Allow cgo to accept multiple .go inputs for a package

Fixes #342.

R=rsc
CC=golang-dev
https://golang.org/cl/179062

4 files changed, 194 insertions, 99 deletions

diff --git a/src/Make.pkg b/src/Make.pkg
index 87b4e442e1..489aa78c27 100644
--- a/src/Make.pkg
+++ b/src/Make.pkg
@@ -36,18 +36,21 @@ INSTALLFILES=$(pkgdir)/$(TARG).a
 
 # The rest of the cgo rules are below, but these variable updates
 # must be done here so they apply to the main rules.
+ifdef CGOFILES
 GOFILES+=$(patsubst %.go,%.cgo1.go,$(CGOFILES))
-GOFILES+=$(patsubst %.go,%.cgo2.go,$(CGOFILES))
-OFILES+=$(patsubst %.go,%.cgo3.$O,$(CGOFILES))
-INSTALLFILES+=$(patsubst %.go,$(pkgdir)/$(dir)/$(elem)_%.so,$(CGOFILES))
+GOFILES+=_cgo_gotypes.go
+OFILES+=_cgo_defun.$O
+GCC_OFILES=$(patsubst %.go,%.cgo2.o,$(CGOFILES))
+INSTALLFILES+=$(pkgdir)/$(dir)/$(TARG).so
 PREREQ+=$(patsubst %,%.make,$(DEPS))
+endif
 
 coverage:
 	$(QUOTED_GOBIN)/gotest
 	$(QUOTED_GOBIN)/6cov -g $(shell pwd) $O.out | grep -v '_test\.go:'
 
 clean:
-	rm -rf *.[$(OS)o] *.a [$(OS)].out *.cgo[12].go *.cgo[34].c *.so _obj _test _testmain.go $(CLEANFILES)
+	rm -rf *.[$(OS)o] *.a [$(OS)].out *.cgo1.go *.cgo2.c _cgo_defun.c _cgo_gotypes.go *.so _obj _test _testmain.go $(CLEANFILES)
 
 test:
 	$(QUOTED_GOBIN)/gotest
@@ -91,32 +94,42 @@ dir:
 
 # To use cgo in a Go package, add a line
 #
-#	CGOFILES=x.go
+#	CGOFILES=x.go y.go
 #
-# to the main Makefile.  This signals that cgo should process x.go.
+# to the main Makefile.  This signals that cgo should process x.go
+# and y.go when building the package.
 # There are two optional variables to set, CGO_CFLAGS and CGO_LDFLAGS,
 # which specify compiler and linker flags to use when compiling
-# (using gcc) the C support for x.go.
+# (using gcc) the C support for x.go and y.go.
 
-# Cgo translates each x.go file listed in $(CGOFILES) into
+# Cgo translates each x.go file listed in $(CGOFILES) into a basic
+# translation of x.go, called x.cgo1.go. Additionally, three other
+# files are created:
 #
-#	x.cgo1.go - basic translation of x.go
-#	x.cgo2.go - declarations needed for x.cgo1.go; imports "unsafe"
-#	x.cgo3.c - C trampoline code to be compiled with 6c and linked into the package
-#	x.cgo4.c - C implementations compiled with gcc to create dynamic library
+#	_cgo_gotypes.go	- declarations needed for all .go files in the package; imports "unsafe"
+#	_cgo_defun.c	- C trampoline code to be compiled with 6c and linked into the package
+#	x.cgo2.c	- C implementations compiled with gcc to create a dynamic library
 #
-%.cgo1.go %.cgo2.go %.cgo3.c %.cgo4.c: %.go
-	CGOPKGPATH=$(dir) $(QUOTED_GOBIN)/cgo $(CGO_CFLAGS) $*.go
 
-# The rules above added x.cgo1.go and x.cgo2.go to $(GOFILES),
-# added x.cgo3.$O to $OFILES, and added the installed copy of
-# package_x.so (built from x.cgo4.c) to $(INSTALLFILES).
+_cgo_defun.c _cgo_gotypes.go: $(CGOFILES)
+	CGOPKGPATH=$(dir) $(QUOTED_GOBIN)/cgo $(CGO_CFLAGS) $(CGOFILES)
+
+# Ugly but necessary
+%.cgo1.go: _cgo_defun.c _cgo_gotypes.go
+	@true
+
+%.cgo2.c: _cgo_defun.c _cgo_gotypes.go
+	@true
+
+%.cgo2.o: %.cgo2.c
+	gcc $(_CGO_CFLAGS_$(GOARCH)) -fPIC -O2 -o $@ -c $(CGO_CFLAGS) $*.cgo2.c
+
+# The rules above added x.cgo1.go and _cgo_gotypes.go to $(GOFILES),
+# added _cgo_defun.$O to $OFILES, and added the installed copy of
+# package_x.so (built from x.cgo2.c) to $(INSTALLFILES).
 
