Add lint and go generate steps to CI (#254)

* Add lint and go generate stages to CI

Add CI step to verify `go generate` was run on repo.
Add linter stage to CI along with linter config file,
`.golangci.yml`.
Will likely prefer revive over static-check.

Updated README Contributing section on linting requirements.

Added sequence ordering to make sure lint and go generate stages run
before tests and build.
This way, build and tests are not run on code that could potentially:

    1. not build due to `gofmt` issues;
    2. contain bugs;
    3. have to be re-submitted after issues are fixed; or
    4. contain outdated Win32 syscall or other auto-generated files.

Signed-off-by: Hamza El-Saawy <hamzaelsaawy@microsoft.com>

* Fixed linter issues

Code changes to satisfy linters:

 - Ran `gofmt -s -w` on repo.
 - Broke up long lines.
 - When possible, changed names with incorrect initialism formatting
   - Added exceptions for exported variables.
 - Added exceptions for ALL_CAPS_WITH_UNDERSCORES code.
   - Switched to using `windows` or `syscall` definitions if possible;
     especially if some constants were unused.
 - Added `_ =` to satisfy error linter, and acknowledge that errors are
   being ignored.
 - Switched to using `errors.Is` and `As` in places, elsewhere added
   exceptions if error value was known to be `syscall.Errno`.
 - Removed bare returns.
 - Prevented variables from being overshadowed in certain places
   (ignoring cases of overshadowing `err`).
 - Renamed variables and functions (eg, `len`, `eventMetadata.bytes`) to
   prevent shadowing pre-built functions and imported pacakges.
 - Removed unused method receivers.
 - Added exceptions to certain unused (unexported) constants and
   functions.
   - Deleted unused `once` from `pkg/etw.providerMap`.
 - Renamed `noop.go` files to `main_other.go` or `doc.go`, to better fit
   style recommendations.
 - Added exceptions for non-secure use of SHA1 and weak crypto
   libraries.
 - Replaced `ioutil` with `io` and `os` (and `t.TempDir` in tests).
 - Added fully exhaustive checks for `switch` statements in `pkg/etw`.
 - Defined constant strings for `tools/mkwinsyscall`.
 - Removed unnecessary conversions.
 - Made sure `context.Cancel` was called.

Additionally, added `//go:build windows" constraints on files with
unexported code, since linter will complain about unused code on
non-Windows platforms.

Added a stub `main() {}` for `mkwinsyscall` for non-Windows builds, just in
case `//go:generate` directives are added to OS-agnostic files.

Signed-off-by: Hamza El-Saawy <hamzaelsaawy@microsoft.com>

* PR: spelling, constants, fuzzing

Moved HVSocket fuzzing tests to separate file with go 1.18 build
constraint.

Signed-off-by: Hamza El-Saawy <hamzaelsaawy@microsoft.com>

Signed-off-by: Hamza El-Saawy <hamzaelsaawy@microsoft.com>

wim/decompress.go

@@ -1,3 +1,4 @@
+//go:build windows || linux
 // +build windows linux
 
 package wim
@@ -5,7 +6,6 @@ package wim
 import (
 	"encoding/binary"
 	"io"
-	"io/ioutil"
 
 	"github.com/Microsoft/go-winio/wim/lzx"
 )
@@ -35,7 +35,6 @@ func newCompressedReader(r *io.SectionReader, originalSize int64, offset int64)
 		for i, n := range chunks32 {
 			chunks[i+1] = int64(n)
 		}
-
 	} else {
 		// 64-bit chunk offsets
 		base = (nchunks - 1) * 8
@@ -62,7 +61,7 @@ func newCompressedReader(r *io.SectionReader, originalSize int64, offset int64)
 
