os/user: use libc (not cgo) on macOS

With net converted to libc, os/user is the last remaining
cgo code in the standard libary on macOS.
Convert it to libc too.

Now only plugin remains as a cgo-using package on macOS.

Change-Id: Ibb518b5c62ef9ec1e6ab6191f4b576f7c5a4501c
Reviewed-on: https://go-review.googlesource.com/c/go/+/449316
Reviewed-by: Ian Lance Taylor <[email protected]>
Auto-Submit: Russ Cox <[email protected]>
Run-TryBot: Russ Cox <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: rsc

src/internal/syscall/unix/asm_darwin.s

@@ -4,38 +4,21 @@
 
 #include "textflag.h"
 
-TEXT ·libc_getentropy_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_getentropy(SB)
-
-TEXT ·libc_getaddrinfo_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_getaddrinfo(SB)
-
-TEXT ·libc_freeaddrinfo_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_freeaddrinfo(SB)
-
-TEXT ·libc_getnameinfo_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_getnameinfo(SB)
-
-TEXT ·libc_gai_strerror_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_gai_strerror(SB)
-
-TEXT ·libresolv_res_9_ninit_trampoline(SB),NOSPLIT,$0-0
-	JMP	libresolv_res_9_ninit(SB)
-
-TEXT ·libresolv_res_9_nclose_trampoline(SB),NOSPLIT,$0-0
-	JMP	libresolv_res_9_nclose(SB)
-
-TEXT ·libresolv_res_9_nsearch_trampoline(SB),NOSPLIT,$0-0
-	JMP	libresolv_res_9_nsearch(SB)
-
-TEXT ·libc_grantpt_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_grantpt(SB)
-
-TEXT ·libc_unlockpt_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_unlockpt(SB)
-
-TEXT ·libc_ptsname_r_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_ptsname_r(SB)
-
-TEXT ·libc_posix_openpt_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_posix_openpt(SB)
+TEXT ·libc_getentropy_trampoline(SB),NOSPLIT,$0-0; JMP libc_getentropy(SB)
+TEXT ·libc_getaddrinfo_trampoline(SB),NOSPLIT,$0-0; JMP libc_getaddrinfo(SB)
+TEXT ·libc_freeaddrinfo_trampoline(SB),NOSPLIT,$0-0; JMP libc_freeaddrinfo(SB)
+TEXT ·libc_getnameinfo_trampoline(SB),NOSPLIT,$0-0; JMP libc_getnameinfo(SB)
+TEXT ·libc_gai_strerror_trampoline(SB),NOSPLIT,$0-0; JMP libc_gai_strerror(SB)
+TEXT ·libresolv_res_9_ninit_trampoline(SB),NOSPLIT,$0-0; JMP libresolv_res_9_ninit(SB)
+TEXT ·libresolv_res_9_nclose_trampoline(SB),NOSPLIT,$0-0; JMP libresolv_res_9_nclose(SB)
+TEXT ·libresolv_res_9_nsearch_trampoline(SB),NOSPLIT,$0-0; JMP libresolv_res_9_nsearch(SB)
+TEXT ·libc_grantpt_trampoline(SB),NOSPLIT,$0-0; JMP libc_grantpt(SB)
+TEXT ·libc_unlockpt_trampoline(SB),NOSPLIT,$0-0; JMP libc_unlockpt(SB)
+TEXT ·libc_ptsname_r_trampoline(SB),NOSPLIT,$0-0; JMP libc_ptsname_r(SB)
+TEXT ·libc_posix_openpt_trampoline(SB),NOSPLIT,$0-0; JMP libc_posix_openpt(SB)
+TEXT ·libc_getgrouplist_trampoline(SB),NOSPLIT,$0-0; JMP libc_getgrouplist(SB)
+TEXT ·libc_getpwnam_r_trampoline(SB),NOSPLIT,$0-0; JMP libc_getpwnam_r(SB)
+TEXT ·libc_getpwuid_r_trampoline(SB),NOSPLIT,$0-0; JMP libc_getpwuid_r(SB)
+TEXT ·libc_getgrnam_r_trampoline(SB),NOSPLIT,$0-0; JMP libc_getgrnam_r(SB)
+TEXT ·libc_getgrgid_r_trampoline(SB),NOSPLIT,$0-0; JMP libc_getgrgid_r(SB)
+TEXT ·libc_sysconf_trampoline(SB),NOSPLIT,$0-0; JMP libc_sysconf(SB)

src/internal/syscall/unix/net_darwin.go

@@ -111,9 +111,15 @@ func GoString(p *byte) string {
 //go:linkname syscall_syscall syscall.syscall
 func syscall_syscall(fn, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno)
 
