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cgo: avoid self-interference of global names

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Fixes #1332.

R=iant, iant2
CC=golang-dev
https://golang.org/cl/3555041
This commit is contained in:
Russ Cox 2010-12-10 11:32:58 -08:00
parent 4324a31376
commit e454af4d64
2 changed files with 23 additions and 3 deletions
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20
src/cmd/cgo/main.go
View File

@ -11,10 +11,12 @@
package main
import (
"crypto/md5"
"flag"
"fmt"
"go/ast"
"go/token"
"io"
"os"
"reflect"
"strings"
@ -105,6 +107,8 @@ var ptrSizeMap = map[string]int64{
"arm": 4,
}
var cPrefix string
var fset = token.NewFileSet()
var dynobj = flag.String("dynimport", "", "if non-empty, print dynamic import data for that file")
@ -170,6 +174,22 @@ func main() {
Written: make(map[string]bool),
}
// Need a unique prefix for the global C symbols that
// we use to coordinate between gcc and ourselves.
// We already put _cgo_ at the beginning, so the main
// concern is other cgo wrappers for the same functions.
// Use the beginning of the md5 of the input to disambiguate.
h := md5.New()
for _, input := range goFiles {
f, err := os.Open(input, os.O_RDONLY, 0)
if err != nil {
fatal("%s", err)
}
io.Copy(h, f)
f.Close()
}
cPrefix = fmt.Sprintf("_%x", h.Sum()[0:6])
for _, input := range goFiles {
f := new(File)
// Reset f.Preamble so that we don't end up with conflicting headers / defines

6
src/cmd/cgo/out.go
View File

@ -212,12 +212,12 @@ func (p *Package) writeDefsFunc(fc, fgo2 *os.File, n *Name, soprefix, sopath str
_, argSize = p.structType(n)
// C wrapper calls into gcc, passing a pointer to the argument frame.
fmt.Fprintf(fc, "void _cgo%s(void*);\n", n.Mangle)
fmt.Fprintf(fc, "void _cgo%s%s(void*);\n", cPrefix, n.Mangle)
fmt.Fprintf(fc, "\n")
fmt.Fprintf(fc, "void\n")
fmt.Fprintf(fc, "·%s(struct{uint8 x[%d];}p)\n", n.Mangle, argSize)
fmt.Fprintf(fc, "{\n")
fmt.Fprintf(fc, "\truntime·cgocall(_cgo%s, &p);\n", n.Mangle)
fmt.Fprintf(fc, "\truntime·cgocall(_cgo%s%s, &p);\n", cPrefix, n.Mangle)
if n.AddError {
// gcc leaves errno in first word of interface at end of p.
// check whether it is zero; if so, turn interface into nil.
@ -292,7 +292,7 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
// Gcc wrapper unpacks the C argument struct
// and calls the actual C function.
fmt.Fprintf(fgcc, "void\n")
fmt.Fprintf(fgcc, "_cgo%s(void *v)\n", n.Mangle)
fmt.Fprintf(fgcc, "_cgo%s%s(void *v)\n", cPrefix, n.Mangle)
fmt.Fprintf(fgcc, "{\n")
if n.AddError {
fmt.Fprintf(fgcc, "\tint e;\n") // assuming 32 bit (see comment above structType)