Golang syscall.Entersyscall函數代碼示例

func (file *File) readdirnames(n int) (names []string, err error) {
	if elen == 0 {
		var dummy syscall.Dirent
		elen = (int(unsafe.Offsetof(dummy.Name)) +
			libc_pathconf(syscall.StringBytePtr(file.name), syscall.PC_NAME_MAX) +
			1)
	}

	if file.dirinfo == nil {
		file.dirinfo = new(dirInfo)
		file.dirinfo.buf = make([]byte, elen)
		p := syscall.StringBytePtr(file.name)
		syscall.Entersyscall()
		r := libc_opendir(p)
		syscall.Exitsyscall()
		file.dirinfo.dir = r
	}

	entry_dirent := (*syscall.Dirent)(unsafe.Pointer(&file.dirinfo.buf[0]))

	size := n
	if size <= 0 {
		size = 100
		n = -1
	}

	names = make([]string, 0, size) // Empty with room to grow.

	dir := file.dirinfo.dir
	if dir == nil {
		return names, NewSyscallError("opendir", syscall.GetErrno())
	}

	for n != 0 {
		var result *syscall.Dirent
		pr := &result
		syscall.Entersyscall()
		i := libc_readdir_r(dir, entry_dirent, pr)
		syscall.Exitsyscall()
		if i != 0 {
			return names, NewSyscallError("readdir_r", i)
		}
		if result == nil {
			break // EOF
		}
		var name = string(result.Name[0:clen(result.Name[0:])])
		if name == "." || name == ".." { // Useless names
			continue
		}
		names = append(names, name)
		n--
	}
	if n >= 0 && len(names) == 0 {
		return names, io.EOF
	}
	return names, nil
}

func lookupUnix(uid int, username string, lookupByName bool) (*User, error) {
	var pwd syscall.Passwd
	var result *syscall.Passwd

	// FIXME: Should let buf grow if necessary.
	const bufSize = 1024
	buf := make([]byte, bufSize)
	if lookupByName {
		nameC := syscall.StringBytePtr(username)
		syscall.Entersyscall()
		rv := libc_getpwnam_r(nameC,
			&pwd,
			&buf[0],
			bufSize,
			&result)
		syscall.Exitsyscall()
		if rv != 0 {
			return nil, fmt.Errorf("user: lookup username %s: %s", username, syscall.GetErrno())
		}
		if result == nil {
			return nil, UnknownUserError(username)
		}
	} else {
		syscall.Entersyscall()
		rv := libc_getpwuid_r(syscall.Uid_t(uid),
			&pwd,
			&buf[0],
			bufSize,
			&result)
		syscall.Exitsyscall()
		if rv != 0 {
			return nil, fmt.Errorf("user: lookup userid %d: %s", uid, syscall.GetErrno())
		}
		if result == nil {
			return nil, UnknownUserIdError(uid)
		}
	}
	u := &User{
		Uid:      strconv.Itoa(int(pwd.Pw_uid)),
		Gid:      strconv.Itoa(int(pwd.Pw_gid)),
		Username: bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_name))),
		Name:     bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_gecos))),
		HomeDir:  bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_dir))),
	}
	// The pw_gecos field isn't quite standardized.  Some docs
	// say: "It is expected to be a comma separated list of
	// personal data where the first item is the full name of the
	// user."
	if i := strings.Index(u.Name, ","); i >= 0 {
		u.Name = u.Name[:i]
	}
	return u, nil
}

func dupCloseOnExec(fd int) (newfd int, err error) {
	if atomic.LoadInt32(&tryDupCloexec) == 1 && syscall.F_DUPFD_CLOEXEC != 0 {
		syscall.Entersyscall()
		r0, errno := fcntl(uintptr(fd), syscall.F_DUPFD_CLOEXEC, 0)
		syscall.Exitsyscall()
		e1 := syscall.Errno(errno)
		if runtime.GOOS == "darwin" && e1 == syscall.EBADF {
			// On OS X 10.6 and below (but we only support
			// >= 10.6), F_DUPFD_CLOEXEC is unsupported
			// and fcntl there falls back (undocumented)
			// to doing an ioctl instead, returning EBADF
			// in this case because fd is not of the
			// expected device fd type.  Treat it as
			// EINVAL instead, so we fall back to the
			// normal dup path.
			// TODO: only do this on 10.6 if we can detect 10.6
			// cheaply.
			e1 = syscall.EINVAL
		}
		switch e1 {
		case 0:
			return int(r0), nil
		case syscall.EINVAL:
			// Old kernel. Fall back to the portable way
			// from now on.
			atomic.StoreInt32(&tryDupCloexec, 0)
		default:
			return -1, os.NewSyscallError("fcntl", e1)
		}
	}
	return dupCloseOnExecOld(fd)
}

