112 lines
3.1 KiB
Go
112 lines
3.1 KiB
Go
// syscall.go -- Basic syscall interface.
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// 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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// This package contains an interface to the low-level operating system
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// primitives. The details vary depending on the underlying system.
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// Its primary use is inside other packages that provide a more portable
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// interface to the system, such as "os", "time" and "net". Use those
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// packages rather than this one if you can.
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// For details of the functions and data types in this package consult
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// the manuals for the appropriate operating system.
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package syscall
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import (
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"sync"
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"unsafe"
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)
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func libc_syscall32(trap int32, a1, a2, a3, a4, a5, a6 int32) int32 __asm__ ("syscall");
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func libc_syscall64(trap int64, a1, a2, a3, a4, a5, a6 int64) int64 __asm__ ("syscall");
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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, err uintptr) {
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var r uintptr;
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if unsafe.Sizeof(r) == 4 {
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r1 := libc_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 := libc_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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return r, 0, uintptr(GetErrno());
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}
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func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
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var r uintptr;
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if unsafe.Sizeof(r) == 4 {
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r1 := libc_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 := libc_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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return r, 0, uintptr(GetErrno());
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}
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// Mmap manager, for use by operating system-specific implementations.
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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, int)
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munmap func(addr uintptr, length uintptr) int
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}
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func (m *mmapper) Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, errno int) {
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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 != 0 {
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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, 0
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}
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func (m *mmapper) Munmap(data []byte) (errno int) {
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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 != 0 {
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return errno
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}
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m.active[p] = nil, false
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return 0
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}
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