Adding upstream version 2.7.12.upstream/2.7.12

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1218 insertions, 0 deletions

diff --git a/apt-pkg/acquire-item.h b/apt-pkg/acquire-item.h
new file mode 100644
index 0000000..22da981
--- /dev/null
+++ b/apt-pkg/acquire-item.h
@@ -0,0 +1,1218 @@
+// -*- mode: cpp; mode: fold -*-
+// Description								/*{{{*/
+/* ######################################################################
+
+   Acquire Item - Item to acquire
+
+   When an item is instantiated it will add it self to the local list in
+   the Owner Acquire class. Derived classes will then call QueueURI to
+   register all the URI's they wish to fetch at the initial moment.
+
+   Three item classes are provided to provide functionality for
+   downloading of Index, Translation and Packages files.
+
+   A Archive class is provided for downloading .deb files. It does Hash
+   checking and source location as well as a retry algorithm.
+
+   ##################################################################### */
+									/*}}}*/
+#ifndef PKGLIB_ACQUIRE_ITEM_H
+#define PKGLIB_ACQUIRE_ITEM_H
+
+#include <apt-pkg/acquire.h>
+#include <apt-pkg/hashes.h>
+#include <apt-pkg/indexfile.h>
+#include <apt-pkg/pkgcache.h>
+#include <apt-pkg/weakptr.h>
+
+#include <map>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+
+/** \addtogroup acquire
+ *  @{
+ *
+ *  \file acquire-item.h
+ */
+
+class pkgRecords;
+class pkgSourceList;
+class pkgAcqMetaClearSig;
+class pkgAcqIndexMergeDiffs;
+class metaIndex;
+
+class APT_PUBLIC pkgAcquire::Item : public WeakPointable				/*{{{*/
+/** \brief Represents the process by which a pkgAcquire object should
+ *  retrieve a file or a collection of files.
+ *
+ *  By convention, Item subclasses should insert themselves into the
+ *  acquire queue when they are created by calling QueueURI(), and
+ *  remove themselves by calling Dequeue() when either Done() or
+ *  Failed() is invoked.  Item objects are also responsible for
+ *  notifying the download progress indicator (accessible via
+ *  #Owner->Log) of their status.
+ *
+ *  \see pkgAcquire
+ */
+{
+   public:
+
+   /** \brief The current status of this item. */
+   enum ItemState
+     {
+       /** \brief The item is waiting to be downloaded. */
+       StatIdle,
+
+       /** \brief The item is currently being downloaded. */
+       StatFetching,
+
+       /** \brief The item has been successfully downloaded. */
+       StatDone,
+
+       /** \brief An error was encountered while downloading this
+	*  item.
+	*/
+       StatError,
+
+       /** \brief The item was downloaded but its authenticity could
+	*  not be verified.
+	*/
+       StatAuthError,
+
+       /** \brief The item was could not be downloaded because of
+	*  a transient network error (e.g. network down)
+	*/
+       StatTransientNetworkError,
+     } Status;
+
+   /** \brief Contains a textual description of the error encountered
+    *  if #ItemState is #StatError or #StatAuthError.
+    */
+   std::string ErrorText;
+
+   /** \brief The size of the object to fetch. */
+   unsigned long long FileSize;
+
+   /** \brief How much of the object was already fetched. */
+   unsigned long long PartialSize;
+
+   /** \brief contains the name of the subprocess that is operating on this object
+    * (for instance, "gzip", "rred" or "gpgv"). This is obsoleting #Mode from above
+    * as it can manage the lifetime of included string properly. */
+   std::string ActiveSubprocess;
+
+   /** \brief A client-supplied unique identifier.
+    *
+    *  This field is initialized to 0; it is meant to be filled in by
+    *  clients that wish to use it to uniquely identify items.
+    *
+    *  APT progress reporting will store an ID there as shown in "Get:42 …"
+    */
+   unsigned long ID;
+
+   /** \brief If \b true, the entire object has been successfully fetched.
+    *
+    *  Subclasses should set this to \b true when appropriate.
+    */
+   bool Complete;
+
+   /** \brief If \b true, the URI of this object is "local".