+//go:linkname syscall_syscallPtr syscall.syscallPtr
+func syscall_syscallPtr(fn, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno)
+
 //go:linkname syscall_syscall6 syscall.syscall6
 func syscall_syscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err syscall.Errno)
 
+//go:linkname syscall_syscall6X syscall.syscall6X
+func syscall_syscall6X(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err syscall.Errno)
+
 //go:linkname syscall_syscall9 syscall.syscall9
 func syscall_syscall9(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err syscall.Errno)
 

src/internal/syscall/unix/user_darwin.go

@@ -0,0 +1,117 @@
+// Copyright 2022 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.
+
+package unix
+
+import (
+	"internal/abi"
+	"syscall"
+	"unsafe"
+)
+
+//go:cgo_import_dynamic libc_getgrouplist getgrouplist "/usr/lib/libSystem.B.dylib"
+func libc_getgrouplist_trampoline()
+
+func Getgrouplist(name *byte, gid uint32, gids *uint32, n *int32) error {
+	_, _, errno := syscall_syscall6(abi.FuncPCABI0(libc_getgrouplist_trampoline),
+		uintptr(unsafe.Pointer(name)), uintptr(gid), uintptr(unsafe.Pointer(gids)),
+		uintptr(unsafe.Pointer(n)), 0, 0)
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
+
+const (
+	SC_GETGR_R_SIZE_MAX = 0x46
+	SC_GETPW_R_SIZE_MAX = 0x47
+)
+
+type Passwd struct {
+	Name   *byte
+	Passwd *byte
+	Uid    uint32 // uid_t
+	Gid    uint32 // gid_t
+	Change int64  // time_t
+	Class  *byte
+	Gecos  *byte
+	Dir    *byte
+	Shell  *byte
+	Expire int64 // time_t
+}
+
+type Group struct {
+	Name   *byte
+	Passwd *byte
+	Gid    uint32 // gid_t
+	Mem    **byte
+}
+
+//go:cgo_import_dynamic libc_getpwnam_r getpwnam_r  "/usr/lib/libSystem.B.dylib"
+func libc_getpwnam_r_trampoline()
+
+func Getpwnam(name *byte, pwd *Passwd, buf *byte, size uintptr, result **Passwd) syscall.Errno {
+	_, _, errno := syscall_syscall6(abi.FuncPCABI0(libc_getpwnam_r_trampoline),
+		uintptr(unsafe.Pointer(name)),
+		uintptr(unsafe.Pointer(pwd)),
+		uintptr(unsafe.Pointer(buf)),
+		size,
+		uintptr(unsafe.Pointer(result)),
+		0)
+	return errno
+}
+
+//go:cgo_import_dynamic libc_getpwuid_r getpwuid_r  "/usr/lib/libSystem.B.dylib"
+func libc_getpwuid_r_trampoline()
+
+func Getpwuid(uid uint32, pwd *Passwd, buf *byte, size uintptr, result **Passwd) syscall.Errno {
+	_, _, errno := syscall_syscall6(abi.FuncPCABI0(libc_getpwuid_r_trampoline),
+		uintptr(uid),
+		uintptr(unsafe.Pointer(pwd)),
+		uintptr(unsafe.Pointer(buf)),
+		size,
+		uintptr(unsafe.Pointer(result)),
+		0)
+	return errno
+}
+
+//go:cgo_import_dynamic libc_getgrnam_r getgrnam_r  "/usr/lib/libSystem.B.dylib"
+func libc_getgrnam_r_trampoline()
+
+func Getgrnam(name *byte, grp *Group, buf *byte, size uintptr, result **Group) syscall.Errno {
+	_, _, errno := syscall_syscall6(abi.FuncPCABI0(libc_getgrnam_r_trampoline),
+		uintptr(unsafe.Pointer(name)),
+		uintptr(unsafe.Pointer(grp)),
+		uintptr(unsafe.Pointer(buf)),
+		size,
+		uintptr(unsafe.Pointer(result)),
+		0)
+	return errno
+}
+
+//go:cgo_import_dynamic libc_getgrgid_r getgrgid_r  "/usr/lib/libSystem.B.dylib"
+func libc_getgrgid_r_trampoline()
+
+func Getgrgid(gid uint32, grp *Group, buf *byte, size uintptr, result **Group) syscall.Errno {
+	_, _, errno := syscall_syscall6(abi.FuncPCABI0(libc_getgrgid_r_trampoline),
+		uintptr(gid),
+		uintptr(unsafe.Pointer(grp)),
+		uintptr(unsafe.Pointer(buf)),
+		size,
+		uintptr(unsafe.Pointer(result)),
+		0)
+	return errno
+}
+
+//go:cgo_import_dynamic libc_sysconf sysconf "/usr/lib/libSystem.B.dylib"
+func libc_sysconf_trampoline()
+
+func Sysconf(key int32) int64 {
+	val, _, errno := syscall_syscall6X(abi.FuncPCABI0(libc_sysconf_trampoline),
+		uintptr(key), 0, 0, 0, 0, 0)
+	if errno != 0 {
+		return -1
+	}
+	return int64(val)
+}

