Source file src/pkg/syscall/syscall_linux.go

     1	// Copyright 2009 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	// Linux system calls.
     6	// This file is compiled as ordinary Go code,
     7	// but it is also input to mksyscall,
     8	// which parses the //sys lines and generates system call stubs.
     9	// Note that sometimes we use a lowercase //sys name and
    10	// wrap it in our own nicer implementation.
    11	
    12	package syscall
    13	
    14	import "unsafe"
    15	
    16	/*
    17	 * Wrapped
    18	 */
    19	
    20	//sys	open(path string, mode int, perm uint32) (fd int, err error)
    21	func Open(path string, mode int, perm uint32) (fd int, err error) {
    22		return open(path, mode|O_LARGEFILE, perm)
    23	}
    24	
    25	//sys	openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
    26	func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
    27		return openat(dirfd, path, flags|O_LARGEFILE, mode)
    28	}
    29	
    30	//sysnb	pipe(p *[2]_C_int) (err error)
    31	func Pipe(p []int) (err error) {
    32		if len(p) != 2 {
    33			return EINVAL
    34		}
    35		var pp [2]_C_int
    36		err = pipe(&pp)
    37		p[0] = int(pp[0])
    38		p[1] = int(pp[1])
    39		return
    40	}
    41	
    42	//sys	utimes(path string, times *[2]Timeval) (err error)
    43	func Utimes(path string, tv []Timeval) (err error) {
    44		if len(tv) != 2 {
    45			return EINVAL
    46		}
    47		return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
    48	}
    49	
    50	//sys	futimesat(dirfd int, path *byte, times *[2]Timeval) (err error)
    51	func Futimesat(dirfd int, path string, tv []Timeval) (err error) {
    52		if len(tv) != 2 {
    53			return EINVAL
    54		}
    55		return futimesat(dirfd, StringBytePtr(path), (*[2]Timeval)(unsafe.Pointer(&tv[0])))
    56	}
    57	
    58	func Futimes(fd int, tv []Timeval) (err error) {
    59		// Believe it or not, this is the best we can do on Linux
    60		// (and is what glibc does).
    61		return Utimes("/proc/self/fd/"+itoa(fd), tv)
    62	}
    63	
    64	const ImplementsGetwd = true
    65	
    66	//sys	Getcwd(buf []byte) (n int, err error)
    67	func Getwd() (wd string, err error) {
    68		var buf [PathMax]byte
    69		n, err := Getcwd(buf[0:])
    70		if err != nil {
    71			return "", err
    72		}
    73		// Getcwd returns the number of bytes written to buf, including the NUL.
    74		if n < 1 || n > len(buf) || buf[n-1] != 0 {
    75			return "", EINVAL
    76		}
    77		return string(buf[0 : n-1]), nil
    78	}
    79	
    80	func Getgroups() (gids []int, err error) {
    81		n, err := getgroups(0, nil)
    82		if err != nil {
    83			return nil, err
    84		}
    85		if n == 0 {
    86			return nil, nil
    87		}
    88	
    89		// Sanity check group count.  Max is 1<<16 on Linux.
    90		if n < 0 || n > 1<<20 {
    91			return nil, EINVAL
    92		}
    93	
    94		a := make([]_Gid_t, n)
    95		n, err = getgroups(n, &a[0])
    96		if err != nil {
    97			return nil, err
    98		}
    99		gids = make([]int, n)
   100		for i, v := range a[0:n] {
   101			gids[i] = int(v)
   102		}
   103		return
   104	}
   105	
   106	func Setgroups(gids []int) (err error) {
   107		if len(gids) == 0 {
   108			return setgroups(0, nil)
   109		}
   110	
   111		a := make([]_Gid_t, len(gids))
   112		for i, v := range gids {
   113			a[i] = _Gid_t(v)
   114		}
   115		return setgroups(len(a), &a[0])
   116	}
   117	
   118	type WaitStatus uint32
   119	
   120	// Wait status is 7 bits at bottom, either 0 (exited),
   121	// 0x7F (stopped), or a signal number that caused an exit.
   122	// The 0x80 bit is whether there was a core dump.
   123	// An extra number (exit code, signal causing a stop)
   124	// is in the high bits.  At least that's the idea.
   125	// There are various irregularities.  For example, the
   126	// "continued" status is 0xFFFF, distinguishing itself
   127	// from stopped via the core dump bit.
