// 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 errorstest
import (
"bytes"
"flag"
"fmt"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"strings"
"sync/atomic"
"testing"
)
var tmp = flag.String("tmp", "", "use `dir` for temporary files and do not clean up")
// ptrTest is the tests without the boilerplate.
type ptrTest struct {
name string // for reporting
c string // the cgo comment
c1 string // cgo comment forced into non-export cgo file
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 s1 { int *p; } s1; void f1(s1 *ps) {}`,
body: `C.f1(&C.s1{new(C.int)})`,
fail: true,
},
{
// Passing a pointer to a struct that contains a Go pointer.
name: "ptr2",
c: `typedef struct s2 { int *p; } s2; void f2(s2 *ps) {}`,
body: `p := &C.s2{new(C.int)}; C.f2(p)`,
fail: true,
},
{
// Passing a pointer to an int field of a Go struct
// that (irrelevantly) contains a Go pointer.
name: "ok1",
c: `struct s3 { int i; int *p; }; void f3(int *p) {}`,
body: `p := &C.struct_s3{i: 0, p: new(C.int)}; C.f3(&p.i)`,
fail: false,
},
{
// Passing a pointer to a pointer field of a Go struct.
name: "ptrfield",
c: `struct s4 { int i; int *p; }; void f4(int **p) {}`,
body: `p := &C.struct_s4{i: 0, p: new(C.int)}; C.f4(&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: "ptrfieldok",
c: `struct s5 { int *p1; int *p2; }; void f5(int **p) {}`,
body: `p := &C.struct_s5{p1: nil, p2: new(C.int)}; C.f5(&p.p1)`,
fail: false,
},
{
// Passing the address of a slice with no Go pointers.
name: "sliceok1",
c: `void f6(void **p) {}`,
imports: []string{"unsafe"},
body: `s := []unsafe.Pointer{nil}; C.f6(&s[0])`,
fail: false,
},
{
// Passing the address of a slice with a Go pointer.
name: "sliceptr1",
c: `void f7(void **p) {}`,
imports: []string{"unsafe"},
body: `i := 0; s := []unsafe.Pointer{unsafe.Pointer(&i)}; C.f7(&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: "sliceptr2",
c: `void f8(void **p) {}`,
imports: []string{"unsafe"},
body: `i := 0; s := []unsafe.Pointer{nil, unsafe.Pointer(&i)}; C.f8(&s[0])`,
fail: true,
},
{
// Passing the address of a slice that is an element
// in a struct only looks at the slice.
name: "sliceok2",
c: `void f9(void **p) {}`,
imports: []string{"unsafe"},
support: `type S9 struct { p *int; s []unsafe.Pointer }`,
body: `i := 0; p := &S9{p:&i, s:[]unsafe.Pointer{nil}}; C.f9(&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: "sliceok3",
c: `void f10(void* p) {}`,
imports: []string{"unsafe"},
support: `type S10 struct { p *int; a [4]byte }`,
body: `i := 0; p := &S10{p:&i}; s := p.a[:]; C.f10(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: "sliceok4",
c: `typedef void* PV11; void f11(PV11 p) {}`,
imports: []string{"unsafe"},
support: `type S11 struct { p *int; a [4]byte }`,
body: `i := 0; p := &S11{p:&i}; C.f11(C.PV11(unsafe.Pointer(&p.a[0])))`,
fail: false,
},
{
// Passing the address of a static variable with no
// pointers doesn't matter.
name: "varok",
c: `void f12(char** parg) {}`,
support: `var hello12 = [...]C.char{'h', 'e', 'l', 'l', 'o'}`,
body: `parg := [1]*C.char{&hello12[0]}; C.f12(&parg[0])`,
fail: false,
},
{
// Passing the address of a static variable with
// pointers does matter.
name: "var1",
c: `void f13(char*** parg) {}`,
support: `var hello13 = [...]*C.char{new(C.char)}`,
body: `parg := [1]**C.char{&hello13[0]}; C.f13(&parg[0])`,
fail: true,
},
{
// Storing a Go pointer into C memory should fail.
