container/mount: unwrap vfs decoder errors

These are now handled by init. This eliminates generic WrapErr from mount and procPaths.

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

container/errors.go

@@ -4,17 +4,19 @@ import (
 	"errors"
 	"os"
 	"syscall"
+
+	"hakurei.app/container/vfs"
 )
 
 // messageFromError returns a printable error message for a supported concrete type.
 func messageFromError(err error) (string, bool) {
-	if m, ok := messagePrefixP[MountError, *MountError]("cannot ", err); ok {
+	if m, ok := messagePrefixP[MountError]("cannot ", err); ok {
 		return m, ok
 	}
-	if m, ok := messagePrefixP[os.PathError, *os.PathError]("cannot ", err); ok {
+	if m, ok := messagePrefixP[os.PathError]("cannot ", err); ok {
 		return m, ok
 	}
-	if m, ok := messagePrefixP[AbsoluteError, *AbsoluteError]("", err); ok {
+	if m, ok := messagePrefixP[AbsoluteError]("", err); ok {
 		return m, ok
 	}
 	if m, ok := messagePrefix[OpRepeatError]("", err); ok {
@@ -24,6 +26,9 @@ func messageFromError(err error) (string, bool) {
 		return m, ok
 	}
 
+	if m, ok := messagePrefixP[vfs.DecoderError]("cannot ", err); ok {
+		return m, ok
+	}
 	if m, ok := messagePrefix[TmpfsSizeError]("", err); ok {
 		return m, ok
 	}

container/errors_test.go

@@ -4,8 +4,11 @@ import (
 	"errors"
 	"os"
 	"reflect"
+	"strconv"
 	"syscall"
 	"testing"
+
+	"hakurei.app/container/vfs"
 )
 
 func TestMessageFromError(t *testing.T) {
@@ -39,6 +42,9 @@ func TestMessageFromError(t *testing.T) {
 		{"state", OpStateError("overlay"),
 			"impossible overlay state reached", true},
 
+		{"vfs parse", &vfs.DecoderError{Op: "parse", Line: 0xdeadbeef, Err: &strconv.NumError{Func: "Atoi", Num: "meow", Err: strconv.ErrSyntax}},
+			`cannot parse mountinfo at line 3735928559: numeric field "meow" invalid syntax`, true},
+
 		{"tmpfs", TmpfsSizeError(-1),
 			"tmpfs size -1 out of bounds", true},
 

container/mount.go

@@ -149,12 +149,7 @@ func (p *procPaths) remount(target string, flags uintptr) error {
 	return p.mountinfo(func(d *vfs.MountInfoDecoder) error {
 		n, err := d.Unfold(targetKFinal)
 		if err != nil {
-			if errors.As(err, new(vfs.UnfoldTargetError)) {
-				return msg.WrapErr(err,
-					fmt.Sprintf("mount point %q never appeared in mountinfo", targetKFinal))
-			}
-			return wrapErrSuffix(err,
-				"cannot unfold mount hierarchy:")
+			return err
 		}
 
 		if err = remountWithFlags(p.k, n, mf); err != nil {

container/mount_test.go

@@ -118,7 +118,7 @@ func TestRemount(t *testing.T) {
 			{"readlink", expectArgs{"/host/proc/self/fd/3735928559"}, "/sysroot/.hakurei", nil},
 			{"close", expectArgs{0xdeadbeef}, nil, nil},
 			{"openNew", expectArgs{"/host/proc/self/mountinfo"}, newConstFile(sampleMountinfoNix), nil},
-		}}, msg.WrapErr(&vfs.DecoderError{Op: "unfold", Line: -1, Err: vfs.UnfoldTargetError("/sysroot/.hakurei")}, `mount point "/sysroot/.hakurei" never appeared in mountinfo`)},
+		}}, &vfs.DecoderError{Op: "unfold", Line: -1, Err: vfs.UnfoldTargetError("/sysroot/.hakurei")}},
 
 		{"mountinfo", func(k syscallDispatcher) error {
 			return newProcPaths(k, hostPath).remount("/sysroot/nix", syscall.MS_REC|syscall.MS_RDONLY|syscall.MS_NODEV)
@@ -128,7 +128,7 @@ func TestRemount(t *testing.T) {
 			{"readlink", expectArgs{"/host/proc/self/fd/3735928559"}, "/sysroot/nix", nil},
 			{"close", expectArgs{0xdeadbeef}, nil, nil},
 			{"openNew", expectArgs{"/host/proc/self/mountinfo"}, newConstFile("\x00"), nil},
-		}}, wrapErrSuffix(&vfs.DecoderError{Op: "parse", Line: 0, Err: vfs.ErrMountInfoFields}, `cannot parse mountinfo:`)},
+		}}, &vfs.DecoderError{Op: "parse", Line: 0, Err: vfs.ErrMountInfoFields}},
 
 		{"mount", func(k syscallDispatcher) error {
 			return newProcPaths(k, hostPath).remount("/sysroot/nix", syscall.MS_REC|syscall.MS_RDONLY|syscall.MS_NODEV)

container/path.go

@@ -152,8 +152,7 @@ func (p *procPaths) mountinfo(f func(d *vfs.MountInfoDecoder) error) error {
 		if err = r.Close(); err != nil {
 			return err
 		} else if err = d.Err(); err != nil {
-			return wrapErrSuffix(err,
-				"cannot parse mountinfo:")
+			return err
 		}
 		return err0
 	}

container/path_test.go

@@ -1,7 +1,6 @@
 package container
 
 import (
-	"errors"
 	"io"
 	"math"
 	"os"
@@ -248,8 +247,8 @@ func TestProcPaths(t *testing.T) {
 					t.Fatalf("WriteFile: error = %v", err)
 				}
 
-				wantErr := wrapErrSuffix(&vfs.DecoderError{Op: "parse", Line: 0, Err: vfs.ErrMountInfoFields}, "cannot parse mountinfo:")
-				if err := newProcPaths(direct{}, tempDir).mountinfo(func(d *vfs.MountInfoDecoder) error { return d.Decode(new(*vfs.MountInfo)) }); !errors.Is(err, wantErr) {
+				wantErr := &vfs.DecoderError{Op: "parse", Line: 0, Err: vfs.ErrMountInfoFields}
+				if err := newProcPaths(direct{}, tempDir).mountinfo(func(d *vfs.MountInfoDecoder) error { return d.Decode(new(*vfs.MountInfo)) }); !reflect.DeepEqual(err, wantErr) {
 					t.Fatalf("mountinfo: error = %v, want %v", err, wantErr)
 				}
 			})