x01\x06sCheck\x01\xff\x84\x00\x01\x02\x01\bPathname\x01\xff\x80\x00\x01\x05Magic\x01\x06\x00\x00\x00\t\x7f\x05\x01\x02\xff\x82\x00\x00\x00\x0f\xff\x84\x01\x03etc\x01\xfb\x01\x81\xda\x00\x00\x00",
 
diff --git a/container/errors.go b/container/errors.go
index 2bcb4974..d7651aa9 100644
--- a/container/errors.go
+++ b/container/errors.go
@@ -18,7 +18,7 @@ func messageFromError(err error) (m string, ok bool) {
 	if m, ok = messagePrefixP[os.PathError]("cannot ", err); ok {
 		return
 	}
-	if m, ok = messagePrefixP[check.AbsoluteError](zeroString, err); ok {
+	if m, ok = messagePrefix[check.AbsoluteError](zeroString, err); ok {
 		return
 	}
 	if m, ok = messagePrefix[OpRepeatError](zeroString, err); ok {
diff --git a/container/errors_test.go b/container/errors_test.go
index 5c55af45..71b4a9ac 100644
--- a/container/errors_test.go
+++ b/container/errors_test.go
@@ -37,7 +37,7 @@ func TestMessageFromError(t *testing.T) {
 			Err:  stub.UniqueError(0xdeadbeef),
 		}, "cannot mount /sysroot: unique error 3735928559 injected by the test suite", true},
 
-		{"absolute", &check.AbsoluteError{Pathname: "etc/mtab"},
+		{"absolute", check.AbsoluteError("etc/mtab"),
 			`path "etc/mtab" is not absolute`, true},
 
 		{"repeat", OpRepeatError("autoetc"),
diff --git a/container/initoverlay_test.go b/container/initoverlay_test.go
index 1c0e642a..0ff3cb41 100644
--- a/container/initoverlay_test.go
+++ b/container/initoverlay_test.go
@@ -312,7 +312,10 @@ func TestMountOverlayOp(t *testing.T) {
 			},
 		}},
 
-		{"ephemeral", new(Ops).OverlayEphemeral(check.MustAbs("/nix/store"), check.MustAbs("/mnt-root/nix/.ro-store")), Ops{
+		{"ephemeral", new(Ops).OverlayEphemeral(
+			check.MustAbs("/nix/store"),
+			check.MustAbs("/mnt-root/nix/.ro-store"),
+		), Ops{
 			&MountOverlayOp{
 				Target: check.MustAbs("/nix/store"),
 				Lower:  []*check.Absolute{check.MustAbs("/mnt-root/nix/.ro-store")},
@@ -320,7 +323,10 @@ func TestMountOverlayOp(t *testing.T) {
 			},
 		}},
 
-		{"readonly", new(Ops).OverlayReadonly(check.MustAbs("/nix/store"), check.MustAbs("/mnt-root/nix/.ro-store")), Ops{
+		{"readonly", new(Ops).OverlayReadonly(
+			check.MustAbs("/nix/store"),
+			check.MustAbs("/mnt-root/nix/.ro-store"),
+		), Ops{
 			&MountOverlayOp{
 				Target: check.MustAbs("/nix/store"),
 				Lower:  []*check.Absolute{check.MustAbs("/mnt-root/nix/.ro-store")},
diff --git a/container/initsymlink.go b/container/initsymlink.go
index be0ce2a2..df0ddc11 100644
--- a/container/initsymlink.go
+++ b/container/initsymlink.go
@@ -31,7 +31,7 @@ func (l *SymlinkOp) Valid() bool { return l != nil && l.Target != nil && l.LinkN
 func (l *SymlinkOp) early(_ *setupState, k syscallDispatcher) error {
 	if l.Dereference {
 		if !path.IsAbs(l.LinkName) {
-			return &check.AbsoluteError{Pathname: l.LinkName}
+			return check.AbsoluteError(l.LinkName)
 		}
 		if name, err := k.readlink(l.LinkName); err != nil {
 			return err
diff --git a/container/initsymlink_test.go b/container/initsymlink_test.go
index e260b518..86d0be1f 100644
--- a/container/initsymlink_test.go
+++ b/container/initsymlink_test.go
@@ -23,7 +23,7 @@ func TestSymlinkOp(t *testing.T) {
 			Target:      check.MustAbs("/etc/mtab"),
 			LinkName:    "etc/mtab",
 			Dereference: true,
-		}, nil, &check.AbsoluteError{Pathname: "etc/mtab"}, nil, nil},
+		}, nil, check.AbsoluteError("etc/mtab"), nil, nil},
 
 		{"readlink", &Params{ParentPerm: 0755}, &SymlinkOp{
 			Target:      check.MustAbs("/etc/mtab"),