go out 源码
golang out 代码
文件路径：/src/cmd/cgo/out.go
// Copyright 2009 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"
"cmd/internal/pkgpath"
"debug/elf"
"debug/macho"
"debug/pe"
"fmt"
"go/ast"
"go/printer"
"go/token"
"internal/xcoff"
"io"
"os"
"os/exec"
"path/filepath"
"regexp"
"sort"
"strings"
"unicode"
)
var (
conf = printer.Config{Mode: printer.SourcePos, Tabwidth: 8}
noSourceConf = printer.Config{Tabwidth: 8}
)
// writeDefs creates output files to be compiled by gc and gcc.
func (p *Package) writeDefs() {
var fgo2, fc io.Writer
f := creat(*objDir + "_cgo_gotypes.go")
defer f.Close()
fgo2 = f
if *gccgo {
f := creat(*objDir + "_cgo_defun.c")
defer f.Close()
fc = f
}
fm := creat(*objDir + "_cgo_main.c")
var gccgoInit bytes.Buffer
fflg := creat(*objDir + "_cgo_flags")
for k, v := range p.CgoFlags {
fmt.Fprintf(fflg, "_CGO_%s=%s\n", k, strings.Join(v, " "))
if k == "LDFLAGS" && !*gccgo {
for _, arg := range v {
fmt.Fprintf(fgo2, "//go:cgo_ldflag %q\n", arg)
}
}
}
fflg.Close()
// Write C main file for using gcc to resolve imports.
fmt.Fprintf(fm, "#include <stddef.h>\n") // For size_t below.
fmt.Fprintf(fm, "int main() { return 0; }\n")
if *importRuntimeCgo {
fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*) __attribute__((unused)), void *a __attribute__((unused)), int c __attribute__((unused)), size_t ctxt __attribute__((unused))) { }\n")
fmt.Fprintf(fm, "size_t _cgo_wait_runtime_init_done(void) { return 0; }\n")
fmt.Fprintf(fm, "void _cgo_release_context(size_t ctxt __attribute__((unused))) { }\n")
fmt.Fprintf(fm, "char* _cgo_topofstack(void) { return (char*)0; }\n")
} else {
// If we're not importing runtime/cgo, we *are* runtime/cgo,
// which provides these functions. We just need a prototype.
fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*), void *a, int c, size_t ctxt);\n")
fmt.Fprintf(fm, "size_t _cgo_wait_runtime_init_done(void);\n")
fmt.Fprintf(fm, "void _cgo_release_context(size_t);\n")
}
fmt.Fprintf(fm, "void _cgo_allocate(void *a __attribute__((unused)), int c __attribute__((unused))) { }\n")
fmt.Fprintf(fm, "void _cgo_panic(void *a __attribute__((unused)), int c __attribute__((unused))) { }\n")
fmt.Fprintf(fm, "void _cgo_reginit(void) { }\n")
// Write second Go output: definitions of _C_xxx.
// In a separate file so that the import of "unsafe" does not
// pollute the original file.
fmt.Fprintf(fgo2, "// Code generated by cmd/cgo; DO NOT EDIT.\n\n")
fmt.Fprintf(fgo2, "package %s\n\n", p.PackageName)
fmt.Fprintf(fgo2, "import \"unsafe\"\n\n")
if !*gccgo && *importRuntimeCgo {
fmt.Fprintf(fgo2, "import _ \"runtime/cgo\"\n\n")
}
if *importSyscall {
fmt.Fprintf(fgo2, "import \"syscall\"\n\n")
fmt.Fprintf(fgo2, "var _ syscall.Errno\n")
}
fmt.Fprintf(fgo2, "func _Cgo_ptr(ptr unsafe.Pointer) unsafe.Pointer { return ptr }\n\n")
if !*gccgo {
fmt.Fprintf(fgo2, "//go:linkname _Cgo_always_false runtime.cgoAlwaysFalse\n")
fmt.Fprintf(fgo2, "var _Cgo_always_false bool\n")
fmt.Fprintf(fgo2, "//go:linkname _Cgo_use runtime.cgoUse\n")
fmt.Fprintf(fgo2, "func _Cgo_use(interface{})\n")
}
typedefNames := make([]string, 0, len(typedef))
for name := range typedef {
if name == "_Ctype_void" {
// We provide an appropriate declaration for
// _Ctype_void below (#39877).
continue
}
typedefNames = append(typedefNames, name)
}
sort.Strings(typedefNames)
for _, name := range typedefNames {
def := typedef[name]
if def.NotInHeap {
fmt.Fprintf(fgo2, "//go:notinheap\n")
}
fmt.Fprintf(fgo2, "type %s ", name)
// We don't have source info for these types, so write them out without source info.
// Otherwise types would look like:
//
// type _Ctype_struct_cb struct {
// //line :1
// on_test *[0]byte
// //line :1
// }
//
// Which is not useful. Moreover we never override source info,
// so subsequent source code uses the same source info.
// Moreover, empty file name makes compile emit no source debug info at all.
var buf bytes.Buffer
noSourceConf.Fprint(&buf, fset, def.Go)
if bytes.HasPrefix(buf.Bytes(), []byte("_Ctype_")) ||
strings.HasPrefix(name, "_Ctype_enum_") ||
strings.HasPrefix(name, "_Ctype_union_") {
// This typedef is of the form `typedef a b` and should be an alias.
fmt.Fprintf(fgo2, "= ")
}
fmt.Fprintf(fgo2, "%s", buf.Bytes())
fmt.Fprintf(fgo2, "\n\n")
}
fmt.Fprintf(fgo2, "//go:notinheap\ntype _Ctype_void_notinheap struct{}\n\n")
if *gccgo {
fmt.Fprintf(fgo2, "type _Ctype_void byte\n")
} else {
fmt.Fprintf(fgo2, "type _Ctype_void [0]byte\n")
}
if *gccgo {
fmt.Fprint(fgo2, gccgoGoProlog)
fmt.Fprint(fc, p.cPrologGccgo())
} else {
fmt.Fprint(fgo2, goProlog)
}
if fc != nil {
fmt.Fprintf(fc, "#line 1 \"cgo-generated-wrappers\"\n")
}
if fm != nil {
fmt.Fprintf(fm, "#line 1 \"cgo-generated-wrappers\"\n")
}
gccgoSymbolPrefix := p.gccgoSymbolPrefix()
cVars := make(map[string]bool)
for _, key := range nameKeys(p.Name) {
n := p.Name[key]
if !n.IsVar() {
continue
}
if !cVars[n.C] {
if *gccgo {
fmt.Fprintf(fc, "extern byte *%s;\n", n.C)
} else {
// Force a reference to all symbols so that
// the external linker will add DT_NEEDED
// entries as needed on ELF systems.
// Treat function variables differently
// to avoid type conflict errors from LTO
// (Link Time Optimization).
if n.Kind == "fpvar" {
fmt.Fprintf(fm, "extern void %s();\n", n.C)
} else {
fmt.Fprintf(fm, "extern char %s[];\n", n.C)
fmt.Fprintf(fm, "void *_cgohack_%s = %s;\n\n", n.C, n.C)
}
fmt.Fprintf(fgo2, "//go:linkname __cgo_%s %s\n", n.C, n.C)
fmt.Fprintf(fgo2, "//go:cgo_import_static %s\n", n.C)
fmt.Fprintf(fgo2, "var __cgo_%s byte\n", n.C)
}
cVars[n.C] = true
}
var node ast.Node
if n.Kind == "var" {
node = &ast.StarExpr{X: n.Type.Go}
} else if n.Kind == "fpvar" {
node = n.Type.Go
} else {
panic(fmt.Errorf("invalid var kind %q", n.Kind))
}
if *gccgo {
fmt.Fprintf(fc, `extern void *%s __asm__("%s.%s");`, n.Mangle, gccgoSymbolPrefix, gccgoToSymbol(n.Mangle))
fmt.Fprintf(&gccgoInit, "\t%s = &%s;\n", n.Mangle, n.C)
fmt.Fprintf(fc, "\n")
}
fmt.Fprintf(fgo2, "var %s ", n.Mangle)
conf.Fprint(fgo2, fset, node)
if !*gccgo {
fmt.Fprintf(fgo2, " = (")
conf.Fprint(fgo2, fset, node)
fmt.Fprintf(fgo2, ")(unsafe.Pointer(&__cgo_%s))", n.C)
}
fmt.Fprintf(fgo2, "\n")
}
if *gccgo {
fmt.Fprintf(fc, "\n")
}
for _, key := range nameKeys(p.Name) {
n := p.Name[key]
if n.Const != "" {
fmt.Fprintf(fgo2, "const %s = %s\n", n.Mangle, n.Const)
}
}
fmt.Fprintf(fgo2, "\n")
callsMalloc := false
for _, key := range nameKeys(p.Name) {
n := p.Name[key]
if n.FuncType != nil {
p.writeDefsFunc(fgo2, n, &callsMalloc)
}
}
fgcc := creat(*objDir + "_cgo_export.c")
fgcch := creat(*objDir + "_cgo_export.h")
if *gccgo {
p.writeGccgoExports(fgo2, fm, fgcc, fgcch)
} else {
p.writeExports(fgo2, fm, fgcc, fgcch)
}
if callsMalloc && !*gccgo {
fmt.Fprint(fgo2, strings.Replace(cMallocDefGo, "PREFIX", cPrefix, -1))
fmt.Fprint(fgcc, strings.Replace(strings.Replace(cMallocDefC, "PREFIX", cPrefix, -1), "PACKED", p.packedAttribute(), -1))
}
if err := fgcc.Close(); err != nil {
fatalf("%s", err)
}
if err := fgcch.Close(); err != nil {
fatalf("%s", err)
}
if *exportHeader != "" && len(p.ExpFunc) > 0 {
fexp := creat(*exportHeader)
fgcch, err := os.Open(*objDir + "_cgo_export.h")
if err != nil {
fatalf("%s", err)
}
defer fgcch.Close()
_, err = io.Copy(fexp, fgcch)
if err != nil {
fatalf("%s", err)
}
if err = fexp.Close(); err != nil {
fatalf("%s", err)
}
}
init := gccgoInit.String()
if init != "" {
// The init function does nothing but simple
// assignments, so it won't use much stack space, so
// it's OK to not split the stack. Splitting the stack
// can run into a bug in clang (as of 2018-11-09):
// this is a leaf function, and when clang sees a leaf
// function it won't emit the split stack prologue for
// the function. However, if this function refers to a
// non-split-stack function, which will happen if the
// cgo code refers to a C function not compiled with
// -fsplit-stack, then the linker will think that it
// needs to adjust the split stack prologue, but there
// won't be one. Marking the function explicitly
// no_split_stack works around this problem by telling
// the linker that it's OK if there is no split stack
// prologue.