 	suboff := offset % chunkSize
 	if suboff != 0 {
-		_, err := io.CopyN(ioutil.Discard, cr.d, suboff)
+		_, err := io.CopyN(io.Discard, cr.d, suboff)
 		if err != nil {
 			return nil, err
 		}
@@ -110,7 +109,7 @@ func (r *compressedReader) reset(n int) error {
 		}
 		r.d = d
 	} else {
-		r.d = ioutil.NopCloser(section)
+		r.d = io.NopCloser(section)
 	}
 
 	return nil
@@ -119,7 +118,7 @@ func (r *compressedReader) reset(n int) error {
 func (r *compressedReader) Read(b []byte) (int, error) {
 	for {
 		n, err := r.d.Read(b)
-		if err != io.EOF {
+		if err != io.EOF { //nolint:errorlint
 			return n, err
 		}
 

wim/lzx/lzx.go

@@ -100,7 +100,7 @@ func (f *decompressor) ensureAtLeast(n int) error {
 	}
 	n, err := io.ReadAtLeast(f.r, f.b[f.bv-f.bo:], n)
 	if err != nil {
-		if err == io.EOF {
+		if err == io.EOF { //nolint:errorlint
 			err = io.ErrUnexpectedEOF
 		} else {
 			f.fail(err)
@@ -117,10 +117,8 @@ func (f *decompressor) ensureAtLeast(n int) error {
 // Otherwise, on error, it sets f.err.
 func (f *decompressor) feed() bool {
 	err := f.ensureAtLeast(2)
-	if err != nil {
-		if err == io.ErrUnexpectedEOF {
-			return false
-		}
+	if err == io.ErrUnexpectedEOF { //nolint:errorlint // returns io.ErrUnexpectedEOF by contract
+		return false
 	}
 	f.c |= (uint32(f.b[f.bo+1])<<8 | uint32(f.b[f.bo])) << (16 - f.nbits)
 	f.nbits += 16
@@ -232,9 +230,8 @@ func (f *decompressor) getCode(h *huffman) uint16 {
 		// are, since entries with all possible suffixes were
 		// added to the table.
 		c := h.table[f.c>>(32-tablebits)]
-		if c >= 1<<lenshift {
-			// The code is already in c.
-		} else {
+		if !(c >= 1<<lenshift) {
+			// The code is not in c.
 			c = h.extra[c][f.c<<tablebits>>(32-(h.maxbits-tablebits))]
 		}
 
@@ -399,41 +396,37 @@ func (f *decompressor) readTrees(readAligned bool) (main *huffman, length *huffm
 		}
 		aligned = buildTable(alignedLen[:])
 		if aligned == nil {
-			err = errors.New("corrupt")
-			return
+			return main, length, aligned, errors.New("corrupt")
 		}
 	}
 
 	// The main tree is encoded in two parts.
 	err = f.readTree(f.mainlens[:maincodesplit])
 	if err != nil {
-		return
+		return main, length, aligned, err
 	}
 	err = f.readTree(f.mainlens[maincodesplit:])
 	if err != nil {
-		return
+		return main, length, aligned, err
 	}
 
 	main = buildTable(f.mainlens[:])
 	if main == nil {
-		err = errors.New("corrupt")
-		return
+		return main, length, aligned, errors.New("corrupt")
 	}
 
 	// The length tree is encoding in a single part.
 	err = f.readTree(f.lenlens[:])
 	if err != nil {
-		return
+		return main, length, aligned, err
 	}
 
 	length = buildTable(f.lenlens[:])
 	if length == nil {
-		err = errors.New("corrupt")
-		return
+		return main, length, aligned, errors.New("corrupt")
 	}
 
-	err = f.err
-	return
+	return main, length, aligned, f.err
 }
 
 // readCompressedBlock decodes a compressed block, writing into the window
@@ -465,7 +458,7 @@ func (f *decompressor) readCompressedBlock(start, end uint16, hmain, hlength, ha
 		matchlen += 2
 
 		var matchoffset uint16
-		if slot < 3 {
+		if slot < 3 { //nolint:nestif // todo: simplify nested complexity
 			// The offset is one of the LRU values.
 			matchoffset = f.lru[slot]
 			f.lru[slot] = f.lru[0]
@@ -586,7 +579,7 @@ func (f *decompressor) Read(b []byte) (int, error) {
 	return f.windowReader.Read(b)
 }
 