   128	
   129	const (
   130		mask    = 0x7F
   131		core    = 0x80
   132		exited  = 0x00
   133		stopped = 0x7F
   134		shift   = 8
   135	)
   136	
   137	func (w WaitStatus) Exited() bool { return w&mask == exited }
   138	
   139	func (w WaitStatus) Signaled() bool { return w&mask != stopped && w&mask != exited }
   140	
   141	func (w WaitStatus) Stopped() bool { return w&0xFF == stopped }
   142	
   143	func (w WaitStatus) Continued() bool { return w == 0xFFFF }
   144	
   145	func (w WaitStatus) CoreDump() bool { return w.Signaled() && w&core != 0 }
   146	
   147	func (w WaitStatus) ExitStatus() int {
   148		if !w.Exited() {
   149			return -1
   150		}
   151		return int(w>>shift) & 0xFF
   152	}
   153	
   154	func (w WaitStatus) Signal() Signal {
   155		if !w.Signaled() {
   156			return -1
   157		}
   158		return Signal(w & mask)
   159	}
   160	
   161	func (w WaitStatus) StopSignal() Signal {
   162		if !w.Stopped() {
   163			return -1
   164		}
   165		return Signal(w>>shift) & 0xFF
   166	}
   167	
   168	func (w WaitStatus) TrapCause() int {
   169		if w.StopSignal() != SIGTRAP {
   170			return -1
   171		}
   172		return int(w>>shift) >> 8
   173	}
   174	
   175	//sys	wait4(pid int, wstatus *_C_int, options int, rusage *Rusage) (wpid int, err error)
   176	func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
   177		var status _C_int
   178		wpid, err = wait4(pid, &status, options, rusage)
   179		if wstatus != nil {
   180			*wstatus = WaitStatus(status)
   181		}
   182		return
   183	}
   184	
   185	func Mkfifo(path string, mode uint32) (err error) {
   186		return Mknod(path, mode|S_IFIFO, 0)
   187	}
   188	
   189	// For testing: clients can set this flag to force
   190	// creation of IPv6 sockets to return EAFNOSUPPORT.
   191	var SocketDisableIPv6 bool
   192	
   193	type Sockaddr interface {
   194		sockaddr() (ptr uintptr, len _Socklen, err error) // lowercase; only we can define Sockaddrs
   195	}
   196	
   197	type SockaddrInet4 struct {
   198		Port int
   199		Addr [4]byte
   200		raw  RawSockaddrInet4
   201	}
   202	
   203	func (sa *SockaddrInet4) sockaddr() (uintptr, _Socklen, error) {
   204		if sa.Port < 0 || sa.Port > 0xFFFF {
   205			return 0, 0, EINVAL
   206		}
   207		sa.raw.Family = AF_INET
   208		p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   209		p[0] = byte(sa.Port >> 8)
   210		p[1] = byte(sa.Port)
   211		for i := 0; i < len(sa.Addr); i++ {
   212			sa.raw.Addr[i] = sa.Addr[i]
   213		}
   214		return uintptr(unsafe.Pointer(&sa.raw)), SizeofSockaddrInet4, nil
   215	}
   216	
   217	type SockaddrInet6 struct {
   218		Port   int
   219		ZoneId uint32
   220		Addr   [16]byte
   221		raw    RawSockaddrInet6
   222	}
   223	
   224	func (sa *SockaddrInet6) sockaddr() (uintptr, _Socklen, error) {
   225		if sa.Port < 0 || sa.Port > 0xFFFF {
   226			return 0, 0, EINVAL
   227		}
   228		sa.raw.Family = AF_INET6
   229		p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
   230		p[0] = byte(sa.Port >> 8)
   231		p[1] = byte(sa.Port)
   232		sa.raw.Scope_id = sa.ZoneId
   233		for i := 0; i < len(sa.Addr); i++ {
   234			sa.raw.Addr[i] = sa.Addr[i]
   235		}
   236		return uintptr(unsafe.Pointer(&sa.raw)), SizeofSockaddrInet6, nil
   237	}
   238	
   239	type SockaddrUnix struct {
   240		Name string
   241		raw  RawSockaddrUnix
   242	}
   243	
   244	func (sa *SockaddrUnix) sockaddr() (uintptr, _Socklen, error) {
   245		name := sa.Name
   246		n := len(name)
   247		if n >= len(sa.raw.Path) || n == 0 {
   248			return 0, 0, EINVAL
   249		}
   250		sa.raw.Family = AF_UNIX
   251		for i := 0; i < n; i++ {
   252			sa.raw.Path[i] = int8(name[i])
   253		}
   254		// length is family (uint16), name, NUL.
   255		sl := 2 + _Socklen(n) + 1
   256		if sa.raw.Path[0] == '@' {
   257			sa.raw.Path[0] = 0
   258			// Don't count trailing NUL for abstract address.
