src/cmd/cgo/godefs.go - go - Git at Google

 // Copyright 2011 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.

 package main

 import (
 	"bytes"
 	"fmt"
 	"go/ast"
 	"go/printer"
 	"go/token"
 	"os"
 	"strings"
 )

 // godefs returns the output for -godefs mode.
 func (p *Package) godefs(f *File, srcfile string) string {
 	var buf bytes.Buffer

 	fmt.Fprintf(&buf, "// Created by cgo -godefs - DO NOT EDIT\n")
 	fmt.Fprintf(&buf, "// %s\n", strings.Join(os.Args, " "))
 	fmt.Fprintf(&buf, "\n")

 	override := make(map[string]string)

 	// Allow source file to specify override mappings.
 	// For example, the socket data structures refer
 	// to in_addr and in_addr6 structs but we want to be
 	// able to treat them as byte arrays, so the godefs
 	// inputs in package syscall say
 	//
 	//	// +godefs map struct_in_addr [4]byte
 	//	// +godefs map struct_in_addr6 [16]byte
 	//
 	for _, g := range f.Comments {
 		for _, c := range g.List {
 			i := strings.Index(c.Text, "+godefs map")
 			if i < 0 {
 				continue
 			}
 			s := strings.TrimSpace(c.Text[i+len("+godefs map"):])
 			i = strings.Index(s, " ")
 			if i < 0 {
 				fmt.Fprintf(os.Stderr, "invalid +godefs map comment: %s\n", c.Text)
 				continue
 			}
 			override["_Ctype_"+strings.TrimSpace(s[:i])] = strings.TrimSpace(s[i:])
 		}
 	}
 	for _, n := range f.Name {
 		if s := override[n.Go]; s != "" {
 			override[n.Mangle] = s
 		}
 	}

 	// Otherwise, if the source file says type T C.whatever,
 	// use "T" as the mangling of C.whatever,
 	// except in the definition (handled at end of function).
 	refName := make(map[*ast.Expr]*Name)
 	for _, r := range f.Ref {
 		refName[r.Expr] = r.Name
 	}
 	for _, d := range f.AST.Decls {
 		d, ok := d.(*ast.GenDecl)
 		if !ok || d.Tok != token.TYPE {
 			continue
 		}
 		for _, s := range d.Specs {
 			s := s.(*ast.TypeSpec)
 			n := refName[&s.Type]
 			if n != nil && n.Mangle != "" {
 				override[n.Mangle] = s.Name.Name
 			}
 		}
 	}

 	// Extend overrides using typedefs:
 	// If we know that C.xxx should format as T
 	// and xxx is a typedef for yyy, make C.yyy format as T.
 	for typ, def := range typedef {
 		if new := override[typ]; new != "" {
 			if id, ok := def.Go.(*ast.Ident); ok {
 				override[id.Name] = new
 			}
 		}
 	}

 	// Apply overrides.
 	for old, new := range override {
 		if id := goIdent[old]; id != nil {
 			id.Name = new
 		}
 	}

 	// Any names still using the _C syntax are not going to compile,
 	// although in general we don't know whether they all made it
 	// into the file, so we can't warn here.
 	//
 	// The most common case is union types, which begin with
 	// _Ctype_union and for which typedef[name] is a Go byte
 	// array of the appropriate size (such as [4]byte).
 	// Substitute those union types with byte arrays.
 	for name, id := range goIdent {
 		if id.Name == name && strings.Contains(name, "_Ctype_union") {
 			if def := typedef[name]; def != nil {
 				id.Name = gofmt(def)
 			}
 		}
 	}

 	conf.Fprint(&buf, fset, f.AST)

 	return buf.String()
 }

 // cdefs returns the output for -cdefs mode.
 // The easiest way to do this is to translate the godefs Go to C.
 func (p *Package) cdefs(f *File, srcfile string) string {
 	godefsOutput := p.godefs(f, srcfile)

 	lines := strings.Split(godefsOutput, "\n")
 	lines[0] = "// Created by cgo -cdefs - DO NOT EDIT"

 	for i, line := range lines {
 		lines[i] = strings.TrimSpace(line)
 	}

 	var out bytes.Buffer
 	printf := func(format string, args ...interface{}) { fmt.Fprintf(&out, format, args...) }

 	didTypedef := false
 	for i := 0; i < len(lines); i++ {
 		line := lines[i]