-func (f *decompressor) Close() error {
+func (*decompressor) Close() error {
 	return nil
 }
 

wim/validate/main_other.go

@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 package main

wim/validate/main_windows.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 package main
@@ -20,7 +21,6 @@ func main() {
 	w, err := wim.NewReader(f)
 	if err != nil {
 		panic(err)
-
 	}
 
 	fmt.Printf("%#v\n%#v\n", w.Image[0], w.Image[0].Windows)
@@ -39,13 +39,13 @@ func main() {
 func recur(d *wim.File) error {
 	files, err := d.Readdir()
 	if err != nil {
-		return fmt.Errorf("%s: %s", d.Name, err)
+		return fmt.Errorf("%s: %w", d.Name, err)
 	}
 	for _, f := range files {
 		if f.IsDir() {
 			err = recur(f)
 			if err != nil {
-				return fmt.Errorf("%s: %s", f.Name, err)
+				return fmt.Errorf("%s: %w", f.Name, err)
 			}
 		}
 	}

wim/wim.go

@@ -1,3 +1,4 @@
+//go:build windows || linux
 // +build windows linux
 
 // Package wim implements a WIM file parser.
@@ -8,13 +9,12 @@ package wim
 
 import (
 	"bytes"
-	"crypto/sha1"
+	"crypto/sha1" //nolint:gosec // not used for secure application
 	"encoding/binary"
 	"encoding/xml"
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"strconv"
 	"sync"
 	"time"
@@ -22,6 +22,8 @@ import (
 )
 
 // File attribute constants from Windows.
+//
+//nolint:revive // var-naming: ALL_CAPS
 const (
 	FILE_ATTRIBUTE_READONLY            = 0x00000001
 	FILE_ATTRIBUTE_HIDDEN              = 0x00000002
@@ -44,6 +46,8 @@ const (
 )
 
 // Windows processor architectures.
+//
+//nolint:revive // var-naming: ALL_CAPS
 const (
 	PROCESSOR_ARCHITECTURE_INTEL         = 0
 	PROCESSOR_ARCHITECTURE_MIPS          = 1
@@ -62,6 +66,8 @@ const (
 
 var wimImageTag = [...]byte{'M', 'S', 'W', 'I', 'M', 0, 0, 0}
 
+// todo: replace this with pkg/guid.GUID (and add tests to make sure nothing breaks)
+
 type guid struct {
 	Data1 uint32
 	Data2 uint16
@@ -70,7 +76,18 @@ type guid struct {
 }
 
 func (g guid) String() string {
-	return fmt.Sprintf("%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x", g.Data1, g.Data2, g.Data3, g.Data4[0], g.Data4[1], g.Data4[2], g.Data4[3], g.Data4[4], g.Data4[5], g.Data4[6], g.Data4[7])
+	return fmt.Sprintf("%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+		g.Data1,
+		g.Data2,
+		g.Data3,
+		g.Data4[0],
+		g.Data4[1],
+		g.Data4[2],
+		g.Data4[3],
+		g.Data4[4],
+		g.Data4[5],
+		g.Data4[6],
+		g.Data4[7])
 }
 
 type resourceDescriptor struct {
@@ -81,6 +98,7 @@ type resourceDescriptor struct {
 
 type resFlag byte
 
+//nolint:deadcode,varcheck // need unused variables for iota to work
 const (
 	resFlagFree resFlag = 1 << iota
 	resFlagMetadata
@@ -120,6 +138,7 @@ type streamDescriptor struct {
 
 type hdrFlag uint32
 
+//nolint:deadcode,varcheck // need unused variables for iota to work
 const (
 	hdrFlagReserved hdrFlag = 1 << iota
 	hdrFlagCompressed
@@ -131,6 +150,7 @@ const (
 	hdrFlagRpFix
 )
 
