| // Copyright 2011 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| //go:build unix |
| |
| package mmap |
| |
| import ( |
| "fmt" |
| "io/fs" |
| "os" |
| "syscall" |
| ) |
| |
| func mmapFile(f *os.File) (Data, error) { |
| st, err := f.Stat() |
| if err != nil { |
| return Data{}, err |
| } |
| size := st.Size() |
| pagesize := int64(os.Getpagesize()) |
| if int64(int(size+(pagesize-1))) != size+(pagesize-1) { |
| return Data{}, fmt.Errorf("%s: too large for mmap", f.Name()) |
| } |
| n := int(size) |
| if n == 0 { |
| return Data{f, nil}, nil |
| } |
| mmapLength := int(((size + pagesize - 1) / pagesize) * pagesize) // round up to page size |
| data, err := syscall.Mmap(int(f.Fd()), 0, mmapLength, syscall.PROT_READ, syscall.MAP_SHARED) |
| if err != nil { |
| return Data{}, &fs.PathError{Op: "mmap", Path: f.Name(), Err: err} |
| } |
| return Data{f, data[:n]}, nil |
| } |