 		// Delete
 		//	package x
 		if strings.HasPrefix(line, "package ") {
 			continue
 		}

 		// Convert
 		//	const (
 		//		A = 1
 		//		B = 2
 		//	)
 		//
 		// to
 		//
 		//	enum {
 		//		A = 1,
 		//		B = 2,
 		//	};
 		if line == "const (" {
 			printf("enum {\n")
 			for i++; i < len(lines) && lines[i] != ")"; i++ {
 				line = lines[i]
 				if line != "" {
 					printf("\t%s,", line)
 				}
 				printf("\n")
 			}
 			printf("};\n")
 			continue
 		}

 		// Convert
 		//	const A = 1
 		// to
 		//	enum { A = 1 };
 		if strings.HasPrefix(line, "const ") {
 			printf("enum { %s };\n", line[len("const "):])
 			continue
 		}

 		// On first type definition, typedef all the structs
 		// in case there are dependencies between them.
 		if !didTypedef && strings.HasPrefix(line, "type ") {
 			didTypedef = true
 			for _, line := range lines {
 				line = strings.TrimSpace(line)
 				if strings.HasPrefix(line, "type ") && strings.HasSuffix(line, " struct {") {
 					s := strings.TrimSuffix(strings.TrimPrefix(line, "type "), " struct {")
 					printf("typedef struct %s %s;\n", s, s)
 				}
 			}
 			printf("\n")
 			printf("#pragma pack on\n")
 			printf("\n")
 		}

 		// Convert
 		//	type T struct {
 		//		X int64
 		//		Y *int32
 		//		Z [4]byte
 		//	}
 		//
 		// to
 		//
 		//	struct T {
 		//		int64 X;
 		//		int32 *Y;
 		//		byte Z[4];
 		//	}
 		if strings.HasPrefix(line, "type ") && strings.HasSuffix(line, " struct {") {
 			if len(lines) > i+1 && lines[i+1] == "}" {
 				// do not output empty struct
 				i++
 				continue
 			}
 			s := line[len("type ") : len(line)-len(" struct {")]
 			printf("struct %s {\n", s)
 			for i++; i < len(lines) && lines[i] != "}"; i++ {
 				line := lines[i]
 				if line != "" {
 					f := strings.Fields(line)
 					if len(f) != 2 {
 						fmt.Fprintf(os.Stderr, "cgo: cannot parse struct field: %s\n", line)
 						nerrors++
 						continue
 					}
 					printf("\t%s;", cdecl(f[0], f[1]))
 				}
 				printf("\n")
 			}
 			printf("};\n")
 			continue
 		}

 		// Convert
 		//	type T int
 		// to
 		//	typedef int T;
 		if strings.HasPrefix(line, "type ") {
 			f := strings.Fields(line[len("type "):])
 			if len(f) != 2 {
 				fmt.Fprintf(os.Stderr, "cgo: cannot parse type definition: %s\n", line)
 				nerrors++
 				continue
 			}
 			printf("typedef\t%s;\n", cdecl(f[0], f[1]))
 			continue
 		}

 		printf("%s\n", line)
 	}

 	if didTypedef {
 		printf("\n")
 		printf("#pragma pack off\n")
 	}

 	return out.String()
 }

 // cdecl returns the C declaration for the given Go name and type.
 // It only handles the specific cases necessary for converting godefs output.
 func cdecl(name, typ string) string {
 	// X *[0]byte -> X *void
 	if strings.HasPrefix(typ, "*[0]") {
 		typ = "*void"
 	}
 	// X [4]byte -> X[4] byte
 	for strings.HasPrefix(typ, "[") {
 		i := strings.Index(typ, "]") + 1
 		name = name + typ[:i]
 		typ = typ[i:]
 	}
 	// X *byte -> *X byte
 	for strings.HasPrefix(typ, "*") {
 		name = "*" + name
 		typ = typ[1:]
 	}
 	// X T -> T X
 	// Handle the special case: 'unsafe.Pointer' is 'void *'
 	if typ == "unsafe.Pointer" {
 		typ = "void"
 		name = "*" + name
 	}
 	return typ + "\t" + name
 }

 var gofmtBuf bytes.Buffer

 // gofmt returns the gofmt-formatted string for an AST node.
 func gofmt(n interface{}) string {
 	gofmtBuf.Reset()
 	err := printer.Fprint(&gofmtBuf, fset, n)
 	if err != nil {
 		return "<" + err.Error() + ">"
 	}
 	return gofmtBuf.String()
 }
	// Copyright 2011 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.