+    *
+    *  The only effect of this field is to exclude the object from the
+    *  download progress indicator's overall statistics.
+    */
+   bool Local;
+
+   std::string UsedMirror;
+
+   /** \brief The number of fetch queues into which this item has been
+    *  inserted.
+    *
+    *  There is one queue for each source from which an item could be
+    *  downloaded.
+    *
+    *  \sa pkgAcquire
+    */
+   unsigned int QueueCounter;
+
+   /** \brief The number of additional fetch items that are expected
+    *  once this item is done.
+    *
+    *  Some items like pkgAcqMeta{Index,Sig} will queue additional
+    *  items. This variable can be set by the methods if it knows
+    *  in advance how many items to expect to get a more accurate
+    *  progress.
+    */
+   unsigned int ExpectedAdditionalItems;
+
+   /** \brief The name of the file into which the retrieved object
+    *  will be written.
+    */
+   std::string DestFile;
+
+   /** \brief Number of retries */
+   unsigned int Retries;
+
+   /** \brief Invoked by the acquire worker when the object couldn't
+    *  be fetched.
+    *
+    *  This is a branch of the continuation of the fetch process.
+    *
+    *  \param Message An RFC822-formatted message from the acquire
+    *  method describing what went wrong.  Use LookupTag() to parse
+    *  it.
+    *
+    *  \param Cnf The method via which the worker tried to fetch this object.
+    *
+    *  \sa pkgAcqMethod
+    */
+   virtual void Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf);
+   APT_HIDDEN void FailMessage(std::string const &Message);
+
+   /** \brief Invoked by the acquire worker to check if the successfully
+    * fetched object is also the objected we wanted to have.
+    *
+    *  Note that the object might \e not have been written to
+    *  DestFile; check for the presence of an Alt-Filename entry in
+    *  Message to find the file to which it was really written.
+    *
+    *  This is called before Done is called and can prevent it by returning
+    *  \b false which will result in Failed being called instead.
+    *
+    *  You should prefer to use this method over calling Failed() from Done()
+    *  as this has e.g. the wrong progress reporting.
+    *
+    *  \param Message Data from the acquire method.  Use LookupTag()
+    *  to parse it.
+    *  \param Cnf The method via which the object was fetched.
+    *
+    *  \sa pkgAcqMethod
+    */
+   virtual bool VerifyDone(std::string const &Message,
+	 pkgAcquire::MethodConfig const * const Cnf);
+
+   /** \brief Invoked by the acquire worker when the object was
+    *  fetched successfully.
+    *
+    *  Note that the object might \e not have been written to
+    *  DestFile; check for the presence of an Alt-Filename entry in
+    *  Message to find the file to which it was really written.
+    *
+    *  Done is often used to switch from one stage of the processing
+    *  to the next (e.g. fetching, unpacking, copying).  It is one
+    *  branch of the continuation of the fetch process.
+    *
+    *  \param Message Data from the acquire method.  Use LookupTag()
+    *  to parse it.
+    *  \param Hashes The HashSums of the object that was fetched.
+    *  \param Cnf The method via which the object was fetched.
+    *
+    *  \sa pkgAcqMethod
+    */
+   virtual void Done(std::string const &Message, HashStringList const &Hashes,
+		     pkgAcquire::MethodConfig const * const Cnf);
+
+   /** \brief Invoked when the worker starts to fetch this object.
+    *
+    *  \param Message RFC822-formatted data from the worker process.
+    *  Use LookupTag() to parse it.
+    *
+    *  \param Hashes The expected hashes of the object being fetched.
+    *
+    *  \sa pkgAcqMethod
+    */
+   virtual void Start(std::string const &Message, unsigned long long const Size);
+
+   /** \brief Custom headers to be sent to the fetch process.
+    *
+    *  \return a string containing RFC822-style headers that are to be
+    *  inserted into the 600 URI Acquire message sent to the fetch
+    *  subprocess.  The headers are inserted after a newline-less
+    *  line, so they should (if nonempty) have a leading newline and
+    *  no trailing newline.