+//nolint:deadcode,varcheck // need unused variables for iota to work
 const (
 	hdrFlagCompressReserved hdrFlag = 1 << (iota + 16)
 	hdrFlagCompressXpress
@@ -208,13 +228,13 @@ func (ft *Filetime) Time() time.Time {
 	return time.Unix(0, nsec)
 }
 
-// UnmarshalXML unmarshals the time from a WIM XML blob.
+// UnmarshalXML unmarshalls the time from a WIM XML blob.
 func (ft *Filetime) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
-	type time struct {
+	type Time struct {
 		Low  string `xml:"LOWPART"`
 		High string `xml:"HIGHPART"`
 	}
-	var t time
+	var t Time
 	err := d.DecodeElement(&t, &start)
 	if err != nil {
 		return err
@@ -283,6 +303,8 @@ func (e *ParseError) Error() string {
 	return fmt.Sprintf("WIM parse error: %s %s: %s", e.Oper, e.Path, e.Err.Error())
 }
 
+func (e *ParseError) Unwrap() error { return e.Err }
+
 // Reader provides functions to read a WIM file.
 type Reader struct {
 	hdr      wimHeader
@@ -380,14 +402,14 @@ func NewReader(f io.ReaderAt) (*Reader, error) {
 		return nil, err
 	}
 
-	var info info
-	err = xml.Unmarshal([]byte(xmlinfo), &info)
+	var inf info
+	err = xml.Unmarshal([]byte(xmlinfo), &inf)
 	if err != nil {
 		return nil, &ParseError{Oper: "XML info", Err: err}
 	}
 
 	for i, img := range images {
-		for _, imgInfo := range info.Image {
+		for _, imgInfo := range inf.Image {
 			if imgInfo.Index == i+1 {
 				img.ImageInfo = imgInfo
 				break
@@ -417,8 +439,8 @@ func (r *Reader) resourceReaderWithOffset(hdr *resourceDescriptor, offset int64)
 	var sr io.ReadCloser
 	section := io.NewSectionReader(r.r, hdr.Offset, hdr.CompressedSize())
 	if hdr.Flags()&resFlagCompressed == 0 {
-		section.Seek(offset, 0)
-		sr = ioutil.NopCloser(section)
+		_, _ = section.Seek(offset, 0)
+		sr = io.NopCloser(section)
 	} else {
 		cr, err := newCompressedReader(section, hdr.OriginalSize, offset)
 		if err != nil {
@@ -436,7 +458,7 @@ func (r *Reader) readResource(hdr *resourceDescriptor) ([]byte, error) {
 		return nil, err
 	}
 	defer rsrc.Close()
-	return ioutil.ReadAll(rsrc)
+	return io.ReadAll(rsrc)
 }
 
 func (r *Reader) readXML() (string, error) {
@@ -449,17 +471,17 @@ func (r *Reader) readXML() (string, error) {
 	}
 	defer rsrc.Close()
 
-	XMLData := make([]uint16, r.hdr.XMLData.OriginalSize/2)
-	err = binary.Read(rsrc, binary.LittleEndian, XMLData)
+	xmlData := make([]uint16, r.hdr.XMLData.OriginalSize/2)
+	err = binary.Read(rsrc, binary.LittleEndian, xmlData)
 	if err != nil {
 		return "", &ParseError{Oper: "XML data", Err: err}
 	}
 