	package main

	import (
	"bytes"
	"fmt"
	"go/ast"
	"go/printer"
	"go/token"
	"os"
	"strings"
	)

	// godefs returns the output for -godefs mode.
	func (p Package) godefs(f File, srcfile string) string {
	var buf bytes.Buffer

	fmt.Fprintf(&buf, "// Created by cgo -godefs - DO NOT EDIT\n")
	fmt.Fprintf(&buf, "// %s\n", strings.Join(os.Args, " "))
	fmt.Fprintf(&buf, "\n")

	override := make(map[string]string)

	// Allow source file to specify override mappings.
	// For example, the socket data structures refer
	// to in_addr and in_addr6 structs but we want to be
	// able to treat them as byte arrays, so the godefs
	// inputs in package syscall say
	//
	// // +godefs map struct_in_addr [4]byte
	// // +godefs map struct_in_addr6 [16]byte
	//
	for _, g := range f.Comments {
	for _, c := range g.List {
	i := strings.Index(c.Text, "+godefs map")
	if i < 0 {
	continue
	}
	s := strings.TrimSpace(c.Text[i+len("+godefs map"):])
	i = strings.Index(s, " ")
	if i < 0 {
	fmt.Fprintf(os.Stderr, "invalid +godefs map comment: %s\n", c.Text)
	continue
	}
	override["_Ctype_"+strings.TrimSpace(s[:i])] = strings.TrimSpace(s[i:])
	}
	}
	for _, n := range f.Name {
	if s := override[n.Go]; s != "" {
	override[n.Mangle] = s
	}
	}

	// Otherwise, if the source file says type T C.whatever,
	// use "T" as the mangling of C.whatever,
	// except in the definition (handled at end of function).
	refName := make(map[ast.Expr]Name)
	for _, r := range f.Ref {
	refName[r.Expr] = r.Name
	}
	for _, d := range f.AST.Decls {
	d, ok := d.(*ast.GenDecl)
	if !ok \|\| d.Tok != token.TYPE {
	continue
	}
	for _, s := range d.Specs {
	s := s.(*ast.TypeSpec)
	n := refName[&s.Type]
	if n != nil && n.Mangle != "" {
	override[n.Mangle] = s.Name.Name
	}
	}
	}

	// Extend overrides using typedefs:
	// If we know that C.xxx should format as T
	// and xxx is a typedef for yyy, make C.yyy format as T.
	for typ, def := range typedef {
	if new := override[typ]; new != "" {
	if id, ok := def.Go.(*ast.Ident); ok {
	override[id.Name] = new
	}
	}
	}

	// Apply overrides.
	for old, new := range override {
	if id := goIdent[old]; id != nil {
	id.Name = new
	}
	}

	// Any names still using the _C syntax are not going to compile,
	// although in general we don't know whether they all made it
	// into the file, so we can't warn here.
	//
	// The most common case is union types, which begin with
	// _Ctype_union and for which typedef[name] is a Go byte
	// array of the appropriate size (such as [4]byte).
	// Substitute those union types with byte arrays.
	for name, id := range goIdent {
	if id.Name == name && strings.Contains(name, "_Ctype_union") {
	if def := typedef[name]; def != nil {
	id.Name = gofmt(def)
	}
	}
	}

	conf.Fprint(&buf, fset, f.AST)

	return buf.String()
	}

	// cdefs returns the output for -cdefs mode.
	// The easiest way to do this is to translate the godefs Go to C.
	func (p Package) cdefs(f File, srcfile string) string {
	godefsOutput := p.godefs(f, srcfile)

	lines := strings.Split(godefsOutput, "\n")
	lines[0] = "// Created by cgo -cdefs - DO NOT EDIT"

	for i, line := range lines {
	lines[i] = strings.TrimSpace(line)
	}

	var out bytes.Buffer
	printf := func(format string, args ...interface{}) { fmt.Fprintf(&out, format, args...) }

	didTypedef := false
	for i := 0; i < len(lines); i++ {
	line := lines[i]