-# Compile x.cgo3.c with 6c; needs access to the runtime headers.
 RUNTIME_CFLAGS_amd64=-D_64BIT
 RUNTIME_CFLAGS=-I"$(GOROOT)/src/pkg/runtime" $(RUNTIME_CFLAGS_$(GOARCH))
-%.cgo3.$O: %.cgo3.c
-	$(QUOTED_GOBIN)/$(CC) $(CFLAGS) $(RUNTIME_CFLAGS) $*.cgo3.c
 
 # Have to run gcc with the right size argument on hybrid 32/64 machines.
 _CGO_CFLAGS_386=-m32
@@ -127,15 +140,17 @@ _CGO_LDFLAGS_darwin=-dynamiclib -Wl,-undefined,dynamic_lookup
 
 
 # Compile x.cgo4.c with gcc to make package_x.so.
-%.cgo4.o: %.cgo4.c
-	gcc $(_CGO_CFLAGS_$(GOARCH)) -fPIC -O2 -o $@ -c $(CGO_CFLAGS) $*.cgo4.c
 
-$(elem)_%.so: %.cgo4.o
-	gcc $(_CGO_CFLAGS_$(GOARCH)) -o $@ $*.cgo4.o $(CGO_LDFLAGS)  $(_CGO_LDFLAGS_$(GOOS))
+# Compile _cgo_defun.c with 6c; needs access to the runtime headers.
+_cgo_defun.$O: _cgo_defun.c
+	$(QUOTED_GOBIN)/$(CC) $(CFLAGS) $(RUNTIME_CFLAGS) _cgo_defun.c
+
+_cgo_.so: $(GCC_OFILES)
+	gcc $(_CGO_CFLAGS_$(GOARCH)) -o $@ $(GCC_OFILES) $(CGO_LDFLAGS)  $(_CGO_LDFLAGS_$(GOOS))
 
-$(pkgdir)/$(dir)/$(elem)_%.so: $(elem)_%.so
+$(pkgdir)/$(dir)/$(TARG).so: _cgo_.so
 	@test -d $(QUOTED_GOROOT/pkg && mkdir -p $(pkgdir)/$(dir)
-	cp $(elem)_$*.so "$@"
+	cp _cgo_.so "$@"
 
 # Generic build rules.
 # These come last so that the rules above can override them
diff --git a/src/cmd/cgo/ast.go b/src/cmd/cgo/ast.go
index 301516c43a..76ff9ec653 100644
--- a/src/cmd/cgo/ast.go
+++ b/src/cmd/cgo/ast.go
@@ -38,6 +38,7 @@ type Prog struct {
 	Enumdef     map[string]int64
 	PtrSize     int64
 	GccOptions  []string
+	OutDefs     map[string]bool
 }
 
 // A Type collects information about a type in both the C and Go worlds.
@@ -56,8 +57,7 @@ type FuncType struct {
 	Go     *ast.FuncType
 }
 
-func openProg(name string) *Prog {
-	p := new(Prog)
+func openProg(name string, p *Prog) {
 	var err os.Error
 	p.AST, err = parser.ParsePkgFile("", name, parser.ParseComments)
 	if err != nil {
@@ -120,7 +120,6 @@ func openProg(name string) *Prog {
 	// Accumulate pointers to uses of C.x.
 	p.Crefs = make([]*Cref, 0, 8)
 	walk(p.AST, p, "prog")
-	return p
 }
 
 func walk(x interface{}, p *Prog, context string) {
diff --git a/src/cmd/cgo/main.go b/src/cmd/cgo/main.go
index 5aa17397bd..c3e319f92c 100644
--- a/src/cmd/cgo/main.go
+++ b/src/cmd/cgo/main.go
@@ -14,9 +14,10 @@ import (
 	"fmt"
 	"go/ast"
 	"os"
+	"strings"
 )
 