 	// The BOM will always indicate little-endian UTF-16.
-	if XMLData[0] != 0xfeff {
+	if xmlData[0] != 0xfeff {
 		return "", &ParseError{Oper: "XML data", Err: errors.New("invalid BOM")}
 	}
-	return string(utf16.Decode(XMLData[1:])), nil
+	return string(utf16.Decode(xmlData[1:])), nil
 }
 
 func (r *Reader) readOffsetTable(res *resourceDescriptor) (map[SHA1Hash]resourceDescriptor, []*Image, error) {
@@ -475,7 +497,7 @@ func (r *Reader) readOffsetTable(res *resourceDescriptor) (map[SHA1Hash]resource
 	for i := 0; ; i++ {
 		var res streamDescriptor
 		err := binary.Read(br, binary.LittleEndian, &res)
-		if err == io.EOF {
+		if err == io.EOF { //nolint:errorlint
 			break
 		}
 		if err != nil {
@@ -491,7 +513,7 @@ func (r *Reader) readOffsetTable(res *resourceDescriptor) (map[SHA1Hash]resource
 			if err != nil {
 				panic(fmt.Sprint(i, err))
 			}
-			hash := sha1.New()
+			hash := sha1.New() //nolint:gosec // not used for secure application
 			_, err = io.Copy(hash, sec)
 			sec.Close()
 			if err != nil {
@@ -522,12 +544,11 @@ func (r *Reader) readOffsetTable(res *resourceDescriptor) (map[SHA1Hash]resource
 	return fileData, images, nil
 }
 
-func (r *Reader) readSecurityDescriptors(rsrc io.Reader) (sds [][]byte, n int64, err error) {
+func (*Reader) readSecurityDescriptors(rsrc io.Reader) (sds [][]byte, n int64, err error) {
 	var secBlock securityblockDisk
 	err = binary.Read(rsrc, binary.LittleEndian, &secBlock)
 	if err != nil {
-		err = &ParseError{Oper: "security table", Err: err}
-		return
+		return sds, 0, &ParseError{Oper: "security table", Err: err}
 	}
 
 	n += securityblockDiskSize
@@ -535,8 +556,7 @@ func (r *Reader) readSecurityDescriptors(rsrc io.Reader) (sds [][]byte, n int64,
 	secSizes := make([]int64, secBlock.NumEntries)
 	err = binary.Read(rsrc, binary.LittleEndian, &secSizes)
 	if err != nil {
-		err = &ParseError{Oper: "security table sizes", Err: err}
-		return
+		return sds, n, &ParseError{Oper: "security table sizes", Err: err}
 	}
 
 	n += int64(secBlock.NumEntries * 8)
@@ -546,8 +566,7 @@ func (r *Reader) readSecurityDescriptors(rsrc io.Reader) (sds [][]byte, n int64,
 		sd := make([]byte, size&0xffffffff)
 		_, err = io.ReadFull(rsrc, sd)
 		if err != nil {
-			err = &ParseError{Oper: "security descriptor", Err: err}
-			return
+			return sds, n, &ParseError{Oper: "security descriptor", Err: err}
 		}
 		n += int64(len(sd))
 		sds[i] = sd
@@ -555,17 +574,16 @@ func (r *Reader) readSecurityDescriptors(rsrc io.Reader) (sds [][]byte, n int64,
 
 	secsize := int64((secBlock.TotalLength + 7) &^ 7)
 	if n > secsize {
-		err = &ParseError{Oper: "security descriptor", Err: errors.New("security descriptor table too small")}
-		return
+		return sds, n, &ParseError{Oper: "security descriptor", Err: errors.New("security descriptor table too small")}
 	}
 
-	_, err = io.CopyN(ioutil.Discard, rsrc, secsize-n)
+	_, err = io.CopyN(io.Discard, rsrc, secsize-n)
 	if err != nil {
-		return
+		return sds, n, err
 	}
 
