/
buffer_mmap.go
52 lines (42 loc) · 942 Bytes
/
buffer_mmap.go
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// +build !purego
// +build aix android darwin dragonfly freebsd illumos ios linux netbsd openbsd plan9 solaris
package buffer
import (
"syscall"
)
type Buffer struct {
n int
pg int
mmap []byte
}
func New(n int) (Buffer, error) {
pg := syscall.Getpagesize()
full := ((n+(pg-1))/pg + 2) * pg
b, err := syscall.Mmap(-1, 0, full, syscall.PROT_NONE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
if err != nil {
return Buffer{}, err
}
if n > 0 {
err = syscall.Mprotect(b[pg:full-pg], syscall.PROT_READ|syscall.PROT_WRITE)
if err != nil {
syscall.Munmap(b)
return Buffer{}, err
}
}
return Buffer{
n: n,
pg: pg,
mmap: b,
}, nil
}
func (a *Buffer) ProtectHead() []byte {
head := a.pg
return a.mmap[head : head+a.n : head+a.n]
}
func (a *Buffer) ProtectTail() []byte {
tail := len(a.mmap) - a.pg - a.n
return a.mmap[tail : tail+a.n : tail+a.n]
}
func (a *Buffer) Release() {
syscall.Munmap(a.mmap)
}