container/initsymlink: unwrap mount errors

The mount function now wraps its own errors in a much more descriptive type with proper message formatting. Wrapping them no longer makes any sense.

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

container/init_test.go

@@ -377,7 +377,7 @@ func TestInitEntrypoint(t *testing.T) {
 			},
 		}, nil},
 
-		{"apply", func(k syscallDispatcher) error { initEntrypoint(k, assertPrefix, assertVerboseTrue); return nil }, [][]kexpect{
+		{"early unhandled error", func(k syscallDispatcher) error { initEntrypoint(k, assertPrefix, assertVerboseTrue); return nil }, [][]kexpect{
 			{
 				{"lockOSThread", expectArgs{}, nil, nil},
 				{"getpid", expectArgs{}, 1, nil},
@@ -759,10 +759,8 @@ func TestInitEntrypoint(t *testing.T) {
 				{"bindMount", expectArgs{"/host", "/sysroot", uintptr(0x4001), false}, nil, nil},
 				{"verbosef", expectArgs{"%s %s", []any{"mounting", &MountProcOp{Target: MustAbs("/proc/")}}}, nil, nil},
 				{"mkdirAll", expectArgs{"/sysroot/proc", os.FileMode(0755)}, nil, nil},
-				{"mount", expectArgs{"proc", "/sysroot/proc", "proc", uintptr(0xe), ""}, nil, errUnique},
-				{"printBaseErr", expectArgs{wrapErrSuffix(errUnique, `cannot mount proc on "/proc/":`), "cannot apply op at index 1:"}, nil, nil},
-				{"beforeExit", expectArgs{}, nil, nil},
-				{"exit", expectArgs{1}, nil, nil},
+				{"mount", expectArgs{"proc", "/sysroot/proc", "proc", uintptr(0xe), ""}, nil, &MountError{"proc", "/sysroot/proc", "proc", uintptr(0xe), "", syscall.ENOTRECOVERABLE}},
+				{"fatal", expectArgs{[]any{"cannot mount proc on /sysroot/proc: state not recoverable"}}, nil, nil},
 				/* end apply */
 			},
 		}, nil},

container/initdev.go

@@ -82,8 +82,7 @@ func (d *MountDevOp) apply(state *setupState, k syscallDispatcher) error {
 
 	if err := k.mount(SourceDevpts, devPtsPath, FstypeDevpts, MS_NOSUID|MS_NOEXEC,
 		"newinstance,ptmxmode=0666,mode=620"); err != nil {
-		return wrapErrSuffix(err,
-			fmt.Sprintf("cannot mount devpts on %q:", devPtsPath))
+		return err
 	}
 
 	if state.RetainSession {
@@ -111,7 +110,7 @@ func (d *MountDevOp) apply(state *setupState, k syscallDispatcher) error {
 			return wrapErrSelf(err)
 		}
 		if err := k.mount(SourceMqueue, mqueueTarget, FstypeMqueue, MS_NOSUID|MS_NOEXEC|MS_NODEV, zeroString); err != nil {
-			return wrapErrSuffix(err, "cannot mount mqueue:")
+			return err
 		}
 	}
 
@@ -120,8 +119,7 @@ func (d *MountDevOp) apply(state *setupState, k syscallDispatcher) error {
 	}
 
 	if err := k.remount(target, MS_RDONLY); err != nil {
-		return wrapErrSuffix(k.remount(target, MS_RDONLY),
-			fmt.Sprintf("cannot remount %q:", target))
+		return err
 	}
 	return k.mountTmpfs(SourceTmpfs, devShmPath, MS_NOSUID|MS_NODEV, 0, 01777)
 }

container/initdev_test.go

@@ -390,7 +390,7 @@ func TestMountDevOp(t *testing.T) {
 			{"mkdir", expectArgs{"/sysroot/dev/shm", os.FileMode(0750)}, nil, nil},
 			{"mkdir", expectArgs{"/sysroot/dev/pts", os.FileMode(0750)}, nil, nil},
 			{"mount", expectArgs{"devpts", "/sysroot/dev/pts", "devpts", uintptr(0xa), "newinstance,ptmxmode=0666,mode=620"}, nil, errUnique},
-		}, wrapErrSuffix(errUnique, `cannot mount devpts on "/sysroot/dev/pts":`)},
+		}, errUnique},
 
