main.go

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Cgo; see doc.go for an overview.
     6  
     7  // TODO(rsc):
     8  //	Emit correct line number annotations.
     9  //	Make gc understand the annotations.
    10  
    11  package main
    12  
    13  import (
    14  	"flag"
    15  	"fmt"
    16  	"go/ast"
    17  	"go/printer"
    18  	"go/token"
    19  	"internal/buildcfg"
    20  	"io"
    21  	"maps"
    22  	"os"
    23  	"path/filepath"
    24  	"reflect"
    25  	"runtime"
    26  	"sort"
    27  	"strings"
    28  	"sync"
    29  
    30  	"cmd/internal/edit"
    31  	"cmd/internal/hash"
    32  	"cmd/internal/objabi"
    33  	"cmd/internal/par"
    34  	"cmd/internal/telemetry/counter"
    35  )
    36  
    37  // A Package collects information about the package we're going to write.
    38  type Package struct {
    39  	PackageName string // name of package
    40  	PackagePath string
    41  	PtrSize     int64
    42  	IntSize     int64
    43  	GccOptions  []string
    44  	GccIsClang  bool
    45  	LdFlags     []string // #cgo LDFLAGS
    46  	Written     map[string]bool
    47  	Name        map[string]*Name // accumulated Name from Files
    48  	ExpFunc     []*ExpFunc       // accumulated ExpFunc from Files
    49  	Decl        []ast.Decl
    50  	GoFiles     []string        // list of Go files
    51  	GccFiles    []string        // list of gcc output files
    52  	Preamble    string          // collected preamble for _cgo_export.h
    53  	noCallbacks map[string]bool // C function names with #cgo nocallback directive
    54  	noEscapes   map[string]bool // C function names with #cgo noescape directive
    55  }
    56  
    57  // A typedefInfo is an element on Package.typedefList: a typedef name
    58  // and the position where it was required.
    59  type typedefInfo struct {
    60  	typedef string
    61  	pos     token.Pos
    62  }
    63  
    64  // A File collects information about a single Go input file.
    65  type File struct {
    66  	AST         *ast.File           // parsed AST
    67  	Comments    []*ast.CommentGroup // comments from file
    68  	Package     string              // Package name
    69  	Preamble    string              // C preamble (doc comment on import "C")
    70  	Ref         []*Ref              // all references to C.xxx in AST
    71  	Calls       []*Call             // all calls to C.xxx in AST
    72  	ExpFunc     []*ExpFunc          // exported functions for this file
    73  	Name        map[string]*Name    // map from Go name to Name
    74  	NamePos     map[*Name]token.Pos // map from Name to position of the first reference
    75  	NoCallbacks map[string]bool     // C function names with #cgo nocallback directive
    76  	NoEscapes   map[string]bool     // C function names with #cgo noescape directive
    77  	Edit        *edit.Buffer
    78  
    79  	debugs []*debug // debug data from iterations of gccDebug. Initialized by File.loadDebug.
    80  }
    81  
    82  func (f *File) offset(p token.Pos) int {
    83  	return fset.Position(p).Offset
    84  }
    85  
    86  func nameKeys(m map[string]*Name) []string {
    87  	ks := make([]string, 0, len(m))
    88  	for k := range m {
    89  		ks = append(ks, k)
    90  	}
    91  	sort.Strings(ks)
    92  	return ks
    93  }
    94  
    95  // A Call refers to a call of a C.xxx function in the AST.
    96  type Call struct {
    97  	Call     *ast.CallExpr
    98  	Deferred bool
    99  	Done     bool
   100  }
   101  
   102  // A Ref refers to an expression of the form C.xxx in the AST.
   103  type Ref struct {
   104  	Name    *Name
   105  	Expr    *ast.Expr
   106  	Context astContext
   107  	Done    bool
   108  }
   109  
   110  func (r *Ref) Pos() token.Pos {
   111  	return (*r.Expr).Pos()
   112  }
   113  
   114  var nameKinds = []string{"iconst", "fconst", "sconst", "type", "var", "fpvar", "func", "macro", "not-type"}
   115  
   116  // A Name collects information about C.xxx.
