mirror of
https://github.com/42wim/matterbridge.git
synced 2024-11-23 19:22:03 -08:00
92 lines
2.1 KiB
Go
92 lines
2.1 KiB
Go
// Copyright 2011 Evan Shaw. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE-MMAP-GO file.
|
|
|
|
// Modifications (c) 2022 The Memory Authors.
|
|
|
|
package memory // import "modernc.org/memory"
|
|
|
|
import (
|
|
"os"
|
|
"syscall"
|
|
_ "unsafe"
|
|
)
|
|
|
|
const (
|
|
pageSizeLog = 20
|
|
|
|
// $ find /usr/include -name syscall.h
|
|
// /usr/include/sys/syscall.h
|
|
// $ grep -ni munmap /usr/include/sys/syscall.h
|
|
// 293:#define SYS_munmap 117
|
|
// $ grep -ni mmap /usr/include/sys/syscall.h
|
|
// 291:#define SYS_mmap 115
|
|
// 303:#define SYS_mmapobj 127
|
|
// 442:#define SYS_mmap64 214
|
|
// $
|
|
// $ uname -a
|
|
// SunOS omnios64 5.11 omnios-r151044-d3b715b9d1 i86pc i386 i86pc
|
|
// $
|
|
sys_MUNMAP = 117
|
|
sys_MMAP = 214
|
|
)
|
|
|
|
var (
|
|
osPageMask = osPageSize - 1
|
|
osPageSize = os.Getpagesize()
|
|
)
|
|
|
|
//go:linkname mmapSyscall syscall.mmap
|
|
func mmapSyscall(addr uintptr, length uintptr, prot int, flags int, fd int, offset int64) (xaddr uintptr, err error)
|
|
|
|
func unmap(addr uintptr, size int) error {
|
|
_, _, errno := syscall.Syscall(sys_MUNMAP, addr, uintptr(size), 0)
|
|
if errno != 0 {
|
|
return errno
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// pageSize aligned.
|
|
func mmap(size int) (uintptr, int, error) {
|
|
size = roundup(size, osPageSize)
|
|
// The actual mmap syscall varies by architecture. mmapSyscall provides same
|
|
// functionality as the unexported funtion syscall.mmap and is declared in
|
|
// mmap_*_*.go and mmap_fallback.go. To add support for a new architecture,
|
|
// check function mmap in src/syscall/syscall_*_*.go or
|
|
// src/syscall/zsyscall_*_*.go in Go's source code.
|
|
p, err := mmapSyscall(0, uintptr(size+pageSize), syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_PRIVATE|syscall.MAP_ANON, -1, 0)
|
|
if err != nil {
|
|
return 0, 0, err
|
|
}
|
|
|
|
n := size + pageSize
|
|
if p&uintptr(osPageMask) != 0 {
|
|
panic("internal error")
|
|
}
|
|
|
|
mod := int(p) & pageMask
|
|
if mod != 0 {
|
|
m := pageSize - mod
|
|
if err := unmap(p, m); err != nil {
|
|
return 0, 0, err
|
|
}
|
|
|
|
n -= m
|
|
p += uintptr(m)
|
|
}
|
|
|
|
if p&uintptr(pageMask) != 0 {
|
|
panic("internal error")
|
|
}
|
|
|
|
if n-size != 0 {
|
|
if err := unmap(p+uintptr(size), n-size); err != nil {
|
|
return 0, 0, err
|
|
}
|
|
}
|
|
|
|
return p, size, nil
|
|
}
|