 	n = secsize
-	return
+	return sds, n, nil
 }
 
 // Open parses the image and returns the root directory.
@@ -621,10 +639,10 @@ func (img *Image) readdir(offset int64) ([]*File, error) {
 		img.curOffset = offset
 	}
 	if offset > img.curOffset {
-		_, err := io.CopyN(ioutil.Discard, img.r, offset-img.curOffset)
+		_, err := io.CopyN(io.Discard, img.r, offset-img.curOffset)
 		if err != nil {
 			img.reset()
-			if err == io.EOF {
+			if err == io.EOF { //nolint:errorlint
 				err = io.ErrUnexpectedEOF
 			}
 			return nil, err
@@ -635,7 +653,7 @@ func (img *Image) readdir(offset int64) ([]*File, error) {
 	for {
 		e, n, err := img.readNextEntry(img.r)
 		img.curOffset += n
-		if err == io.EOF {
+		if err == io.EOF { //nolint:errorlint
 			break
 		}
 		if err != nil {
@@ -699,7 +717,11 @@ func (img *Image) readNextEntry(r io.Reader) (*File, int64, error) {
 		var ok bool
 		offset, ok = img.wim.fileData[dentry.Hash]
 		if !ok {
-			return nil, 0, &ParseError{Oper: "directory entry", Path: name, Err: fmt.Errorf("could not find file data matching hash %#v", dentry)}
+			return nil, 0, &ParseError{
+				Oper: "directory entry",
+				Path: name,
+				Err:  fmt.Errorf("could not find file data matching hash %#v", dentry),
+			}
 		}
 	}
 
@@ -742,9 +764,9 @@ func (img *Image) readNextEntry(r io.Reader) (*File, int64, error) {
 		f.SecurityDescriptor = img.sds[dentry.SecurityID]
 	}
 
-	_, err = io.CopyN(ioutil.Discard, r, left)
+	_, err = io.CopyN(io.Discard, r, left)
 	if err != nil {
-		if err == io.EOF {
+		if err == io.EOF { //nolint:errorlint
 			err = io.ErrUnexpectedEOF
 		}
 		return nil, 0, err
@@ -771,7 +793,11 @@ func (img *Image) readNextEntry(r io.Reader) (*File, int64, error) {
 	}
 
 	if dentry.Attributes&FILE_ATTRIBUTE_REPARSE_POINT != 0 && f.Size == 0 {
-		return nil, 0, &ParseError{Oper: "directory entry", Path: name, Err: errors.New("reparse point is missing reparse stream")}
+		return nil, 0, &ParseError{
+			Oper: "directory entry",
+			Path: name,
+			Err:  errors.New("reparse point is missing reparse stream"),
+		}
 	}
 
 	return f, length, nil
@@ -781,7 +807,7 @@ func (img *Image) readNextStream(r io.Reader) (*Stream, int64, error) {
 	var length int64
 	err := binary.Read(r, binary.LittleEndian, &length)
 	if err != nil {
-		if err == io.EOF {
+		if err == io.EOF { //nolint:errorlint
 			err = io.ErrUnexpectedEOF
 		}
 		return nil, 0, &ParseError{Oper: "stream length check", Err: err}
@@ -818,7 +844,11 @@ func (img *Image) readNextStream(r io.Reader) (*Stream, int64, error) {
 		var ok bool
 		offset, ok = img.wim.fileData[sentry.Hash]
 		if !ok {
-			return nil, 0, &ParseError{Oper: "stream entry", Path: name, Err: fmt.Errorf("could not find file data matching hash %v", sentry.Hash)}
+			return nil, 0, &ParseError{
+				Oper: "stream entry",
+				Path: name,
+				Err:  fmt.Errorf("could not find file data matching hash %v", sentry.Hash),
+			}
 		}
 	}
 
@@ -832,9 +862,9 @@ func (img *Image) readNextStream(r io.Reader) (*Stream, int64, error) {
 		offset: offset,
 	}
 
-	_, err = io.CopyN(ioutil.Discard, r, left)
+	_, err = io.CopyN(io.Discard, r, left)
 	if err != nil {
-		if err == io.EOF {
+		if err == io.EOF { //nolint:errorlint
 			err = io.ErrUnexpectedEOF
 		}
 		return nil, 0, err