src/os/user/cgo_listgroups_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (dragonfly || darwin || freebsd || (!android && linux) || netbsd || openbsd || (solaris && !illumos)) && cgo && !osusergo
+//go:build (cgo || darwin) && !osusergo && (darwin || dragonfly || freebsd || (linux && !android) || netbsd || openbsd || (solaris && !illumos))
 
 package user
 
@@ -12,26 +12,20 @@ import (
 	"unsafe"
 )
 
-/*
-#include <unistd.h>
-#include <sys/types.h>
-*/
-import "C"
-
 const maxGroups = 2048
 
 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)
+	userGID := _C_gid_t(ug)
 	nameC := make([]byte, len(u.Username)+1)
 	copy(nameC, u.Username)
 
-	n := C.int(256)
-	gidsC := make([]C.gid_t, n)
-	rv := getGroupList((*C.char)(unsafe.Pointer(&nameC[0])), userGID, &gidsC[0], &n)
+	n := _C_int(256)
+	gidsC := make([]_C_gid_t, n)
+	rv := getGroupList((*_C_char)(unsafe.Pointer(&nameC[0])), userGID, &gidsC[0], &n)
 	if rv == -1 {
 		// Mac is the only Unix that does not set n properly when rv == -1, so
 		// we need to use different logic for Mac vs. the other OS's.
@@ -46,3 +40,18 @@ func listGroups(u *User) ([]string, error) {
 	}
 	return gids, nil
 }
+
+// groupRetry retries getGroupList with much larger size for n. The result is
+// stored in gids.
+func groupRetry(username string, name []byte, userGID _C_gid_t, gids *[]_C_gid_t, n *_C_int) error {
+	// More than initial buffer, but now n contains the correct size.
+	if *n > maxGroups {
+		return fmt.Errorf("user: %q is a member of more than %d groups", username, maxGroups)
+	}
+	*gids = make([]_C_gid_t, *n)
+	rv := getGroupList((*_C_char)(unsafe.Pointer(&name[0])), userGID, &(*gids)[0], n)
+	if rv == -1 {
+		return fmt.Errorf("user: list groups for %s failed", username)
+	}
+	return nil
+}