-func usage() { fmt.Fprint(os.Stderr, "usage: cgo [compiler options] file.go\n") }
+func usage() { fmt.Fprint(os.Stderr, "usage: cgo [compiler options] file.go ...\n") }
 
 var ptrSizeMap = map[string]int64{
 	"386": 4,
@@ -40,8 +41,19 @@ func main() {
 		usage()
 		os.Exit(2)
 	}
-	gccOptions := args[1 : len(args)-1]
-	input := args[len(args)-1]
+
+	// Find first arg that looks like a go file and assume everything before
+	// that are options to pass to gcc.
+	var i int
+	for i = len(args) - 1; i > 0; i-- {
+		if !strings.HasSuffix(args[i], ".go") {
+			break
+		}
+	}
+
+	i += 1
+
+	gccOptions, goFiles := args[1:i], args[i:]
 
 	arch := os.Getenv("GOARCH")
 	if arch == "" {
@@ -57,59 +69,66 @@ func main() {
 	os.Setenv("LC_ALL", "C")
 	os.Setenv("LC_CTYPE", "C")
 
-	p := openProg(input)
-	for _, cref := range p.Crefs {
-		// Convert C.ulong to C.unsigned long, etc.
-		if expand, ok := expandName[cref.Name]; ok {
-			cref.Name = expand
-		}
-	}
+	p := new(Prog)
 
 	p.PtrSize = ptrSize
-	p.Preamble = p.Preamble + "\n" + builtinProlog
 	p.GccOptions = gccOptions
-	p.loadDebugInfo()
 	p.Vardef = make(map[string]*Type)
 	p.Funcdef = make(map[string]*FuncType)
 	p.Enumdef = make(map[string]int64)
+	p.OutDefs = make(map[string]bool)
 
-	for _, cref := range p.Crefs {
-		switch cref.Context {
-		case "call":
-			if !cref.TypeName {
-				// Is an actual function call.
-				*cref.Expr = &ast.Ident{Value: "_C_" + cref.Name}
-				p.Funcdef[cref.Name] = cref.FuncType
-				break
+	for _, input := range goFiles {
+		// Reset p.Preamble so that we don't end up with conflicting headers / defines
+		p.Preamble = builtinProlog
+		openProg(input, p)
+		for _, cref := range p.Crefs {
+			// Convert C.ulong to C.unsigned long, etc.
+			if expand, ok := expandName[cref.Name]; ok {
+				cref.Name = expand
 			}
-			*cref.Expr = cref.Type.Go
-		case "expr":
-			if cref.TypeName {
-				error((*cref.Expr).Pos(), "type C.%s used as expression", cref.Name)
-			}
-			// If the expression refers to an enumerated value, then
-			// place the identifier for the value and add it to Enumdef so
-			// it will be declared as a constant in the later stage.
-			if cref.Type.EnumValues != nil {
-				*cref.Expr = &ast.Ident{Value: cref.Name}
-				p.Enumdef[cref.Name] = cref.Type.EnumValues[cref.Name]
-				break
-			}
-			// Reference to C variable.
-			// We declare a pointer and arrange to have it filled in.
-			*cref.Expr = &ast.StarExpr{X: &ast.Ident{Value: "_C_" + cref.Name}}
-			p.Vardef[cref.Name] = cref.Type
-		case "type":
-			if !cref.TypeName {
-				error((*cref.Expr).Pos(), "expression C.%s used as type", cref.Name)
+		}
+		p.loadDebugInfo()
+		for _, cref := range p.Crefs {
+			switch cref.Context {
+			case "call":
+				if !cref.TypeName {
+					// Is an actual function call.
+					*cref.Expr = &ast.Ident{Value: "_C_" + cref.Name}
+					p.Funcdef[cref.Name] = cref.FuncType
+					break
+				}
+				*cref.Expr = cref.Type.Go
+			case "expr":
+				if cref.TypeName {
+					error((*cref.Expr).Pos(), "type C.%s used as expression", cref.Name)
+				}
+				// If the expression refers to an enumerated value, then
+				// place the identifier for the value and add it to Enumdef so
+				// it will be declared as a constant in the later stage.
+				if cref.Type.EnumValues != nil {
+					*cref.Expr = &ast.Ident{Value: cref.Name}
+					p.Enumdef[cref.Name] = cref.Type.EnumValues[cref.Name]
+					break
+				}
+				// Reference to C variable.
+				// We declare a pointer and arrange to have it filled in.
+				*cref.Expr = &ast.StarExpr{X: &ast.Ident{Value: "_C_" + cref.Name}}
+				p.Vardef[cref.Name] = cref.Type
+			case "type":
+				if !cref.TypeName {
+					error((*cref.Expr).Pos(), "expression C.%s used as type", cref.Name)
+				}
+				*cref.Expr = cref.Type.Go
 			}
-			*cref.Expr = cref.Type.Go
 		}
-	}
-	if nerrors > 0 {
-		os.Exit(2)
+		if nerrors > 0 {
+			os.Exit(2)
+		}
+
+		p.PackagePath = os.Getenv("CGOPKGPATH") + "/" + p.Package
+		p.writeOutput(input)
 	}
 