fmt.Fprintln(fc, "static void init(void) __attribute__ ((constructor, no_split_stack));")
fmt.Fprintln(fc, "static void init(void) {")
fmt.Fprint(fc, init)
fmt.Fprintln(fc, "}")
}
}
// elfImportedSymbols is like elf.File.ImportedSymbols, but it
// includes weak symbols.
//
// A bug in some versions of LLD (at least LLD 8) cause it to emit
// several pthreads symbols as weak, but we need to import those. See
// issue #31912 or https://bugs.llvm.org/show_bug.cgi?id=42442.
//
// When doing external linking, we hand everything off to the external
// linker, which will create its own dynamic symbol tables. For
// internal linking, this may turn weak imports into strong imports,
// which could cause dynamic linking to fail if a symbol really isn't
// defined. However, the standard library depends on everything it
// imports, and this is the primary use of dynamic symbol tables with
// internal linking.
func elfImportedSymbols(f *elf.File) []elf.ImportedSymbol {
syms, _ := f.DynamicSymbols()
var imports []elf.ImportedSymbol
for _, s := range syms {
if (elf.ST_BIND(s.Info) == elf.STB_GLOBAL || elf.ST_BIND(s.Info) == elf.STB_WEAK) && s.Section == elf.SHN_UNDEF {
imports = append(imports, elf.ImportedSymbol{
Name: s.Name,
Library: s.Library,
Version: s.Version,
})
}
}
return imports
}
func dynimport(obj string) {
stdout := os.Stdout
if *dynout != "" {
f, err := os.Create(*dynout)
if err != nil {
fatalf("%s", err)
}
stdout = f
}
fmt.Fprintf(stdout, "package %s\n", *dynpackage)
if f, err := elf.Open(obj); err == nil {
if *dynlinker {
// Emit the cgo_dynamic_linker line.
if sec := f.Section(".interp"); sec != nil {
if data, err := sec.Data(); err == nil && len(data) > 1 {
// skip trailing \0 in data
fmt.Fprintf(stdout, "//go:cgo_dynamic_linker %q\n", string(data[:len(data)-1]))
}
}
}
sym := elfImportedSymbols(f)
for _, s := range sym {
targ := s.Name
if s.Version != "" {
targ += "#" + s.Version
}
checkImportSymName(s.Name)
checkImportSymName(targ)
fmt.Fprintf(stdout, "//go:cgo_import_dynamic %s %s %q\n", s.Name, targ, s.Library)
}
lib, _ := f.ImportedLibraries()
for _, l := range lib {
fmt.Fprintf(stdout, "//go:cgo_import_dynamic _ _ %q\n", l)
}
return
}
if f, err := macho.Open(obj); err == nil {
sym, _ := f.ImportedSymbols()
for _, s := range sym {
if len(s) > 0 && s[0] == '_' {
s = s[1:]
}
checkImportSymName(s)
fmt.Fprintf(stdout, "//go:cgo_import_dynamic %s %s %q\n", s, s, "")
}
lib, _ := f.ImportedLibraries()
for _, l := range lib {
fmt.Fprintf(stdout, "//go:cgo_import_dynamic _ _ %q\n", l)
}
return
}
if f, err := pe.Open(obj); err == nil {
sym, _ := f.ImportedSymbols()
for _, s := range sym {
ss := strings.Split(s, ":")
name := strings.Split(ss[0], "@")[0]
checkImportSymName(name)
checkImportSymName(ss[0])
fmt.Fprintf(stdout, "//go:cgo_import_dynamic %s %s %q\n", name, ss[0], strings.ToLower(ss[1]))
}
return
}
if f, err := xcoff.Open(obj); err == nil {
sym, err := f.ImportedSymbols()
if err != nil {
fatalf("cannot load imported symbols from XCOFF file %s: %v", obj, err)
}
for _, s := range sym {
if s.Name == "runtime_rt0_go" || s.Name == "_rt0_ppc64_aix_lib" {
// These symbols are imported by runtime/cgo but
// must not be added to _cgo_import.go as there are
// Go symbols.
continue
}
checkImportSymName(s.Name)
fmt.Fprintf(stdout, "//go:cgo_import_dynamic %s %s %q\n", s.Name, s.Name, s.Library)
}
lib, err := f.ImportedLibraries()
if err != nil {
fatalf("cannot load imported libraries from XCOFF file %s: %v", obj, err)
}
for _, l := range lib {
fmt.Fprintf(stdout, "//go:cgo_import_dynamic _ _ %q\n", l)
}
return
}
fatalf("cannot parse %s as ELF, Mach-O, PE or XCOFF", obj)
}
// checkImportSymName checks a symbol name we are going to emit as part
// of a //go:cgo_import_dynamic pragma. These names come from object
// files, so they may be corrupt. We are going to emit them unquoted,
// so while they don't need to be valid symbol names (and in some cases,
// involving symbol versions, they won't be) they must contain only
// graphic characters and must not contain Go comments.
func checkImportSymName(s string) {
for _, c := range s {
if !unicode.IsGraphic(c) || unicode.IsSpace(c) {
fatalf("dynamic symbol %q contains unsupported character", s)
}
}
if strings.Index(s, "//") >= 0 || strings.Index(s, "/*") >= 0 {
fatalf("dynamic symbol %q contains Go comment")
}
}
// Construct a gcc struct matching the gc argument frame.
// Assumes that in gcc, char is 1 byte, short 2 bytes, int 4 bytes, long long 8 bytes.
// These assumptions are checked by the gccProlog.
// Also assumes that gc convention is to word-align the
// input and output parameters.
func (p *Package) structType(n *Name) (string, int64) {
var buf bytes.Buffer
fmt.Fprint(&buf, "struct {\n")
off := int64(0)
for i, t := range n.FuncType.Params {
if off%t.Align != 0 {
pad := t.Align - off%t.Align
fmt.Fprintf(&buf, "\t\tchar __pad%d[%d];\n", off, pad)
off += pad
}
c := t.Typedef
if c == "" {
c = t.C.String()
}
fmt.Fprintf(&buf, "\t\t%s p%d;\n", c, i)
off += t.Size
}
if off%p.PtrSize != 0 {
pad := p.PtrSize - off%p.PtrSize
fmt.Fprintf(&buf, "\t\tchar __pad%d[%d];\n", off, pad)
off += pad
}
if t := n.FuncType.Result; t != nil {
if off%t.Align != 0 {
pad := t.Align - off%t.Align
fmt.Fprintf(&buf, "\t\tchar __pad%d[%d];\n", off, pad)
off += pad
}
fmt.Fprintf(&buf, "\t\t%s r;\n", t.C)
off += t.Size
}
if off%p.PtrSize != 0 {
pad := p.PtrSize - off%p.PtrSize
fmt.Fprintf(&buf, "\t\tchar __pad%d[%d];\n", off, pad)
off += pad
}
if off == 0 {
fmt.Fprintf(&buf, "\t\tchar unused;\n") // avoid empty struct
}
fmt.Fprintf(&buf, "\t}")
return buf.String(), off
}
func (p *Package) writeDefsFunc(fgo2 io.Writer, n *Name, callsMalloc *bool) {
name := n.Go
gtype := n.FuncType.Go
void := gtype.Results == nil || len(gtype.Results.List) == 0
if n.AddError {
// Add "error" to return type list.
