// ReadAt blocks until either all the data is available or an error occurs.
// In this respect ReadAt is different from Read.
//
// If the n = len(p) bytes returned by ReadAt are at the end of the
// input source, ReadAt may return either err == EOF or err == nil.
//
// If ReadAt is reading from an input source with a seek offset,
// ReadAt should not affect nor be affected by the underlying

			err = machoUpdateLoadCommand(reader, linkseg, linkoffset, &linkEditDataCmd{}, "DataOff")
		case LC_ENCRYPTION_INFO, LC_ENCRYPTION_INFO_64:
			err = machoUpdateLoadCommand(reader, linkseg, linkoffset, &encryptionInfoCmd{}, "CryptOff")
		case LC_UUID:
			var u uuidCmd
			err = reader.ReadAt(0, &u)
			if err == nil {
				copy(u.Uuid[:], uuidFromGoBuildId(*flagBuildid))
				err = reader.WriteAt(0, &u)
			}

	}
	return asString(s[n : n+int(v)])
}

// A reader reads sequential fields from a section of the index format.
type reader struct {
	d   *decoder
	pos int
}

// readAt returns a reader starting at the given position in d.
func (d *decoder) readAt(pos int) *reader {
	return &reader{d, pos}
}

// int reads the next int.
func (r *reader) int() int {
	i := r.d.intAt(r.pos)
	r.pos += 4

	return nil
}

// NewFile creates a new [File] for accessing an ELF binary in an underlying reader.
// The ELF binary is expected to start at position 0 in the ReaderAt.
func NewFile(r io.ReaderAt) (*File, error) {
	sr := io.NewSectionReader(r, 0, 1<<63-1)
	// Read and decode ELF identifier
	var ident [16]uint8
	if _, err := r.ReadAt(ident[0:], 0); err != nil {
		return nil, err
	}

	return e.Err
}

// Read reads up to len(b) bytes from the File and stores them in b.
// It returns the number of bytes read and any error encountered.
// At end of file, Read returns 0, io.EOF.
func (f *File) Read(b []byte) (n int, err error) {
	if err := f.checkValid("read"); err != nil {
		return 0, err
	}
	n, e := f.read(b)
	return n, f.wrapErr("read", e)
}

}

func (f *sftpDriver) Fileread(r *sftp.Request) (ra io.ReaderAt, err error) {
	// This is not timing the actual read operation, but the time it takes to prepare the reader.
	stopFn := globalSftpMetrics.log(r, f.AccessKey())
	defer stopFn(0, err)

	flags := r.Pflags()
	if !flags.Read {
		// sanity check
		return nil, os.ErrInvalid
	}

	bucket, object := path2BucketObject(r.Filepath)
	if bucket == "" {

		} else {
			bo = binary.LittleEndian
		}
		var readPtr func([]byte) uint64
		if ptrSize == 4 {
			readPtr = func(b []byte) uint64 { return uint64(bo.Uint32(b)) }
		} else if ptrSize == 8 {
			readPtr = bo.Uint64
		} else {
			return "", "", errNotGoExe
		}
		vers = readString(x, ptrSize, readPtr, readPtr(data[16:]))
		mod = readString(x, ptrSize, readPtr, readPtr(data[16+ptrSize:]))
	}
	if vers == "" {

	files  []file // the directory contents
	offset int    // the read offset, an index into the files slice
}

func (d *openDir) Close() error               { return nil }
func (d *openDir) Stat() (fs.FileInfo, error) { return d.f, nil }

func (d *openDir) Read([]byte) (int, error) {
	return 0, &fs.PathError{Op: "read", Path: d.f.name, Err: errors.New("is a directory")}
}

	if err != nil {
		t.errorf("%s: fs.ReadFile: %w", file, err)
		return
	}
	t.checkFileRead(file, "ReadAll vs fs.ReadFile", data, data2)

	// Use iotest.TestReader to check small reads, Seek, ReadAt.
	f, err = t.fsys.Open(file)
	if err != nil {
		t.errorf("%s: second Open: %w", file, err)
		return
	}
	defer f.Close()
	if err := iotest.TestReader(f, data); err != nil {

	if err != nil {
		return "", err
	}
	return sum, nil
}

var errNotCached = fmt.Errorf("not in cache")

// readDiskStat reads a cached stat result from disk,
// returning the name of the cache file and the result.
// If the read fails, the caller can use
// writeDiskStat(file, info) to write a new cache entry.