Fix simple mistakes identified by goreportcard.

These are primarily simplification and lint mistakes. However, minor
fixes are also included and tests added where appropriate.

PiperOrigin-RevId: 351425971

pkg/abi/linux/fadvise.go

@@ -14,6 +14,7 @@
 
 package linux
 
+// Fadvise constants.
 const (
 	POSIX_FADV_NORMAL     = 0
 	POSIX_FADV_RANDOM     = 1

pkg/abi/linux/ipc.go

@@ -14,8 +14,9 @@
 
 package linux
 
-// Control commands used with semctl, shmctl, and msgctl. Source:
-// include/uapi/linux/ipc.h.
+// Control commands used with semctl, shmctl, and msgctl.
+//
+// Source: include/uapi/linux/ipc.h.
 const (
 	IPC_RMID = 0
 	IPC_SET  = 1
@@ -23,14 +24,19 @@ const (
 	IPC_INFO = 3
 )
 
-// resource get request flags. Source: include/uapi/linux/ipc.h
+// Resource get request flags.
+//
+// Source: include/uapi/linux/ipc.h
 const (
 	IPC_CREAT  = 00001000
 	IPC_EXCL   = 00002000
 	IPC_NOWAIT = 00004000
 )
 
-const IPC_PRIVATE = 0
+// IPC flags.
+const (
+	IPC_PRIVATE = 0
+)
 
 // In Linux, amd64 does not enable CONFIG_ARCH_WANT_IPC_PARSE_VERSION, so SysV
 // IPC unconditionally uses the "new" 64-bit structures that are needed for

pkg/abi/linux/netfilter_ipv6.go

@@ -288,6 +288,7 @@ type IP6TIP struct {
 	_ [3]byte
 }
 
+// SizeOfIP6TIP is the size of an IP6 header.
 const SizeOfIP6TIP = 136
 
 // Flags in IP6TIP.Flags. Corresponding constants are in

pkg/abi/linux/sched.go

@@ -29,6 +29,7 @@ const (
 	SCHED_RESET_ON_FORK = 0x40000000
 )
 
+// Scheduling priority group selectors.
 const (
 	PRIO_PGRP    = 0x1
 	PRIO_PROCESS = 0x0

pkg/abi/linux/seccomp.go

@@ -30,8 +30,10 @@ const (
 	SECCOMP_GET_ACTION_AVAIL  = 2
 )
 
+// BPFAction is an action for a BPF filter.
 type BPFAction uint32
 
+// BPFAction definitions.
 const (
 	SECCOMP_RET_KILL_PROCESS BPFAction = 0x80000000
 	SECCOMP_RET_KILL_THREAD  BPFAction = 0x00000000

pkg/abi/linux/sem.go

@@ -49,7 +49,10 @@ const (
 	SEMUSZ = 20
 )
 
-const SEM_UNDO = 0x1000
+// Semaphore flags.
+const (
+	SEM_UNDO = 0x1000
+)
 
 // Sembuf is equivalent to struct sembuf.
 //

pkg/cpuid/cpuid_arm64.go

@@ -267,7 +267,7 @@ func (fs *FeatureSet) UseXsave() bool {
 // FlagsString prints out supported CPU "flags" field in /proc/cpuinfo.
 func (fs *FeatureSet) FlagsString() string {
 	var s []string
-	for f, _ := range arm64FeatureStrings {
+	for f := range arm64FeatureStrings {
 		if fs.Set[f] {
 			if fstr := f.flagString(); fstr != "" {
 				s = append(s, fstr)
@@ -296,7 +296,7 @@ func (fs FeatureSet) WriteCPUInfoTo(cpu uint, b *bytes.Buffer) {
 func HostFeatureSet() *FeatureSet {
 	s := make(map[Feature]bool)
 
-	for f, _ := range arm64FeatureStrings {
+	for f := range arm64FeatureStrings {
 		if hwCap&(1<<f) != 0 {
 			s[f] = true
 		}

pkg/p9/client.go

@@ -241,7 +241,7 @@ func (c *Client) watch(socket *unet.Socket) {
 	defer c.closedWg.Done()
 
 	events := []unix.PollFd{
-		unix.PollFd{
+		{
 			Fd:     int32(socket.FD()),
 			Events: unix.POLLHUP | unix.POLLRDHUP,
 		},

pkg/seccomp/seccomp.go

@@ -61,7 +61,7 @@ func Install(rules SyscallRules) error {
 	log.Infof("Installing seccomp filters for %d syscalls (action=%v)", len(rules), defaultAction)
 
 	instrs, err := BuildProgram([]RuleSet{
-		RuleSet{
+		{
 			Rules:  rules,
 			Action: linux.SECCOMP_RET_ALLOW,
 		},
@@ -160,7 +160,7 @@ func buildIndex(rules []RuleSet, program *bpf.ProgramBuilder) error {
 		}
 	}
 	syscalls := make([]uintptr, 0, len(requiredSyscalls))
-	for sysno, _ := range requiredSyscalls {
+	for sysno := range requiredSyscalls {
 		syscalls = append(syscalls, sysno)
 	}
 	sort.Slice(syscalls, func(i, j int) bool { return syscalls[i] < syscalls[j] })

pkg/seccomp/seccomp_test.go

@@ -932,7 +932,7 @@ func TestRandom(t *testing.T) {
 
 	t.Logf("Testing filters: %v", syscallRules)
 	instrs, err := BuildProgram([]RuleSet{
-		RuleSet{
+		{
 			Rules:  syscallRules,
 			Action: linux.SECCOMP_RET_ALLOW,
 		},

pkg/segment/set.go

@@ -1680,8 +1680,8 @@ type SegmentDataSlices struct {
 	Values []Value
 }
 
-// ExportSortedSlice returns a copy of all segments in the given set, in ascending
-// key order.
+// ExportSortedSlices returns a copy of all segments in the given set, in
+// ascending key order.
 func (s *Set) ExportSortedSlices() *SegmentDataSlices {
 	var sds SegmentDataSlices
 	for seg := s.FirstSegment(); seg.Ok(); seg = seg.NextSegment() {
@@ -1695,7 +1695,7 @@ func (s *Set) ExportSortedSlices() *SegmentDataSlices {
 	return &sds
 }
 
