// Copyright 2015 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.
// Tests that cgo detects invalid pointer passing at runtime.
package main
import (
"bufio"
"bytes"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"runtime"
"strings"
"sync"
)
// ptrTest is the tests without the boilerplate.
type ptrTest struct {
name string // for reporting
c string // the cgo comment
imports []string // a list of imports
support string // supporting functions
body string // the body of the main function
extra []extra // extra files
fail bool // whether the test should fail
expensive bool // whether the test requires the expensive check
}
type extra struct {
name string
contents string
}
var ptrTests = []ptrTest{
{
// Passing a pointer to a struct that contains a Go pointer.
name: "ptr1",
c: `typedef struct s { int *p; } s; void f(s *ps) {}`,
body: `C.f(&C.s{new(C.int)})`,
fail: true,
},
{
// Passing a pointer to a struct that contains a Go pointer.
name: "ptr2",
c: `typedef struct s { int *p; } s; void f(s *ps) {}`,
body: `p := &C.s{new(C.int)}; C.f(p)`,
fail: true,
},
{
// Passing a pointer to an int field of a Go struct
// that (irrelevantly) contains a Go pointer.
name: "ok1",
c: `struct s { int i; int *p; }; void f(int *p) {}`,
body: `p := &C.struct_s{i: 0, p: new(C.int)}; C.f(&p.i)`,
fail: false,
},
{
// Passing a pointer to a pointer field of a Go struct.
name: "ptr-field",
c: `struct s { int i; int *p; }; void f(int **p) {}`,
body: `p := &C.struct_s{i: 0, p: new(C.int)}; C.f(&p.p)`,
fail: true,
},
{
// Passing a pointer to a pointer field of a Go
// struct, where the field does not contain a Go
// pointer, but another field (irrelevantly) does.
name: "ptr-field-ok",
c: `struct s { int *p1; int *p2; }; void f(int **p) {}`,
body: `p := &C.struct_s{p1: nil, p2: new(C.int)}; C.f(&p.p1)`,
fail: false,
},
{
// Passing the address of a slice with no Go pointers.
name: "slice-ok-1",
c: `void f(void **p) {}`,
imports: []string{"unsafe"},
body: `s := []unsafe.Pointer{nil}; C.f(&s[0])`,
fail: false,
},
{
// Passing the address of a slice with a Go pointer.
name: "slice-ptr-1",
c: `void f(void **p) {}`,
imports: []string{"unsafe"},
body: `i := 0; s := []unsafe.Pointer{unsafe.Pointer(&i)}; C.f(&s[0])`,
fail: true,
},
{
// Passing the address of a slice with a Go pointer,
// where we are passing the address of an element that
// is not a Go pointer.
name: "slice-ptr-2",
c: `void f(void **p) {}`,
imports: []string{"unsafe"},
body: `i := 0; s := []unsafe.Pointer{nil, unsafe.Pointer(&i)}; C.f(&s[0])`,
fail: true,
},
{
// Passing the address of a slice that is an element
// in a struct only looks at the slice.
name: "slice-ok-2",
c: `void f(void **p) {}`,
imports: []string{"unsafe"},
support: `type S struct { p *int; s []unsafe.Pointer }`,
body: `i := 0; p := &S{p:&i, s:[]unsafe.Pointer{nil}}; C.f(&p.s[0])`,
fail: false,
},
{
// Passing the address of a slice of an array that is
// an element in a struct, with a type conversion.
name: "slice-ok-3",
c: `void f(void* p) {}`,
imports: []string{"unsafe"},
support: `type S struct { p *int; a [4]byte }`,
body: `i := 0; p := &S{p:&i}; s := p.a[:]; C.f(unsafe.Pointer(&s[0]))`,
fail: false,
},
{
// Passing the address of a slice of an array that is
// an element in a struct, with a type conversion.
name: "slice-ok-4",
c: `typedef void* PV; void f(PV p) {}`,
imports: []string{"unsafe"},
support: `type S struct { p *int; a [4]byte }`,
body: `i := 0; p := &S{p:&i}; C.f(C.PV(unsafe.Pointer(&p.a[0])))`,
fail: false,
},
{
// Passing the address of a static variable with no
// pointers doesn't matter.
name: "varok",
c: `void f(char** parg) {}`,
support: `var hello = [...]C.char{'h', 'e', 'l', 'l', 'o'}`,
body: `parg := [1]*C.char{&hello[0]}; C.f(&parg[0])`,
fail: false,
},
{
// Passing the address of a static variable with
// pointers does matter.