// Type list is known to be 0 or 1 element - it's a C function.
err := &ast.Field{Type: ast.NewIdent("error")}
l := gtype.Results.List
if len(l) == 0 {
l = []*ast.Field{err}
} else {
l = []*ast.Field{l[0], err}
}
t := new(ast.FuncType)
*t = *gtype
t.Results = &ast.FieldList{List: l}
gtype = t
}
// Go func declaration.
d := &ast.FuncDecl{
Name: ast.NewIdent(n.Mangle),
Type: gtype,
}
// Builtins defined in the C prolog.
inProlog := builtinDefs[name] != ""
cname := fmt.Sprintf("_cgo%s%s", cPrefix, n.Mangle)
paramnames := []string(nil)
if d.Type.Params != nil {
for i, param := range d.Type.Params.List {
paramName := fmt.Sprintf("p%d", i)
param.Names = []*ast.Ident{ast.NewIdent(paramName)}
paramnames = append(paramnames, paramName)
}
}
if *gccgo {
// Gccgo style hooks.
fmt.Fprint(fgo2, "\n")
conf.Fprint(fgo2, fset, d)
fmt.Fprint(fgo2, " {\n")
if !inProlog {
fmt.Fprint(fgo2, "\tdefer syscall.CgocallDone()\n")
fmt.Fprint(fgo2, "\tsyscall.Cgocall()\n")
}
if n.AddError {
fmt.Fprint(fgo2, "\tsyscall.SetErrno(0)\n")
}
fmt.Fprint(fgo2, "\t")
if !void {
fmt.Fprint(fgo2, "r := ")
}
fmt.Fprintf(fgo2, "%s(%s)\n", cname, strings.Join(paramnames, ", "))
if n.AddError {
fmt.Fprint(fgo2, "\te := syscall.GetErrno()\n")
fmt.Fprint(fgo2, "\tif e != 0 {\n")
fmt.Fprint(fgo2, "\t\treturn ")
if !void {
fmt.Fprint(fgo2, "r, ")
}
fmt.Fprint(fgo2, "e\n")
fmt.Fprint(fgo2, "\t}\n")
fmt.Fprint(fgo2, "\treturn ")
if !void {
fmt.Fprint(fgo2, "r, ")
}
fmt.Fprint(fgo2, "nil\n")
} else if !void {
fmt.Fprint(fgo2, "\treturn r\n")
}
fmt.Fprint(fgo2, "}\n")
// declare the C function.
fmt.Fprintf(fgo2, "//extern %s\n", cname)
d.Name = ast.NewIdent(cname)
if n.AddError {
l := d.Type.Results.List
d.Type.Results.List = l[:len(l)-1]
}
conf.Fprint(fgo2, fset, d)
fmt.Fprint(fgo2, "\n")
return
}
if inProlog {
fmt.Fprint(fgo2, builtinDefs[name])
if strings.Contains(builtinDefs[name], "_cgo_cmalloc") {
*callsMalloc = true
}
return
}
// Wrapper calls into gcc, passing a pointer to the argument frame.
fmt.Fprintf(fgo2, "//go:cgo_import_static %s\n", cname)
fmt.Fprintf(fgo2, "//go:linkname __cgofn_%s %s\n", cname, cname)
fmt.Fprintf(fgo2, "var __cgofn_%s byte\n", cname)
fmt.Fprintf(fgo2, "var %s = unsafe.Pointer(&__cgofn_%s)\n", cname, cname)
nret := 0
if !void {
d.Type.Results.List[0].Names = []*ast.Ident{ast.NewIdent("r1")}
nret = 1
}
if n.AddError {
d.Type.Results.List[nret].Names = []*ast.Ident{ast.NewIdent("r2")}
}
fmt.Fprint(fgo2, "\n")
fmt.Fprint(fgo2, "//go:cgo_unsafe_args\n")
conf.Fprint(fgo2, fset, d)
fmt.Fprint(fgo2, " {\n")
// NOTE: Using uintptr to hide from escape analysis.
arg := "0"
if len(paramnames) > 0 {
arg = "uintptr(unsafe.Pointer(&p0))"
} else if !void {
arg = "uintptr(unsafe.Pointer(&r1))"
}
prefix := ""
if n.AddError {
prefix = "errno := "
}
fmt.Fprintf(fgo2, "\t%s_cgo_runtime_cgocall(%s, %s)\n", prefix, cname, arg)
if n.AddError {
fmt.Fprintf(fgo2, "\tif errno != 0 { r2 = syscall.Errno(errno) }\n")
}
fmt.Fprintf(fgo2, "\tif _Cgo_always_false {\n")
if d.Type.Params != nil {
for i := range d.Type.Params.List {
fmt.Fprintf(fgo2, "\t\t_Cgo_use(p%d)\n", i)
}
}
fmt.Fprintf(fgo2, "\t}\n")
fmt.Fprintf(fgo2, "\treturn\n")
fmt.Fprintf(fgo2, "}\n")
}
// writeOutput creates stubs for a specific source file to be compiled by gc
func (p *Package) writeOutput(f *File, srcfile string) {
base := srcfile
if strings.HasSuffix(base, ".go") {
base = base[0 : len(base)-3]
}
base = filepath.Base(base)
fgo1 := creat(*objDir + base + ".cgo1.go")
fgcc := creat(*objDir + base + ".cgo2.c")
p.GoFiles = append(p.GoFiles, base+".cgo1.go")
p.GccFiles = append(p.GccFiles, base+".cgo2.c")
// Write Go output: Go input with rewrites of C.xxx to _C_xxx.
fmt.Fprintf(fgo1, "// Code generated by cmd/cgo; DO NOT EDIT.\n\n")
fmt.Fprintf(fgo1, "//line %s:1:1\n", srcfile)
fgo1.Write(f.Edit.Bytes())
// While we process the vars and funcs, also write gcc output.
// Gcc output starts with the preamble.
fmt.Fprintf(fgcc, "%s\n", builtinProlog)
fmt.Fprintf(fgcc, "%s\n", f.Preamble)
fmt.Fprintf(fgcc, "%s\n", gccProlog)
fmt.Fprintf(fgcc, "%s\n", tsanProlog)
fmt.Fprintf(fgcc, "%s\n", msanProlog)
for _, key := range nameKeys(f.Name) {
n := f.Name[key]
if n.FuncType != nil {
p.writeOutputFunc(fgcc, n)
}
}
fgo1.Close()
fgcc.Close()
}
// fixGo converts the internal Name.Go field into the name we should show
// to users in error messages. There's only one for now: on input we rewrite
// C.malloc into C._CMalloc, so change it back here.
func fixGo(name string) string {
if name == "_CMalloc" {
return "malloc"
}
return name
}
var isBuiltin = map[string]bool{
"_Cfunc_CString": true,
"_Cfunc_CBytes": true,
"_Cfunc_GoString": true,
"_Cfunc_GoStringN": true,
"_Cfunc_GoBytes": true,
"_Cfunc__CMalloc": true,
}
func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
name := n.Mangle
if isBuiltin[name] || p.Written[name] {
// The builtins are already defined in the C prolog, and we don't
// want to duplicate function definitions we've already done.
return
}
p.Written[name] = true
if *gccgo {
p.writeGccgoOutputFunc(fgcc, n)
return
}
ctype, _ := p.structType(n)
// Gcc wrapper unpacks the C argument struct
// and calls the actual C function.
fmt.Fprintf(fgcc, "CGO_NO_SANITIZE_THREAD\n")
if n.AddError {
fmt.Fprintf(fgcc, "int\n")
} else {
fmt.Fprintf(fgcc, "void\n")
}
fmt.Fprintf(fgcc, "_cgo%s%s(void *v)\n", cPrefix, n.Mangle)
fmt.Fprintf(fgcc, "{\n")
if n.AddError {
fmt.Fprintf(fgcc, "\tint _cgo_errno;\n")
}
// We're trying to write a gcc struct that matches gc's layout.
// Use packed attribute to force no padding in this struct in case
// gcc has different packing requirements.
fmt.Fprintf(fgcc, "\t%s %v *_cgo_a = v;\n", ctype, p.packedAttribute())
if n.FuncType.Result != nil {
// Save the stack top for use below.
fmt.Fprintf(fgcc, "\tchar *_cgo_stktop = _cgo_topofstack();\n")
}
tr := n.FuncType.Result
if tr != nil {
fmt.Fprintf(fgcc, "\t__typeof__(_cgo_a->r) _cgo_r;\n")
}
fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
if n.AddError {
fmt.Fprintf(fgcc, "\terrno = 0;\n")
}
fmt.Fprintf(fgcc, "\t")
if tr != nil {
fmt.Fprintf(fgcc, "_cgo_r = ")
if c := tr.C.String(); c[len(c)-1] == '*' {
fmt.Fprint(fgcc, "(__typeof__(_cgo_a->r)) ")
}
}
if n.Kind == "macro" {
fmt.Fprintf(fgcc, "%s;\n", n.C)
} else {
fmt.Fprintf(fgcc, "%s(", n.C)
for i := range n.FuncType.Params {
if i > 0 {
fmt.Fprintf(fgcc, ", ")
}
fmt.Fprintf(fgcc, "_cgo_a->p%d", i)
}
fmt.Fprintf(fgcc, ");\n")
}
if n.AddError {
fmt.Fprintf(fgcc, "\t_cgo_errno = errno;\n")
}
fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
if n.FuncType.Result != nil {
// The cgo call may have caused a stack copy (via a callback).