   117  type Name struct {
   118  	Go       string // name used in Go referring to package C
   119  	Mangle   string // name used in generated Go
   120  	C        string // name used in C
   121  	Define   string // #define expansion
   122  	Kind     string // one of the nameKinds
   123  	Type     *Type  // the type of xxx
   124  	FuncType *FuncType
   125  	AddError bool
   126  	Const    string // constant definition
   127  }
   128  
   129  // IsVar reports whether Kind is either "var" or "fpvar"
   130  func (n *Name) IsVar() bool {
   131  	return n.Kind == "var" || n.Kind == "fpvar"
   132  }
   133  
   134  // IsConst reports whether Kind is either "iconst", "fconst" or "sconst"
   135  func (n *Name) IsConst() bool {
   136  	return strings.HasSuffix(n.Kind, "const")
   137  }
   138  
   139  // An ExpFunc is an exported function, callable from C.
   140  // Such functions are identified in the Go input file
   141  // by doc comments containing the line //export ExpName
   142  type ExpFunc struct {
   143  	Func    *ast.FuncDecl
   144  	ExpName string // name to use from C
   145  	Doc     string
   146  }
   147  
   148  // A TypeRepr contains the string representation of a type.
   149  type TypeRepr struct {
   150  	Repr       string
   151  	FormatArgs []any
   152  }
   153  
   154  // A Type collects information about a type in both the C and Go worlds.
   155  type Type struct {
   156  	Size       int64
   157  	Align      int64
   158  	C          *TypeRepr
   159  	Go         ast.Expr
   160  	EnumValues map[string]int64
   161  	Typedef    string
   162  	BadPointer bool // this pointer type should be represented as a uintptr (deprecated)
   163  }
   164  
   165  func (t *Type) fuzzyMatch(t2 *Type) bool {
   166  	if t == nil || t2 == nil {
   167  		return false
   168  	}
   169  	return t.Size == t2.Size && t.Align == t2.Align
   170  }
   171  
   172  // A FuncType collects information about a function type in both the C and Go worlds.
   173  type FuncType struct {
   174  	Params []*Type
   175  	Result *Type
   176  	Go     *ast.FuncType
   177  }
   178  
   179  func (t *FuncType) fuzzyMatch(t2 *FuncType) bool {
   180  	if t == nil || t2 == nil {
   181  		return false
   182  	}
   183  	if !t.Result.fuzzyMatch(t2.Result) {
   184  		return false
   185  	}
   186  	if len(t.Params) != len(t2.Params) {
   187  		return false
   188  	}
   189  	for i := range t.Params {
   190  		if !t.Params[i].fuzzyMatch(t2.Params[i]) {
   191  			return false
   192  		}
   193  	}
   194  	return true
   195  }
   196  
   197  func usage() {
   198  	fmt.Fprint(os.Stderr, "usage: cgo -- [compiler options] file.go ...\n")
   199  	flag.PrintDefaults()
   200  	os.Exit(2)
   201  }
   202  
   203  var ptrSizeMap = map[string]int64{
   204  	"386":      4,
   205  	"alpha":    8,
   206  	"amd64":    8,
   207  	"arm":      4,
   208  	"arm64":    8,
   209  	"loong64":  8,
   210  	"m68k":     4,
   211  	"mips":     4,
   212  	"mipsle":   4,
   213  	"mips64":   8,
   214  	"mips64le": 8,
   215  	"nios2":    4,
   216  	"ppc":      4,
   217  	"ppc64":    8,
   218  	"ppc64le":  8,
   219  	"riscv":    4,
   220  	"riscv64":  8,
   221  	"s390":     4,
   222  	"s390x":    8,
   223  	"sh":       4,
   224  	"shbe":     4,
   225  	"sparc":    4,
   226  	"sparc64":  8,
   227  }
   228  
   229  var intSizeMap = map[string]int64{
   230  	"386":      4,
   231  	"alpha":    8,
   232  	"amd64":    8,
   233  	"arm":      4,
   234  	"arm64":    8,
   235  	"loong64":  8,
   236  	"m68k":     4,
   237  	"mips":     4,
