1 files changed, 522 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/internal/mkmerge/mkmerge.go b/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/internal/mkmerge/mkmerge.go
new file mode 100644
index 0000000..3dda84d
--- /dev/null
+++ b/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/internal/mkmerge/mkmerge.go
@@ -0,0 +1,522 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The mkmerge command parses generated source files and merges common
+// consts, funcs, and types into a common source file, per GOOS.
+//
+// Usage:
+//
+//	$ mkmerge -out MERGED FILE [FILE ...]
+//
+// Example:
+//
+//	# Remove all common consts, funcs, and types from zerrors_linux_*.go
+//	# and write the common code into zerrors_linux.go
+//	$ mkmerge -out zerrors_linux.go zerrors_linux_*.go
+//
+// mkmerge performs the merge in the following steps:
+//  1. Construct the set of common code that is identical in all
+//     architecture-specific files.
+//  2. Write this common code to the merged file.
+//  3. Remove the common code from all architecture-specific files.
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/format"
+	"go/parser"
+	"go/token"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"path"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+const validGOOS = "aix|darwin|dragonfly|freebsd|linux|netbsd|openbsd|solaris"
+
+// getValidGOOS returns GOOS, true if filename ends with a valid "_GOOS.go"
+func getValidGOOS(filename string) (string, bool) {
+	matches := regexp.MustCompile(`_(` + validGOOS + `)\.go$`).FindStringSubmatch(filename)
+	if len(matches) != 2 {
+		return "", false
+	}
+	return matches[1], true
+}
+
+// codeElem represents an ast.Decl in a comparable way.
+type codeElem struct {
+	tok token.Token // e.g. token.CONST, token.TYPE, or token.FUNC
+	src string      // the declaration formatted as source code
+}
+
+// newCodeElem returns a codeElem based on tok and node, or an error is returned.
+func newCodeElem(tok token.Token, node ast.Node) (codeElem, error) {
+	var b strings.Builder
+	err := format.Node(&b, token.NewFileSet(), node)
+	if err != nil {
+		return codeElem{}, err
+	}
+	return codeElem{tok, b.String()}, nil
+}
+
+// codeSet is a set of codeElems
+type codeSet struct {
+	set map[codeElem]bool // true for all codeElems in the set
+}
+
+// newCodeSet returns a new codeSet
+func newCodeSet() *codeSet { return &codeSet{make(map[codeElem]bool)} }
+
+// add adds elem to c
+func (c *codeSet) add(elem codeElem) { c.set[elem] = true }
+
+// has returns true if elem is in c
+func (c *codeSet) has(elem codeElem) bool { return c.set[elem] }
+
+// isEmpty returns true if the set is empty
+func (c *codeSet) isEmpty() bool { return len(c.set) == 0 }
+
+// intersection returns a new set which is the intersection of c and a
+func (c *codeSet) intersection(a *codeSet) *codeSet {
+	res := newCodeSet()
+
+	for elem := range c.set {
+		if a.has(elem) {
+			res.add(elem)
+		}
+	}
+	return res
+}
+
+// keepCommon is a filterFn for filtering the merged file with common declarations.
+func (c *codeSet) keepCommon(elem codeElem) bool {
+	switch elem.tok {
+	case token.VAR:
+		// Remove all vars from the merged file
+		return false
+	case token.CONST, token.TYPE, token.FUNC, token.COMMENT:
+		// Remove arch-specific consts, types, functions, and file-level comments from the merged file
+		return c.has(elem)
+	case token.IMPORT:
+		// Keep imports, they are handled by filterImports
+		return true
+	}
+
+	log.Fatalf("keepCommon: invalid elem %v", elem)
+	return true
+}
+
+// keepArchSpecific is a filterFn for filtering the GOARC-specific files.
+func (c *codeSet) keepArchSpecific(elem codeElem) bool {
+	switch elem.tok {
+	case token.CONST, token.TYPE, token.FUNC:
+		// Remove common consts, types, or functions from the arch-specific file
+		return !c.has(elem)
+	}
+	return true
+}
+
+// srcFile represents a source file
+type srcFile struct {
+	name string
+	src  []byte
+}
+
+// filterFn is a helper for filter
+type filterFn func(codeElem) bool
+
+// filter parses and filters Go source code from src, removing top
+// level declarations using keep as predicate.
+// For src parameter, please see docs for parser.ParseFile.