// Adjust the return value pointer appropriately.
fmt.Fprintf(fgcc, "\t_cgo_a = (void*)((char*)_cgo_a + (_cgo_topofstack() - _cgo_stktop));\n")
// Save the return value.
fmt.Fprintf(fgcc, "\t_cgo_a->r = _cgo_r;\n")
// The return value is on the Go stack. If we are using msan,
// and if the C value is partially or completely uninitialized,
// the assignment will mark the Go stack as uninitialized.
// The Go compiler does not update msan for changes to the
// stack. It is possible that the stack will remain
// uninitialized, and then later be used in a way that is
// visible to msan, possibly leading to a false positive.
// Mark the stack space as written, to avoid this problem.
// See issue 26209.
fmt.Fprintf(fgcc, "\t_cgo_msan_write(&_cgo_a->r, sizeof(_cgo_a->r));\n")
}
if n.AddError {
fmt.Fprintf(fgcc, "\treturn _cgo_errno;\n")
}
fmt.Fprintf(fgcc, "}\n")
fmt.Fprintf(fgcc, "\n")
}
// Write out a wrapper for a function when using gccgo. This is a
// simple wrapper that just calls the real function. We only need a
// wrapper to support static functions in the prologue--without a
// wrapper, we can't refer to the function, since the reference is in
// a different file.
func (p *Package) writeGccgoOutputFunc(fgcc *os.File, n *Name) {
fmt.Fprintf(fgcc, "CGO_NO_SANITIZE_THREAD\n")
if t := n.FuncType.Result; t != nil {
fmt.Fprintf(fgcc, "%s\n", t.C.String())
} else {
fmt.Fprintf(fgcc, "void\n")
}
fmt.Fprintf(fgcc, "_cgo%s%s(", cPrefix, n.Mangle)
for i, t := range n.FuncType.Params {
if i > 0 {
fmt.Fprintf(fgcc, ", ")
}
c := t.Typedef
if c == "" {
c = t.C.String()
}
fmt.Fprintf(fgcc, "%s p%d", c, i)
}
fmt.Fprintf(fgcc, ")\n")
fmt.Fprintf(fgcc, "{\n")
if t := n.FuncType.Result; t != nil {
fmt.Fprintf(fgcc, "\t%s _cgo_r;\n", t.C.String())
}
fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
fmt.Fprintf(fgcc, "\t")
if t := n.FuncType.Result; t != nil {
fmt.Fprintf(fgcc, "_cgo_r = ")
// Cast to void* to avoid warnings due to omitted qualifiers.
if c := t.C.String(); c[len(c)-1] == '*' {
fmt.Fprintf(fgcc, "(void*)")
}
}
if n.Kind == "macro" {
fmt.Fprintf(fgcc, "%s;\n", n.C)
} else {
fmt.Fprintf(fgcc, "%s(", n.C)
for i := range n.FuncType.Params {
if i > 0 {
fmt.Fprintf(fgcc, ", ")
}
fmt.Fprintf(fgcc, "p%d", i)
}
fmt.Fprintf(fgcc, ");\n")
}
fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
if t := n.FuncType.Result; t != nil {
fmt.Fprintf(fgcc, "\treturn ")
// Cast to void* to avoid warnings due to omitted qualifiers
// and explicit incompatible struct types.
if c := t.C.String(); c[len(c)-1] == '*' {
fmt.Fprintf(fgcc, "(void*)")
}
fmt.Fprintf(fgcc, "_cgo_r;\n")
}
fmt.Fprintf(fgcc, "}\n")
fmt.Fprintf(fgcc, "\n")
}
// packedAttribute returns host compiler struct attribute that will be
// used to match gc's struct layout. For example, on 386 Windows,
// gcc wants to 8-align int64s, but gc does not.
// Use __gcc_struct__ to work around https://gcc.gnu.org/PR52991 on x86,
// and https://golang.org/issue/5603.
func (p *Package) packedAttribute() string {
s := "__attribute__((__packed__"
if !p.GccIsClang && (goarch == "amd64" || goarch == "386") {
s += ", __gcc_struct__"
}
return s + "))"
}
// exportParamName returns the value of param as it should be
// displayed in a c header file. If param contains any non-ASCII
// characters, this function will return the character p followed by
// the value of position; otherwise, this function will return the
// value of param.
func exportParamName(param string, position int) string {
if param == "" {
return fmt.Sprintf("p%d", position)
}
pname := param
for i := 0; i < len(param); i++ {
if param[i] > unicode.MaxASCII {
pname = fmt.Sprintf("p%d", position)
break
}
}
return pname
}
// Write out the various stubs we need to support functions exported
// from Go so that they are callable from C.
func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
p.writeExportHeader(fgcch)
fmt.Fprintf(fgcc, "/* Code generated by cmd/cgo; DO NOT EDIT. */\n\n")
fmt.Fprintf(fgcc, "#include <stdlib.h>\n")
fmt.Fprintf(fgcc, "#include \"_cgo_export.h\"\n\n")
// We use packed structs, but they are always aligned.
// The pragmas and address-of-packed-member are only recognized as
// warning groups in clang 4.0+, so ignore unknown pragmas first.
fmt.Fprintf(fgcc, "#pragma GCC diagnostic ignored \"-Wunknown-pragmas\"\n")
fmt.Fprintf(fgcc, "#pragma GCC diagnostic ignored \"-Wpragmas\"\n")
fmt.Fprintf(fgcc, "#pragma GCC diagnostic ignored \"-Waddress-of-packed-member\"\n")
fmt.Fprintf(fgcc, "extern void crosscall2(void (*fn)(void *), void *, int, size_t);\n")
fmt.Fprintf(fgcc, "extern size_t _cgo_wait_runtime_init_done(void);\n")
fmt.Fprintf(fgcc, "extern void _cgo_release_context(size_t);\n\n")
fmt.Fprintf(fgcc, "extern char* _cgo_topofstack(void);")
fmt.Fprintf(fgcc, "%s\n", tsanProlog)
fmt.Fprintf(fgcc, "%s\n", msanProlog)
for _, exp := range p.ExpFunc {
fn := exp.Func
// Construct a struct that will be used to communicate
// arguments from C to Go. The C and Go definitions
// just have to agree. The gcc struct will be compiled
// with __attribute__((packed)) so all padding must be
// accounted for explicitly.
ctype := "struct {\n"
gotype := new(bytes.Buffer)
fmt.Fprintf(gotype, "struct {\n")
off := int64(0)
npad := 0
argField := func(typ ast.Expr, namePat string, args ...interface{}) {
name := fmt.Sprintf(namePat, args...)
t := p.cgoType(typ)
if off%t.Align != 0 {
pad := t.Align - off%t.Align
ctype += fmt.Sprintf("\t\tchar __pad%d[%d];\n", npad, pad)
off += pad
npad++
}
ctype += fmt.Sprintf("\t\t%s %s;\n", t.C, name)
fmt.Fprintf(gotype, "\t\t%s ", name)
noSourceConf.Fprint(gotype, fset, typ)
fmt.Fprintf(gotype, "\n")
off += t.Size
}
if fn.Recv != nil {
argField(fn.Recv.List[0].Type, "recv")
}
fntype := fn.Type
forFieldList(fntype.Params,
func(i int, aname string, atype ast.Expr) {
argField(atype, "p%d", i)
})
forFieldList(fntype.Results,
func(i int, aname string, atype ast.Expr) {
argField(atype, "r%d", i)
})
if ctype == "struct {\n" {
ctype += "\t\tchar unused;\n" // avoid empty struct
}
ctype += "\t}"
fmt.Fprintf(gotype, "\t}")
// Get the return type of the wrapper function
// compiled by gcc.
gccResult := ""
if fntype.Results == nil || len(fntype.Results.List) == 0 {
gccResult = "void"
} else if len(fntype.Results.List) == 1 && len(fntype.Results.List[0].Names) <= 1 {
gccResult = p.cgoType(fntype.Results.List[0].Type).C.String()
} else {
fmt.Fprintf(fgcch, "\n/* Return type for %s */\n", exp.ExpName)
fmt.Fprintf(fgcch, "struct %s_return {\n", exp.ExpName)
forFieldList(fntype.Results,
func(i int, aname string, atype ast.Expr) {
fmt.Fprintf(fgcch, "\t%s r%d;", p.cgoType(atype).C, i)
if len(aname) > 0 {
fmt.Fprintf(fgcch, " /* %s */", aname)
}
fmt.Fprint(fgcch, "\n")
})
fmt.Fprintf(fgcch, "};\n")
gccResult = "struct " + exp.ExpName + "_return"
}
// Build the wrapper function compiled by gcc.
gccExport := ""
if goos == "windows" {
gccExport = "__declspec(dllexport) "
}
s := fmt.Sprintf("%s%s %s(", gccExport, gccResult, exp.ExpName)
if fn.Recv != nil {
s += p.cgoType(fn.Recv.List[0].Type).C.String()
s += " recv"
}
forFieldList(fntype.Params,
func(i int, aname string, atype ast.Expr) {
if i > 0 || fn.Recv != nil {
s += ", "
}
s += fmt.Sprintf("%s %s", p.cgoType(atype).C, exportParamName(aname, i))
})
s += ")"
if len(exp.Doc) > 0 {
fmt.Fprintf(fgcch, "\n%s", exp.Doc)
if !strings.HasSuffix(exp.Doc, "\n") {
fmt.Fprint(fgcch, "\n")
}
}
fmt.Fprintf(fgcch, "extern %s;\n", s)
fmt.Fprintf(fgcc, "extern void _cgoexp%s_%s(void *);\n", cPrefix, exp.ExpName)
fmt.Fprintf(fgcc, "\nCGO_NO_SANITIZE_THREAD")
fmt.Fprintf(fgcc, "\n%s\n", s)
fmt.Fprintf(fgcc, "{\n")
fmt.Fprintf(fgcc, "\tsize_t _cgo_ctxt = _cgo_wait_runtime_init_done();\n")
// The results part of the argument structure must be
// initialized to 0 so the write barriers generated by
// the assignments to these fields in Go are safe.