func lookupUnixUid(uid int) (*User, error) {
	var pwd syscall.Passwd
	var result *syscall.Passwd

	buf := alloc(userBuffer)
	defer buf.free()

	err := retryWithBuffer(buf, func() syscall.Errno {
		syscall.Entersyscall()
		rv := libc_getpwuid_r(syscall.Uid_t(uid),
			&pwd,
			buf.ptr,
			buf.size,
			&result)
		syscall.Exitsyscall()
		if rv != 0 {
			return syscall.GetErrno()
		}
		return 0
	})
	if err != nil {
		return nil, fmt.Errorf("user: lookup userid %d: %v", uid, err)
	}
	if result == nil {
		return nil, UnknownUserIdError(uid)
	}
	return buildUser(&pwd), nil
}

func lookupUser(username string) (*User, error) {
	var pwd syscall.Passwd
	var result *syscall.Passwd
	p := syscall.StringBytePtr(username)

	buf := alloc(userBuffer)
	defer buf.free()

	err := retryWithBuffer(buf, func() syscall.Errno {
		syscall.Entersyscall()
		rv := libc_getpwnam_r(p,
			&pwd,
			buf.ptr,
			buf.size,
			&result)
		syscall.Exitsyscall()
		if rv != 0 {
			return syscall.GetErrno()
		}
		return 0
	})
	if err != nil {
		return nil, fmt.Errorf("user: lookup username %s: %v", username, err)
	}
	if result == nil {
		return nil, UnknownUserError(username)
	}
	return buildUser(&pwd), err
}

func lookupUnixGid(gid int) (*Group, error) {
	var grp syscall.Group
	var result *syscall.Group

	buf := alloc(groupBuffer)
	defer buf.free()

	err := retryWithBuffer(buf, func() syscall.Errno {
		syscall.Entersyscall()
		rv := libc_getgrgid_r(syscall.Gid_t(gid),
			&grp,
			buf.ptr,
			buf.size,
			&result)
		syscall.Exitsyscall()
		if rv != 0 {
			return syscall.GetErrno()
		}
		return 0
	})
	if err != nil {
		return nil, fmt.Errorf("user: lookup groupid %d: %v", gid, err)
	}
	if result == nil {
		return nil, UnknownGroupIdError(strconv.Itoa(gid))
	}
	return buildGroup(&grp), nil
}

func lookupGroup(groupname string) (*Group, error) {
	var grp syscall.Group
	var result *syscall.Group

	buf := alloc(groupBuffer)
	defer buf.free()
	p := syscall.StringBytePtr(groupname)

	err := retryWithBuffer(buf, func() syscall.Errno {
		syscall.Entersyscall()
		rv := libc_getgrnam_r(p,
			&grp,
			buf.ptr,
			buf.size,
			&result)
		syscall.Exitsyscall()
		if rv != 0 {
			return syscall.GetErrno()
		}
		return 0
	})
	if err != nil {
		return nil, fmt.Errorf("user: lookup groupname %s: %v", groupname, err)
	}
	if result == nil {
		return nil, UnknownGroupError(groupname)
	}
	return buildGroup(&grp), nil
}

func (file *file) close() error {
	if file == nil || file.fd < 0 {
		return syscall.EINVAL
	}
	var err error
	if e := syscall.Close(file.fd); e != nil {
		err = &PathError{"close", file.name, e}
	}

	if file.dirinfo != nil {
		syscall.Entersyscall()
		i := libc_closedir(file.dirinfo.dir)
		errno := syscall.GetErrno()
		syscall.Exitsyscall()
		file.dirinfo = nil
		if i < 0 && err == nil {
			err = &PathError{"closedir", file.name, errno}
		}
	}

	file.fd = -1 // so it can't be closed again

	// no need for a finalizer anymore
	runtime.SetFinalizer(file, nil)
	return err
}

func cgoLookupPort(network, service string) (port int, err error, completed bool) {
	acquireThread()
	defer releaseThread()