+    */
+   virtual std::string Custom600Headers() const;
+   // this is more a hack than a proper external interface, hence hidden
+   APT_HIDDEN std::unordered_map<std::string, std::string> &ModifyCustomFields();
+   // this isn't the super nicest interface either…
+   APT_HIDDEN bool PopAlternativeURI(std::string &NewURI);
+   APT_HIDDEN bool IsGoodAlternativeURI(std::string const &AltUri) const;
+   APT_HIDDEN void PushAlternativeURI(std::string &&NewURI, std::unordered_map<std::string, std::string> &&fields, bool const at_the_back);
+   APT_HIDDEN void RemoveAlternativeSite(std::string &&OldSite);
+
+   /** \brief A "descriptive" URI-like string.
+    *
+    *  \return a URI that should be used to describe what is being fetched.
+    */
+   virtual std::string DescURI() const = 0;
+   /** \brief Short item description.
+    *
+    *  \return a brief description of the object being fetched.
+    */
+   virtual std::string ShortDesc() const;
+
+   /** \brief Invoked by the worker when the download is completely done. */
+   virtual void Finished();
+
+   /** \return HashSums the DestFile is supposed to have in this stage */
+   virtual HashStringList GetExpectedHashes() const = 0;
+   /** \return the 'best' hash for display proposes like --print-uris */
+   std::string HashSum() const;
+
+   /** \return if having no hashes is a hard failure or not
+    *
+    * Idealy this is always \b true for every subclass, but thanks to
+    * historical grow we don't have hashes for all files in all cases
+    * in all steps, so it is slightly more complicated than it should be.
+    */
+   virtual bool HashesRequired() const { return true; }
+
+   /** \return the acquire process with which this item is associated. */
+   pkgAcquire *GetOwner() const;
+   pkgAcquire::ItemDesc &GetItemDesc();
+
+   /** \return \b true if this object is being fetched from a trusted source. */
+   virtual bool IsTrusted() const;
+
+   /** \brief Set the name of the current active subprocess
+    *
+    *  See also #ActiveSubprocess
+    */
+   void SetActiveSubprocess(std::string const &subprocess);
+
+   /** \brief Initialize an item.
+    *
+    *  Adds the item to the list of items known to the acquire
+    *  process, but does not place it into any fetch queues (you must
+    *  manually invoke QueueURI() to do so).
+    *
+    *  \param Owner The new owner of this item.
+    */
+   explicit Item(pkgAcquire * const Owner);
+
+   /** \brief Remove this item from its owner's queue by invoking
+    *  pkgAcquire::Remove.
+    */
+   virtual ~Item();
+
+   bool APT_HIDDEN IsRedirectionLoop(std::string const &NewURI);
+   /** \brief The priority of the item, used for queuing */
+   int APT_HIDDEN Priority();
+
+   /** \brief internal clock definitions to avoid typing all that all over the place */
+   void APT_HIDDEN FetchAfter(time_point FetchAfter);
+   time_point APT_HIDDEN FetchAfter();
+
+   protected:
+   /** \brief The acquire object with which this item is associated. */
+   pkgAcquire * const Owner;
+
+   /** \brief The item that is currently being downloaded. */
+   pkgAcquire::ItemDesc Desc;
+
+   enum RenameOnErrorState {
+      HashSumMismatch,
+      SizeMismatch,
+      InvalidFormat,
+      SignatureError,
+      NotClearsigned,
+      MaximumSizeExceeded,
+      PDiffError,
+   };
+
+   /** \brief Rename failed file and set error
+    *
+    * \param state respresenting the error we encountered
+    */
+   bool RenameOnError(RenameOnErrorState const state);
+
+   /** \brief Insert this item into its owner's queue.
+    *
+    *  The method is designed to check if the request would end
+    *  in an IMSHit and if it determines that it would, it isn't
+    *  queueing the Item and instead sets it to completion instantly.
+    *
+    *  \param Item Metadata about this item (its URI and
+    *  description).
+    *  \return true if the item was inserted, false if IMSHit was detected
+    */
+   virtual bool QueueURI(ItemDesc &Item);
+
+   /** \brief Remove this item from its owner's queue. */
+   void Dequeue();
+
+   /** \brief Rename a file without modifying its timestamp.
