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-rw-r--r--tools/go_fieldenum/BUILD15
-rw-r--r--tools/go_fieldenum/defs.bzl29
-rw-r--r--tools/go_fieldenum/main.go310
3 files changed, 354 insertions, 0 deletions
diff --git a/tools/go_fieldenum/BUILD b/tools/go_fieldenum/BUILD
new file mode 100644
index 000000000..2bfdaeb2f
--- /dev/null
+++ b/tools/go_fieldenum/BUILD
@@ -0,0 +1,15 @@
+load("//tools:defs.bzl", "bzl_library", "go_binary")
+
+licenses(["notice"])
+
+go_binary(
+ name = "fieldenum",
+ srcs = ["main.go"],
+ visibility = ["//:sandbox"],
+)
+
+bzl_library(
+ name = "defs_bzl",
+ srcs = ["defs.bzl"],
+ visibility = ["//visibility:private"],
+)
diff --git a/tools/go_fieldenum/defs.bzl b/tools/go_fieldenum/defs.bzl
new file mode 100644
index 000000000..0cd2679ca
--- /dev/null
+++ b/tools/go_fieldenum/defs.bzl
@@ -0,0 +1,29 @@
+"""The go_fieldenum target infers Field, Fields, and FieldSet types for each
+struct in an input source file marked +fieldenum.
+"""
+
+def _go_fieldenum_impl(ctx):
+ output = ctx.outputs.out
+
+ args = ["-pkg=%s" % ctx.attr.package, "-out=%s" % output.path]
+ for src in ctx.attr.srcs:
+ args += [f.path for f in src.files.to_list()]
+
+ ctx.actions.run(
+ inputs = ctx.files.srcs,
+ outputs = [output],
+ mnemonic = "GoFieldenum",
+ progress_message = "Generating Go field enumerators %s" % ctx.label,
+ arguments = args,
+ executable = ctx.executable._tool,
+ )
+
+go_fieldenum = rule(
+ implementation = _go_fieldenum_impl,
+ attrs = {
+ "srcs": attr.label_list(doc = "input source files", mandatory = True, allow_files = True),
+ "package": attr.string(doc = "the package for the generated source file", mandatory = True),
+ "out": attr.output(doc = "output file", mandatory = True),
+ "_tool": attr.label(executable = True, cfg = "host", default = Label("//tools/go_fieldenum:fieldenum")),
+ },
+)
diff --git a/tools/go_fieldenum/main.go b/tools/go_fieldenum/main.go
new file mode 100644
index 000000000..68dfdb3db
--- /dev/null
+++ b/tools/go_fieldenum/main.go
@@ -0,0 +1,310 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Binary fieldenum emits field bitmasks for all structs in a package marked
+// "+fieldenum".
+package main
+
+import (
+ "flag"
+ "fmt"
+ "go/ast"
+ "go/parser"
+ "go/token"
+ "log"
+ "os"
+ "strings"
+)
+
+var (
+ outputPkg = flag.String("pkg", "", "output package")
+ outputFilename = flag.String("out", "-", "output filename")
+)
+
+func main() {
+ // Parse command line arguments.
+ flag.Parse()
+ if len(*outputPkg) == 0 {
+ log.Fatalf("-pkg must be provided")
+ }
+ if len(flag.Args()) == 0 {
+ log.Fatalf("Input files must be provided")
+ }
+
+ // Parse input files.
+ inputFiles := make([]*ast.File, 0, len(flag.Args()))
+ fset := token.NewFileSet()
+ for _, filename := range flag.Args() {
+ f, err := parser.ParseFile(fset, filename, nil, parser.ParseComments)
+ if err != nil {
+ log.Fatalf("Failed to parse input file %q: %v", filename, err)
+ }
+ inputFiles = append(inputFiles, f)
+ }
+
+ // Determine which types are marked "+fieldenum" and will consequently have
+ // code generated.
