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jeremybenn |
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build darwin freebsd linux netbsd openbsd
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package syscall
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import (
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"runtime"
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"sync"
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"unsafe"
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)
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var (
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Stdin = 0
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Stdout = 1
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Stderr = 2
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)
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//extern syscall
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func c_syscall32(trap int32, a1, a2, a3, a4, a5, a6 int32) int32
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//extern syscall
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func c_syscall64(trap int64, a1, a2, a3, a4, a5, a6 int64) int64
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const darwinAMD64 = runtime.GOOS == "darwin" && runtime.GOARCH == "amd64"
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// Do a system call. We look at the size of uintptr to see how to pass
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// the arguments, so that we don't pass a 64-bit value when the function
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// expects a 32-bit one.
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func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
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entersyscall()
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var r uintptr
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if unsafe.Sizeof(r) == 4 {
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r1 := c_syscall32(int32(trap), int32(a1), int32(a2), int32(a3), 0, 0, 0)
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r = uintptr(r1)
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} else {
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r1 := c_syscall64(int64(trap), int64(a1), int64(a2), int64(a3), 0, 0, 0)
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r = uintptr(r1)
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}
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err = GetErrno()
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exitsyscall()
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return r, 0, err
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}
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func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) {
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entersyscall()
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var r uintptr
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if unsafe.Sizeof(r) == 4 {
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r1 := c_syscall32(int32(trap), int32(a1), int32(a2), int32(a3),
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int32(a4), int32(a5), int32(a6))
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r = uintptr(r1)
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} else {
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r1 := c_syscall64(int64(trap), int64(a1), int64(a2), int64(a3),
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int64(a4), int64(a5), int64(a6))
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r = uintptr(r1)
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}
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err = GetErrno()
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exitsyscall()
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return r, 0, err
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}
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func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
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var r uintptr
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if unsafe.Sizeof(r) == 4 {
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r1 := c_syscall32(int32(trap), int32(a1), int32(a2), int32(a3), 0, 0, 0)
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r = uintptr(r1)
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} else {
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r1 := c_syscall64(int64(trap), int64(a1), int64(a2), int64(a3), 0, 0, 0)
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r = uintptr(r1)
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}
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err = GetErrno()
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return r, 0, err
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}
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func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) {
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var r uintptr
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if unsafe.Sizeof(r) == 4 {
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r1 := c_syscall32(int32(trap), int32(a1), int32(a2), int32(a3),
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int32(a4), int32(a5), int32(a6))
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r = uintptr(r1)
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} else {
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r1 := c_syscall64(int64(trap), int64(a1), int64(a2), int64(a3),
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int64(a4), int64(a5), int64(a6))
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r = uintptr(r1)
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}
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err = GetErrno()
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return r, 0, err
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}
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// Mmap manager, for use by operating system-specific implementations.
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// Gccgo only has one implementation but we do this to correspond to gc.
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type mmapper struct {
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sync.Mutex
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active map[*byte][]byte // active mappings; key is last byte in mapping
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mmap func(addr, length uintptr, prot, flags, fd int, offset int64) (uintptr, error)
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munmap func(addr uintptr, length uintptr) error
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}
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func (m *mmapper) Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
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if length <= 0 {
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return nil, EINVAL
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}
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// Map the requested memory.
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addr, errno := m.mmap(0, uintptr(length), prot, flags, fd, offset)
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if errno != nil {
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return nil, errno
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}
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// Slice memory layout
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var sl = struct {
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addr uintptr
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len int
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cap int
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}{addr, length, length}
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// Use unsafe to turn sl into a []byte.
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b := *(*[]byte)(unsafe.Pointer(&sl))
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// Register mapping in m and return it.
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p := &b[cap(b)-1]
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m.Lock()
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defer m.Unlock()
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m.active[p] = b
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return b, nil
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}
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func (m *mmapper) Munmap(data []byte) (err error) {
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if len(data) == 0 || len(data) != cap(data) {
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return EINVAL
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}
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// Find the base of the mapping.
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p := &data[cap(data)-1]
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m.Lock()
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defer m.Unlock()
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b := m.active[p]
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if b == nil || &b[0] != &data[0] {
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return EINVAL
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}
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// Unmap the memory and update m.
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if errno := m.munmap(uintptr(unsafe.Pointer(&b[0])), uintptr(len(b))); errno != nil {
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return errno
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}
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m.active[p] = nil, false
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return nil
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}
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var mapper = &mmapper{
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active: make(map[*byte][]byte),
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mmap: mmap,
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munmap: munmap,
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}
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func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
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return mapper.Mmap(fd, offset, length, prot, flags)
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}
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func Munmap(b []byte) (err error) {
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return mapper.Munmap(b)
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}
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