+    *
+    *  Many item methods call this as their final action.
+    *
+    *  \param From The file to be renamed.
+    *
+    *  \param To The new name of \a From.  If \a To exists it will be
+    *  overwritten. If \a From and \a To are equal nothing happens.
+    */
+   bool Rename(std::string const &From, std::string const &To);
+
+   /** \brief Get the full pathname of the final file for the current URI */
+   virtual std::string GetFinalFilename() const;
+
+   private:
+   class Private;
+   Private * const d;
+
+   friend class pkgAcqMetaBase;
+   friend class pkgAcqMetaClearSig;
+};
+									/*}}}*/
+class APT_HIDDEN pkgAcqTransactionItem: public pkgAcquire::Item		/*{{{*/
+/** \brief baseclass for the indexes files to manage them all together */
+{
+   void * const d;
+   protected:
+   HashStringList GetExpectedHashesFor(std::string const &MetaKey) const;
+
+   bool QueueURI(pkgAcquire::ItemDesc &Item) APT_OVERRIDE;
+
+   public:
+   IndexTarget const Target;
+
+   /** \brief storge name until a transaction is finished */
+   std::string PartialFile;
+
+   /** \brief TransactionManager */
+   pkgAcqMetaClearSig * const TransactionManager;
+
+   enum TransactionStates {
+      TransactionStarted,
+      TransactionCommit,
+      TransactionAbort,
+   };
+   virtual bool TransactionState(TransactionStates const state);
+
+   virtual std::string DescURI() const APT_OVERRIDE { return Target.URI; }
+   virtual HashStringList GetExpectedHashes() const APT_OVERRIDE;
+   virtual std::string GetMetaKey() const;
+   virtual bool HashesRequired() const APT_OVERRIDE;
+   virtual bool AcquireByHash() const;
+
+   pkgAcqTransactionItem(pkgAcquire * const Owner, pkgAcqMetaClearSig * const TransactionManager, IndexTarget const &Target) APT_NONNULL(2, 3);
+   virtual ~pkgAcqTransactionItem();
+
+   friend class pkgAcqMetaBase;
+   friend class pkgAcqMetaClearSig;
+};
+									/*}}}*/
+class APT_HIDDEN pkgAcqMetaBase : public pkgAcqTransactionItem		/*{{{*/
+/** \brief the manager of a transaction */
+{
+   void * const d;
+ protected:
+   std::vector<pkgAcqTransactionItem*> Transaction;
+
+   /** \brief If \b true, the index's signature is currently being verified.
+    */
+   bool AuthPass;
+
+   /** \brief Called when a file is finished being retrieved.
+    *
+    *  If the file was not downloaded to DestFile, a copy process is
+    *  set up to copy it to DestFile; otherwise, Complete is set to \b
+    *  true and the file is moved to its final location.
+    *
+    *  \param Message The message block received from the fetch
+    *  subprocess.
+    */
+   bool CheckDownloadDone(pkgAcqTransactionItem * const I, const std::string &Message, HashStringList const &Hashes) const;
+
+   /** \brief Queue the downloaded Signature for verification */
+   void QueueForSignatureVerify(pkgAcqTransactionItem * const I, std::string const &File, std::string const &Signature);
+
+   virtual std::string Custom600Headers() const APT_OVERRIDE;
+
+   /** \brief Called when authentication succeeded.
+    *
+    *  Sanity-checks the authenticated file, queues up the individual
+    *  index files for download, and saves the signature in the lists
+    *  directory next to the authenticated list file.
+    *
+    *  \param Message The message block received from the fetch
+    *  subprocess.
+    *  \param Cnf The method and its configuration which handled the request
+    */
+   bool CheckAuthDone(std::string const &Message, pkgAcquire::MethodConfig const *const Cnf);
+
+   /** Check if the current item should fail at this point */
+   bool CheckStopAuthentication(pkgAcquire::Item * const I, const std::string &Message);
+
+   /** \brief Check that the release file is a release file for the
+    *  correct distribution.