-// ImportSortedSlice initializes the given set from the given slice.
+// ImportSortedSlices initializes the given set from the given slice.
 //
 // Preconditions:
 // * s must be empty.

pkg/sentry/fs/fsutil/inode.go

@@ -510,6 +510,7 @@ func (InodeDenyWriteChecker) Check(ctx context.Context, inode *fs.Inode, p fs.Pe
 //InodeNotAllocatable can be used by Inodes that do not support Allocate().
 type InodeNotAllocatable struct{}
 
+// Allocate implements fs.InodeOperations.Allocate.
 func (InodeNotAllocatable) Allocate(_ context.Context, _ *fs.Inode, _, _ int64) error {
 	return syserror.EOPNOTSUPP
 }

pkg/sentry/fs/inode.go

@@ -367,6 +367,7 @@ func (i *Inode) Truncate(ctx context.Context, d *Dirent, size int64) error {
 	return i.InodeOperations.Truncate(ctx, i, size)
 }
 
+// Allocate calls i.InodeOperations.Allocate with i as the Inode.
 func (i *Inode) Allocate(ctx context.Context, d *Dirent, offset int64, length int64) error {
 	if i.overlay != nil {
 		return overlayAllocate(ctx, i.overlay, d, offset, length)

pkg/sentry/fsimpl/testutil/kernel.go

@@ -114,7 +114,7 @@ func Boot() (*kernel.Kernel, error) {
 		return nil, err
 	}
 	tg := k.NewThreadGroup(nil, k.RootPIDNamespace(), kernel.NewSignalHandlers(), linux.SIGCHLD, ls)
-	k.TestOnly_SetGlobalInit(tg)
+	k.TestOnlySetGlobalInit(tg)
 
 	return k, nil
 }

pkg/sentry/kernel/auth/id.go

@@ -62,18 +62,28 @@ const (
 	// field is displayed as 4294967295 (-1 as an unsigned integer);" -
 	// user_namespaces(7)
 	OverflowUID = UID(65534)
+
+	// OverflowGID is the group equivalent to OverflowUID.
 	OverflowGID = GID(65534)
 
 	// NobodyKUID is the user ID usually reserved for the least privileged user
 	// "nobody".
 	NobodyKUID = KUID(65534)
+
+	// NobodyKGID is the group equivalent to NobodyKUID.
 	NobodyKGID = KGID(65534)
 
 	// RootKUID is the user ID usually used for the most privileged user "root".
 	RootKUID = KUID(0)
+
+	// RootKGID is the group equivalent to RootKUID.
 	RootKGID = KGID(0)
-	RootUID  = UID(0)
-	RootGID  = GID(0)
+
+	// RootUID is the root user.
+	RootUID = UID(0)
+
+	// RootGID is the root group.
+	RootGID = GID(0)
 )
 
 // Ok returns true if uid is not -1.

pkg/sentry/kernel/kernel.go

@@ -1433,8 +1433,8 @@ func (k *Kernel) GlobalInit() *ThreadGroup {
 	return k.globalInit
 }
 
-// TestOnly_SetGlobalInit sets the thread group with ID 1 in the root PID namespace.
-func (k *Kernel) TestOnly_SetGlobalInit(tg *ThreadGroup) {
+// TestOnlySetGlobalInit sets the thread group with ID 1 in the root PID namespace.
+func (k *Kernel) TestOnlySetGlobalInit(tg *ThreadGroup) {
 	k.globalInit = tg
 }
 

pkg/sentry/platform/ring0/kernel_amd64.go

@@ -65,6 +65,7 @@ func (k *Kernel) init(maxCPUs int) {
 	}
 }
 
+// EntryRegions returns the set of kernel entry regions (must be mapped).
 func (k *Kernel) EntryRegions() map[uintptr]uintptr {
 	regions := make(map[uintptr]uintptr)
 

pkg/sentry/socket/netfilter/netfilter.go

@@ -205,7 +205,7 @@ func SetEntries(stk *stack.Stack, optVal []byte, ipv6 bool) *syserr.Error {
 
 	// Go through the list of supported hooks for this table and, for each
 	// one, set the rule it corresponds to.
-	for hook, _ := range replace.HookEntry {
+	for hook := range replace.HookEntry {
 		if table.ValidHooks()&(1<<hook) != 0 {
 			hk := hookFromLinux(hook)
 			table.BuiltinChains[hk] = stack.HookUnset

pkg/sentry/socket/netfilter/owner_matcher.go

@@ -96,6 +96,7 @@ func (ownerMarshaler) unmarshal(buf []byte, filter stack.IPHeaderFilter) (stack.
 	return &owner, nil
 }
 
+// OwnerMatcher matches against a UID and/or GID.
 type OwnerMatcher struct {
 	uid       uint32
 	gid       uint32

pkg/sentry/socket/unix/unix.go

@@ -471,7 +471,7 @@ func (s *socketOpsCommon) SendMsg(t *kernel.Task, src usermem.IOSequence, to []b
 	if len(to) > 0 {
 		switch s.stype {
 		case linux.SOCK_SEQPACKET:
-			to = nil
+			// to is ignored.
 		case linux.SOCK_STREAM:
 			if s.State() == linux.SS_CONNECTED {
 				return 0, syserr.ErrAlreadyConnected