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 contain outdated Win32 syscall or other auto-generated files.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>

tools/mkwinsyscall/mkwinsyscall.go

@@ -16,7 +16,6 @@ import (
 	"go/parser"
 	"go/token"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -29,6 +28,24 @@ import (
 	"golang.org/x/sys/windows"
 )
 
+const (
+	pkgSyscall = "syscall"
+	pkgWindows = "windows"
+
+	// common types.
+
+	tBool    = "bool"
+	tBoolPtr = "*bool"
+	tError   = "error"
+	tString  = "string"
+
+	// error variable names.
+
+	varErr         = "err"
+	varErrNTStatus = "ntStatus"
+	varErrHR       = "hr"
+)
+
 var (
 	filename       = flag.String("output", "", "output file name (standard output if omitted)")
 	printTraceFlag = flag.Bool("trace", false, "generate print statement after every syscall")
@@ -53,20 +70,20 @@ func packagename() string {
 }
 
 func windowsdot() string {
-	if packageName == "windows" {
+	if packageName == pkgWindows {
 		return ""
 	}
-	return "windows."
+	return pkgWindows + "."
 }
 
 func syscalldot() string {
-	if packageName == "syscall" {
+	if packageName == pkgSyscall {
 		return ""
 	}
-	return "syscall."
+	return pkgSyscall + "."
 }
 
-// Param is function parameter
+// Param is function parameter.
 type Param struct {
 	Name      string
 	Type      string
@@ -134,9 +151,9 @@ func (p *Param) StringTmpVarCode() string {
 // TmpVarCode returns source code for temp variable.
 func (p *Param) TmpVarCode() string {
 	switch {
-	case p.Type == "bool":
+	case p.Type == tBool:
 		return p.BoolTmpVarCode()
-	case p.Type == "*bool":
+	case p.Type == tBoolPtr:
 		return p.BoolPointerTmpVarCode()
 	case strings.HasPrefix(p.Type, "[]"):
 		return p.SliceTmpVarCode()
@@ -148,7 +165,7 @@ func (p *Param) TmpVarCode() string {
 // TmpVarReadbackCode returns source code for reading back the temp variable into the original variable.
 func (p *Param) TmpVarReadbackCode() string {
 	switch {
-	case p.Type == "*bool":
+	case p.Type == tBoolPtr:
 		return fmt.Sprintf("*%s = %s != 0", p.Name, p.tmpVar())
 	default:
 		return ""
@@ -170,11 +187,11 @@ func (p *Param) SyscallArgList() []string {
 	t := p.HelperType()
 	var s string
 	switch {
-	case t == "*bool":
+	case t == tBoolPtr:
 		s = fmt.Sprintf("unsafe.Pointer(&%s)", p.tmpVar())
 	case t[0] == '*':
 		s = fmt.Sprintf("unsafe.Pointer(%s)", p.Name)
-	case t == "bool":
+	case t == tBool:
 		s = p.tmpVar()
 	case strings.HasPrefix(t, "[]"):
 		return []string{
@@ -189,12 +206,12 @@ func (p *Param) SyscallArgList() []string {
 
 // IsError determines if p parameter is used to return error.
 func (p *Param) IsError() bool {
-	return p.Name == "err" && p.Type == "error"
+	return p.Name == varErr && p.Type == tError
 }
 
 // HelperType returns type of parameter p used in helper function.
 func (p *Param) HelperType() string {
-	if p.Type == "string" {
+	if p.Type == tString {
 		return p.fn.StrconvType()
 	}
 	return p.Type
@@ -226,9 +243,9 @@ type Rets struct {
 // ErrorVarName returns error variable name for r.
 func (r *Rets) ErrorVarName() string {
 	if r.ReturnsError {
-		return "err"
+		return varErr
 	}
-	if r.Type == "error" {
+	if r.Type == tError {
 		return r.Name
 	}
 	return ""
@@ -241,7 +258,7 @@ func (r *Rets) ToParams() []*Param {
 		ps = append(ps, &Param{Name: r.Name, Type: r.Type})
 	}
 	if r.ReturnsError {
-		ps = append(ps, &Param{Name: "err", Type: "error"})
+		ps = append(ps, &Param{Name: varErr, Type: tError})
 	}
 	return ps
 }
@@ -295,8 +312,8 @@ func (r *Rets) SetErrorCode() string {
 	const code = `if r0 != 0 {
 		%s = %sErrno(r0)
 	}`
-	const ntstatus = `if r0 != 0 {
-		ntstatus = %sNTStatus(r0)
+	const ntStatus = `if r0 != 0 {
+		%s = %sNTStatus(r0)
 	}`
 	const hrCode = `if int32(r0) < 0 {
 		if r0&0x1fff0000 == 0x00070000 {
@@ -311,22 +328,22 @@ func (r *Rets) SetErrorCode() string {
 	if r.Name == "" {
 		return r.useLongHandleErrorCode("r1")
 	}
-	if r.Type == "error" {
+	if r.Type == tError {
 		switch r.Name {
-		case "ntstatus":
-			return fmt.Sprintf(ntstatus, windowsdot())
-		case "hr":
+		case varErrNTStatus, strings.ToLower(varErrNTStatus): // allow ntstatus to work
+			return fmt.Sprintf(ntStatus, r.Name, windowsdot())
+		case varErrHR:
 			return fmt.Sprintf(hrCode, r.Name, syscalldot())
 		default:
 			return fmt.Sprintf(code, r.Name, syscalldot())
 		}
 	}
 
-	s := ""
+	var s string
 	switch {
 	case r.Type[0] == '*':
 		s = fmt.Sprintf("%s = (%s)(unsafe.Pointer(r0))", r.Name, r.Type)
-	case r.Type == "bool":
+	case r.Type == tBool:
 		s = fmt.Sprintf("%s = r0 != 0", r.Name)
 	default:
 		s = fmt.Sprintf("%s = %s(r0)", r.Name, r.Type)
@@ -564,7 +581,7 @@ func (f *Fn) HelperCallParamList() string {
 	a := make([]string, 0, len(f.Params))
 	for _, p := range f.Params {
 		s := p.Name
-		if p.Type == "string" {
+		if p.Type == tString {
 			s = p.tmpVar()
 		}
 		a = append(a, s)
@@ -583,7 +600,7 @@ func (f *Fn) MaybeAbsent() string {
 	}`
 	errorVar := f.Rets.ErrorVarName()
 	if errorVar == "" {
-		errorVar = "err"
+		errorVar = varErr
 	}
 	return fmt.Sprintf(code, errorVar, f.DLLFuncName())
 }
@@ -616,7 +633,7 @@ func (f *Fn) StrconvType() string {
 // Otherwise it is false.
 func (f *Fn) HasStringParam() bool {
 	for _, p := range f.Params {
-		if p.Type == "string" {
+		if p.Type == tString {
 			return true
 		}
 	}
@@ -892,7 +909,8 @@ func main() {
 	if *filename == "" {
 		_, err = os.Stdout.Write(data)
 	} else {
-		err = ioutil.WriteFile(*filename, data, 0644)
+		//nolint:gosec // G306: code file, no need for wants 0600
+		err = os.WriteFile(*filename, data, 0644)
 	}
 	if err != nil {
 		log.Fatal(err)
@@ -900,6 +918,7 @@ func main() {
 }
 
 // TODO: use println instead to print in the following template
+
 const srcTemplate = `
 {{define "main"}} //go:build windows