//
// We use a local static variable to get the zeroed
// value of the argument type. This avoids including
// string.h for memset, and is also robust to C++
// types with constructors. Both GCC and LLVM optimize
// this into just zeroing _cgo_a.
fmt.Fprintf(fgcc, "\ttypedef %s %v _cgo_argtype;\n", ctype, p.packedAttribute())
fmt.Fprintf(fgcc, "\tstatic _cgo_argtype _cgo_zero;\n")
fmt.Fprintf(fgcc, "\t_cgo_argtype _cgo_a = _cgo_zero;\n")
if gccResult != "void" && (len(fntype.Results.List) > 1 || len(fntype.Results.List[0].Names) > 1) {
fmt.Fprintf(fgcc, "\t%s r;\n", gccResult)
}
if fn.Recv != nil {
fmt.Fprintf(fgcc, "\t_cgo_a.recv = recv;\n")
}
forFieldList(fntype.Params,
func(i int, aname string, atype ast.Expr) {
fmt.Fprintf(fgcc, "\t_cgo_a.p%d = %s;\n", i, exportParamName(aname, i))
})
fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
fmt.Fprintf(fgcc, "\tcrosscall2(_cgoexp%s_%s, &_cgo_a, %d, _cgo_ctxt);\n", cPrefix, exp.ExpName, off)
fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
fmt.Fprintf(fgcc, "\t_cgo_release_context(_cgo_ctxt);\n")
if gccResult != "void" {
if len(fntype.Results.List) == 1 && len(fntype.Results.List[0].Names) <= 1 {
fmt.Fprintf(fgcc, "\treturn _cgo_a.r0;\n")
} else {
forFieldList(fntype.Results,
func(i int, aname string, atype ast.Expr) {
fmt.Fprintf(fgcc, "\tr.r%d = _cgo_a.r%d;\n", i, i)
})
fmt.Fprintf(fgcc, "\treturn r;\n")
}
}
fmt.Fprintf(fgcc, "}\n")
// In internal linking mode, the Go linker sees both
// the C wrapper written above and the Go wrapper it
// references. Hence, export the C wrapper (e.g., for
// if we're building a shared object). The Go linker
// will resolve the C wrapper's reference to the Go
// wrapper without a separate export.
fmt.Fprintf(fgo2, "//go:cgo_export_dynamic %s\n", exp.ExpName)
// cgo_export_static refers to a symbol by its linker
// name, so set the linker name of the Go wrapper.
fmt.Fprintf(fgo2, "//go:linkname _cgoexp%s_%s _cgoexp%s_%s\n", cPrefix, exp.ExpName, cPrefix, exp.ExpName)
// In external linking mode, the Go linker sees the Go
// wrapper, but not the C wrapper. For this case,
// export the Go wrapper so the host linker can
// resolve the reference from the C wrapper to the Go
// wrapper.
fmt.Fprintf(fgo2, "//go:cgo_export_static _cgoexp%s_%s\n", cPrefix, exp.ExpName)
// Build the wrapper function compiled by cmd/compile.
// This unpacks the argument struct above and calls the Go function.
fmt.Fprintf(fgo2, "func _cgoexp%s_%s(a *%s) {\n", cPrefix, exp.ExpName, gotype)
fmt.Fprintf(fm, "void _cgoexp%s_%s(void* p){}\n", cPrefix, exp.ExpName)
fmt.Fprintf(fgo2, "\t")
if gccResult != "void" {
// Write results back to frame.
forFieldList(fntype.Results,
func(i int, aname string, atype ast.Expr) {
if i > 0 {
fmt.Fprintf(fgo2, ", ")
}
fmt.Fprintf(fgo2, "a.r%d", i)
})
fmt.Fprintf(fgo2, " = ")
}
if fn.Recv != nil {
fmt.Fprintf(fgo2, "a.recv.")
}
fmt.Fprintf(fgo2, "%s(", exp.Func.Name)
forFieldList(fntype.Params,
func(i int, aname string, atype ast.Expr) {
if i > 0 {
fmt.Fprint(fgo2, ", ")
}
fmt.Fprintf(fgo2, "a.p%d", i)
})
fmt.Fprint(fgo2, ")\n")
if gccResult != "void" {
// Verify that any results don't contain any
// Go pointers.
forFieldList(fntype.Results,
func(i int, aname string, atype ast.Expr) {
if !p.hasPointer(nil, atype, false) {
return
}
fmt.Fprintf(fgo2, "\t_cgoCheckResult(a.r%d)\n", i)
})
}
fmt.Fprint(fgo2, "}\n")
}
fmt.Fprintf(fgcch, "%s", gccExportHeaderEpilog)
}
// Write out the C header allowing C code to call exported gccgo functions.
func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
gccgoSymbolPrefix := p.gccgoSymbolPrefix()
p.writeExportHeader(fgcch)
fmt.Fprintf(fgcc, "/* Code generated by cmd/cgo; DO NOT EDIT. */\n\n")
fmt.Fprintf(fgcc, "#include \"_cgo_export.h\"\n")
fmt.Fprintf(fgcc, "%s\n", gccgoExportFileProlog)
fmt.Fprintf(fgcc, "%s\n", tsanProlog)
fmt.Fprintf(fgcc, "%s\n", msanProlog)
for _, exp := range p.ExpFunc {
fn := exp.Func
fntype := fn.Type
cdeclBuf := new(bytes.Buffer)
resultCount := 0
forFieldList(fntype.Results,
func(i int, aname string, atype ast.Expr) { resultCount++ })
switch resultCount {
case 0:
fmt.Fprintf(cdeclBuf, "void")
case 1:
forFieldList(fntype.Results,
func(i int, aname string, atype ast.Expr) {
t := p.cgoType(atype)
fmt.Fprintf(cdeclBuf, "%s", t.C)
})
default:
// Declare a result struct.
fmt.Fprintf(fgcch, "\n/* Return type for %s */\n", exp.ExpName)
fmt.Fprintf(fgcch, "struct %s_return {\n", exp.ExpName)
forFieldList(fntype.Results,
func(i int, aname string, atype ast.Expr) {
t := p.cgoType(atype)
fmt.Fprintf(fgcch, "\t%s r%d;", t.C, i)
if len(aname) > 0 {
fmt.Fprintf(fgcch, " /* %s */", aname)
}
fmt.Fprint(fgcch, "\n")
})
fmt.Fprintf(fgcch, "};\n")
fmt.Fprintf(cdeclBuf, "struct %s_return", exp.ExpName)
}
cRet := cdeclBuf.String()
cdeclBuf = new(bytes.Buffer)
fmt.Fprintf(cdeclBuf, "(")
if fn.Recv != nil {
fmt.Fprintf(cdeclBuf, "%s recv", p.cgoType(fn.Recv.List[0].Type).C.String())
}
// Function parameters.
forFieldList(fntype.Params,
func(i int, aname string, atype ast.Expr) {
if i > 0 || fn.Recv != nil {
fmt.Fprintf(cdeclBuf, ", ")
}
t := p.cgoType(atype)
fmt.Fprintf(cdeclBuf, "%s p%d", t.C, i)
})
fmt.Fprintf(cdeclBuf, ")")
cParams := cdeclBuf.String()
if len(exp.Doc) > 0 {
fmt.Fprintf(fgcch, "\n%s", exp.Doc)
}
fmt.Fprintf(fgcch, "extern %s %s%s;\n", cRet, exp.ExpName, cParams)
// We need to use a name that will be exported by the
// Go code; otherwise gccgo will make it static and we
// will not be able to link against it from the C
// code.
goName := "Cgoexp_" + exp.ExpName
fmt.Fprintf(fgcc, `extern %s %s %s __asm__("%s.%s");`, cRet, goName, cParams, gccgoSymbolPrefix, gccgoToSymbol(goName))
fmt.Fprint(fgcc, "\n")
fmt.Fprint(fgcc, "\nCGO_NO_SANITIZE_THREAD\n")
fmt.Fprintf(fgcc, "%s %s %s {\n", cRet, exp.ExpName, cParams)
if resultCount > 0 {
fmt.Fprintf(fgcc, "\t%s r;\n", cRet)
}
fmt.Fprintf(fgcc, "\tif(_cgo_wait_runtime_init_done)\n")
fmt.Fprintf(fgcc, "\t\t_cgo_wait_runtime_init_done();\n")
fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
fmt.Fprint(fgcc, "\t")
if resultCount > 0 {
fmt.Fprint(fgcc, "r = ")
}
fmt.Fprintf(fgcc, "%s(", goName)
if fn.Recv != nil {
fmt.Fprint(fgcc, "recv")
}
forFieldList(fntype.Params,
func(i int, aname string, atype ast.Expr) {
if i > 0 || fn.Recv != nil {
fmt.Fprintf(fgcc, ", ")
}
fmt.Fprintf(fgcc, "p%d", i)
})
fmt.Fprint(fgcc, ");\n")
fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
if resultCount > 0 {
fmt.Fprint(fgcc, "\treturn r;\n")
}
fmt.Fprint(fgcc, "}\n")
// Dummy declaration for _cgo_main.c
fmt.Fprintf(fm, `char %s[1] __asm__("%s.%s");`, goName, gccgoSymbolPrefix, gccgoToSymbol(goName))
fmt.Fprint(fm, "\n")
// For gccgo we use a wrapper function in Go, in order
// to call CgocallBack and CgocallBackDone.