   238  	"mipsle":   4,
   239  	"mips64":   8,
   240  	"mips64le": 8,
   241  	"nios2":    4,
   242  	"ppc":      4,
   243  	"ppc64":    8,
   244  	"ppc64le":  8,
   245  	"riscv":    4,
   246  	"riscv64":  8,
   247  	"s390":     4,
   248  	"s390x":    8,
   249  	"sh":       4,
   250  	"shbe":     4,
   251  	"sparc":    4,
   252  	"sparc64":  8,
   253  }
   254  
   255  var cPrefix string
   256  
   257  var fset = token.NewFileSet()
   258  
   259  var dynobj = flag.String("dynimport", "", "if non-empty, print dynamic import data for that file")
   260  var dynout = flag.String("dynout", "", "write -dynimport output to this file")
   261  var dynpackage = flag.String("dynpackage", "main", "set Go package for -dynimport output")
   262  var dynlinker = flag.Bool("dynlinker", false, "record dynamic linker information in -dynimport mode")
   263  
   264  // This flag is for bootstrapping a new Go implementation,
   265  // to generate Go types that match the data layout and
   266  // constant values used in the host's C libraries and system calls.
   267  var godefs = flag.Bool("godefs", false, "for bootstrap: write Go definitions for C file to standard output")
   268  
   269  var srcDir = flag.String("srcdir", "", "source directory")
   270  var objDir = flag.String("objdir", "", "object directory")
   271  var importPath = flag.String("importpath", "", "import path of package being built (for comments in generated files)")
   272  var exportHeader = flag.String("exportheader", "", "where to write export header if any exported functions")
   273  
   274  var ldflags = flag.String("ldflags", "", "flags to pass to C linker")
   275  
   276  var gccgo = flag.Bool("gccgo", false, "generate files for use with gccgo")
   277  var gccgoprefix = flag.String("gccgoprefix", "", "-fgo-prefix option used with gccgo")
   278  var gccgopkgpath = flag.String("gccgopkgpath", "", "-fgo-pkgpath option used with gccgo")
   279  var gccgoMangler func(string) string
   280  var gccgoDefineCgoIncomplete = flag.Bool("gccgo_define_cgoincomplete", false, "define cgo.Incomplete for older gccgo/GoLLVM")
   281  var importRuntimeCgo = flag.Bool("import_runtime_cgo", true, "import runtime/cgo in generated code")
   282  var importSyscall = flag.Bool("import_syscall", true, "import syscall in generated code")
   283  var trimpath = flag.String("trimpath", "", "applies supplied rewrites or trims prefixes to recorded source file paths")
   284  
   285  var goarch, goos, gomips, gomips64 string
   286  var gccBaseCmd []string
   287  
   288  func main() {
   289  	counter.Open()
   290  	objabi.AddVersionFlag() // -V
   291  	objabi.Flagparse(usage)
   292  	counter.Inc("cgo/invocations")
   293  	counter.CountFlags("cgo/flag:", *flag.CommandLine)
   294  
   295  	if *gccgoDefineCgoIncomplete {
   296  		if !*gccgo {
   297  			fmt.Fprintf(os.Stderr, "cgo: -gccgo_define_cgoincomplete without -gccgo\n")
   298  			os.Exit(2)
   299  		}
   300  		incomplete = "_cgopackage_Incomplete"
   301  	}
   302  
   303  	if *dynobj != "" {
   304  		// cgo -dynimport is essentially a separate helper command
   305  		// built into the cgo binary. It scans a gcc-produced executable
   306  		// and dumps information about the imported symbols and the
   307  		// imported libraries. The 'go build' rules for cgo prepare an
   308  		// appropriate executable and then use its import information
   309  		// instead of needing to make the linkers duplicate all the
   310  		// specialized knowledge gcc has about where to look for imported
   311  		// symbols and which ones to use.