	// Delete
	// package x
	if strings.HasPrefix(line, "package ") {
	continue
	}

	// Convert
	// const (
	// A = 1
	// B = 2
	// )
	//
	// to
	//
	// enum {
	// A = 1,
	// B = 2,
	// };
	if line == "const (" {
	printf("enum {\n")
	for i++; i < len(lines) && lines[i] != ")"; i++ {
	line = lines[i]
	if line != "" {
	printf("\t%s,", line)
	}
	printf("\n")
	}
	printf("};\n")
	continue
	}

	// Convert
	// const A = 1
	// to
	// enum { A = 1 };
	if strings.HasPrefix(line, "const ") {
	printf("enum { %s };\n", line[len("const "):])
	continue
	}

	// On first type definition, typedef all the structs
	// in case there are dependencies between them.
	if !didTypedef && strings.HasPrefix(line, "type ") {
	didTypedef = true
	for _, line := range lines {
	line = strings.TrimSpace(line)
	if strings.HasPrefix(line, "type ") && strings.HasSuffix(line, " struct {") {
	s := strings.TrimSuffix(strings.TrimPrefix(line, "type "), " struct {")
	printf("typedef struct %s %s;\n", s, s)
	}
	}
	printf("\n")
	printf("#pragma pack on\n")
	printf("\n")
	}

	// Convert
	// type T struct {
	// X int64
	// Y *int32
	// Z [4]byte
	// }
	//
	// to
	//
	// struct T {
	// int64 X;
	// int32 *Y;
	// byte Z[4];
	// }
	if strings.HasPrefix(line, "type ") && strings.HasSuffix(line, " struct {") {
	if len(lines) > i+1 && lines[i+1] == "}" {
	// do not output empty struct
	i++
	continue
	}
	s := line[len("type ") : len(line)-len(" struct {")]
	printf("struct %s {\n", s)
	for i++; i < len(lines) && lines[i] != "}"; i++ {
	line := lines[i]
	if line != "" {
	f := strings.Fields(line)
	if len(f) != 2 {
	fmt.Fprintf(os.Stderr, "cgo: cannot parse struct field: %s\n", line)
	nerrors++
	continue
	}
	printf("\t%s;", cdecl(f[0], f[1]))
	}
	printf("\n")
	}
	printf("};\n")
	continue
	}

	// Convert
	// type T int
	// to
	// typedef int T;
	if strings.HasPrefix(line, "type ") {
	f := strings.Fields(line[len("type "):])
	if len(f) != 2 {
	fmt.Fprintf(os.Stderr, "cgo: cannot parse type definition: %s\n", line)
	nerrors++
	continue
	}
	printf("typedef\t%s;\n", cdecl(f[0], f[1]))
	continue
	}

	printf("%s\n", line)
	}

	if didTypedef {
	printf("\n")
	printf("#pragma pack off\n")
	}

	return out.String()
	}

	// cdecl returns the C declaration for the given Go name and type.
	// It only handles the specific cases necessary for converting godefs output.
	func cdecl(name, typ string) string {
	// X [0]byte -> X void
	if strings.HasPrefix(typ, "*[0]") {
	typ = "*void"
	}
	// X [4]byte -> X[4] byte
	for strings.HasPrefix(typ, "[") {
	i := strings.Index(typ, "]") + 1
	name = name + typ[:i]
	typ = typ[i:]
	}
	// X byte -> X byte
	for strings.HasPrefix(typ, "*") {
	name = "*" + name
	typ = typ[1:]
	}
	// X T -> T X
	// Handle the special case: 'unsafe.Pointer' is 'void *'
	if typ == "unsafe.Pointer" {
	typ = "void"
	name = "*" + name
	}
	return typ + "\t" + name
	}

	var gofmtBuf bytes.Buffer

	// gofmt returns the gofmt-formatted string for an AST node.
	func gofmt(n interface{}) string {
	gofmtBuf.Reset()
	err := printer.Fprint(&gofmtBuf, fset, n)
	if err != nil {
	return "<" + err.Error() + ">"
	}
	return gofmtBuf.String()
	}