// This code uses printer.Fprint, not conf.Fprint,
// because we don't want //line comments in the middle
// of the function types.
fmt.Fprint(fgo2, "\n")
fmt.Fprintf(fgo2, "func %s(", goName)
if fn.Recv != nil {
fmt.Fprint(fgo2, "recv ")
printer.Fprint(fgo2, fset, fn.Recv.List[0].Type)
}
forFieldList(fntype.Params,
func(i int, aname string, atype ast.Expr) {
if i > 0 || fn.Recv != nil {
fmt.Fprintf(fgo2, ", ")
}
fmt.Fprintf(fgo2, "p%d ", i)
printer.Fprint(fgo2, fset, atype)
})
fmt.Fprintf(fgo2, ")")
if resultCount > 0 {
fmt.Fprintf(fgo2, " (")
forFieldList(fntype.Results,
func(i int, aname string, atype ast.Expr) {
if i > 0 {
fmt.Fprint(fgo2, ", ")
}
printer.Fprint(fgo2, fset, atype)
})
fmt.Fprint(fgo2, ")")
}
fmt.Fprint(fgo2, " {\n")
fmt.Fprint(fgo2, "\tsyscall.CgocallBack()\n")
fmt.Fprint(fgo2, "\tdefer syscall.CgocallBackDone()\n")
fmt.Fprint(fgo2, "\t")
if resultCount > 0 {
fmt.Fprint(fgo2, "return ")
}
if fn.Recv != nil {
fmt.Fprint(fgo2, "recv.")
}
fmt.Fprintf(fgo2, "%s(", exp.Func.Name)
forFieldList(fntype.Params,
func(i int, aname string, atype ast.Expr) {
if i > 0 {
fmt.Fprint(fgo2, ", ")
}
fmt.Fprintf(fgo2, "p%d", i)
})
fmt.Fprint(fgo2, ")\n")
fmt.Fprint(fgo2, "}\n")
}
fmt.Fprintf(fgcch, "%s", gccExportHeaderEpilog)
}
// writeExportHeader writes out the start of the _cgo_export.h file.
func (p *Package) writeExportHeader(fgcch io.Writer) {
fmt.Fprintf(fgcch, "/* Code generated by cmd/cgo; DO NOT EDIT. */\n\n")
pkg := *importPath
if pkg == "" {
pkg = p.PackagePath
}
fmt.Fprintf(fgcch, "/* package %s */\n\n", pkg)
fmt.Fprintf(fgcch, "%s\n", builtinExportProlog)
// Remove absolute paths from #line comments in the preamble.
// They aren't useful for people using the header file,
// and they mean that the header files change based on the
// exact location of GOPATH.
re := regexp.MustCompile(`(?m)^(#line\s+[0-9]+\s+")[^"]*[/\\]([^"]*")`)
preamble := re.ReplaceAllString(p.Preamble, "$1$2")
fmt.Fprintf(fgcch, "/* Start of preamble from import \"C\" comments. */\n\n")
fmt.Fprintf(fgcch, "%s\n", preamble)
fmt.Fprintf(fgcch, "\n/* End of preamble from import \"C\" comments. */\n\n")
fmt.Fprintf(fgcch, "%s\n", p.gccExportHeaderProlog())
}
// gccgoToSymbol converts a name to a mangled symbol for gccgo.
func gccgoToSymbol(ppath string) string {
if gccgoMangler == nil {
var err error
cmd := os.Getenv("GCCGO")
if cmd == "" {
cmd, err = exec.LookPath("gccgo")
if err != nil {
fatalf("unable to locate gccgo: %v", err)
}
}
gccgoMangler, err = pkgpath.ToSymbolFunc(cmd, *objDir)
if err != nil {
fatalf("%v", err)
}
}
return gccgoMangler(ppath)
}
// Return the package prefix when using gccgo.
func (p *Package) gccgoSymbolPrefix() string {
if !*gccgo {
return ""
}
if *gccgopkgpath != "" {
return gccgoToSymbol(*gccgopkgpath)
}
if *gccgoprefix == "" && p.PackageName == "main" {
return "main"
}
prefix := gccgoToSymbol(*gccgoprefix)
if prefix == "" {
prefix = "go"
}
return prefix + "." + p.PackageName
}
// Call a function for each entry in an ast.FieldList, passing the
// index into the list, the name if any, and the type.
func forFieldList(fl *ast.FieldList, fn func(int, string, ast.Expr)) {
if fl == nil {
return
}
i := 0
for _, r := range fl.List {
if r.Names == nil {
fn(i, "", r.Type)
i++
} else {
for _, n := range r.Names {
fn(i, n.Name, r.Type)
i++
}
}
}
}
func c(repr string, args ...interface{}) *TypeRepr {
return &TypeRepr{repr, args}
}
// Map predeclared Go types to Type.
var goTypes = map[string]*Type{
"bool": {Size: 1, Align: 1, C: c("GoUint8")},
"byte": {Size: 1, Align: 1, C: c("GoUint8")},
"int": {Size: 0, Align: 0, C: c("GoInt")},
"uint": {Size: 0, Align: 0, C: c("GoUint")},
"rune": {Size: 4, Align: 4, C: c("GoInt32")},
"int8": {Size: 1, Align: 1, C: c("GoInt8")},
"uint8": {Size: 1, Align: 1, C: c("GoUint8")},
"int16": {Size: 2, Align: 2, C: c("GoInt16")},
"uint16": {Size: 2, Align: 2, C: c("GoUint16")},
"int32": {Size: 4, Align: 4, C: c("GoInt32")},
"uint32": {Size: 4, Align: 4, C: c("GoUint32")},
"int64": {Size: 8, Align: 8, C: c("GoInt64")},
"uint64": {Size: 8, Align: 8, C: c("GoUint64")},
"float32": {Size: 4, Align: 4, C: c("GoFloat32")},
"float64": {Size: 8, Align: 8, C: c("GoFloat64")},
"complex64": {Size: 8, Align: 4, C: c("GoComplex64")},
"complex128": {Size: 16, Align: 8, C: c("GoComplex128")},
}
// Map an ast type to a Type.
func (p *Package) cgoType(e ast.Expr) *Type {
switch t := e.(type) {
case *ast.StarExpr:
x := p.cgoType(t.X)
return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("%s*", x.C)}
case *ast.ArrayType:
if t.Len == nil {
// Slice: pointer, len, cap.
return &Type{Size: p.PtrSize * 3, Align: p.PtrSize, C: c("GoSlice")}
}
// Non-slice array types are not supported.
case *ast.StructType:
// Not supported.
case *ast.FuncType:
return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("void*")}
case *ast.InterfaceType:
return &Type{Size: 2 * p.PtrSize, Align: p.PtrSize, C: c("GoInterface")}
case *ast.MapType:
return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("GoMap")}
case *ast.ChanType:
return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("GoChan")}
case *ast.Ident:
goTypesFixup := func(r *Type) *Type {
if r.Size == 0 { // int or uint
rr := new(Type)
*rr = *r
rr.Size = p.IntSize
rr.Align = p.IntSize
r = rr
}
if r.Align > p.PtrSize {
r.Align = p.PtrSize
}
return r
}
// Look up the type in the top level declarations.
// TODO: Handle types defined within a function.
for _, d := range p.Decl {
gd, ok := d.(*ast.GenDecl)
if !ok || gd.Tok != token.TYPE {
continue
}
for _, spec := range gd.Specs {
ts, ok := spec.(*ast.TypeSpec)
if !ok {
continue
}
if ts.Name.Name == t.Name {
return p.cgoType(ts.Type)
}
}
}
if def := typedef[t.Name]; def != nil {
if defgo, ok := def.Go.(*ast.Ident); ok {
switch defgo.Name {
case "complex64", "complex128":
// MSVC does not support the _Complex keyword
// nor the complex macro.
// Use GoComplex64 and GoComplex128 instead,
// which are typedef-ed to a compatible type.