-	p.PackagePath = os.Getenv("CGOPKGPATH") + "/" + p.Package
-	p.writeOutput(input)
+	p.writeDefs()
 }
diff --git a/src/cmd/cgo/out.go b/src/cmd/cgo/out.go
index 2b42edbe09..8720d6ff7e 100644
--- a/src/cmd/cgo/out.go
+++ b/src/cmd/cgo/out.go
@@ -20,24 +20,13 @@ func creat(name string) *os.File {
 	return f
 }
 
-// writeOutput creates output files to be compiled by 6g, 6c, and gcc.
+// writeDefs creates output files to be compiled by 6g, 6c, and gcc.
 // (The comments here say 6g and 6c but the code applies to the 8 and 5 tools too.)
-func (p *Prog) writeOutput(srcfile string) {
+func (p *Prog) writeDefs() {
 	pkgroot := os.Getenv("GOROOT") + "/pkg/" + os.Getenv("GOOS") + "_" + os.Getenv("GOARCH")
 
-	base := srcfile
-	if strings.HasSuffix(base, ".go") {
-		base = base[0 : len(base)-3]
-	}
-	fgo1 := creat(base + ".cgo1.go")
-	fgo2 := creat(base + ".cgo2.go")
-	fc := creat(base + ".cgo3.c")
-	fgcc := creat(base + ".cgo4.c")
-
-	// Write Go output: Go input with rewrites of C.xxx to _C_xxx.
-	fmt.Fprintf(fgo1, "// Created by cgo - DO NOT EDIT\n")
-	fmt.Fprintf(fgo1, "//line %s:1\n", srcfile)
-	printer.Fprint(fgo1, p.AST)
+	fgo2 := creat("_cgo_gotypes.go")
+	fc := creat("_cgo_defun.c")
 
 	// Write second Go output: definitions of _C_xxx.
 	// In a separate file so that the import of "unsafe" does not
@@ -54,15 +43,10 @@ func (p *Prog) writeOutput(srcfile string) {
 	}
 	fmt.Fprintf(fgo2, "type _C_void [0]byte\n")
 
-	// While we process the vars and funcs, also write 6c and gcc output.
-	// Gcc output starts with the preamble.
-	fmt.Fprintf(fgcc, "%s\n", p.Preamble)
-	fmt.Fprintf(fgcc, "%s\n", gccProlog)
-
 	fmt.Fprintf(fc, cProlog, pkgroot, pkgroot, pkgroot, pkgroot, p.Package, p.Package)
 
 	for name, def := range p.Vardef {
-		fmt.Fprintf(fc, "#pragma dynld %s·_C_%s %s \"%s/%s_%s.so\"\n", p.Package, name, name, pkgroot, p.PackagePath, base)
+		fmt.Fprintf(fc, "#pragma dynld %s·_C_%s %s \"%s/%s.so\"\n", p.Package, name, name, pkgroot, p.PackagePath)
 		fmt.Fprintf(fgo2, "var _C_%s ", name)
 		printer.Fprint(fgo2, &ast.StarExpr{X: def.Go})
 		fmt.Fprintf(fgo2, "\n")
@@ -137,7 +121,7 @@ func (p *Prog) writeOutput(srcfile string) {
 
