mirror of
https://github.com/Binject/debug
synced 2026-06-08 10:28:33 +00:00
Joe Tsai
66b4997c90
CL/19862 (f79b50b8d5bc159561c1dcf7c17e2a0db96a9a11) recently introduced the constants SeekStart, SeekCurrent, and SeekEnd to the io package. We should use these constants consistently throughout the code base. Updates #15269 Change-Id: If7fcaca7676e4a51f588528f5ced28220d9639a2 Reviewed-on: https://go-review.googlesource.com/22097 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Joe Tsai <joetsai@digital-static.net> TryBot-Result: Gobot Gobot <gobot@golang.org>
109 lines
2.1 KiB
Go
109 lines
2.1 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package elf
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import (
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"io"
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"os"
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)
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// errorReader returns error from all operations.
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type errorReader struct {
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error
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}
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func (r errorReader) Read(p []byte) (n int, err error) {
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return 0, r.error
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}
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func (r errorReader) ReadAt(p []byte, off int64) (n int, err error) {
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return 0, r.error
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}
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func (r errorReader) Seek(offset int64, whence int) (int64, error) {
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return 0, r.error
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}
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func (r errorReader) Close() error {
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return r.error
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}
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// readSeekerFromReader converts an io.Reader into an io.ReadSeeker.
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// In general Seek may not be efficient, but it is optimized for
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// common cases such as seeking to the end to find the length of the
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// data.
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type readSeekerFromReader struct {
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reset func() (io.Reader, error)
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r io.Reader
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size int64
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offset int64
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}
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func (r *readSeekerFromReader) start() {
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x, err := r.reset()
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if err != nil {
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r.r = errorReader{err}
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} else {
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r.r = x
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}
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r.offset = 0
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}
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func (r *readSeekerFromReader) Read(p []byte) (n int, err error) {
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if r.r == nil {
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r.start()
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}
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n, err = r.r.Read(p)
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r.offset += int64(n)
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return n, err
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}
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func (r *readSeekerFromReader) Seek(offset int64, whence int) (int64, error) {
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var newOffset int64
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switch whence {
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case io.SeekStart:
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newOffset = offset
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case io.SeekCurrent:
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newOffset = r.offset + offset
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case io.SeekEnd:
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newOffset = r.size + offset
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default:
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return 0, os.ErrInvalid
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}
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switch {
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case newOffset == r.offset:
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return newOffset, nil
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case newOffset < 0, newOffset > r.size:
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return 0, os.ErrInvalid
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case newOffset == 0:
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r.r = nil
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case newOffset == r.size:
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r.r = errorReader{io.EOF}
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default:
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if newOffset < r.offset {
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// Restart at the beginning.
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r.start()
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}
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// Read until we reach offset.
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var buf [512]byte
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for r.offset < newOffset {
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b := buf[:]
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if newOffset-r.offset < int64(len(buf)) {
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b = buf[:newOffset-r.offset]
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}
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if _, err := r.Read(b); err != nil {
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return 0, err
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}
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}
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}
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r.offset = newOffset
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return r.offset, nil
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}
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