name: "var",
c: `void f(char*** parg) {}`,
support: `var hello = [...]*C.char{new(C.char)}`,
body: `parg := [1]**C.char{&hello[0]}; C.f(&parg[0])`,
fail: true,
},
{
// Storing a Go pointer into C memory should fail.
name: "barrier",
c: `#include <stdlib.h>
char **f1() { return malloc(sizeof(char*)); }
void f2(char **p) {}`,
body: `p := C.f1(); *p = new(C.char); C.f2(p)`,
fail: true,
expensive: true,
},
{
// Storing a Go pointer into C memory by assigning a
// large value should fail.
name: "barrier-struct",
c: `#include <stdlib.h>
struct s { char *a[10]; };
struct s *f1() { return malloc(sizeof(struct s)); }
void f2(struct s *p) {}`,
body: `p := C.f1(); p.a = [10]*C.char{new(C.char)}; C.f2(p)`,
fail: true,
expensive: true,
},
{
// Storing a Go pointer into C memory using a slice
// copy should fail.
name: "barrier-slice",
c: `#include <stdlib.h>
struct s { char *a[10]; };
struct s *f1() { return malloc(sizeof(struct s)); }
void f2(struct s *p) {}`,
body: `p := C.f1(); copy(p.a[:], []*C.char{new(C.char)}); C.f2(p)`,
fail: true,
expensive: true,
},
{
// A very large value uses a GC program, which is a
// different code path.
name: "barrier-gcprog-array",
c: `#include <stdlib.h>
struct s { char *a[32769]; };
struct s *f1() { return malloc(sizeof(struct s)); }
void f2(struct s *p) {}`,
body: `p := C.f1(); p.a = [32769]*C.char{new(C.char)}; C.f2(p)`,
fail: true,
expensive: true,
},
{
// Similar case, with a source on the heap.
name: "barrier-gcprog-array-heap",
c: `#include <stdlib.h>
struct s { char *a[32769]; };
struct s *f1() { return malloc(sizeof(struct s)); }
void f2(struct s *p) {}
void f3(void *p) {}`,
imports: []string{"unsafe"},
body: `p := C.f1(); n := &[32769]*C.char{new(C.char)}; p.a = *n; C.f2(p); n[0] = nil; C.f3(unsafe.Pointer(n))`,
fail: true,
expensive: true,
},
{
// A GC program with a struct.
name: "barrier-gcprog-struct",
c: `#include <stdlib.h>
struct s { char *a[32769]; };
struct s2 { struct s f; };
struct s2 *f1() { return malloc(sizeof(struct s2)); }
void f2(struct s2 *p) {}`,
body: `p := C.f1(); p.f = C.struct_s{[32769]*C.char{new(C.char)}}; C.f2(p)`,
fail: true,
expensive: true,
},
{
// Similar case, with a source on the heap.
name: "barrier-gcprog-struct-heap",
c: `#include <stdlib.h>
struct s { char *a[32769]; };
struct s2 { struct s f; };
struct s2 *f1() { return malloc(sizeof(struct s2)); }
void f2(struct s2 *p) {}
void f3(void *p) {}`,
imports: []string{"unsafe"},
body: `p := C.f1(); n := &C.struct_s{[32769]*C.char{new(C.char)}}; p.f = *n; C.f2(p); n.a[0] = nil; C.f3(unsafe.Pointer(n))`,
fail: true,
expensive: true,
},
{
// Exported functions may not return Go pointers.
name: "export1",
c: `extern unsigned char *GoFn();`,
support: `//export GoFn
func GoFn() *byte { return new(byte) }`,
body: `C.GoFn()`,
fail: true,
},
{
// Returning a C pointer is fine.
name: "exportok",
c: `#include <stdlib.h>
extern unsigned char *GoFn();`,
support: `//export GoFn
func GoFn() *byte { return (*byte)(C.malloc(1)) }`,
body: `C.GoFn()`,
},
{
// Passing a Go string is fine.
name: "pass-string",
c: `#include <stddef.h>
typedef struct { const char *p; ptrdiff_t n; } gostring;
gostring f(gostring s) { return s; }`,
imports: []string{"unsafe"},
body: `s := "a"; r := C.f(*(*C.gostring)(unsafe.Pointer(&s))); if *(*string)(unsafe.Pointer(&r)) != s { panic(r) }`,
},
{
// Passing a slice of Go strings fails.
name: "pass-string-slice",
c: `void f(void *p) {}`,
imports: []string{"strings", "unsafe"},
support: `type S struct { a [1]string }`,
body: `s := S{a:[1]string{strings.Repeat("a", 2)}}; C.f(unsafe.Pointer(&s.a[0]))`,
fail: true,
},
{
// Exported functions may not return strings.
name: "ret-string",
c: `extern void f();`,
imports: []string{"strings"},
support: `//export GoStr
func GoStr() string { return strings.Repeat("a", 2) }`,
body: `C.f()`,
extra: []extra{
{
"call.c",
`#include <stddef.h>
typedef struct { const char *p; ptrdiff_t n; } gostring;
extern gostring GoStr();
void f() { GoStr(); }`,
},
},
fail: true,
},
{
// Don't check non-pointer data.