	var hints syscall.Addrinfo
	switch network {
	case "": // no hints
	case "tcp", "tcp4", "tcp6":
		hints.Ai_socktype = syscall.SOCK_STREAM
		hints.Ai_protocol = syscall.IPPROTO_TCP
	case "udp", "udp4", "udp6":
		hints.Ai_socktype = syscall.SOCK_DGRAM
		hints.Ai_protocol = syscall.IPPROTO_UDP
	default:
		return 0, &DNSError{Err: "unknown network", Name: network + "/" + service}, true
	}
	if len(network) >= 4 {
		switch network[3] {
		case '4':
			hints.Ai_family = syscall.AF_INET
		case '6':
			hints.Ai_family = syscall.AF_INET6
		}
	}

	s := syscall.StringBytePtr(service)
	var res *syscall.Addrinfo
	syscall.Entersyscall()
	gerrno := libc_getaddrinfo(nil, s, &hints, &res)
	syscall.Exitsyscall()
	if gerrno != 0 {
		switch gerrno {
		case syscall.EAI_SYSTEM:
			errno := syscall.GetErrno()
			if errno == 0 { // see golang.org/issue/6232
				errno = syscall.EMFILE
			}
			err = errno
		default:
			err = addrinfoErrno(gerrno)
		}
		return 0, &DNSError{Err: err.Error(), Name: network + "/" + service}, true
	}
	defer libc_freeaddrinfo(res)

	for r := res; r != nil; r = r.Ai_next {
		switch r.Ai_family {
		case syscall.AF_INET:
			sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.Ai_addr))
			p := (*[2]byte)(unsafe.Pointer(&sa.Port))
			return int(p[0])<<8 | int(p[1]), nil, true
		case syscall.AF_INET6:
			sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.Ai_addr))
			p := (*[2]byte)(unsafe.Pointer(&sa.Port))
			return int(p[0])<<8 | int(p[1]), nil, true
		}
	}
	return 0, &DNSError{Err: "unknown port", Name: network + "/" + service}, true
}

func cgoLookupIPCNAME(name string) (addrs []IP, cname string, err error, completed bool) {
	var res *syscall.Addrinfo
	var hints syscall.Addrinfo

	// NOTE(rsc): In theory there are approximately balanced
	// arguments for and against including AI_ADDRCONFIG
	// in the flags (it includes IPv4 results only on IPv4 systems,
	// and similarly for IPv6), but in practice setting it causes
	// getaddrinfo to return the wrong canonical name on Linux.
	// So definitely leave it out.
	hints.Ai_flags = int32((syscall.AI_ALL | syscall.AI_V4MAPPED | syscall.AI_CANONNAME) & cgoAddrInfoMask())

	h := syscall.StringBytePtr(name)
	syscall.Entersyscall()
	gerrno := libc_getaddrinfo(h, nil, &hints, &res)
	syscall.Exitsyscall()
	if gerrno != 0 {
		var str string
		if gerrno == syscall.EAI_NONAME {
			str = noSuchHost
		} else if gerrno == syscall.EAI_SYSTEM {
			str = syscall.GetErrno().Error()
		} else {
			str = bytePtrToString(libc_gai_strerror(gerrno))
		}
		return nil, "", &DNSError{Err: str, Name: name}, true
	}
	defer libc_freeaddrinfo(res)
	if res != nil {
		cname = bytePtrToString((*byte)(unsafe.Pointer(res.Ai_canonname)))
		if cname == "" {
			cname = name
		}
		if len(cname) > 0 && cname[len(cname)-1] != '.' {
			cname += "."
		}
	}
	for r := res; r != nil; r = r.Ai_next {
		// Everything comes back twice, once for UDP and once for TCP.
		if r.Ai_socktype != syscall.SOCK_STREAM {
			continue
		}
		switch r.Ai_family {
		default:
			continue
		case syscall.AF_INET:
			sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.Ai_addr))
			addrs = append(addrs, copyIP(sa.Addr[:]))
		case syscall.AF_INET6:
			sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.Ai_addr))
			addrs = append(addrs, copyIP(sa.Addr[:]))
		}
	}
	return addrs, cname, nil, true
}

func (libcConn) writeString(p Priority, hostname, tag, msg, nl string) error {
	timestamp := time.Now().Format(time.RFC3339)
	log := fmt.Sprintf("%s %s %s[%d]: %s%s", timestamp, hostname, tag, os.Getpid(), msg, nl)
	buf, err := syscall.BytePtrFromString(log)
	if err != nil {
		return err
	}
	syscall.Entersyscall()
	syslog_c(int(p), buf)
	syscall.Exitsyscall()
	return nil
}