 		{"ensureFile stdout", &Params{ParentPerm: 0750, RetainSession: true}, &MountDevOp{
 			Target: MustAbs("/dev/"),
@@ -550,7 +550,7 @@ func TestMountDevOp(t *testing.T) {
 			{"bindMount", expectArgs{"/host/dev/pts/2", "/sysroot/dev/console", uintptr(0), false}, nil, nil},
 			{"mkdir", expectArgs{"/sysroot/dev/mqueue", os.FileMode(0750)}, nil, nil},
 			{"mount", expectArgs{"mqueue", "/sysroot/dev/mqueue", "mqueue", uintptr(0xe), ""}, nil, errUnique},
-		}, wrapErrSuffix(errUnique, "cannot mount mqueue:")},
+		}, errUnique},
 
 		{"success no session", &Params{ParentPerm: 0755}, &MountDevOp{
 			Target: MustAbs("/dev/"),

container/initoverlay.go

@@ -167,8 +167,7 @@ func (o *MountOverlayOp) apply(state *setupState, k syscallDispatcher) error {
 		OptionOverlayLowerdir+"="+strings.Join(o.lower, SpecialOverlayPath),
 		OptionOverlayUserxattr)
 
-	return wrapErrSuffix(k.mount(SourceOverlay, target, FstypeOverlay, 0, strings.Join(options, SpecialOverlayOption)),
-		fmt.Sprintf("cannot mount overlay on %q:", o.Target))
+	return k.mount(SourceOverlay, target, FstypeOverlay, 0, strings.Join(options, SpecialOverlayOption))
 }
 
 func (o *MountOverlayOp) Is(op Op) bool {

container/initoverlay_test.go

@@ -186,7 +186,7 @@ func TestMountOverlayOp(t *testing.T) {
 		}, nil, []kexpect{
 			{"mkdirAll", expectArgs{"/sysroot/nix/store", os.FileMode(0700)}, nil, nil},
 			{"mount", expectArgs{"overlay", "/sysroot/nix/store", "overlay", uintptr(0), "upperdir=/host/mnt-root/nix/.rw-store/.upper,workdir=/host/mnt-root/nix/.rw-store/.work,lowerdir=/host/mnt-root/nix/ro-store,userxattr"}, nil, errUnique},
-		}, wrapErrSuffix(errUnique, `cannot mount overlay on "/nix/store":`)},
+		}, errUnique},
 
 		{"success single layer", &Params{ParentPerm: 0700}, &MountOverlayOp{
 			Target: MustAbs("/nix/store"),

container/initproc.go

@@ -24,8 +24,7 @@ func (p *MountProcOp) apply(state *setupState, k syscallDispatcher) error {
 	if err := k.mkdirAll(target, state.ParentPerm); err != nil {
 		return wrapErrSelf(err)
 	}
-	return wrapErrSuffix(k.mount(SourceProc, target, FstypeProc, MS_NOSUID|MS_NOEXEC|MS_NODEV, zeroString),
-		fmt.Sprintf("cannot mount proc on %q:", p.Target.String()))
+	return k.mount(SourceProc, target, FstypeProc, MS_NOSUID|MS_NOEXEC|MS_NODEV, zeroString)
 }
 
 func (p *MountProcOp) Is(op Op) bool {

container/initremount.go

@@ -22,8 +22,7 @@ type RemountOp struct {
 func (r *RemountOp) Valid() bool                              { return r != nil && r.Target != nil }
 func (*RemountOp) early(*setupState, syscallDispatcher) error { return nil }
 func (r *RemountOp) apply(_ *setupState, k syscallDispatcher) error {
-	return wrapErrSuffix(k.remount(toSysroot(r.Target.String()), r.Flags),
-		fmt.Sprintf("cannot remount %q:", r.Target))
+	return k.remount(toSysroot(r.Target.String()), r.Flags)
 }
 
 func (r *RemountOp) Is(op Op) bool {

container/mount.go

@@ -106,8 +106,7 @@ func (p *procPaths) bindMount(source, target string, flags uintptr, eq bool) err
 	}
 