name: "barrier",
c: `#include <stdlib.h>
char **f14a() { return malloc(sizeof(char*)); }
void f14b(char **p) {}`,
body: `p := C.f14a(); *p = new(C.char); C.f14b(p)`,
fail: true,
expensive: true,
},
{
// Storing a Go pointer into C memory by assigning a
// large value should fail.
name: "barrierstruct",
c: `#include <stdlib.h>
struct s15 { char *a[10]; };
struct s15 *f15() { return malloc(sizeof(struct s15)); }
void f15b(struct s15 *p) {}`,
body: `p := C.f15(); p.a = [10]*C.char{new(C.char)}; C.f15b(p)`,
fail: true,
expensive: true,
},
{
// Storing a Go pointer into C memory using a slice
// copy should fail.
name: "barrierslice",
c: `#include <stdlib.h>
struct s16 { char *a[10]; };
struct s16 *f16() { return malloc(sizeof(struct s16)); }
void f16b(struct s16 *p) {}`,
body: `p := C.f16(); copy(p.a[:], []*C.char{new(C.char)}); C.f16b(p)`,
fail: true,
expensive: true,
},
{
// A very large value uses a GC program, which is a
// different code path.
name: "barriergcprogarray",
c: `#include <stdlib.h>
struct s17 { char *a[32769]; };
struct s17 *f17() { return malloc(sizeof(struct s17)); }
void f17b(struct s17 *p) {}`,
body: `p := C.f17(); p.a = [32769]*C.char{new(C.char)}; C.f17b(p)`,
fail: true,
expensive: true,
},
{
// Similar case, with a source on the heap.
name: "barriergcprogarrayheap",
c: `#include <stdlib.h>
struct s18 { char *a[32769]; };
struct s18 *f18() { return malloc(sizeof(struct s18)); }
void f18b(struct s18 *p) {}
void f18c(void *p) {}`,
imports: []string{"unsafe"},
body: `p := C.f18(); n := &[32769]*C.char{new(C.char)}; p.a = *n; C.f18b(p); n[0] = nil; C.f18c(unsafe.Pointer(n))`,
fail: true,
expensive: true,
},
{
// A GC program with a struct.
name: "barriergcprogstruct",
c: `#include <stdlib.h>
struct s19a { char *a[32769]; };
struct s19b { struct s19a f; };
struct s19b *f19() { return malloc(sizeof(struct s19b)); }
void f19b(struct s19b *p) {}`,
body: `p := C.f19(); p.f = C.struct_s19a{[32769]*C.char{new(C.char)}}; C.f19b(p)`,
fail: true,
expensive: true,
},
{
// Similar case, with a source on the heap.
name: "barriergcprogstructheap",
c: `#include <stdlib.h>
struct s20a { char *a[32769]; };
struct s20b { struct s20a f; };
struct s20b *f20() { return malloc(sizeof(struct s20b)); }
void f20b(struct s20b *p) {}
void f20c(void *p) {}`,
imports: []string{"unsafe"},
body: `p := C.f20(); n := &C.struct_s20a{[32769]*C.char{new(C.char)}}; p.f = *n; C.f20b(p); n.a[0] = nil; C.f20c(unsafe.Pointer(n))`,
fail: true,
expensive: true,
},
{
// Exported functions may not return Go pointers.
name: "export1",
c: `extern unsigned char *GoFn21();`,
support: `//export GoFn21
func GoFn21() *byte { return new(byte) }`,
body: `C.GoFn21()`,
fail: true,
},
{
// Returning a C pointer is fine.
name: "exportok",
c: `#include <stdlib.h>
extern unsigned char *GoFn22();`,
support: `//export GoFn22
func GoFn22() *byte { return (*byte)(C.malloc(1)) }`,
body: `C.GoFn22()`,
},
{
// Passing a Go string is fine.
name: "passstring",
c: `#include <stddef.h>
typedef struct { const char *p; ptrdiff_t n; } gostring23;
gostring23 f23(gostring23 s) { return s; }`,
imports: []string{"unsafe"},
body: `s := "a"; r := C.f23(*(*C.gostring23)(unsafe.Pointer(&s))); if *(*string)(unsafe.Pointer(&r)) != s { panic(r) }`,
},
{
// Passing a slice of Go strings fails.