func cgoNameinfoPTR(b []byte, sa *syscall.RawSockaddr, salen syscall.Socklen_t) (int, error) {
	syscall.Entersyscall()
	gerrno := libc_getnameinfo(sa, salen, &b[0], syscall.Size_t(len(b)), nil, 0, syscall.NI_NAMEREQD)
	syscall.Exitsyscall()
	var err error
	if gerrno == syscall.EAI_SYSTEM {
		errno := syscall.GetErrno()
		if errno != 0 {
			err = errno
		}
	}
	return gerrno, err
}

func cgoLookupPort(net, service string) (port int, err error, completed bool) {
	acquireThread()
	defer releaseThread()

	var res *syscall.Addrinfo
	var hints syscall.Addrinfo

	switch net {
	case "":
		// no hints
	case "tcp", "tcp4", "tcp6":
		hints.Ai_socktype = syscall.SOCK_STREAM
		hints.Ai_protocol = syscall.IPPROTO_TCP
	case "udp", "udp4", "udp6":
		hints.Ai_socktype = syscall.SOCK_DGRAM
		hints.Ai_protocol = syscall.IPPROTO_UDP
	default:
		return 0, UnknownNetworkError(net), true
	}
	if len(net) >= 4 {
		switch net[3] {
		case '4':
			hints.Ai_family = syscall.AF_INET
		case '6':
			hints.Ai_family = syscall.AF_INET6
		}
	}

	s := syscall.StringBytePtr(service)
	syscall.Entersyscall()
	gerrno := libc_getaddrinfo(nil, s, &hints, &res)
	syscall.Exitsyscall()
	if gerrno == 0 {
		defer libc_freeaddrinfo(res)
		for r := res; r != nil; r = r.Ai_next {
			switch r.Ai_family {
			default:
				continue
			case syscall.AF_INET:
				sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.Ai_addr))
				p := (*[2]byte)(unsafe.Pointer(&sa.Port))
				return int(p[0])<<8 | int(p[1]), nil, true
			case syscall.AF_INET6:
				sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.Ai_addr))
				p := (*[2]byte)(unsafe.Pointer(&sa.Port))
				return int(p[0])<<8 | int(p[1]), nil, true
			}
		}
	}
	return 0, &AddrError{"unknown port", net + "/" + service}, true
}

func cgoLookupIPCNAME(name string) (addrs []IP, cname string, err error, completed bool) {
	var res *syscall.Addrinfo
	var hints syscall.Addrinfo

	hints.Ai_flags = int32(cgoAddrInfoFlags())
	hints.Ai_socktype = syscall.SOCK_STREAM

	h := syscall.StringBytePtr(name)
	syscall.Entersyscall()
	gerrno := libc_getaddrinfo(h, nil, &hints, &res)
	syscall.Exitsyscall()
	if gerrno != 0 {
		var str string
		if gerrno == syscall.EAI_NONAME {
			str = noSuchHost
		} else if gerrno == syscall.EAI_SYSTEM {
			str = syscall.GetErrno().Error()
		} else {
			str = bytePtrToString(libc_gai_strerror(gerrno))
		}
		return nil, "", &DNSError{Err: str, Name: name}, true
	}
	defer libc_freeaddrinfo(res)
	if res != nil {
		cname = bytePtrToString((*byte)(unsafe.Pointer(res.Ai_canonname)))
		if cname == "" {
			cname = name
		}
		if len(cname) > 0 && cname[len(cname)-1] != '.' {
			cname += "."
		}
	}
	for r := res; r != nil; r = r.Ai_next {
		// We only asked for SOCK_STREAM, but check anyhow.
		if r.Ai_socktype != syscall.SOCK_STREAM {
			continue
		}
		switch r.Ai_family {
		default:
			continue
		case syscall.AF_INET:
			sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.Ai_addr))
			addrs = append(addrs, copyIP(sa.Addr[:]))
		case syscall.AF_INET6:
			sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.Ai_addr))
			addrs = append(addrs, copyIP(sa.Addr[:]))
		}
	}
	return addrs, cname, nil, true
}

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 := syscall.Gid_t(ug)
	nameC, err := syscall.BytePtrFromString(u.Username)
	if err != nil {
		return nil, fmt.Errorf("user: invalid user name %q: %v", strconv.Quote(u.Username), err)
	}

	n := int32(256)
	gidsC := make([]syscall.Gid_t, n)
	syscall.Entersyscall()
	rv := libc_getgrouplist(nameC, userGID, &gidsC[0], &n)
	syscall.Exitsyscall()
	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([]syscall.Gid_t, n)
		syscall.Entersyscall()
		rv := libc_getgrouplist(nameC, userGID, &gidsC[0], &n)
		syscall.Exitsyscall()
		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
}