os/user: make OS-specific getgrouplist calls

getgrouplist is non-standard and has slightly different semantics on
each platform.  Darwin defines the function in terms of ints instead of
gid_ts.  Solaris only recently supported the call, so stubbing out for
now.

Fixes #14696
Fixes #14709

Change-Id: I5a44538d41594909efb6f3f9610c55d638c36757
Reviewed-on: https://go-review.googlesource.com/20348
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/os/user/getgrouplist_darwin.c

+// Copyright 2016 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.
+
+// +build cgo
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <stdlib.h>
+
+int mygetgrouplist(const char* user, gid_t group, gid_t* groups, int* ngroups) {
+	int* buf = malloc(*ngroups * sizeof(int));
+	int rv = getgrouplist(user, (int) group, buf, ngroups);
+	int i;
+	if (rv == 0) {
+		for (i = 0; i < *ngroups; i++) {
+			groups[i] = (gid_t) buf[i];
+		}
+	}
+	free(buf);
+	return rv;
+}

src/os/user/getgrouplist_unix.c

+// Copyright 2016 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.
+
+// +build cgo
+// +build dragonfly freebsd !android,linux netbsd openbsd
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <grp.h>
+
+int mygetgrouplist(const char* user, gid_t group, gid_t* groups, int* ngroups) {
+	return getgrouplist(user, group, groups, ngroups);
+}

src/os/user/listgroups_solaris.go

+// Copyright 2016 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.
+
+// +build cgo
+
+// Even though this file requires no C, it is used to provide a
+// listGroup stub because all the other Solaris calls work.  Otherwise,
+// this stub will conflict with the lookup_stubs.go fallback.
+
+package user
+
+import "fmt"
+
+func listGroups(u *User) ([]string, error) {
+	return nil, fmt.Errorf("user: list groups for %s: not supported on Solaris", u.Username)
+}

src/os/user/listgroups_unix.go

+// Copyright 2016 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.
+
+// +build dragonfly darwin freebsd !android,linux netbsd openbsd
+
+package user
+
+import (
+	"fmt"
+	"strconv"
+	"unsafe"
+)
+
+/*
+#include <unistd.h>
+#include <sys/types.h>
+#include <stdlib.h>
+
+extern int mygetgrouplist(const char* user, gid_t group, gid_t* groups, int* ngroups);
+*/
+import "C"
+
+func listGroups(u *User) ([]string, error) {
+	ug, err := strconv.Atoi(u.Gid)
+	if err != nil {
+		return nil, fmt.Errorf("user: list groups for %s: invalid gid %q", u.Username, u.Gid)
+	}
+	userGID := C.gid_t(ug)
+	nameC := C.CString(u.Username)
+	defer C.free(unsafe.Pointer(nameC))
+
+	n := C.int(256)
+	gidsC := make([]C.gid_t, n)
+	rv := C.mygetgrouplist(nameC, userGID, &gidsC[0], &n)
+	if rv == -1 {
+		// More than initial buffer, but now n contains the correct size.
+		const maxGroups = 2048
+		if n > maxGroups {
+			return nil, fmt.Errorf("user: list groups for %s: member of more than %d groups", u.Username, maxGroups)
+		}
+		gidsC = make([]C.gid_t, n)
+		rv := C.mygetgrouplist(nameC, userGID, &gidsC[0], &n)
+		if rv == -1 {
+			return nil, fmt.Errorf("user: list groups for %s failed (changed groups?)", u.Username)
+		}
+	}
+	gidsC = gidsC[:n]
+	gids := make([]string, 0, n)
+	for _, g := range gidsC[:n] {
+		gids = append(gids, strconv.Itoa(int(g)))
+	}
+	return gids, nil
+}

src/os/user/lookup_unix.go

@@ -37,11 +37,6 @@ static int mygetgrgid_r(int gid, struct group *grp,
 	char *buf, size_t buflen, struct group **result) {
  return getgrgid_r(gid, grp, buf, buflen, result);
 }
-
-static int mygetgrouplist(const char *user, gid_t group, gid_t *groups,
-	int *ngroups) {
- return getgrouplist(user, group, groups, ngroups);
-}
 */
 import "C"
 
@@ -112,38 +107,6 @@ func lookupUnixUid(uid int) (*User, error) {
 	return buildUser(&pwd), nil
 }
 
-func listGroups(u *User) ([]string, error) {
-	ug, err := strconv.Atoi(u.Gid)
-	if err != nil {
-		return nil, fmt.Errorf("user: list groups for %s: invalid gid %q", u.Username, u.Gid)
-	}
-	userGID := C.gid_t(ug)
-	nameC := C.CString(u.Username)
-	defer C.free(unsafe.Pointer(nameC))
-
-	n := C.int(256)
-	gidsC := make([]C.gid_t, n)
-	rv := C.mygetgrouplist(nameC, userGID, &gidsC[0], &n)
-	if rv == -1 {
-		// More than initial buffer, but now n contains the correct size.
-		const maxGroups = 2048
-		if n > maxGroups {
-			return nil, fmt.Errorf("user: list groups for %s: member of more than %d groups", u.Username, maxGroups)
-		}
-		gidsC = make([]C.gid_t, n)
-		rv := C.mygetgrouplist(nameC, userGID, &gidsC[0], &n)
-		if rv == -1 {
-			return nil, fmt.Errorf("user: list groups for %s failed (changed groups?)", u.Username)
-		}
-	}
-	gidsC = gidsC[:n]
-	gids := make([]string, 0, n)
-	for _, g := range gidsC[:n] {
-		gids = append(gids, strconv.Itoa(int(g)))
-	}
-	return gids, nil
-}
-
 func buildUser(pwd *C.struct_passwd) *User {
 	u := &User{
 		Uid:      strconv.Itoa(int(pwd.pw_uid)),

src/os/user/user_test.go

@@ -121,6 +121,9 @@ func TestLookupGroup(t *testing.T) {
 
 func TestGroupIds(t *testing.T) {
 	checkGroup(t)
+	if runtime.GOOS == "solaris" {
+		t.Skip("skipping GroupIds, see golang.org/issue/14709")
+	}
 	user, err := Current()
 	if err != nil {
 		t.Fatalf("Current(): %v", err)