mirror of
https://github.com/rclone/rclone
synced 2024-11-29 07:55:12 +01:00
e43b5ce5e5
This is possible now that we no longer support go1.12 and brings rclone into line with standard practices in the Go world. This also removes errors.New and errors.Errorf from lib/errors and prefers the stdlib errors package over lib/errors.
44 lines
1.2 KiB
Go
44 lines
1.2 KiB
Go
// Package mmap implements a large block memory allocator using
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// anonymous memory maps.
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//go:build windows
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// +build windows
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package mmap
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import (
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"fmt"
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"reflect"
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"unsafe"
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"golang.org/x/sys/windows"
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)
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// Alloc allocates size bytes and returns a slice containing them. If
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// the allocation fails it will return with an error. This is best
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// used for allocations which are a multiple of the PageSize.
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func Alloc(size int) ([]byte, error) {
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p, err := windows.VirtualAlloc(0, uintptr(size), windows.MEM_COMMIT, windows.PAGE_READWRITE)
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if err != nil {
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return nil, fmt.Errorf("mmap: failed to allocate memory for buffer: %w", err)
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}
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var mem []byte
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sh := (*reflect.SliceHeader)(unsafe.Pointer(&mem))
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sh.Data = p
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sh.Len = size
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sh.Cap = size
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return mem, nil
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}
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// Free frees buffers allocated by Alloc. Note it should be passed
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// the same slice (not a derived slice) that Alloc returned. If the
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// free fails it will return with an error.
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func Free(mem []byte) error {
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sh := (*reflect.SliceHeader)(unsafe.Pointer(&mem))
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err := windows.VirtualFree(sh.Data, 0, windows.MEM_RELEASE)
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if err != nil {
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return fmt.Errorf("mmap: failed to unmap memory: %w", err)
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}
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return nil
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}
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