/usr/share/gocode/src/golang.org/x/exp/mmap/mmap_other.go is in golang-golang-x-exp-dev 0.0~git20150826.1.eb7c1fa-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 | // Copyright 2015 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.
// +build !linux
// Package mmap provides a way to memory-map a file.
package mmap
import (
"fmt"
"os"
)
// ReaderAt reads a memory-mapped file.
//
// Like any io.ReaderAt, clients can execute parallel ReadAt calls, but it is
// not safe to call Close and reading methods concurrently.
type ReaderAt struct {
f *os.File
len int
}
// Close closes the reader.
func (r *ReaderAt) Close() error {
return r.f.Close()
}
// Len returns the length of the underlying memory-mapped file.
func (r *ReaderAt) Len() int {
return r.len
}
// At returns the byte at index i.
func (r *ReaderAt) At(i int) byte {
if i < 0 || r.len <= i {
panic("index out of range")
}
var b [1]byte
r.ReadAt(b[:], int64(i))
return b[0]
}
// ReadAt implements the io.ReaderAt interface.
func (r *ReaderAt) ReadAt(p []byte, off int64) (int, error) {
return r.f.ReadAt(p, off)
}
// Open memory-maps the named file for reading.
func Open(filename string) (*ReaderAt, error) {
f, err := os.Open(filename)
if err != nil {
return nil, err
}
fi, err := f.Stat()
if err != nil {
f.Close()
return nil, err
}
size := fi.Size()
if size < 0 {
f.Close()
return nil, fmt.Errorf("mmap: file %q has negative size", filename)
}
if size != int64(int(size)) {
f.Close()
return nil, fmt.Errorf("mmap: file %q is too large", filename)
}
return &ReaderAt{
f: f,
len: int(fi.Size()),
}, nil
}
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