+ fieldEnumTypes := make(map[string]fieldEnumTypeInfo)
+ for _, f := range inputFiles {
+ for _, decl := range f.Decls {
+ d, ok := decl.(*ast.GenDecl)
+ if !ok || d.Tok != token.TYPE || d.Doc == nil || len(d.Specs) == 0 {
+ continue
+ }
+ for _, l := range d.Doc.List {
+ const fieldenumPrefixWithSpace = "// +fieldenum "
+ if l.Text == "// +fieldenum" || strings.HasPrefix(l.Text, fieldenumPrefixWithSpace) {
+ spec := d.Specs[0].(*ast.TypeSpec)
+ name := spec.Name.Name
+ prefix := name
+ if len(l.Text) > len(fieldenumPrefixWithSpace) {
+ prefix = strings.TrimSpace(l.Text[len(fieldenumPrefixWithSpace):])
+ }
+ st, ok := spec.Type.(*ast.StructType)
+ if !ok {
+ log.Fatalf("Type %s is marked +fieldenum, but is not a struct", name)
+ }
+ fieldEnumTypes[name] = fieldEnumTypeInfo{
+ prefix: prefix,
+ structType: st,
+ }
+ break
+ }
+ }
+ }
+ }
+
+ // Collect information for each type for which code is being generated.
+ structInfos := make([]structInfo, 0, len(fieldEnumTypes))
+ needSyncAtomic := false
+ for typeName, typeInfo := range fieldEnumTypes {
+ var si structInfo
+ si.name = typeName
+ si.prefix = typeInfo.prefix
+ for _, field := range typeInfo.structType.Fields.List {
+ name := structFieldName(field)
+ // If the field's type is a type that is also marked +fieldenum,
+ // include a FieldSet for that type in this one's. The field must
+ // be a struct by value, since if it's a pointer then that struct
+ // might also point to or include this one (which would make
+ // FieldSet inclusion circular). It must also be a type defined in
+ // this package, since otherwise we don't know whether it's marked
+ // +fieldenum. Thus, field.Type must be an identifier (rather than
+ // an ast.StarExpr or SelectorExpr).
+ if tident, ok := field.Type.(*ast.Ident); ok {
+ if fieldTypeInfo, ok := fieldEnumTypes[tident.Name]; ok {
+ fsf := fieldSetField{
+ fieldName: name,
+ typePrefix: fieldTypeInfo.prefix,
+ }
+ si.reprByFieldSet = append(si.reprByFieldSet, fsf)
+ si.allFields = append(si.allFields, fsf)
+ continue
+ }
+ }
+ si.reprByBit = append(si.reprByBit, name)
+ si.allFields = append(si.allFields, fieldSetField{
+ fieldName: name,
+ })
+ // sync/atomic import will be needed for FieldSet.Load().
+ needSyncAtomic = true
+ }
+ structInfos = append(structInfos, si)
+ }
+
+ // Build the output file.
+ var b strings.Builder
+ fmt.Fprintf(&b, "// Generated by go_fieldenum.\n\n")
+ fmt.Fprintf(&b, "package %s\n\n", *outputPkg)
+ if needSyncAtomic {
+ fmt.Fprintf(&b, "import \"sync/atomic\"\n\n")
+ }
+ for _, si := range structInfos {
+ si.writeTo(&b)
+ }
+
+ if *outputFilename == "-" {
+ // Write output to stdout.
+ fmt.Printf("%s", b.String())
+ } else {
+ // Write output to file.
+ f, err := os.OpenFile(*outputFilename, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0644)
+ if err != nil {
+ log.Fatalf("Failed to open output file %q: %v", *outputFilename, err)
+ }
+ if _, err := f.WriteString(b.String()); err != nil {
+ log.Fatalf("Failed to write output file %q: %v", *outputFilename, err)
+ }
+ f.Close()
+ }
+}
+
+type fieldEnumTypeInfo struct {
+ prefix string
+ structType *ast.StructType
+}
+
+// structInfo contains information about the code generated for a given struct.
+type structInfo struct {
+ // name is the name of the represented struct.
+ name string
+
+ // prefix is the prefix X applied to the name of each generated type and
+ // constant, referred to as X in the comments below for convenience.
+ prefix string
+
+ // reprByBit contains the names of fields in X that should be represented
+ // by a bit in the bit mask XFieldSet.fields, and by a bool in XFields.