// See go.dev/issues/36233.
return goTypesFixup(goTypes[defgo.Name])
}
}
return def
}
if t.Name == "uintptr" {
return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("GoUintptr")}
}
if t.Name == "string" {
// The string data is 1 pointer + 1 (pointer-sized) int.
return &Type{Size: 2 * p.PtrSize, Align: p.PtrSize, C: c("GoString")}
}
if t.Name == "error" {
return &Type{Size: 2 * p.PtrSize, Align: p.PtrSize, C: c("GoInterface")}
}
if r, ok := goTypes[t.Name]; ok {
return goTypesFixup(r)
}
error_(e.Pos(), "unrecognized Go type %s", t.Name)
return &Type{Size: 4, Align: 4, C: c("int")}
case *ast.SelectorExpr:
id, ok := t.X.(*ast.Ident)
if ok && id.Name == "unsafe" && t.Sel.Name == "Pointer" {
return &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("void*")}
}
}
error_(e.Pos(), "Go type not supported in export: %s", gofmt(e))
return &Type{Size: 4, Align: 4, C: c("int")}
}
const gccProlog = `
#line 1 "cgo-gcc-prolog"
/*
If x and y are not equal, the type will be invalid
(have a negative array count) and an inscrutable error will come
out of the compiler and hopefully mention "name".
*/
#define __cgo_compile_assert_eq(x, y, name) typedef char name[(x-y)*(x-y)*-2UL+1UL];
/* Check at compile time that the sizes we use match our expectations. */
#define __cgo_size_assert(t, n) __cgo_compile_assert_eq(sizeof(t), (size_t)n, _cgo_sizeof_##t##_is_not_##n)
__cgo_size_assert(char, 1)
__cgo_size_assert(short, 2)
__cgo_size_assert(int, 4)
typedef long long __cgo_long_long;
__cgo_size_assert(__cgo_long_long, 8)
__cgo_size_assert(float, 4)
__cgo_size_assert(double, 8)
extern char* _cgo_topofstack(void);
/*
We use packed structs, but they are always aligned.
The pragmas and address-of-packed-member are only recognized as warning
groups in clang 4.0+, so ignore unknown pragmas first.
*/
#pragma GCC diagnostic ignored "-Wunknown-pragmas"
#pragma GCC diagnostic ignored "-Wpragmas"
#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
#include <errno.h>
#include <string.h>
`
// Prologue defining TSAN functions in C.
const noTsanProlog = `
#define CGO_NO_SANITIZE_THREAD
#define _cgo_tsan_acquire()
#define _cgo_tsan_release()
`
// This must match the TSAN code in runtime/cgo/libcgo.h.
// This is used when the code is built with the C/C++ Thread SANitizer,
// which is not the same as the Go race detector.
// __tsan_acquire tells TSAN that we are acquiring a lock on a variable,
// in this case _cgo_sync. __tsan_release releases the lock.
// (There is no actual lock, we are just telling TSAN that there is.)
//
// When we call from Go to C we call _cgo_tsan_acquire.
// When the C function returns we call _cgo_tsan_release.
// Similarly, when C calls back into Go we call _cgo_tsan_release
// and then call _cgo_tsan_acquire when we return to C.
// These calls tell TSAN that there is a serialization point at the C call.
//
// This is necessary because TSAN, which is a C/C++ tool, can not see
// the synchronization in the Go code. Without these calls, when
// multiple goroutines call into C code, TSAN does not understand
// that the calls are properly synchronized on the Go side.
//
// To be clear, if the calls are not properly synchronized on the Go side,
// we will be hiding races. But when using TSAN on mixed Go C/C++ code
// it is more important to avoid false positives, which reduce confidence
// in the tool, than to avoid false negatives.
const yesTsanProlog = `
#line 1 "cgo-tsan-prolog"
#define CGO_NO_SANITIZE_THREAD __attribute__ ((no_sanitize_thread))
long long _cgo_sync __attribute__ ((common));
extern void __tsan_acquire(void*);
extern void __tsan_release(void*);
__attribute__ ((unused))
static void _cgo_tsan_acquire() {
__tsan_acquire(&_cgo_sync);
}
__attribute__ ((unused))
static void _cgo_tsan_release() {
__tsan_release(&_cgo_sync);
}
`
// Set to yesTsanProlog if we see -fsanitize=thread in the flags for gcc.
var tsanProlog = noTsanProlog
// noMsanProlog is a prologue defining an MSAN function in C.
// This is used when not compiling with -fsanitize=memory.
const noMsanProlog = `
#define _cgo_msan_write(addr, sz)
`
// yesMsanProlog is a prologue defining an MSAN function in C.
// This is used when compiling with -fsanitize=memory.
// See the comment above where _cgo_msan_write is called.
const yesMsanProlog = `
extern void __msan_unpoison(const volatile void *, size_t);
#define _cgo_msan_write(addr, sz) __msan_unpoison((addr), (sz))
`
// msanProlog is set to yesMsanProlog if we see -fsanitize=memory in the flags
// for the C compiler.
var msanProlog = noMsanProlog
const builtinProlog = `
#line 1 "cgo-builtin-prolog"
#include <stddef.h>
/* Define intgo when compiling with GCC. */
typedef ptrdiff_t intgo;
#define GO_CGO_GOSTRING_TYPEDEF
typedef struct { const char *p; intgo n; } _GoString_;
typedef struct { char *p; intgo n; intgo c; } _GoBytes_;
_GoString_ GoString(char *p);
_GoString_ GoStringN(char *p, int l);
_GoBytes_ GoBytes(void *p, int n);
char *CString(_GoString_);
void *CBytes(_GoBytes_);
void *_CMalloc(size_t);
__attribute__ ((unused))
static size_t _GoStringLen(_GoString_ s) { return (size_t)s.n; }
__attribute__ ((unused))
static const char *_GoStringPtr(_GoString_ s) { return s.p; }
`
const goProlog = `
//go:linkname _cgo_runtime_cgocall runtime.cgocall
func _cgo_runtime_cgocall(unsafe.Pointer, uintptr) int32
//go:linkname _cgoCheckPointer runtime.cgoCheckPointer
func _cgoCheckPointer(interface{}, interface{})
//go:linkname _cgoCheckResult runtime.cgoCheckResult
func _cgoCheckResult(interface{})
`
const gccgoGoProlog = `
func _cgoCheckPointer(interface{}, interface{})
func _cgoCheckResult(interface{})
`
const goStringDef = `
//go:linkname _cgo_runtime_gostring runtime.gostring
func _cgo_runtime_gostring(*_Ctype_char) string
// GoString converts the C string p into a Go string.
func _Cfunc_GoString(p *_Ctype_char) string {
return _cgo_runtime_gostring(p)
}
`
const goStringNDef = `
//go:linkname _cgo_runtime_gostringn runtime.gostringn
func _cgo_runtime_gostringn(*_Ctype_char, int) string
// GoStringN converts the C data p with explicit length l to a Go string.
func _Cfunc_GoStringN(p *_Ctype_char, l _Ctype_int) string {
return _cgo_runtime_gostringn(p, int(l))
}
`
const goBytesDef = `
//go:linkname _cgo_runtime_gobytes runtime.gobytes
func _cgo_runtime_gobytes(unsafe.Pointer, int) []byte
// GoBytes converts the C data p with explicit length l to a Go []byte.
func _Cfunc_GoBytes(p unsafe.Pointer, l _Ctype_int) []byte {
return _cgo_runtime_gobytes(p, int(l))
}
`
const cStringDef = `
// CString converts the Go string s to a C string.
//
// The C string is allocated in the C heap using malloc.
// It is the caller's responsibility to arrange for it to be
// freed, such as by calling C.free (be sure to include stdlib.h
// if C.free is needed).
func _Cfunc_CString(s string) *_Ctype_char {
if len(s)+1 <= 0 {
panic("string too large")
}
p := _cgo_cmalloc(uint64(len(s)+1))
sliceHeader := struct {
p unsafe.Pointer
len int
cap int
}{p, len(s)+1, len(s)+1}
b := *(*[]byte)(unsafe.Pointer(&sliceHeader))
copy(b, s)
b[len(s)] = 0
return (*_Ctype_char)(p)
}
`
const cBytesDef = `
// CBytes converts the Go []byte slice b to a C array.
//
// The C array is allocated in the C heap using malloc.
// It is the caller's responsibility to arrange for it to be
// freed, such as by calling C.free (be sure to include stdlib.h
// if C.free is needed).
func _Cfunc_CBytes(b []byte) unsafe.Pointer {
p := _cgo_cmalloc(uint64(len(b)))
sliceHeader := struct {
p unsafe.Pointer
len int
cap int
}{p, len(b), len(b)}
s := *(*[]byte)(unsafe.Pointer(&sliceHeader))
copy(s, b)
return p
}
`
const cMallocDef = `
func _Cfunc__CMalloc(n _Ctype_size_t) unsafe.Pointer {
return _cgo_cmalloc(uint64(n))
}
`
var builtinDefs = map[string]string{
"GoString": goStringDef,
"GoStringN": goStringNDef,
"GoBytes": goBytesDef,
"CString": cStringDef,
"CBytes": cBytesDef,
"_CMalloc": cMallocDef,
}
// Definitions for C.malloc in Go and in C. We define it ourselves
// since we call it from functions we define, such as C.CString.