src/os/user/cgo_lookup_cgo.go

@@ -0,0 +1,106 @@
+// Copyright 2011 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.
+
+//go:build cgo && !osusergo && unix && !android && !darwin
+
+package user
+
+import (
+	"syscall"
+)
+
+/*
+#cgo solaris CFLAGS: -D_POSIX_PTHREAD_SEMANTICS
+#include <unistd.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+#include <stdlib.h>
+
+static struct passwd mygetpwuid_r(int uid, char *buf, size_t buflen, int *found, int *perr) {
+	struct passwd pwd;
+        struct passwd *result;
+        *perr = getpwuid_r(uid, &pwd, buf, buflen, &result);
+        *found = result != NULL;
+        return pwd;
+}
+
+static struct passwd mygetpwnam_r(const char *name, char *buf, size_t buflen, int *found, int *perr) {
+	struct passwd pwd;
+        struct passwd *result;
+        *perr = getpwnam_r(name, &pwd, buf, buflen, &result);
+        *found = result != NULL;
+        return pwd;
+}
+
+static struct group mygetgrgid_r(int gid, char *buf, size_t buflen, int *found, int *perr) {
+	struct group grp;
+        struct group *result;
+        *perr = getgrgid_r(gid, &grp, buf, buflen, &result);
+        *found = result != NULL;
+        return grp;
+}
+
+static struct group mygetgrnam_r(const char *name, char *buf, size_t buflen, int *found, int *perr) {
+	struct group grp;
+        struct group *result;
+        *perr = getgrnam_r(name, &grp, buf, buflen, &result);
+        *found = result != NULL;
+        return grp;
+}
+*/
+import "C"
+
+type _C_char = C.char
+type _C_int = C.int
+type _C_gid_t = C.gid_t
+type _C_uid_t = C.uid_t
+type _C_size_t = C.size_t
+type _C_struct_group = C.struct_group
+type _C_struct_passwd = C.struct_passwd
+type _C_long = C.long
+
+func _C_pw_uid(p *_C_struct_passwd) _C_uid_t   { return p.pw_uid }
+func _C_pw_uidp(p *_C_struct_passwd) *_C_uid_t { return &p.pw_uid }
+func _C_pw_gid(p *_C_struct_passwd) _C_gid_t   { return p.pw_gid }
+func _C_pw_gidp(p *_C_struct_passwd) *_C_gid_t { return &p.pw_gid }
+func _C_pw_name(p *_C_struct_passwd) *_C_char  { return p.pw_name }
+func _C_pw_gecos(p *_C_struct_passwd) *_C_char { return p.pw_gecos }
+func _C_pw_dir(p *_C_struct_passwd) *_C_char   { return p.pw_dir }
+
+func _C_gr_gid(g *_C_struct_group) _C_gid_t  { return g.gr_gid }
+func _C_gr_name(g *_C_struct_group) *_C_char { return g.gr_name }
+
+func _C_GoString(p *_C_char) string { return C.GoString(p) }
+
+func _C_getpwnam_r(name *_C_char, buf *_C_char, size _C_size_t) (pwd _C_struct_passwd, found bool, errno syscall.Errno) {
+	var f, e _C_int
+	pwd = C.mygetpwnam_r(name, buf, size, &f, &e)
+	return pwd, f != 0, syscall.Errno(e)
+}
+
+func _C_getpwuid_r(uid _C_uid_t, buf *_C_char, size _C_size_t) (pwd _C_struct_passwd, found bool, errno syscall.Errno) {
+	var f, e _C_int
+	pwd = C.mygetpwuid_r(_C_int(uid), buf, size, &f, &e)
+	return pwd, f != 0, syscall.Errno(e)
+}
+
+func _C_getgrnam_r(name *_C_char, buf *_C_char, size _C_size_t) (grp _C_struct_group, found bool, errno syscall.Errno) {
+	var f, e _C_int
+	grp = C.mygetgrnam_r(name, buf, size, &f, &e)
+	return grp, f != 0, syscall.Errno(e)
+}
+
+func _C_getgrgid_r(gid _C_gid_t, buf *_C_char, size _C_size_t) (grp _C_struct_group, found bool, errno syscall.Errno) {
+	var f, e _C_int
+	grp = C.mygetgrgid_r(_C_int(gid), buf, size, &f, &e)
+	return grp, f != 0, syscall.Errno(e)
+}
+
+const (
+	_C__SC_GETPW_R_SIZE_MAX = C._SC_GETPW_R_SIZE_MAX
+	_C__SC_GETGR_R_SIZE_MAX = C._SC_GETGR_R_SIZE_MAX
+)
+
+func _C_sysconf(key _C_int) _C_long { return C.sysconf(key) }