mirror of
https://github.com/rclone/rclone
synced 2024-12-27 19:43:48 +01:00
43 lines
1.2 KiB
Go
43 lines
1.2 KiB
Go
// Package mmap implements a large block memory allocator using
|
|
// anonymous memory maps.
|
|
|
|
// +build windows
|
|
|
|
package mmap
|
|
|
|
import (
|
|
"reflect"
|
|
"unsafe"
|
|
|
|
"github.com/pkg/errors"
|
|
"golang.org/x/sys/windows"
|
|
)
|
|
|
|
// Alloc allocates size bytes and returns a slice containing them. If
|
|
// the allocation fails it will return with an error. This is best
|
|
// used for allocations which are a multiple of the PageSize.
|
|
func Alloc(size int) ([]byte, error) {
|
|
p, err := windows.VirtualAlloc(0, uintptr(size), windows.MEM_COMMIT, windows.PAGE_READWRITE)
|
|
if err != nil {
|
|
return nil, errors.Wrap(err, "mmap: failed to allocate memory for buffer")
|
|
}
|
|
var mem []byte
|
|
sh := (*reflect.SliceHeader)(unsafe.Pointer(&mem))
|
|
sh.Data = p
|
|
sh.Len = size
|
|
sh.Cap = size
|
|
return mem, nil
|
|
}
|
|
|
|
// Free frees buffers allocated by Alloc. Note it should be passed
|
|
// the same slice (not a derived slice) that Alloc returned. If the
|
|
// free fails it will return with an error.
|
|
func Free(mem []byte) error {
|
|
sh := (*reflect.SliceHeader)(unsafe.Pointer(&mem))
|
|
err := windows.VirtualFree(sh.Data, 0, windows.MEM_RELEASE)
|
|
if err != nil {
|
|
return errors.Wrap(err, "mmap: failed to unmap memory")
|
|
}
|
|
return nil
|
|
}
|