name: "passstringslice",
c: `void f24(void *p) {}`,
imports: []string{"strings", "unsafe"},
support: `type S24 struct { a [1]string }`,
body: `s := S24{a:[1]string{strings.Repeat("a", 2)}}; C.f24(unsafe.Pointer(&s.a[0]))`,
fail: true,
},
{
// Exported functions may not return strings.
name: "retstring",
c: `extern void f25();`,
imports: []string{"strings"},
support: `//export GoStr25
func GoStr25() string { return strings.Repeat("a", 2) }`,
body: `C.f25()`,
c1: `#include <stddef.h>
typedef struct { const char *p; ptrdiff_t n; } gostring25;
extern gostring25 GoStr25();
void f25() { GoStr25(); }`,
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 f26(void* p) {}`,
imports: []string{"unsafe"},
support: `type S26 struct { p *int; a [8*8]byte; u uintptr }`,
body: `i := 0; p := &S26{u:uintptr(unsafe.Pointer(&i))}; q := (*S26)(C.malloc(C.size_t(unsafe.Sizeof(*p)))); *q = *p; C.f26(unsafe.Pointer(q))`,
fail: false,
},
{
// Like ptrdata1, but with a type that uses a GC program.
name: "ptrdata2",
c: `#include <stdlib.h>
void f27(void* p) {}`,
imports: []string{"unsafe"},
support: `type S27 struct { p *int; a [32769*8]byte; q *int; u uintptr }`,
body: `i := 0; p := S27{u:uintptr(unsafe.Pointer(&i))}; q := (*S27)(C.malloc(C.size_t(unsafe.Sizeof(p)))); *q = p; C.f27(unsafe.Pointer(q))`,
fail: false,
},
{
// Check deferred pointers when they are used, not
// when the defer statement is run.
name: "defer1",
c: `typedef struct s28 { int *p; } s28; void f28(s28 *ps) {}`,
body: `p := &C.s28{}; defer C.f28(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; } u29; void f29(u29 *pu) {}`,
imports: []string{"unsafe"},
body: `var b C.char; p := &b; C.f29((*C.u29)(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; } u39; void f39(u39 *pu) {}`,
imports: []string{"unsafe"},
body: `var b C.char; p := &b; C.f39((*C.u39)(unsafe.Pointer(&p)))`,
fail: false,
},
{
// Test preemption while entering a cgo call. Issue #21306.
name: "preemptduringcall",
c: `void f30() {}`,
imports: []string{"runtime", "sync"},
body: `var wg sync.WaitGroup; wg.Add(100); for i := 0; i < 100; i++ { go func(i int) { for j := 0; j < 100; j++ { C.f30(); runtime.GOMAXPROCS(i) }; wg.Done() }(i) }; wg.Wait()`,
fail: false,
},
{
// Test poller deadline with cgocheck=2. Issue #23435.
name: "deadline",
c: `#define US31 10`,
imports: []string{"os", "time"},
body: `r, _, _ := os.Pipe(); r.SetDeadline(time.Now().Add(C.US31 * time.Microsecond))`,
fail: false,
},
{
// Test for double evaluation of channel receive.
name: "chanrecv",
c: `void f32(char** p) {}`,
imports: []string{"time"},
body: `c := make(chan []*C.char, 2); c <- make([]*C.char, 1); go func() { time.Sleep(10 * time.Second); panic("received twice from chan") }(); C.f32(&(<-c)[0]);`,
fail: false,
},
{
// Test that converting the address of a struct field
// to unsafe.Pointer still just checks that field.