+func filter(src interface{}, keep filterFn) ([]byte, error) {
+	// Parse the src into an ast
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
+	if err != nil {
+		return nil, err
+	}
+	cmap := ast.NewCommentMap(fset, f, f.Comments)
+
+	// Group const/type specs on adjacent lines
+	var groups specGroups = make(map[string]int)
+	var groupID int
+
+	decls := f.Decls
+	f.Decls = f.Decls[:0]
+	for _, decl := range decls {
+		switch decl := decl.(type) {
+		case *ast.GenDecl:
+			// Filter imports, consts, types, vars
+			specs := decl.Specs
+			decl.Specs = decl.Specs[:0]
+			for i, spec := range specs {
+				elem, err := newCodeElem(decl.Tok, spec)
+				if err != nil {
+					return nil, err
+				}
+
+				// Create new group if there are empty lines between this and the previous spec
+				if i > 0 && fset.Position(specs[i-1].End()).Line < fset.Position(spec.Pos()).Line-1 {
+					groupID++
+				}
+
+				// Check if we should keep this spec
+				if keep(elem) {
+					decl.Specs = append(decl.Specs, spec)
+					groups.add(elem.src, groupID)
+				}
+			}
+			// Check if we should keep this decl
+			if len(decl.Specs) > 0 {
+				f.Decls = append(f.Decls, decl)
+			}
+		case *ast.FuncDecl:
+			// Filter funcs
+			elem, err := newCodeElem(token.FUNC, decl)
+			if err != nil {
+				return nil, err
+			}
+			if keep(elem) {
+				f.Decls = append(f.Decls, decl)
+			}
+		}
+	}
+
+	// Filter file level comments
+	if cmap[f] != nil {
+		commentGroups := cmap[f]
+		cmap[f] = cmap[f][:0]
+		for _, cGrp := range commentGroups {
+			if keep(codeElem{token.COMMENT, cGrp.Text()}) {
+				cmap[f] = append(cmap[f], cGrp)
+			}
+		}
+	}
+	f.Comments = cmap.Filter(f).Comments()
+
+	// Generate code for the filtered ast
+	var buf bytes.Buffer
+	if err = format.Node(&buf, fset, f); err != nil {
+		return nil, err
+	}
+
+	groupedSrc, err := groups.filterEmptyLines(&buf)
+	if err != nil {
+		return nil, err
+	}
+
+	return filterImports(groupedSrc)
+}
+
+// getCommonSet returns the set of consts, types, and funcs that are present in every file.
+func getCommonSet(files []srcFile) (*codeSet, error) {
+	if len(files) == 0 {
+		return nil, fmt.Errorf("no files provided")
+	}
+	// Use the first architecture file as the baseline
+	baseSet, err := getCodeSet(files[0].src)
+	if err != nil {
+		return nil, err
+	}
+
+	// Compare baseline set with other architecture files: discard any element,
+	// that doesn't exist in other architecture files.
+	for _, f := range files[1:] {
+		set, err := getCodeSet(f.src)
+		if err != nil {
+			return nil, err
+		}
+
+		baseSet = baseSet.intersection(set)
+	}
+	return baseSet, nil
+}
+
+// getCodeSet returns the set of all top-level consts, types, and funcs from src.
+// src must be string, []byte, or io.Reader (see go/parser.ParseFile docs)
+func getCodeSet(src interface{}) (*codeSet, error) {
+	set := newCodeSet()
+
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, decl := range f.Decls {
+		switch decl := decl.(type) {
+		case *ast.GenDecl:
+			// Add const, and type declarations
+			if !(decl.Tok == token.CONST || decl.Tok == token.TYPE) {
+				break
+			}
+
+			for _, spec := range decl.Specs {
+				elem, err := newCodeElem(decl.Tok, spec)
+				if err != nil {
+					return nil, err
+				}
+
+				set.add(elem)
+			}
+		case *ast.FuncDecl:
+			// Add func declarations
+			elem, err := newCodeElem(token.FUNC, decl)
+			if err != nil {
+				return nil, err
+			}
+
+			set.add(elem)
+		}
+	}
+
+	// Add file level comments
+	cmap := ast.NewCommentMap(fset, f, f.Comments)
+	for _, cGrp := range cmap[f] {
+		set.add(codeElem{token.COMMENT, cGrp.Text()})
+	}
+
+	return set, nil
+}
+
+// importName returns the identifier (PackageName) for an imported package
+func importName(iSpec *ast.ImportSpec) (string, error) {
+	if iSpec.Name == nil {
+		name, err := strconv.Unquote(iSpec.Path.Value)
+		if err != nil {
+			return "", err
+		}
+		return path.Base(name), nil
+	}
+	return iSpec.Name.Name, nil
+}
+
+// specGroups tracks grouped const/type specs with a map of line: groupID pairs
+type specGroups map[string]int
+
+// add spec source to group
+func (s specGroups) add(src string, groupID int) error {
+	srcBytes, err := format.Source(bytes.TrimSpace([]byte(src)))
+	if err != nil {
+		return err
+	}
+	s[string(srcBytes)] = groupID
+	return nil
+}
+
+// filterEmptyLines removes empty lines within groups of const/type specs.
+// Returns the filtered source.
+func (s specGroups) filterEmptyLines(src io.Reader) ([]byte, error) {
+	scanner := bufio.NewScanner(src)
+	var out bytes.Buffer
+
+	var emptyLines bytes.Buffer
+	prevGroupID := -1 // Initialize to invalid group
+	for scanner.Scan() {
+		line := bytes.TrimSpace(scanner.Bytes())
+
+		if len(line) == 0 {
+			fmt.Fprintf(&emptyLines, "%s\n", scanner.Bytes())
+			continue
+		}
+
+		// Discard emptyLines if previous non-empty line belonged to the same
+		// group as this line
+		if src, err := format.Source(line); err == nil {
+			groupID, ok := s[string(src)]
+			if ok && groupID == prevGroupID {
+				emptyLines.Reset()
+			}
+			prevGroupID = groupID
+		}
+
+		emptyLines.WriteTo(&out)
+		fmt.Fprintf(&out, "%s\n", scanner.Bytes())
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+	return out.Bytes(), nil
+}
+
+// filterImports removes unused imports from fileSrc, and returns a formatted src.