   312  		dynimport(*dynobj)
   313  		return
   314  	}
   315  
   316  	if *godefs {
   317  		// Generating definitions pulled from header files,
   318  		// to be checked into Go repositories.
   319  		// Line numbers are just noise.
   320  		conf.Mode &^= printer.SourcePos
   321  	}
   322  
   323  	if *objDir == "" {
   324  		*objDir = "_obj"
   325  	}
   326  
   327  	args := flag.Args()
   328  	if len(args) < 1 {
   329  		usage()
   330  	}
   331  
   332  	// Find first arg that looks like a go file and assume everything before
   333  	// that are options to pass to gcc.
   334  	var i int
   335  	for i = len(args); i > 0; i-- {
   336  		if !strings.HasSuffix(args[i-1], ".go") {
   337  			break
   338  		}
   339  	}
   340  	if i == len(args) {
   341  		usage()
   342  	}
   343  
   344  	// Save original command line arguments for the godefs generated comment. Relative file
   345  	// paths in os.Args will be rewritten to absolute file paths in the loop below.
   346  	osArgs := make([]string, len(os.Args))
   347  	copy(osArgs, os.Args[:])
   348  	goFiles := args[i:]
   349  
   350  	for _, arg := range args[:i] {
   351  		if arg == "-fsanitize=thread" {
   352  			tsanProlog = yesTsanProlog
   353  		}
   354  		if arg == "-fsanitize=memory" {
   355  			msanProlog = yesMsanProlog
   356  		}
   357  	}
   358  
   359  	p := newPackage(args[:i])
   360  
   361  	// We need a C compiler to be available. Check this.
   362  	var err error
   363  	gccBaseCmd, err = checkGCCBaseCmd()
   364  	if err != nil {
   365  		fatalf("%v", err)
   366  		os.Exit(2)
   367  	}
   368  
   369  	// Record linker flags for external linking.
   370  	if *ldflags != "" {
   371  		args, err := splitQuoted(*ldflags)
   372  		if err != nil {
   373  			fatalf("bad -ldflags option: %q (%s)", *ldflags, err)
   374  		}
   375  		p.addToFlag("LDFLAGS", args)
   376  	}
   377  
   378  	// For backward compatibility for Bazel, record CGO_LDFLAGS
   379  	// from the environment for external linking.
   380  	// This should not happen with cmd/go, which removes CGO_LDFLAGS
   381  	// from the environment when invoking cgo.
   382  	// This can be removed when we no longer need to support
   383  	// older versions of Bazel. See issue #66456 and
   384  	// https://github.com/bazelbuild/rules_go/issues/3979.
   385  	if envFlags := os.Getenv("CGO_LDFLAGS"); envFlags != "" {
   386  		args, err := splitQuoted(envFlags)
   387  		if err != nil {
   388  			fatalf("bad CGO_LDFLAGS: %q (%s)", envFlags, err)
   389  		}
   390  		p.addToFlag("LDFLAGS", args)
   391  	}
   392  
   393  	// Need a unique prefix for the global C symbols that
   394  	// we use to coordinate between gcc and ourselves.
   395  	// We already put _cgo_ at the beginning, so the main
   396  	// concern is other cgo wrappers for the same functions.
   397  	// Use the beginning of the 16 bytes hash of the input to disambiguate.
   398  	h := hash.New32()
   399  	io.WriteString(h, *importPath)
   400  	var once sync.Once
   401  	q := par.NewQueue(runtime.GOMAXPROCS(0))
   402  	fs := make([]*File, len(goFiles))
   403  	for i, input := range goFiles {
   404  		if *srcDir != "" {
   405  			input = filepath.Join(*srcDir, input)
   406  		}
   407  
   408  		// Create absolute path for file, so that it will be used in error
   409  		// messages and recorded in debug line number information.
   410  		// This matches the rest of the toolchain. See golang.org/issue/5122.