// Also, we have historically ensured that C.malloc does not return
// nil even for an allocation of 0.
const cMallocDefGo = `
//go:cgo_import_static _cgoPREFIX_Cfunc__Cmalloc
//go:linkname __cgofn__cgoPREFIX_Cfunc__Cmalloc _cgoPREFIX_Cfunc__Cmalloc
var __cgofn__cgoPREFIX_Cfunc__Cmalloc byte
var _cgoPREFIX_Cfunc__Cmalloc = unsafe.Pointer(&__cgofn__cgoPREFIX_Cfunc__Cmalloc)
//go:linkname runtime_throw runtime.throw
func runtime_throw(string)
//go:cgo_unsafe_args
func _cgo_cmalloc(p0 uint64) (r1 unsafe.Pointer) {
_cgo_runtime_cgocall(_cgoPREFIX_Cfunc__Cmalloc, uintptr(unsafe.Pointer(&p0)))
if r1 == nil {
runtime_throw("runtime: C malloc failed")
}
return
}
`
// cMallocDefC defines the C version of C.malloc for the gc compiler.
// It is defined here because C.CString and friends need a definition.
// We define it by hand, rather than simply inventing a reference to
// C.malloc, because <stdlib.h> may not have been included.
// This is approximately what writeOutputFunc would generate, but
// skips the cgo_topofstack code (which is only needed if the C code
// calls back into Go). This also avoids returning nil for an
// allocation of 0 bytes.
const cMallocDefC = `
CGO_NO_SANITIZE_THREAD
void _cgoPREFIX_Cfunc__Cmalloc(void *v) {
struct {
unsigned long long p0;
void *r1;
} PACKED *a = v;
void *ret;
_cgo_tsan_acquire();
ret = malloc(a->p0);
if (ret == 0 && a->p0 == 0) {
ret = malloc(1);
}
a->r1 = ret;
_cgo_tsan_release();
}
`
func (p *Package) cPrologGccgo() string {
r := strings.NewReplacer(
"PREFIX", cPrefix,
"GCCGOSYMBOLPREF", p.gccgoSymbolPrefix(),
"_cgoCheckPointer", gccgoToSymbol("_cgoCheckPointer"),
"_cgoCheckResult", gccgoToSymbol("_cgoCheckResult"))
return r.Replace(cPrologGccgo)
}
const cPrologGccgo = `
#line 1 "cgo-c-prolog-gccgo"
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
typedef unsigned char byte;
typedef intptr_t intgo;
struct __go_string {
const unsigned char *__data;
intgo __length;
};
typedef struct __go_open_array {
void* __values;
intgo __count;
intgo __capacity;
} Slice;
struct __go_string __go_byte_array_to_string(const void* p, intgo len);
struct __go_open_array __go_string_to_byte_array (struct __go_string str);
extern void runtime_throw(const char *);
const char *_cgoPREFIX_Cfunc_CString(struct __go_string s) {
char *p = malloc(s.__length+1);
if(p == NULL)
runtime_throw("runtime: C malloc failed");
memmove(p, s.__data, s.__length);
p[s.__length] = 0;
return p;
}
void *_cgoPREFIX_Cfunc_CBytes(struct __go_open_array b) {
char *p = malloc(b.__count);
if(p == NULL)
runtime_throw("runtime: C malloc failed");
memmove(p, b.__values, b.__count);
return p;
}
struct __go_string _cgoPREFIX_Cfunc_GoString(char *p) {
intgo len = (p != NULL) ? strlen(p) : 0;
return __go_byte_array_to_string(p, len);
}
struct __go_string _cgoPREFIX_Cfunc_GoStringN(char *p, int32_t n) {
return __go_byte_array_to_string(p, n);
}
Slice _cgoPREFIX_Cfunc_GoBytes(char *p, int32_t n) {
struct __go_string s = { (const unsigned char *)p, n };
return __go_string_to_byte_array(s);
}
void *_cgoPREFIX_Cfunc__CMalloc(size_t n) {
void *p = malloc(n);
if(p == NULL && n == 0)
p = malloc(1);
if(p == NULL)
runtime_throw("runtime: C malloc failed");
return p;
}
struct __go_type_descriptor;
typedef struct __go_empty_interface {
const struct __go_type_descriptor *__type_descriptor;
void *__object;
} Eface;
extern void runtimeCgoCheckPointer(Eface, Eface)
__asm__("runtime.cgoCheckPointer")
__attribute__((weak));
extern void localCgoCheckPointer(Eface, Eface)
__asm__("GCCGOSYMBOLPREF._cgoCheckPointer");
void localCgoCheckPointer(Eface ptr, Eface arg) {
if(runtimeCgoCheckPointer) {
runtimeCgoCheckPointer(ptr, arg);
}
}
extern void runtimeCgoCheckResult(Eface)
__asm__("runtime.cgoCheckResult")
__attribute__((weak));
extern void localCgoCheckResult(Eface)
__asm__("GCCGOSYMBOLPREF._cgoCheckResult");
void localCgoCheckResult(Eface val) {
if(runtimeCgoCheckResult) {
runtimeCgoCheckResult(val);
}
}
`
// builtinExportProlog is a shorter version of builtinProlog,
// to be put into the _cgo_export.h file.
// For historical reasons we can't use builtinProlog in _cgo_export.h,
// because _cgo_export.h defines GoString as a struct while builtinProlog
// defines it as a function. We don't change this to avoid unnecessarily
// breaking existing code.
// The test of GO_CGO_GOSTRING_TYPEDEF avoids a duplicate definition
// error if a Go file with a cgo comment #include's the export header
// generated by a different package.
const builtinExportProlog = `
#line 1 "cgo-builtin-export-prolog"
#include <stddef.h>
#ifndef GO_CGO_EXPORT_PROLOGUE_H
#define GO_CGO_EXPORT_PROLOGUE_H
#ifndef GO_CGO_GOSTRING_TYPEDEF
typedef struct { const char *p; ptrdiff_t n; } _GoString_;
#endif
#endif
`
func (p *Package) gccExportHeaderProlog() string {
return strings.Replace(gccExportHeaderProlog, "GOINTBITS", fmt.Sprint(8*p.IntSize), -1)
}
// gccExportHeaderProlog is written to the exported header, after the
// import "C" comment preamble but before the generated declarations
// of exported functions. This permits the generated declarations to
// use the type names that appear in goTypes, above.
//
// The test of GO_CGO_GOSTRING_TYPEDEF avoids a duplicate definition
// error if a Go file with a cgo comment #include's the export header
// generated by a different package. Unfortunately GoString means two
// different things: in this prolog it means a C name for the Go type,
// while in the prolog written into the start of the C code generated
// from a cgo-using Go file it means the C.GoString function. There is
// no way to resolve this conflict, but it also doesn't make much
// difference, as Go code never wants to refer to the latter meaning.
const gccExportHeaderProlog = `
/* Start of boilerplate cgo prologue. */
#line 1 "cgo-gcc-export-header-prolog"
#ifndef GO_CGO_PROLOGUE_H
#define GO_CGO_PROLOGUE_H
typedef signed char GoInt8;
typedef unsigned char GoUint8;
typedef short GoInt16;
typedef unsigned short GoUint16;
typedef int GoInt32;
typedef unsigned int GoUint32;
typedef long long GoInt64;
typedef unsigned long long GoUint64;
typedef GoIntGOINTBITS GoInt;
typedef GoUintGOINTBITS GoUint;
typedef size_t GoUintptr;
typedef float GoFloat32;
typedef double GoFloat64;
#ifdef _MSC_VER
#include <complex.h>
typedef _Fcomplex GoComplex64;
typedef _Dcomplex GoComplex128;
#else
typedef float _Complex GoComplex64;
typedef double _Complex GoComplex128;
#endif
/*
static assertion to make sure the file is being used on architecture
at least with matching size of GoInt.
*/
typedef char _check_for_GOINTBITS_bit_pointer_matching_GoInt[sizeof(void*)==GOINTBITS/8 ? 1:-1];
#ifndef GO_CGO_GOSTRING_TYPEDEF
typedef _GoString_ GoString;
#endif
typedef void *GoMap;
typedef void *GoChan;
typedef struct { void *t; void *v; } GoInterface;
typedef struct { void *data; GoInt len; GoInt cap; } GoSlice;
#endif
/* End of boilerplate cgo prologue. */
#ifdef __cplusplus
extern "C" {
#endif
`
// gccExportHeaderEpilog goes at the end of the generated header file.
const gccExportHeaderEpilog = `
#ifdef __cplusplus
}
#endif
`
// gccgoExportFileProlog is written to the _cgo_export.c file when
// using gccgo.
// We use weak declarations, and test the addresses, so that this code
// works with older versions of gccgo.
const gccgoExportFileProlog = `
#line 1 "cgo-gccgo-export-file-prolog"
extern _Bool runtime_iscgo __attribute__ ((weak));
static void GoInit(void) __attribute__ ((constructor));
static void GoInit(void) {
if(&runtime_iscgo)
runtime_iscgo = 1;
}
extern size_t _cgo_wait_runtime_init_done(void) __attribute__ ((weak));
`
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