// Uses unsafe code to get a pointer we shouldn't check.
// Although we use unsafe, the uintptr represents an integer
// that happens to have the same representation as a pointer;
// that is, we are testing something that is not unsafe.
name: "ptrdata1",
c: `#include <stdlib.h>
void f(void* p) {}`,
imports: []string{"unsafe"},
support: `type S struct { p *int; a [8*8]byte; u uintptr }`,
body: `i := 0; p := &S{u:uintptr(unsafe.Pointer(&i))}; q := (*S)(C.malloc(C.size_t(unsafe.Sizeof(*p)))); *q = *p; C.f(unsafe.Pointer(q))`,
fail: false,
},
{
// Like ptrdata1, but with a type that uses a GC program.
name: "ptrdata2",
c: `#include <stdlib.h>
void f(void* p) {}`,
imports: []string{"unsafe"},
support: `type S struct { p *int; a [32769*8]byte; q *int; u uintptr }`,
body: `i := 0; p := S{u:uintptr(unsafe.Pointer(&i))}; q := (*S)(C.malloc(C.size_t(unsafe.Sizeof(p)))); *q = p; C.f(unsafe.Pointer(q))`,
fail: false,
},
{
// Check deferred pointers when they are used, not
// when the defer statement is run.
name: "defer",
c: `typedef struct s { int *p; } s; void f(s *ps) {}`,
body: `p := &C.s{}; defer C.f(p); p.p = new(C.int)`,
fail: true,
},
{
// Check a pointer to a union if the union has any
// pointer fields.
name: "union1",
c: `typedef union { char **p; unsigned long i; } u; void f(u *pu) {}`,
imports: []string{"unsafe"},
body: `var b C.char; p := &b; C.f((*C.u)(unsafe.Pointer(&p)))`,
fail: true,
},
{
// Don't check a pointer to a union if the union does
// not have any pointer fields.
// Like ptrdata1 above, the uintptr represents an
// integer that happens to have the same
// representation as a pointer.
name: "union2",
c: `typedef union { unsigned long i; } u; void f(u *pu) {}`,
imports: []string{"unsafe"},
body: `var b C.char; p := &b; C.f((*C.u)(unsafe.Pointer(&p)))`,
fail: false,
},
}
func main() {
os.Exit(doTests())
}
func doTests() int {
gopath, err := ioutil.TempDir("", "cgoerrors")
if err != nil {
fmt.Fprintln(os.Stderr, err)
return 2
}
defer os.RemoveAll(gopath)
if err := os.MkdirAll(filepath.Join(gopath, "src"), 0777); err != nil {
fmt.Fprintln(os.Stderr, err)
return 2
}
workers := runtime.NumCPU() + 1
var wg sync.WaitGroup
c := make(chan int)
errs := make(chan int)
for i := 0; i < workers; i++ {
wg.Add(1)
go func() {
worker(gopath, c, errs)
wg.Done()
}()
}
for i := range ptrTests {
c <- i
}
close(c)
go func() {
wg.Wait()
close(errs)
}()
tot := 0
for e := range errs {
tot += e
}
return tot
}
func worker(gopath string, c, errs chan int) {
e := 0
for i := range c {
if !doOne(gopath, i) {
e++
}
}
if e > 0 {
errs <- e
}
}
func doOne(gopath string, i int) bool {
t := &ptrTests[i]
dir := filepath.Join(gopath, "src", fmt.Sprintf("dir%d", i))
if err := os.Mkdir(dir, 0777); err != nil {
fmt.Fprintln(os.Stderr, err)
return false
}
name := filepath.Join(dir, fmt.Sprintf("t%d.go", i))
f, err := os.Create(name)
if err != nil {
fmt.Fprintln(os.Stderr, err)
return false
}
b := bufio.NewWriter(f)
fmt.Fprintln(b, `package main`)
fmt.Fprintln(b)
fmt.Fprintln(b, `/*`)
fmt.Fprintln(b, t.c)
fmt.Fprintln(b, `*/`)
fmt.Fprintln(b, `import "C"`)
fmt.Fprintln(b)
for _, imp := range t.imports {
fmt.Fprintln(b, `import "`+imp+`"`)
}
if len(t.imports) > 0 {
fmt.Fprintln(b)
}
if len(t.support) > 0 {
fmt.Fprintln(b, t.support)