   411  		if aname, err := filepath.Abs(input); err == nil {
   412  			input = aname
   413  		}
   414  
   415  		b, err := os.ReadFile(input)
   416  		if err != nil {
   417  			fatalf("%s", err)
   418  		}
   419  		if _, err = h.Write(b); err != nil {
   420  			fatalf("%s", err)
   421  		}
   422  
   423  		q.Add(func() {
   424  			// Apply trimpath to the file path. The path won't be read from after this point.
   425  			input, _ = objabi.ApplyRewrites(input, *trimpath)
   426  			if strings.ContainsAny(input, "\r\n") {
   427  				// ParseGo, (*Package).writeOutput, and printer.Fprint in SourcePos mode
   428  				// all emit line directives, which don't permit newlines in the file path.
   429  				// Bail early if we see anything newline-like in the trimmed path.
   430  				fatalf("input path contains newline character: %q", input)
   431  			}
   432  			goFiles[i] = input
   433  
   434  			f := new(File)
   435  			f.Edit = edit.NewBuffer(b)
   436  			f.ParseGo(input, b)
   437  			f.ProcessCgoDirectives()
   438  			gccIsClang := f.loadDefines(p.GccOptions)
   439  			once.Do(func() {
   440  				p.GccIsClang = gccIsClang
   441  			})
   442  
   443  			fs[i] = f
   444  
   445  			f.loadDebug(p)
   446  		})
   447  	}
   448  
   449  	<-q.Idle()
   450  
   451  	cPrefix = fmt.Sprintf("_%x", h.Sum(nil)[0:6])
   452  
   453  	for i, input := range goFiles {
   454  		f := fs[i]
   455  		p.Translate(f)
   456  		for _, cref := range f.Ref {
   457  			switch cref.Context {
   458  			case ctxCall, ctxCall2:
   459  				if cref.Name.Kind != "type" {
   460  					break
   461  				}
   462  				old := *cref.Expr
   463  				*cref.Expr = cref.Name.Type.Go
   464  				f.Edit.Replace(f.offset(old.Pos()), f.offset(old.End()), gofmt(cref.Name.Type.Go))
   465  			}
   466  		}
   467  		if nerrors > 0 {
   468  			os.Exit(2)
   469  		}
   470  		p.PackagePath = f.Package
   471  		p.Record(f)
   472  		if *godefs {
   473  			os.Stdout.WriteString(p.godefs(f, osArgs))
   474  		} else {
   475  			p.writeOutput(f, input)
   476  		}
   477  	}
   478  	cFunctions := make(map[string]bool)
   479  	for _, key := range nameKeys(p.Name) {
   480  		n := p.Name[key]
   481  		if n.FuncType != nil {
   482  			cFunctions[n.C] = true
   483  		}
   484  	}
   485  
   486  	for funcName := range p.noEscapes {
   487  		if _, found := cFunctions[funcName]; !found {
   488  			error_(token.NoPos, "#cgo noescape %s: no matched C function", funcName)
   489  		}
   490  	}
   491  
   492  	for funcName := range p.noCallbacks {
   493  		if _, found := cFunctions[funcName]; !found {
   494  			error_(token.NoPos, "#cgo nocallback %s: no matched C function", funcName)
   495  		}
   496  	}
   497  
   498  	if !*godefs {
   499  		p.writeDefs()
   500  	}
   501  	if nerrors > 0 {
   502  		os.Exit(2)
   503  	}
   504  }
   505  
   506  // newPackage returns a new Package that will invoke
   507  // gcc with the additional arguments specified in args.
   508  func newPackage(args []string) *Package {
   509  	goarch = runtime.GOARCH
   510  	if s := os.Getenv("GOARCH"); s != "" {
   511  		goarch = s
   512  	}
   513  	goos = runtime.GOOS
   514  	if s := os.Getenv("GOOS"); s != "" {
   515  		goos = s
   516  	}
   517  	buildcfg.Check()
   518  	gomips = buildcfg.GOMIPS
   519  	gomips64 = buildcfg.GOMIPS64
   520  	ptrSize := ptrSizeMap[goarch]
   521  	if ptrSize == 0 {
   522  		fatalf("unknown ptrSize for $GOARCH %q", goarch)
   523  	}
   524  	intSize := intSizeMap[goarch]
   525  	if intSize == 0 {
   526  		fatalf("unknown intSize for $GOARCH %q", goarch)
   527  	}
   528  
   529  	// Reset locale variables so gcc emits English errors [sic].