// Issue #25941.
name: "structfield",
c: `void f33(void* p) {}`,
imports: []string{"unsafe"},
support: `type S33 struct { p *int; a [8]byte; u uintptr }`,
body: `s := &S33{p: new(int)}; C.f33(unsafe.Pointer(&s.a))`,
fail: false,
},
{
// Test that converting multiple struct field
// addresses to unsafe.Pointer still just checks those
// fields. Issue #25941.
name: "structfield2",
c: `void f34(void* p, int r, void* s) {}`,
imports: []string{"unsafe"},
support: `type S34 struct { a [8]byte; p *int; b int64; }`,
body: `s := &S34{p: new(int)}; C.f34(unsafe.Pointer(&s.a), 32, unsafe.Pointer(&s.b))`,
fail: false,
},
{
// Test that second argument to cgoCheckPointer is
// evaluated when a deferred function is deferred, not
// when it is run.
name: "defer2",
c: `void f35(char **pc) {}`,
support: `type S35a struct { s []*C.char }; type S35b struct { ps *S35a }`,
body: `p := &S35b{&S35a{[]*C.char{nil}}}; defer C.f35(&p.ps.s[0]); p.ps = nil`,
fail: false,
},
{
// Test that indexing into a function call still
// examines only the slice being indexed.
name: "buffer",
c: `void f36(void *p) {}`,
imports: []string{"bytes", "unsafe"},
body: `var b bytes.Buffer; b.WriteString("a"); C.f36(unsafe.Pointer(&b.Bytes()[0]))`,
fail: false,
},
{
// Test that bgsweep releasing a finalizer is OK.
name: "finalizer",
c: `// Nothing to declare.`,
imports: []string{"os"},
support: `func open37() { os.Open(os.Args[0]) }; var G37 [][]byte`,
body: `for i := 0; i < 10000; i++ { G37 = append(G37, make([]byte, 4096)); if i % 100 == 0 { G37 = nil; open37() } }`,
fail: false,
},
{
// Test that converting generated struct to interface is OK.
name: "structof",
c: `// Nothing to declare.`,
imports: []string{"reflect"},
support: `type MyInt38 int; func (i MyInt38) Get() int { return int(i) }; type Getter38 interface { Get() int }`,
body: `t := reflect.StructOf([]reflect.StructField{{Name: "MyInt38", Type: reflect.TypeOf(MyInt38(0)), Anonymous: true}}); v := reflect.New(t).Elem(); v.Interface().(Getter38).Get()`,
fail: false,
},
{
// Test that a converted address of a struct field results
// in a check for just that field and not the whole struct.
name: "structfieldcast",
c: `struct S40i { int i; int* p; }; void f40(struct S40i* p) {}`,
support: `type S40 struct { p *int; a C.struct_S40i }`,
body: `s := &S40{p: new(int)}; C.f40((*C.struct_S40i)(&s.a))`,
fail: false,
},
}
func TestPointerChecks(t *testing.T) {
dir, exe := buildPtrTests(t)
// We (TestPointerChecks) return before the parallel subtest functions do,
// so we can't just defer os.RemoveAll(dir). Instead we have to wait for
// the parallel subtests to finish. This code looks racy but is not:
// the add +1 run in serial before testOne blocks. The -1 run in parallel
// after testOne finishes.
var pending int32
for _, pt := range ptrTests {
pt := pt
t.Run(pt.name, func(t *testing.T) {
atomic.AddInt32(&pending, +1)
defer func() {
if atomic.AddInt32(&pending, -1) == 0 {
os.RemoveAll(dir)
}
}()
testOne(t, pt, exe)
})
}
}
func buildPtrTests(t *testing.T) (dir, exe string) {
var gopath string
if *tmp != "" {
gopath = *tmp
dir = ""
} else {
d, err := ioutil.TempDir("", filepath.Base(t.Name()))
if err != nil {
t.Fatal(err)
}
dir = d
gopath = d
}
src := filepath.Join(gopath, "src", "ptrtest")
if err := os.MkdirAll(src, 0777); err != nil {
t.Fatal(err)
}
if err := ioutil.WriteFile(filepath.Join(src, "go.mod"), []byte("module ptrtest"), 0666); err != nil {
t.Fatal(err)
}
// Prepare two cgo inputs: one for standard cgo and one for //export cgo.