+ reprByBit []string
+
+ // reprByFieldSet contains fields in X whose type is a named struct (e.g.
+ // Y) that has a corresponding FieldSet type YFieldSet, and which should
+ // therefore be represented by including a value of type YFieldSet in
+ // XFieldSet, and a value of type YFields in XFields.
+ reprByFieldSet []fieldSetField
+
+ // allFields contains all fields in X in order of declaration. Fields in
+ // reprByBit have fieldSetField.typePrefix == "".
+ allFields []fieldSetField
+}
+
+type fieldSetField struct {
+ fieldName string
+ typePrefix string
+}
+
+func structFieldName(f *ast.Field) string {
+ if len(f.Names) != 0 {
+ return f.Names[0].Name
+ }
+ // For embedded struct fields, the field name is the unqualified type name.
+ texpr := f.Type
+ for {
+ switch t := texpr.(type) {
+ case *ast.StarExpr:
+ texpr = t.X
+ case *ast.SelectorExpr:
+ texpr = t.Sel
+ case *ast.Ident:
+ return t.Name
+ default:
+ panic(fmt.Sprintf("unexpected %T", texpr))
+ }
+ }
+}
+
+// Workaround for Go defect (map membership test isn't usable in an
+// expression).
+func fetContains(xs map[string]*ast.StructType, x string) bool {
+ _, ok := xs[x]
+ return ok
+}
+
+func (si *structInfo) writeTo(b *strings.Builder) {
+ fmt.Fprintf(b, "// A %sField represents a field in %s.\n", si.prefix, si.name)
+ fmt.Fprintf(b, "type %sField uint\n\n", si.prefix)
+ if len(si.reprByBit) != 0 {
+ fmt.Fprintf(b, "// %sFieldX represents %s field X.\n", si.prefix, si.name)
+ fmt.Fprintf(b, "const (\n")
+ fmt.Fprintf(b, "\t%sField%s %sField = iota\n", si.prefix, si.reprByBit[0], si.prefix)
+ for _, fieldName := range si.reprByBit[1:] {
+ fmt.Fprintf(b, "\t%sField%s\n", si.prefix, fieldName)
+ }
+ fmt.Fprintf(b, ")\n\n")
+ }
+
+ fmt.Fprintf(b, "// %sFields represents a set of fields in %s in a literal-friendly form.\n", si.prefix, si.name)
+ fmt.Fprintf(b, "// The zero value of %sFields represents an empty set.\n", si.prefix)
+ fmt.Fprintf(b, "type %sFields struct {\n", si.prefix)
+ for _, fieldSetField := range si.allFields {
+ if fieldSetField.typePrefix == "" {
+ fmt.Fprintf(b, "\t%s bool\n", fieldSetField.fieldName)
+ } else {
+ fmt.Fprintf(b, "\t%s %sFields\n", fieldSetField.fieldName, fieldSetField.typePrefix)
+ }
+ }
+ fmt.Fprintf(b, "}\n\n")
+
+ fmt.Fprintf(b, "// %sFieldSet represents a set of fields in %s in a compact form.\n", si.prefix, si.name)
+ fmt.Fprintf(b, "// The zero value of %sFieldSet represents an empty set.\n", si.prefix)
+ fmt.Fprintf(b, "type %sFieldSet struct {\n", si.prefix)
+ numBitmaskUint32s := (len(si.reprByBit) + 31) / 32
+ for _, fieldSetField := range si.reprByFieldSet {
+ fmt.Fprintf(b, "\t%s %sFieldSet\n", fieldSetField.fieldName, fieldSetField.typePrefix)
+ }
+ if len(si.reprByBit) != 0 {
+ fmt.Fprintf(b, "\tfields [%d]uint32\n", numBitmaskUint32s)
+ }
+ fmt.Fprintf(b, "}\n\n")
+
+ if len(si.reprByBit) != 0 {