fmt.Fprintln(b)
}
fmt.Fprintln(b, `func main() {`)
fmt.Fprintln(b, t.body)
fmt.Fprintln(b, `}`)
if err := b.Flush(); err != nil {
fmt.Fprintf(os.Stderr, "flushing %s: %v\n", name, err)
return false
}
if err := f.Close(); err != nil {
fmt.Fprintf(os.Stderr, "closing %s: %v\n", name, err)
return false
}
for _, e := range t.extra {
if err := ioutil.WriteFile(filepath.Join(dir, e.name), []byte(e.contents), 0644); err != nil {
fmt.Fprintf(os.Stderr, "writing %s: %v\n", e.name, err)
return false
}
}
ok := true
cmd := exec.Command("go", "build")
cmd.Dir = dir
cmd.Env = addEnv("GOPATH", gopath)
buf, err := cmd.CombinedOutput()
if err != nil {
fmt.Fprintf(os.Stderr, "test %s failed to build: %v\n%s", t.name, err, buf)
return false
}
exe := filepath.Join(dir, filepath.Base(dir))
cmd = exec.Command(exe)
cmd.Dir = dir
if t.expensive {
cmd.Env = cgocheckEnv("1")
buf, err := cmd.CombinedOutput()
if err != nil {
var errbuf bytes.Buffer
if t.fail {
fmt.Fprintf(&errbuf, "test %s marked expensive but failed when not expensive: %v\n", t.name, err)
} else {
fmt.Fprintf(&errbuf, "test %s failed unexpectedly with GODEBUG=cgocheck=1: %v\n", t.name, err)
}
reportTestOutput(&errbuf, t.name, buf)
os.Stderr.Write(errbuf.Bytes())
ok = false
}
cmd = exec.Command(exe)
cmd.Dir = dir
}
if t.expensive {
cmd.Env = cgocheckEnv("2")
}
buf, err = cmd.CombinedOutput()
if t.fail {
if err == nil {
var errbuf bytes.Buffer
fmt.Fprintf(&errbuf, "test %s did not fail as expected\n", t.name)
reportTestOutput(&errbuf, t.name, buf)
os.Stderr.Write(errbuf.Bytes())
ok = false
} else if !bytes.Contains(buf, []byte("Go pointer")) {
var errbuf bytes.Buffer
fmt.Fprintf(&errbuf, "test %s output does not contain expected error (failed with %v)\n", t.name, err)
reportTestOutput(&errbuf, t.name, buf)
os.Stderr.Write(errbuf.Bytes())
ok = false
}
} else {
if err != nil {
var errbuf bytes.Buffer
fmt.Fprintf(&errbuf, "test %s failed unexpectedly: %v\n", t.name, err)
reportTestOutput(&errbuf, t.name, buf)
os.Stderr.Write(errbuf.Bytes())
ok = false
}
if !t.expensive && ok {
// Make sure it passes with the expensive checks.
cmd := exec.Command(exe)
cmd.Dir = dir
cmd.Env = cgocheckEnv("2")
buf, err := cmd.CombinedOutput()
if err != nil {
var errbuf bytes.Buffer
fmt.Fprintf(&errbuf, "test %s failed unexpectedly with expensive checks: %v\n", t.name, err)
reportTestOutput(&errbuf, t.name, buf)
os.Stderr.Write(errbuf.Bytes())
ok = false
}
}
}
if t.fail && ok {
cmd = exec.Command(exe)
cmd.Dir = dir
cmd.Env = cgocheckEnv("0")
buf, err := cmd.CombinedOutput()
if err != nil {
var errbuf bytes.Buffer
fmt.Fprintf(&errbuf, "test %s failed unexpectedly with GODEBUG=cgocheck=0: %v\n", t.name, err)
reportTestOutput(&errbuf, t.name, buf)
os.Stderr.Write(errbuf.Bytes())
ok = false
}
}
return ok
}
func reportTestOutput(w io.Writer, name string, buf []byte) {
fmt.Fprintf(w, "=== test %s output ===\n", name)
fmt.Fprintf(w, "%s", buf)
fmt.Fprintf(w, "=== end of test %s output ===\n", name)
}
func cgocheckEnv(val string) []string {
return addEnv("GODEBUG", "cgocheck="+val)
}
func addEnv(key, val string) []string {
env := []string{key + "=" + val}
look := key + "="
for _, e := range os.Environ() {
if !strings.HasPrefix(e, look) {
env = append(env, e)
}
}
return env
}