+func filterImports(fileSrc []byte) ([]byte, error) {
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, "", fileSrc, parser.ParseComments)
+	if err != nil {
+		return nil, err
+	}
+	cmap := ast.NewCommentMap(fset, file, file.Comments)
+
+	// create set of references to imported identifiers
+	keepImport := make(map[string]bool)
+	for _, u := range file.Unresolved {
+		keepImport[u.Name] = true
+	}
+
+	// filter import declarations
+	decls := file.Decls
+	file.Decls = file.Decls[:0]
+	for _, decl := range decls {
+		importDecl, ok := decl.(*ast.GenDecl)
+
+		// Keep non-import declarations
+		if !ok || importDecl.Tok != token.IMPORT {
+			file.Decls = append(file.Decls, decl)
+			continue
+		}
+
+		// Filter the import specs
+		specs := importDecl.Specs
+		importDecl.Specs = importDecl.Specs[:0]
+		for _, spec := range specs {
+			iSpec := spec.(*ast.ImportSpec)
+			name, err := importName(iSpec)
+			if err != nil {
+				return nil, err
+			}
+
+			if keepImport[name] {
+				importDecl.Specs = append(importDecl.Specs, iSpec)
+			}
+		}
+		if len(importDecl.Specs) > 0 {
+			file.Decls = append(file.Decls, importDecl)
+		}
+	}
+
+	// filter file.Imports
+	imports := file.Imports
+	file.Imports = file.Imports[:0]
+	for _, spec := range imports {
+		name, err := importName(spec)
+		if err != nil {
+			return nil, err
+		}
+
+		if keepImport[name] {
+			file.Imports = append(file.Imports, spec)
+		}
+	}
+	file.Comments = cmap.Filter(file).Comments()
+
+	var buf bytes.Buffer
+	err = format.Node(&buf, fset, file)
+	if err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+// merge extracts duplicate code from archFiles and merges it to mergeFile.
+// 1. Construct commonSet: the set of code that is idential in all archFiles.
+// 2. Write the code in commonSet to mergedFile.
+// 3. Remove the commonSet code from all archFiles.
+func merge(mergedFile string, archFiles ...string) error {
+	// extract and validate the GOOS part of the merged filename
+	goos, ok := getValidGOOS(mergedFile)
+	if !ok {
+		return fmt.Errorf("invalid GOOS in merged file name %s", mergedFile)
+	}
+
+	// Read architecture files
+	var inSrc []srcFile
+	for _, file := range archFiles {
+		src, err := ioutil.ReadFile(file)
+		if err != nil {
+			return fmt.Errorf("cannot read archfile %s: %w", file, err)
+		}
+
+		inSrc = append(inSrc, srcFile{file, src})
+	}
+
+	// 1. Construct the set of top-level declarations common for all files
+	commonSet, err := getCommonSet(inSrc)
+	if err != nil {
+		return err
+	}
+	if commonSet.isEmpty() {
+		// No common code => do not modify any files
+		return nil
+	}
+
+	// 2. Write the merged file
+	mergedSrc, err := filter(inSrc[0].src, commonSet.keepCommon)
+	if err != nil {
+		return err
+	}
+
+	f, err := os.Create(mergedFile)
+	if err != nil {
+		return err
+	}
+
+	buf := bufio.NewWriter(f)
+	fmt.Fprintln(buf, "// Code generated by mkmerge; DO NOT EDIT.")
+	fmt.Fprintln(buf)
+	fmt.Fprintf(buf, "//go:build %s\n", goos)
+	fmt.Fprintf(buf, "// +build %s\n", goos)
+	fmt.Fprintln(buf)
+	buf.Write(mergedSrc)
+
+	err = buf.Flush()
+	if err != nil {
+		return err
+	}
+	err = f.Close()
+	if err != nil {
+		return err
+	}
+
+	// 3. Remove duplicate declarations from the architecture files
+	for _, inFile := range inSrc {
+		src, err := filter(inFile.src, commonSet.keepArchSpecific)
+		if err != nil {
+			return err
+		}
+		err = ioutil.WriteFile(inFile.name, src, 0644)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func main() {
+	var mergedFile string
+	flag.StringVar(&mergedFile, "out", "", "Write merged code to `FILE`")
+	flag.Parse()
+
+	// Expand wildcards
+	var filenames []string
+	for _, arg := range flag.Args() {
+		matches, err := filepath.Glob(arg)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Invalid command line argument %q: %v\n", arg, err)
+			os.Exit(1)
+		}
+		filenames = append(filenames, matches...)
+	}
+
+	if len(filenames) < 2 {
+		// No need to merge
+		return
+	}
+
+	err := merge(mergedFile, filenames...)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Merge failed with error: %v\n", err)
+		os.Exit(1)
+	}
+}