   259			sl--
   260		}
   261	
   262		return uintptr(unsafe.Pointer(&sa.raw)), sl, nil
   263	}
   264	
   265	type SockaddrLinklayer struct {
   266		Protocol uint16
   267		Ifindex  int
   268		Hatype   uint16
   269		Pkttype  uint8
   270		Halen    uint8
   271		Addr     [8]byte
   272		raw      RawSockaddrLinklayer
   273	}
   274	
   275	func (sa *SockaddrLinklayer) sockaddr() (uintptr, _Socklen, error) {
   276		if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
   277			return 0, 0, EINVAL
   278		}
   279		sa.raw.Family = AF_PACKET
   280		sa.raw.Protocol = sa.Protocol
   281		sa.raw.Ifindex = int32(sa.Ifindex)
   282		sa.raw.Hatype = sa.Hatype
   283		sa.raw.Pkttype = sa.Pkttype
   284		sa.raw.Halen = sa.Halen
   285		for i := 0; i < len(sa.Addr); i++ {
   286			sa.raw.Addr[i] = sa.Addr[i]
   287		}
   288		return uintptr(unsafe.Pointer(&sa.raw)), SizeofSockaddrLinklayer, nil
   289	}
   290	
   291	type SockaddrNetlink struct {
   292		Family uint16
   293		Pad    uint16
   294		Pid    uint32
   295		Groups uint32
   296		raw    RawSockaddrNetlink
   297	}
   298	
   299	func (sa *SockaddrNetlink) sockaddr() (uintptr, _Socklen, error) {
   300		sa.raw.Family = AF_NETLINK
   301		sa.raw.Pad = sa.Pad
   302		sa.raw.Pid = sa.Pid
   303		sa.raw.Groups = sa.Groups
   304		return uintptr(unsafe.Pointer(&sa.raw)), SizeofSockaddrNetlink, nil
   305	}
   306	
   307	func anyToSockaddr(rsa *RawSockaddrAny) (Sockaddr, error) {
   308		switch rsa.Addr.Family {
   309		case AF_NETLINK:
   310			pp := (*RawSockaddrNetlink)(unsafe.Pointer(rsa))
   311			sa := new(SockaddrNetlink)
   312			sa.Family = pp.Family
   313			sa.Pad = pp.Pad
   314			sa.Pid = pp.Pid
   315			sa.Groups = pp.Groups
   316			return sa, nil
   317	
   318		case AF_PACKET:
   319			pp := (*RawSockaddrLinklayer)(unsafe.Pointer(rsa))
   320			sa := new(SockaddrLinklayer)
   321			sa.Protocol = pp.Protocol
   322			sa.Ifindex = int(pp.Ifindex)
   323			sa.Hatype = pp.Hatype
   324			sa.Pkttype = pp.Pkttype
   325			sa.Halen = pp.Halen
   326			for i := 0; i < len(sa.Addr); i++ {
   327				sa.Addr[i] = pp.Addr[i]
   328			}
   329			return sa, nil
   330	
   331		case AF_UNIX:
   332			pp := (*RawSockaddrUnix)(unsafe.Pointer(rsa))
   333			sa := new(SockaddrUnix)
   334			if pp.Path[0] == 0 {
   335				// "Abstract" Unix domain socket.
   336				// Rewrite leading NUL as @ for textual display.
   337				// (This is the standard convention.)
   338				// Not friendly to overwrite in place,
   339				// but the callers below don't care.
   340				pp.Path[0] = '@'
   341			}
   342	
   343			// Assume path ends at NUL.
   344			// This is not technically the Linux semantics for
   345			// abstract Unix domain sockets--they are supposed
   346			// to be uninterpreted fixed-size binary blobs--but
   347			// everyone uses this convention.
   348			n := 0
   349			for n < len(pp.Path) && pp.Path[n] != 0 {
   350				n++
   351			}
   352			bytes := (*[10000]byte)(unsafe.Pointer(&pp.Path[0]))[0:n]
   353			sa.Name = string(bytes)
   354			return sa, nil
   355	
   356		case AF_INET:
   357			pp := (*RawSockaddrInet4)(unsafe.Pointer(rsa))
   358			sa := new(SockaddrInet4)
   359			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
   360			sa.Port = int(p[0])<<8 + int(p[1])
   361			for i := 0; i < len(sa.Addr); i++ {
   362				sa.Addr[i] = pp.Addr[i]
   363			}
   364			return sa, nil
   365	
   366		case AF_INET6:
   367			pp := (*RawSockaddrInet6)(unsafe.Pointer(rsa))
   368			sa := new(SockaddrInet6)
   369			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
   370			sa.Port = int(p[0])<<8 + int(p[1])
   371			sa.ZoneId = pp.Scope_id
   372			for i := 0; i < len(sa.Addr); i++ {
   373				sa.Addr[i] = pp.Addr[i]
   374			}
   375			return sa, nil
   376		}
   377		return nil, EAFNOSUPPORT
   378	}
   379	
   380	func Accept(fd int) (nfd int, sa Sockaddr, err error) {
   381		var rsa RawSockaddrAny
   382		var len _Socklen = SizeofSockaddrAny
   383		nfd, err = accept(fd, &rsa, &len)
   384		if err != nil {
   385			return
   386		}
   387		sa, err = anyToSockaddr(&rsa)
   388		if err != nil {
   389			Close(nfd)
   390			nfd = 0
   391		}
   392		return
   393	}
   394	
   395	func Getsockname(fd int) (sa Sockaddr, err error) {
   396		var rsa RawSockaddrAny
   397		var len _Socklen = SizeofSockaddrAny
   398		if err = getsockname(fd, &rsa, &len); err != nil {
   399			return
   400		}
   401		return anyToSockaddr(&rsa)
   402	}
   403	
   404	func Getpeername(fd int) (sa Sockaddr, err error) {
   405		var rsa RawSockaddrAny
