139 lines
2.6 KiB
Go
139 lines
2.6 KiB
Go
package zim
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import (
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"encoding/binary"
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"fmt"
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"github.com/pkg/errors"
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)
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type Entry interface {
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Redirect() (*ContentEntry, error)
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Namespace() Namespace
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URL() string
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FullURL() string
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Title() string
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}
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type BaseEntry struct {
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mimeTypeIndex uint16
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namespace Namespace
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url string
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title string
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reader *Reader
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}
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func (e *BaseEntry) Namespace() Namespace {
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return e.namespace
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}
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func (e *BaseEntry) Title() string {
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if e.title == "" {
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return e.url
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}
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return e.title
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}
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func (e *BaseEntry) URL() string {
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return e.url
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}
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func (e *BaseEntry) FullURL() string {
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return toFullURL(e.Namespace(), e.URL())
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}
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func (r *Reader) parseBaseEntry(offset int64) (*BaseEntry, error) {
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entry := &BaseEntry{
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reader: r,
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}
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data := make([]byte, 2)
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if err := r.readRange(offset, data); err != nil {
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return nil, errors.WithStack(err)
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}
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mimeTypeIndex, err := readUint16(data, binary.LittleEndian)
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if err != nil {
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return nil, errors.WithStack(err)
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}
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entry.mimeTypeIndex = mimeTypeIndex
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data = make([]byte, 1)
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if err := r.readRange(offset+3, data); err != nil {
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return nil, errors.WithStack(err)
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}
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entry.namespace = Namespace(data[0])
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return entry, nil
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}
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type RedirectEntry struct {
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*BaseEntry
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redirectIndex uint32
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}
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func (e *RedirectEntry) Redirect() (*ContentEntry, error) {
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if e.redirectIndex >= uint32(len(e.reader.urlIndex)) {
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return nil, errors.Wrapf(ErrInvalidEntryIndex, "entry index '%d' out of bounds", e.redirectIndex)
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}
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entryPtr := e.reader.urlIndex[e.redirectIndex]
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entry, err := e.reader.parseEntryAt(int64(entryPtr))
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if err != nil {
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return nil, errors.WithStack(err)
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}
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entry, err = entry.Redirect()
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if err != nil {
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return nil, errors.WithStack(err)
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}
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contentEntry, ok := entry.(*ContentEntry)
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if !ok {
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return nil, errors.WithStack(ErrInvalidRedirect)
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}
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return contentEntry, nil
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}
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func (r *Reader) parseRedirectEntry(offset int64, base *BaseEntry) (*RedirectEntry, error) {
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entry := &RedirectEntry{
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BaseEntry: base,
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}
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data := make([]byte, 4)
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if err := r.readRange(offset+8, data); err != nil {
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return nil, errors.WithStack(err)
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}
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redirectIndex, err := readUint32(data, binary.LittleEndian)
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if err != nil {
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return nil, errors.WithStack(err)
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}
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entry.redirectIndex = redirectIndex
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url, read, err := r.readStringAt(offset + 12)
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if err != nil {
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return nil, errors.WithStack(err)
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}
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entry.url = url
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title, _, err := r.readStringAt(offset + 12 + read)
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if err != nil {
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return nil, errors.WithStack(err)
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}
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entry.title = title
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return entry, nil
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}
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func toFullURL(ns Namespace, url string) string {
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return fmt.Sprintf("%s/%s", ns, url)
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}
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