// (The latter cannot have C definitions, only declarations.)
var cgo1, cgo2 bytes.Buffer
fmt.Fprintf(&cgo1, "package main\n\n/*\n")
fmt.Fprintf(&cgo2, "package main\n\n/*\n")
// C code
for _, pt := range ptrTests {
cgo := &cgo1
if strings.Contains(pt.support, "//export") {
cgo = &cgo2
}
fmt.Fprintf(cgo, "%s\n", pt.c)
fmt.Fprintf(&cgo1, "%s\n", pt.c1)
}
fmt.Fprintf(&cgo1, "*/\nimport \"C\"\n\n")
fmt.Fprintf(&cgo2, "*/\nimport \"C\"\n\n")
// Imports
did1 := make(map[string]bool)
did2 := make(map[string]bool)
did1["os"] = true // for ptrTestMain
fmt.Fprintf(&cgo1, "import \"os\"\n")
for _, pt := range ptrTests {
did := did1
cgo := &cgo1
if strings.Contains(pt.support, "//export") {
did = did2
cgo = &cgo2
}
for _, imp := range pt.imports {
if !did[imp] {
did[imp] = true
fmt.Fprintf(cgo, "import %q\n", imp)
}
}
}
// Func support and bodies.
for _, pt := range ptrTests {
cgo := &cgo1
if strings.Contains(pt.support, "//export") {
cgo = &cgo2
}
fmt.Fprintf(cgo, "%s\nfunc %s() {\n%s\n}\n", pt.support, pt.name, pt.body)
}
// Func list and main dispatch.
fmt.Fprintf(&cgo1, "var funcs = map[string]func() {\n")
for _, pt := range ptrTests {
fmt.Fprintf(&cgo1, "\t%q: %s,\n", pt.name, pt.name)
}
fmt.Fprintf(&cgo1, "}\n\n")
fmt.Fprintf(&cgo1, "%s\n", ptrTestMain)
if err := ioutil.WriteFile(filepath.Join(src, "cgo1.go"), cgo1.Bytes(), 0666); err != nil {
t.Fatal(err)
}
if err := ioutil.WriteFile(filepath.Join(src, "cgo2.go"), cgo2.Bytes(), 0666); err != nil {
t.Fatal(err)
}
cmd := exec.Command("go", "build", "-o", "ptrtest.exe")
cmd.Dir = src
cmd.Env = append(os.Environ(), "GOPATH="+gopath)
out, err := cmd.CombinedOutput()
if err != nil {
t.Fatalf("go build: %v\n%s", err, out)
}
return dir, filepath.Join(src, "ptrtest.exe")
}
const ptrTestMain = `
func main() {
for _, arg := range os.Args[1:] {
f := funcs[arg]
if f == nil {
panic("missing func "+arg)
}
f()
}
}
`
var csem = make(chan bool, 16)
func testOne(t *testing.T, pt ptrTest, exe string) {
t.Parallel()
// Run the tests in parallel, but don't run too many
// executions in parallel, to avoid overloading the system.
runcmd := func(cgocheck string) ([]byte, error) {
csem <- true
defer func() { <-csem }()
cmd := exec.Command(exe, pt.name)
cmd.Env = append(os.Environ(), "GODEBUG=cgocheck="+cgocheck)
return cmd.CombinedOutput()
}
if pt.expensive {
buf, err := runcmd("1")
if err != nil {
t.Logf("%s", buf)
if pt.fail {
t.Fatalf("test marked expensive, but failed when not expensive: %v", err)
} else {
t.Errorf("failed unexpectedly with GODEBUG=cgocheck=1: %v", err)
}
}
}
cgocheck := ""
if pt.expensive {
cgocheck = "2"
}
buf, err := runcmd(cgocheck)
if pt.fail {
if err == nil {
t.Logf("%s", buf)
t.Fatalf("did not fail as expected")
} else if !bytes.Contains(buf, []byte("Go pointer")) {
t.Logf("%s", buf)
t.Fatalf("did not print expected error (failed with %v)", err)
}
} else {
if err != nil {
t.Logf("%s", buf)
t.Fatalf("failed unexpectedly: %v", err)
}
if !pt.expensive {
// Make sure it passes with the expensive checks.
buf, err := runcmd("2")
if err != nil {
t.Logf("%s", buf)
t.Fatalf("failed unexpectedly with expensive checks: %v", err)
}
}
}
if pt.fail {
buf, err := runcmd("0")
if err != nil {
t.Logf("%s", buf)
t.Fatalf("failed unexpectedly with GODEBUG=cgocheck=0: %v", err)
}
}
}
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