   406		var len _Socklen = SizeofSockaddrAny
   407		if err = getpeername(fd, &rsa, &len); err != nil {
   408			return
   409		}
   410		return anyToSockaddr(&rsa)
   411	}
   412	
   413	func Bind(fd int, sa Sockaddr) (err error) {
   414		ptr, n, err := sa.sockaddr()
   415		if err != nil {
   416			return err
   417		}
   418		return bind(fd, ptr, n)
   419	}
   420	
   421	func Connect(fd int, sa Sockaddr) (err error) {
   422		ptr, n, err := sa.sockaddr()
   423		if err != nil {
   424			return err
   425		}
   426		return connect(fd, ptr, n)
   427	}
   428	
   429	func Socket(domain, typ, proto int) (fd int, err error) {
   430		if domain == AF_INET6 && SocketDisableIPv6 {
   431			return -1, EAFNOSUPPORT
   432		}
   433		fd, err = socket(domain, typ, proto)
   434		return
   435	}
   436	
   437	func Socketpair(domain, typ, proto int) (fd [2]int, err error) {
   438		err = socketpair(domain, typ, proto, &fd)
   439		return
   440	}
   441	
   442	func GetsockoptInt(fd, level, opt int) (value int, err error) {
   443		var n int32
   444		vallen := _Socklen(4)
   445		err = getsockopt(fd, level, opt, uintptr(unsafe.Pointer(&n)), &vallen)
   446		return int(n), err
   447	}
   448	
   449	func GetsockoptInet4Addr(fd, level, opt int) (value [4]byte, err error) {
   450		vallen := _Socklen(4)
   451		err = getsockopt(fd, level, opt, uintptr(unsafe.Pointer(&value[0])), &vallen)
   452		return value, err
   453	}
   454	
   455	func GetsockoptIPMreq(fd, level, opt int) (*IPMreq, error) {
   456		var value IPMreq
   457		vallen := _Socklen(SizeofIPMreq)
   458		err := getsockopt(fd, level, opt, uintptr(unsafe.Pointer(&value)), &vallen)
   459		return &value, err
   460	}
   461	
   462	func GetsockoptIPMreqn(fd, level, opt int) (*IPMreqn, error) {
   463		var value IPMreqn
   464		vallen := _Socklen(SizeofIPMreqn)
   465		err := getsockopt(fd, level, opt, uintptr(unsafe.Pointer(&value)), &vallen)
   466		return &value, err
   467	}
   468	
   469	func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
   470		var value IPv6Mreq
   471		vallen := _Socklen(SizeofIPv6Mreq)
   472		err := getsockopt(fd, level, opt, uintptr(unsafe.Pointer(&value)), &vallen)
   473		return &value, err
   474	}
   475	
   476	func SetsockoptInt(fd, level, opt int, value int) (err error) {
   477		var n = int32(value)
   478		return setsockopt(fd, level, opt, uintptr(unsafe.Pointer(&n)), 4)
   479	}
   480	
   481	func SetsockoptInet4Addr(fd, level, opt int, value [4]byte) (err error) {
   482		return setsockopt(fd, level, opt, uintptr(unsafe.Pointer(&value[0])), 4)
   483	}
   484	
   485	func SetsockoptTimeval(fd, level, opt int, tv *Timeval) (err error) {
   486		return setsockopt(fd, level, opt, uintptr(unsafe.Pointer(tv)), unsafe.Sizeof(*tv))
   487	}
   488	
   489	func SetsockoptLinger(fd, level, opt int, l *Linger) (err error) {
   490		return setsockopt(fd, level, opt, uintptr(unsafe.Pointer(l)), unsafe.Sizeof(*l))
   491	}
   492	
   493	func SetsockoptIPMreq(fd, level, opt int, mreq *IPMreq) (err error) {
   494		return setsockopt(fd, level, opt, uintptr(unsafe.Pointer(mreq)), unsafe.Sizeof(*mreq))
   495	}
   496	
   497	func SetsockoptIPMreqn(fd, level, opt int, mreq *IPMreqn) (err error) {
   498		return setsockopt(fd, level, opt, uintptr(unsafe.Pointer(mreq)), unsafe.Sizeof(*mreq))
   499	}
   500	
   501	func SetsockoptIPv6Mreq(fd, level, opt int, mreq *IPv6Mreq) (err error) {
   502		return setsockopt(fd, level, opt, uintptr(unsafe.Pointer(mreq)), unsafe.Sizeof(*mreq))
   503	}
   504	
   505	func SetsockoptString(fd, level, opt int, s string) (err error) {
   506		return setsockopt(fd, level, opt, uintptr(unsafe.Pointer(&[]byte(s)[0])), uintptr(len(s)))
   507	}
   508	
   509	func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
   510		var rsa RawSockaddrAny
   511		var len _Socklen = SizeofSockaddrAny
   512		if n, err = recvfrom(fd, p, flags, &rsa, &len); err != nil {
   513			return
   514		}
   515		from, err = anyToSockaddr(&rsa)
   516		return
   517	}
   518	
   519	func Sendto(fd int, p []byte, flags int, to Sockaddr) (err error) {
   520		ptr, n, err := to.sockaddr()
   521		if err != nil {
   522			return err
   523		}
   524		return sendto(fd, p, flags, ptr, n)
   525	}
   526	
   527	func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from Sockaddr, err error) {
   528		var msg Msghdr
   529		var rsa RawSockaddrAny
   530		msg.Name = (*byte)(unsafe.Pointer(&rsa))
   531		msg.Namelen = uint32(SizeofSockaddrAny)
   532		var iov Iovec
   533		if len(p) > 0 {