   530  	os.Setenv("LANG", "en_US.UTF-8")
   531  	os.Setenv("LC_ALL", "C")
   532  
   533  	p := &Package{
   534  		PtrSize:     ptrSize,
   535  		IntSize:     intSize,
   536  		Written:     make(map[string]bool),
   537  		noCallbacks: make(map[string]bool),
   538  		noEscapes:   make(map[string]bool),
   539  	}
   540  	p.addToFlag("CFLAGS", args)
   541  	return p
   542  }
   543  
   544  // Record what needs to be recorded about f.
   545  func (p *Package) Record(f *File) {
   546  	if p.PackageName == "" {
   547  		p.PackageName = f.Package
   548  	} else if p.PackageName != f.Package {
   549  		error_(token.NoPos, "inconsistent package names: %s, %s", p.PackageName, f.Package)
   550  	}
   551  
   552  	if p.Name == nil {
   553  		p.Name = f.Name
   554  	} else {
   555  		// Merge the new file's names in with the existing names.
   556  		for k, v := range f.Name {
   557  			if p.Name[k] == nil {
   558  				// Never seen before, just save it.
   559  				p.Name[k] = v
   560  			} else if p.incompleteTypedef(p.Name[k].Type) && p.Name[k].FuncType == nil {
   561  				// Old one is incomplete, just use new one.
   562  				p.Name[k] = v
   563  			} else if p.incompleteTypedef(v.Type) && v.FuncType == nil {
   564  				// New one is incomplete, just use old one.
   565  				// Nothing to do.
   566  			} else if _, ok := nameToC[k]; ok {
   567  				// Names we predefine may appear inconsistent
   568  				// if some files typedef them and some don't.
   569  				// Issue 26743.
   570  			} else if !reflect.DeepEqual(p.Name[k], v) {
   571  				// We don't require strict func type equality, because some functions
   572  				// can have things like typedef'd arguments that are equivalent to
   573  				// the standard arguments. e.g.
   574  				//     int usleep(unsigned);
   575  				//     int usleep(useconds_t);
   576  				// So we just check size/alignment of arguments. At least that
   577  				// avoids problems like those in #67670 and #67699.
   578  				ok := false
   579  				ft1 := p.Name[k].FuncType
   580  				ft2 := v.FuncType
   581  				if ft1.fuzzyMatch(ft2) {
   582  					// Retry DeepEqual with the FuncType field cleared.
   583  					x1 := *p.Name[k]
   584  					x2 := *v
   585  					x1.FuncType = nil
   586  					x2.FuncType = nil
   587  					if reflect.DeepEqual(&x1, &x2) {
   588  						ok = true
   589  					}
   590  				}
   591  				if !ok {
   592  					error_(token.NoPos, "inconsistent definitions for C.%s", fixGo(k))
   593  				}
   594  			}
   595  		}
   596  	}
   597  
   598  	// merge nocallback & noescape
   599  	maps.Copy(p.noCallbacks, f.NoCallbacks)
   600  	maps.Copy(p.noEscapes, f.NoEscapes)
   601  
   602  	if f.ExpFunc != nil {
   603  		p.ExpFunc = append(p.ExpFunc, f.ExpFunc...)
   604  		p.Preamble += "\n" + f.Preamble
   605  	}
   606  	p.Decl = append(p.Decl, f.AST.Decls...)
   607  }
   608  
   609  // incompleteTypedef reports whether t appears to be an incomplete
   610  // typedef definition.
   611  func (p *Package) incompleteTypedef(t *Type) bool {
   612  	return t == nil || (t.Size == 0 && t.Align == -1)
   613  }
   614
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