 	if err := p.k.mount(source, target, FstypeNULL, MS_SILENT|MS_BIND|flags&MS_REC, zeroString); err != nil {
-		return wrapErrSuffix(err,
-			fmt.Sprintf("cannot mount %q on %q:", source, target))
+		return err
 	}
 
 	return p.k.remount(target, flags)
@@ -161,8 +160,7 @@ func (p *procPaths) remount(target string, flags uintptr) error {
 		}
 
 		if err = remountWithFlags(p.k, n, mf); err != nil {
-			return wrapErrSuffix(err,
-				fmt.Sprintf("cannot remount %q:", n.Clean))
+			return err
 		}
 		if flags&MS_REC == 0 {
 			return nil
@@ -174,11 +172,8 @@ func (p *procPaths) remount(target string, flags uintptr) error {
 				continue
 			}
 
-			err = remountWithFlags(p.k, cur, mf)
-
-			if err != nil && !errors.Is(err, EACCES) {
-				return wrapErrSuffix(err,
-					fmt.Sprintf("cannot propagate flags to %q:", cur.Clean))
+			if err = remountWithFlags(p.k, cur, mf); err != nil && !errors.Is(err, EACCES) {
+				return err
 			}
 		}
 
@@ -213,9 +208,7 @@ func mountTmpfs(k syscallDispatcher, fsname, target string, flags uintptr, size
 	if size > 0 {
 		opt += fmt.Sprintf(",size=%d", size)
 	}
-	return wrapErrSuffix(
-		k.mount(fsname, target, FstypeTmpfs, flags, opt),
-		fmt.Sprintf("cannot mount tmpfs on %q:", target))
+	return k.mount(fsname, target, FstypeTmpfs, flags, opt)
 }
 
 func parentPerm(perm os.FileMode) os.FileMode {

container/mount_test.go

@@ -15,7 +15,7 @@ func TestBindMount(t *testing.T) {
 		}, [][]kexpect{{
 			{"verbosef", expectArgs{"resolved %q flags %#x", []any{"/sysroot/nix", uintptr(1)}}, nil, nil},
 			{"mount", expectArgs{"/host/nix", "/sysroot/nix", "", uintptr(0x9000), ""}, nil, errUnique},
-		}}, wrapErrSuffix(errUnique, `cannot mount "/host/nix" on "/sysroot/nix":`)},
+		}}, errUnique},
 
 		{"success ne", func(k syscallDispatcher) error {
 			return newProcPaths(k, hostPath).bindMount("/host/nix", "/sysroot/.host-nix", syscall.MS_RDONLY, false)
@@ -139,7 +139,7 @@ func TestRemount(t *testing.T) {
 			{"close", expectArgs{0xdeadbeef}, nil, nil},
 			{"openNew", expectArgs{"/host/proc/self/mountinfo"}, newConstFile(sampleMountinfoNix), nil},
 			{"mount", expectArgs{"none", "/sysroot/nix", "", uintptr(0x209027), ""}, nil, errUnique},
-		}}, wrapErrSuffix(errUnique, `cannot remount "/sysroot/nix":`)},
+		}}, errUnique},
 
 		{"mount propagate", func(k syscallDispatcher) error {
 			return newProcPaths(k, hostPath).remount("/sysroot/nix", syscall.MS_REC|syscall.MS_RDONLY|syscall.MS_NODEV)
@@ -151,7 +151,7 @@ func TestRemount(t *testing.T) {
 			{"openNew", expectArgs{"/host/proc/self/mountinfo"}, newConstFile(sampleMountinfoNix), nil},
 			{"mount", expectArgs{"none", "/sysroot/nix", "", uintptr(0x209027), ""}, nil, nil},
 			{"mount", expectArgs{"none", "/sysroot/nix/.ro-store", "", uintptr(0x209027), ""}, nil, errUnique},
-		}}, wrapErrSuffix(errUnique, `cannot propagate flags to "/sysroot/nix/.ro-store":`)},
+		}}, errUnique},
 
 		{"success toplevel", func(k syscallDispatcher) error {
 			return newProcPaths(k, hostPath).remount("/sysroot/bin", syscall.MS_REC|syscall.MS_RDONLY|syscall.MS_NODEV)