   534			iov.Base = (*byte)(unsafe.Pointer(&p[0]))
   535			iov.SetLen(len(p))
   536		}
   537		var dummy byte
   538		if len(oob) > 0 {
   539			// receive at least one normal byte
   540			if len(p) == 0 {
   541				iov.Base = &dummy
   542				iov.SetLen(1)
   543			}
   544			msg.Control = (*byte)(unsafe.Pointer(&oob[0]))
   545			msg.SetControllen(len(oob))
   546		}
   547		msg.Iov = &iov
   548		msg.Iovlen = 1
   549		if n, err = recvmsg(fd, &msg, flags); err != nil {
   550			return
   551		}
   552		oobn = int(msg.Controllen)
   553		recvflags = int(msg.Flags)
   554		// source address is only specified if the socket is unconnected
   555		if rsa.Addr.Family != AF_UNSPEC {
   556			from, err = anyToSockaddr(&rsa)
   557		}
   558		return
   559	}
   560	
   561	func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
   562		var ptr uintptr
   563		var salen _Socklen
   564		if to != nil {
   565			var err error
   566			ptr, salen, err = to.sockaddr()
   567			if err != nil {
   568				return err
   569			}
   570		}
   571		var msg Msghdr
   572		msg.Name = (*byte)(unsafe.Pointer(ptr))
   573		msg.Namelen = uint32(salen)
   574		var iov Iovec
   575		if len(p) > 0 {
   576			iov.Base = (*byte)(unsafe.Pointer(&p[0]))
   577			iov.SetLen(len(p))
   578		}
   579		var dummy byte
   580		if len(oob) > 0 {
   581			// send at least one normal byte
   582			if len(p) == 0 {
   583				iov.Base = &dummy
   584				iov.SetLen(1)
   585			}
   586			msg.Control = (*byte)(unsafe.Pointer(&oob[0]))
   587			msg.SetControllen(len(oob))
   588		}
   589		msg.Iov = &iov
   590		msg.Iovlen = 1
   591		if err = sendmsg(fd, &msg, flags); err != nil {
   592			return
   593		}
   594		return
   595	}
   596	
   597	// BindToDevice binds the socket associated with fd to device.
   598	func BindToDevice(fd int, device string) (err error) {
   599		return SetsockoptString(fd, SOL_SOCKET, SO_BINDTODEVICE, device)
   600	}
   601	
   602	//sys	ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
   603	
   604	func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err error) {
   605		// The peek requests are machine-size oriented, so we wrap it
   606		// to retrieve arbitrary-length data.
   607	
   608		// The ptrace syscall differs from glibc's ptrace.
   609		// Peeks returns the word in *data, not as the return value.
   610	
   611		var buf [sizeofPtr]byte
   612	
   613		// Leading edge.  PEEKTEXT/PEEKDATA don't require aligned
   614		// access (PEEKUSER warns that it might), but if we don't
   615		// align our reads, we might straddle an unmapped page
   616		// boundary and not get the bytes leading up to the page
   617		// boundary.
   618		n := 0
   619		if addr%sizeofPtr != 0 {
   620			err = ptrace(req, pid, addr-addr%sizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
   621			if err != nil {
   622				return 0, err
   623			}
   624			n += copy(out, buf[addr%sizeofPtr:])
   625			out = out[n:]
   626		}
   627	
   628		// Remainder.
   629		for len(out) > 0 {
   630			// We use an internal buffer to guarantee alignment.
   631			// It's not documented if this is necessary, but we're paranoid.
   632			err = ptrace(req, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
   633			if err != nil {
   634				return n, err
   635			}
   636			copied := copy(out, buf[0:])
   637			n += copied
   638			out = out[copied:]
   639		}
   640	
   641		return n, nil
   642	}
   643	
   644	func PtracePeekText(pid int, addr uintptr, out []byte) (count int, err error) {
   645		return ptracePeek(PTRACE_PEEKTEXT, pid, addr, out)
   646	}
   647	
   648	func PtracePeekData(pid int, addr uintptr, out []byte) (count int, err error) {
   649		return ptracePeek(PTRACE_PEEKDATA, pid, addr, out)
   650	}
   651	
   652	func ptracePoke(pokeReq int, peekReq int, pid int, addr uintptr, data []byte) (count int, err error) {
   653		// As for ptracePeek, we need to align our accesses to deal
   654		// with the possibility of straddling an invalid page.
   655	
   656		// Leading edge.
   657		n := 0
   658		if addr%sizeofPtr != 0 {
   659			var buf [sizeofPtr]byte
   660			err = ptrace(peekReq, pid, addr-addr%sizeofPtr, uintptr(unsafe.Pointer(&buf[0])))
   661			if err != nil {
   662				return 0, err
   663			}
   664			n += copy(buf[addr%sizeofPtr:], data)
   665			word := *((*uintptr)(unsafe.Pointer(&buf[0])))
   666			err = ptrace(pokeReq, pid, addr-addr%sizeofPtr, word)
   667			if err != nil {
   668				return 0, err
   669			}
   670			data = data[n:]
   671		}
   672	
   673		// Interior.