 		// C wrapper calls into gcc, passing a pointer to the argument frame.
 		// Also emit #pragma to get a pointer to the gcc wrapper.
-		fmt.Fprintf(fc, "#pragma dynld _cgo_%s _cgo_%s \"%s/%s_%s.so\"\n", name, name, pkgroot, p.PackagePath, base)
+		fmt.Fprintf(fc, "#pragma dynld _cgo_%s _cgo_%s \"%s/%s.so\"\n", name, name, pkgroot, p.PackagePath)
 		fmt.Fprintf(fc, "void (*_cgo_%s)(void*);\n", name)
 		fmt.Fprintf(fc, "\n")
 		fmt.Fprintf(fc, "void\n")
@@ -146,6 +130,86 @@ func (p *Prog) writeOutput(srcfile string) {
 		fmt.Fprintf(fc, "\tcgocall(_cgo_%s, &p);\n", name)
 		fmt.Fprintf(fc, "}\n")
 		fmt.Fprintf(fc, "\n")
+	}
+
+	fgo2.Close()
+	fc.Close()
+}
+
+// writeOutput creates stubs for a specific source file to be compiled by 6g
+// (The comments here say 6g and 6c but the code applies to the 8 and 5 tools too.)
+func (p *Prog) writeOutput(srcfile string) {
+	base := srcfile
+	if strings.HasSuffix(base, ".go") {
+		base = base[0 : len(base)-3]
+	}
+	fgo1 := creat(base + ".cgo1.go")
+	fgcc := creat(base + ".cgo2.c")
+
+	// Write Go output: Go input with rewrites of C.xxx to _C_xxx.
+	fmt.Fprintf(fgo1, "// Created by cgo - DO NOT EDIT\n")
+	fmt.Fprintf(fgo1, "//line %s:1\n", srcfile)
+	printer.Fprint(fgo1, p.AST)
+
+	// While we process the vars and funcs, also write 6c and gcc output.
+	// Gcc output starts with the preamble.
+	fmt.Fprintf(fgcc, "%s\n", p.Preamble)
+	fmt.Fprintf(fgcc, "%s\n", gccProlog)
+
+	for name, def := range p.Funcdef {
+		_, ok := p.OutDefs[name]
+		if name == "CString" || name == "GoString" || ok {
+			// The builtins are already defined in the C prolog, and we don't
+			// want to duplicate function definitions we've already done.
+			continue
+		}
+		p.OutDefs[name] = true
+
+		// Construct a gcc struct matching the 6c 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 6c convention is to word-align the
+		// input and output parameters.
+		structType := "struct {\n"
+		off := int64(0)
+		npad := 0
+		for i, t := range def.Params {
+			if off%t.Align != 0 {
+				pad := t.Align - off%t.Align
+				structType += fmt.Sprintf("\t\tchar __pad%d[%d];\n", npad, pad)
+				off += pad
+				npad++
+			}
+			structType += fmt.Sprintf("\t\t%s p%d;\n", t.C, i)
+			off += t.Size
+		}
+		if off%p.PtrSize != 0 {
+			pad := p.PtrSize - off%p.PtrSize
+			structType += fmt.Sprintf("\t\tchar __pad%d[%d];\n", npad, pad)
+			off += pad
+			npad++
+		}
+		if t := def.Result; t != nil {
+			if off%t.Align != 0 {
+				pad := t.Align - off%t.Align
+				structType += fmt.Sprintf("\t\tchar __pad%d[%d];\n", npad, pad)
+				off += pad
+				npad++
+			}
+			structType += fmt.Sprintf("\t\t%s r;\n", t.C)
+			off += t.Size
+		}
+		if off%p.PtrSize != 0 {
+			pad := p.PtrSize - off%p.PtrSize
+			structType += fmt.Sprintf("\t\tchar __pad%d[%d];\n", npad, pad)
+			off += pad
+			npad++
+		}
+		if len(def.Params) == 0 && def.Result == nil {
+			structType += "\t\tchar unused;\n" // avoid empty struct
+			off++
+		}
+		structType += "\t}"
 
 		// Gcc wrapper unpacks the C argument struct
 		// and calls the actual C function.
@@ -170,8 +234,6 @@ func (p *Prog) writeOutput(srcfile string) {
 	}
 
 	fgo1.Close()
-	fgo2.Close()
-	fc.Close()
 	fgcc.Close()
 }