+ fmt.Fprintf(b, "// Contains returns true if f is present in the %sFieldSet.\n", si.prefix)
+ fmt.Fprintf(b, "func (fs %sFieldSet) Contains(f %sField) bool {\n", si.prefix, si.prefix)
+ if numBitmaskUint32s == 1 {
+ fmt.Fprintf(b, "\treturn fs.fields[0] & (uint32(1) << uint(f)) != 0\n")
+ } else {
+ fmt.Fprintf(b, "\treturn fs.fields[f/32] & (uint32(1) << (f%%32)) != 0\n")
+ }
+ fmt.Fprintf(b, "}\n\n")
+
+ fmt.Fprintf(b, "// Add adds f to the %sFieldSet.\n", si.prefix)
+ fmt.Fprintf(b, "func (fs *%sFieldSet) Add(f %sField) {\n", si.prefix, si.prefix)
+ if numBitmaskUint32s == 1 {
+ fmt.Fprintf(b, "\tfs.fields[0] |= uint32(1) << uint(f)\n")
+ } else {
+ fmt.Fprintf(b, "\tfs.fields[f/32] |= uint32(1) << (f%%32)\n")
+ }
+ fmt.Fprintf(b, "}\n\n")
+
+ fmt.Fprintf(b, "// Remove removes f from the %sFieldSet.\n", si.prefix)
+ fmt.Fprintf(b, "func (fs *%sFieldSet) Remove(f %sField) {\n", si.prefix, si.prefix)
+ if numBitmaskUint32s == 1 {
+ fmt.Fprintf(b, "\tfs.fields[0] &^= uint32(1) << uint(f)\n")
+ } else {
+ fmt.Fprintf(b, "\tfs.fields[f/32] &^= uint32(1) << (f%%32)\n")
+ }
+ fmt.Fprintf(b, "}\n\n")
+ }
+
+ fmt.Fprintf(b, "// Load returns a copy of the %sFieldSet.\n", si.prefix)
+ fmt.Fprintf(b, "// Load is safe to call concurrently with AddFieldsLoadable, but not Add or Remove.\n")
+ fmt.Fprintf(b, "func (fs *%sFieldSet) Load() (copied %sFieldSet) {\n", si.prefix, si.prefix)
+ for _, fieldSetField := range si.reprByFieldSet {
+ fmt.Fprintf(b, "\tcopied.%s = fs.%s.Load()\n", fieldSetField.fieldName, fieldSetField.fieldName)
+ }
+ for i := 0; i < numBitmaskUint32s; i++ {
+ fmt.Fprintf(b, "\tcopied.fields[%d] = atomic.LoadUint32(&fs.fields[%d])\n", i, i)
+ }
+ fmt.Fprintf(b, "\treturn\n")
+ fmt.Fprintf(b, "}\n\n")
+
+ fmt.Fprintf(b, "// AddFieldsLoadable adds the given fields to the %sFieldSet.\n", si.prefix)
+ fmt.Fprintf(b, "// AddFieldsLoadable is safe to call concurrently with Load, but not other methods (including other calls to AddFieldsLoadable).\n")
+ fmt.Fprintf(b, "func (fs *%sFieldSet) AddFieldsLoadable(fields %sFields) {\n", si.prefix, si.prefix)
+ for _, fieldSetField := range si.reprByFieldSet {
+ fmt.Fprintf(b, "\tfs.%s.AddFieldsLoadable(fields.%s)\n", fieldSetField.fieldName, fieldSetField.fieldName)
+ }
+ for _, fieldName := range si.reprByBit {
+ fieldConstName := fmt.Sprintf("%sField%s", si.prefix, fieldName)
+ fmt.Fprintf(b, "\tif fields.%s {\n", fieldName)
+ if numBitmaskUint32s == 1 {
+ fmt.Fprintf(b, "\t\tatomic.StoreUint32(&fs.fields[0], fs.fields[0] | (uint32(1) << uint(%s)))\n", fieldConstName)
+ } else {
+ fmt.Fprintf(b, "\t\tword, bit := %s/32, %s%%32\n", fieldConstName, fieldConstName)
+ fmt.Fprintf(b, "\t\tatomic.StoreUint32(&fs.fields[word], fs.fields[word] | (uint32(1) << bit))\n")
+ }
+ fmt.Fprintf(b, "\t}\n")
+ }
+ fmt.Fprintf(b, "}\n\n")
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-27 03:42:23 +0000