   674		for len(data) > sizeofPtr {
   675			word := *((*uintptr)(unsafe.Pointer(&data[0])))
   676			err = ptrace(pokeReq, pid, addr+uintptr(n), word)
   677			if err != nil {
   678				return n, err
   679			}
   680			n += sizeofPtr
   681			data = data[sizeofPtr:]
   682		}
   683	
   684		// Trailing edge.
   685		if len(data) > 0 {
   686			var buf [sizeofPtr]byte
   687			err = ptrace(peekReq, pid, addr+uintptr(n), uintptr(unsafe.Pointer(&buf[0])))
   688			if err != nil {
   689				return n, err
   690			}
   691			copy(buf[0:], data)
   692			word := *((*uintptr)(unsafe.Pointer(&buf[0])))
   693			err = ptrace(pokeReq, pid, addr+uintptr(n), word)
   694			if err != nil {
   695				return n, err
   696			}
   697			n += len(data)
   698		}
   699	
   700		return n, nil
   701	}
   702	
   703	func PtracePokeText(pid int, addr uintptr, data []byte) (count int, err error) {
   704		return ptracePoke(PTRACE_POKETEXT, PTRACE_PEEKTEXT, pid, addr, data)
   705	}
   706	
   707	func PtracePokeData(pid int, addr uintptr, data []byte) (count int, err error) {
   708		return ptracePoke(PTRACE_POKEDATA, PTRACE_PEEKDATA, pid, addr, data)
   709	}
   710	
   711	func PtraceGetRegs(pid int, regsout *PtraceRegs) (err error) {
   712		return ptrace(PTRACE_GETREGS, pid, 0, uintptr(unsafe.Pointer(regsout)))
   713	}
   714	
   715	func PtraceSetRegs(pid int, regs *PtraceRegs) (err error) {
   716		return ptrace(PTRACE_SETREGS, pid, 0, uintptr(unsafe.Pointer(regs)))
   717	}
   718	
   719	func PtraceSetOptions(pid int, options int) (err error) {
   720		return ptrace(PTRACE_SETOPTIONS, pid, 0, uintptr(options))
   721	}
   722	
   723	func PtraceGetEventMsg(pid int) (msg uint, err error) {
   724		var data _C_long
   725		err = ptrace(PTRACE_GETEVENTMSG, pid, 0, uintptr(unsafe.Pointer(&data)))
   726		msg = uint(data)
   727		return
   728	}
   729	
   730	func PtraceCont(pid int, signal int) (err error) {
   731		return ptrace(PTRACE_CONT, pid, 0, uintptr(signal))
   732	}
   733	
   734	func PtraceSingleStep(pid int) (err error) { return ptrace(PTRACE_SINGLESTEP, pid, 0, 0) }
   735	
   736	func PtraceAttach(pid int) (err error) { return ptrace(PTRACE_ATTACH, pid, 0, 0) }
   737	
   738	func PtraceDetach(pid int) (err error) { return ptrace(PTRACE_DETACH, pid, 0, 0) }
   739	
   740	//sys	reboot(magic1 uint, magic2 uint, cmd int, arg string) (err error)
   741	func Reboot(cmd int) (err error) {
   742		return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, "")
   743	}
   744	
   745	func clen(n []byte) int {
   746		for i := 0; i < len(n); i++ {
   747			if n[i] == 0 {
   748				return i
   749			}
   750		}
   751		return len(n)
   752	}
   753	
   754	func ReadDirent(fd int, buf []byte) (n int, err error) {
   755		return Getdents(fd, buf)
   756	}
   757	
   758	func ParseDirent(buf []byte, max int, names []string) (consumed int, count int, newnames []string) {
   759		origlen := len(buf)
   760		count = 0
   761		for max != 0 && len(buf) > 0 {
   762			dirent := (*Dirent)(unsafe.Pointer(&buf[0]))
   763			buf = buf[dirent.Reclen:]
   764			if dirent.Ino == 0 { // File absent in directory.
   765				continue
   766			}
   767			bytes := (*[10000]byte)(unsafe.Pointer(&dirent.Name[0]))
   768			var name = string(bytes[0:clen(bytes[:])])
   769			if name == "." || name == ".." { // Useless names
   770				continue
   771			}
   772			max--
   773			count++
   774			names = append(names, name)
   775		}
   776		return origlen - len(buf), count, names
   777	}
   778	
   779	//sys	mount(source string, target string, fstype string, flags uintptr, data *byte) (err error)
   780	func Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
   781		// Certain file systems get rather angry and EINVAL if you give
   782		// them an empty string of data, rather than NULL.
   783		if data == "" {
   784			return mount(source, target, fstype, flags, nil)
   785		}
   786		return mount(source, target, fstype, flags, StringBytePtr(data))
   787	}
   788	
   789	// Sendto
   790	// Recvfrom
   791	// Socketpair
   792	
   793	/*
   794	 * Direct access
   795	 */
   796	//sys	Access(path string, mode uint32) (err error)
   797	//sys	Acct(path string) (err error)
   798	//sys	Adjtimex(buf *Timex) (state int, err error)
   799	//sys	Chdir(path string) (err error)
   800	//sys	Chmod(path string, mode uint32) (err error)
   801	//sys	Chroot(path string) (err error)
   802	//sys	Close(fd int) (err error)
   803	//sys	Creat(path string, mode uint32) (fd int, err error)
   804	//sysnb	Dup(oldfd int) (fd int, err error)
   805	//sysnb	Dup2(oldfd int, newfd int) (err error)
   806	//sysnb	EpollCreate(size int) (fd int, err error)
   807	//sysnb	EpollCreate1(flag int) (fd int, err error)
   808	//sysnb	EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error)
   809	//sys	EpollWait(epfd int, events []EpollEvent, msec int) (n int, err error)
   810	//sys	Exit(code int) = SYS_EXIT_GROUP
   811	//sys	Faccessat(dirfd int, path string, mode uint32, flags int) (err error)
   812	//sys	Fallocate(fd int, mode uint32, off int64, len int64) (err error)
   813	//sys	Fchdir(fd int) (err error)
   814	//sys	Fchmod(fd int, mode uint32) (err error)
   815	//sys	Fchmodat(dirfd int, path string, mode uint32, flags int) (err error)
   816	//sys	Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error)
   817	//sys	fcntl(fd int, cmd int, arg int) (val int, err error)
   818	//sys	Fdatasync(fd int) (err error)
   819	//sys	Flock(fd int, how int) (err error)
   820	//sys	Fsync(fd int) (err error)
   821	//sys	Getdents(fd int, buf []byte) (n int, err error) = SYS_GETDENTS64
   822	//sysnb	Getpgid(pid int) (pgid int, err error)
   823	//sysnb	Getpgrp() (pid int)
   824	//sysnb	Getpid() (pid int)
   825	//sysnb	Getppid() (ppid int)
   826	//sysnb	Getrlimit(resource int, rlim *Rlimit) (err error)
   827	//sysnb	Getrusage(who int, rusage *Rusage) (err error)
   828	//sysnb	Gettid() (tid int)
   829	//sys	InotifyAddWatch(fd int, pathname string, mask uint32) (watchdesc int, err error)
   830	//sysnb	InotifyInit() (fd int, err error)
   831	//sysnb	InotifyInit1(flags int) (fd int, err error)
   832	//sysnb	InotifyRmWatch(fd int, watchdesc uint32) (success int, err error)
   833	//sysnb	Kill(pid int, sig Signal) (err error)
   834	//sys	Klogctl(typ int, buf []byte) (n int, err error) = SYS_SYSLOG
   835	//sys	Link(oldpath string, newpath string) (err error)
   836	//sys	Mkdir(path string, mode uint32) (err error)
   837	//sys	Mkdirat(dirfd int, path string, mode uint32) (err error)
   838	//sys	Mknod(path string, mode uint32, dev int) (err error)
   839	//sys	Mknodat(dirfd int, path string, mode uint32, dev int) (err error)
   840	//sys	Nanosleep(time *Timespec, leftover *Timespec) (err error)
   841	//sys	Pause() (err error)
   842	//sys	PivotRoot(newroot string, putold string) (err error) = SYS_PIVOT_ROOT
   843	//sys	Read(fd int, p []byte) (n int, err error)
   844	//sys	Readlink(path string, buf []byte) (n int, err error)
   845	//sys	Rename(oldpath string, newpath string) (err error)
   846	//sys	Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)
   847	//sys	Rmdir(path string) (err error)
   848	//sys	Setdomainname(p []byte) (err error)
   849	//sys	Sethostname(p []byte) (err error)
   850	//sysnb	Setpgid(pid int, pgid int) (err error)
   851	//sysnb	Setrlimit(resource int, rlim *Rlimit) (err error)
   852	//sysnb	Setsid() (pid int, err error)
   853	//sysnb	Settimeofday(tv *Timeval) (err error)
   854	//sysnb	Setuid(uid int) (err error)
   855	//sys	Symlink(oldpath string, newpath string) (err error)
   856	//sys	Sync()
   857	//sysnb	Sysinfo(info *Sysinfo_t) (err error)
   858	//sys	Tee(rfd int, wfd int, len int, flags int) (n int64, err error)
   859	//sysnb	Tgkill(tgid int, tid int, sig Signal) (err error)
   860	//sysnb	Times(tms *Tms) (ticks uintptr, err error)
   861	//sysnb	Umask(mask int) (oldmask int)
   862	//sysnb	Uname(buf *Utsname) (err error)
   863	//sys	Unlink(path string) (err error)
   864	//sys	Unlinkat(dirfd int, path string) (err error)
   865	//sys	Unmount(target string, flags int) (err error) = SYS_UMOUNT2
   866	//sys	Unshare(flags int) (err error)
   867	//sys	Ustat(dev int, ubuf *Ustat_t) (err error)
   868	//sys	Utime(path string, buf *Utimbuf) (err error)
   869	//sys	Write(fd int, p []byte) (n int, err error)
   870	//sys	exitThread(code int) (err error) = SYS_EXIT
   871	//sys	read(fd int, p *byte, np int) (n int, err error)
   872	//sys	write(fd int, p *byte, np int) (n int, err error)
   873	
   874	// mmap varies by architecture; see syscall_linux_*.go.
   875	//sys	munmap(addr uintptr, length uintptr) (err error)
   876	
   877	var mapper = &mmapper{
   878		active: make(map[*byte][]byte),
   879		mmap:   mmap,
   880		munmap: munmap,
   881	}
   882	
   883	func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
   884		return mapper.Mmap(fd, offset, length, prot, flags)
   885	}
   886	
   887	func Munmap(b []byte) (err error) {
   888		return mapper.Munmap(b)
   889	}
   890	
   891	//sys	Madvise(b []byte, advice int) (err error)
   892	//sys	Mprotect(b []byte, prot int) (err error)
   893	//sys	Mlock(b []byte) (err error)
   894	//sys	Munlock(b []byte) (err error)
   895	//sys	Mlockall(flags int) (err error)
   896	//sys	Munlockall() (err error)
   897	
   898	/*
   899	 * Unimplemented
   900	 */
   901	// AddKey
   902	// AfsSyscall
   903	// Alarm
   904	// ArchPrctl
   905	// Brk
   906	// Capget
   907	// Capset
   908	// ClockGetres
   909	// ClockGettime
   910	// ClockNanosleep
   911	// ClockSettime
   912	// Clone
   913	// CreateModule
   914	// DeleteModule
   915	// EpollCtlOld
   916	// EpollPwait
   917	// EpollWaitOld
   918	// Eventfd
   919	// Execve
   920	// Fadvise64
   921	// Fgetxattr
   922	// Flistxattr
   923	// Fork
   924	// Fremovexattr
   925	// Fsetxattr
   926	// Futex
   927	// GetKernelSyms
   928	// GetMempolicy
   929	// GetRobustList
   930	// GetThreadArea
   931	// Getitimer
   932	// Getpmsg
   933	// Getpriority
   934	// Getxattr
   935	// IoCancel
   936	// IoDestroy
   937	// IoGetevents
   938	// IoSetup
   939	// IoSubmit
   940	// Ioctl
   941	// IoprioGet
   942	// IoprioSet
   943	// KexecLoad
   944	// Keyctl
   945	// Lgetxattr
   946	// Listxattr
   947	// Llistxattr
   948	// LookupDcookie
   949	// Lremovexattr
   950	// Lsetxattr
   951	// Mbind
   952	// MigratePages
   953	// Mincore
   954	// ModifyLdt
   955	// Mount
   956	// MovePages
   957	// Mprotect
   958	// MqGetsetattr
   959	// MqNotify
   960	// MqOpen
   961	// MqTimedreceive
   962	// MqTimedsend
   963	// MqUnlink
   964	// Mremap
   965	// Msgctl
   966	// Msgget
   967	// Msgrcv
   968	// Msgsnd
   969	// Msync
   970	// Newfstatat
   971	// Nfsservctl
   972	// Personality
   973	// Poll
   974	// Ppoll
   975	// Prctl
   976	// Pselect6
   977	// Ptrace
   978	// Putpmsg
   979	// QueryModule
   980	// Quotactl
   981	// Readahead
   982	// Readv
   983	// RemapFilePages
   984	// Removexattr
   985	// RequestKey
   986	// RestartSyscall
   987	// RtSigaction
   988	// RtSigpending
   989	// RtSigprocmask
   990	// RtSigqueueinfo
   991	// RtSigreturn
   992	// RtSigsuspend
   993	// RtSigtimedwait
   994	// SchedGetPriorityMax
   995	// SchedGetPriorityMin
   996	// SchedGetaffinity
   997	// SchedGetparam
   998	// SchedGetscheduler
   999	// SchedRrGetInterval
  1000	// SchedSetaffinity
  1001	// SchedSetparam
  1002	// SchedYield
  1003	// Security
  1004	// Semctl
  1005	// Semget
  1006	// Semop
  1007	// Semtimedop
  1008	// SetMempolicy
  1009	// SetRobustList
  1010	// SetThreadArea
  1011	// SetTidAddress
  1012	// Setpriority
  1013	// Setxattr
  1014	// Shmat
  1015	// Shmctl
  1016	// Shmdt
  1017	// Shmget
  1018	// Sigaltstack
  1019	// Signalfd
  1020	// Swapoff
  1021	// Swapon
  1022	// Sysfs
  1023	// TimerCreate
  1024	// TimerDelete
  1025	// TimerGetoverrun
  1026	// TimerGettime
  1027	// TimerSettime
  1028	// Timerfd
  1029	// Tkill (obsolete)
  1030	// Tuxcall
  1031	// Umount2
  1032	// Uselib
  1033	// Utimensat
  1034	// Vfork
  1035	// Vhangup
  1036	// Vmsplice
  1037	// Vserver
  1038	// Waitid
  1039	// Writev
  1040	// _Sysctl