+    *
+    *  \return \b true if no fatal errors were encountered.
+    */
+   bool VerifyVendor(std::string const &Message);
+
+   virtual bool TransactionState(TransactionStates const state) APT_OVERRIDE;
+
+ public:
+   // This refers more to the Transaction-Manager than the actual file
+   bool IMSHit;
+   TransactionStates State;
+   std::string BaseURI;
+
+   virtual bool QueueURI(pkgAcquire::ItemDesc &Item) APT_OVERRIDE;
+   virtual HashStringList GetExpectedHashes() const APT_OVERRIDE;
+   virtual bool HashesRequired() const APT_OVERRIDE;
+
+   // transaction code
+   void Add(pkgAcqTransactionItem * const I);
+   void AbortTransaction();
+   bool TransactionHasError() const;
+   void CommitTransaction();
+
+   /** \brief Stage (queue) a copy action when the transaction is committed
+    */
+   void TransactionStageCopy(pkgAcqTransactionItem * const I,
+                             const std::string &From,
+                             const std::string &To);
+   /** \brief Stage (queue) a removal action when the transaction is committed
+    */
+   void TransactionStageRemoval(pkgAcqTransactionItem * const I, const std::string &FinalFile);
+
+   /** \brief Get the full pathname of the final file for the current URI */
+   virtual std::string GetFinalFilename() const APT_OVERRIDE;
+
+   pkgAcqMetaBase(pkgAcquire * const Owner, pkgAcqMetaClearSig * const TransactionManager,
+		  IndexTarget const &DataTarget) APT_NONNULL(2, 3);
+   virtual ~pkgAcqMetaBase();
+};
+									/*}}}*/
+/** \brief An item that is responsible for downloading the meta-index	{{{
+ *  file (i.e., Release) itself and verifying its signature.
+ *
+ *  Once the download and verification are complete, the downloads of
+ *  the individual index files are queued up using pkgAcqDiffIndex.
+ *  If the meta-index file had a valid signature, the expected hashsums
+ *  of the index files will be the md5sums listed in the meta-index;
+ *  otherwise, the expected hashsums will be "" (causing the
+ *  authentication of the index files to be bypassed).
+ */
+class APT_HIDDEN pkgAcqMetaIndex : public pkgAcqMetaBase
+{
+   void * const d;
+   protected:
+   IndexTarget const DetachedSigTarget;
+
+   /** \brief delayed constructor */
+   void Init(std::string const &URIDesc, std::string const &ShortDesc);
+
+   public:
+   virtual std::string DescURI() const APT_OVERRIDE;
+
+   // Specialized action members
+   virtual void Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual void Done(std::string const &Message, HashStringList const &Hashes,
+		     pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+
+   /** \brief Create a new pkgAcqMetaIndex. */
+   pkgAcqMetaIndex(pkgAcquire * const Owner, pkgAcqMetaClearSig * const TransactionManager,
+		   IndexTarget const &DataTarget, IndexTarget const &DetachedSigTarget) APT_NONNULL(2, 3);
+   virtual ~pkgAcqMetaIndex();
+
+   friend class pkgAcqMetaSig;
+};
+									/*}}}*/
+/** \brief An acquire item that downloads the detached signature	{{{
+ *  of a meta-index (Release) file, then queues up the release
+ *  file itself.
+ *
+ *  \todo Why protected members?
+ *
+ *  \sa pkgAcqMetaIndex
+ */
+class APT_HIDDEN pkgAcqMetaSig : public pkgAcqTransactionItem
+{
+   void * const d;
+
+   pkgAcqMetaIndex * const MetaIndex;
+
+   /** \brief The file we use to verify the MetaIndexFile with (not always set!) */
+   std::string MetaIndexFileSignature;
+
+   protected:
+
+   /** \brief Get the full pathname of the final file for the current URI */
+   virtual std::string GetFinalFilename() const APT_OVERRIDE;
+
+   public:
+   virtual bool HashesRequired() const APT_OVERRIDE { return false; }
+
+   // Specialized action members
+   virtual void Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual void Done(std::string const &Message, HashStringList const &Hashes,
+		     pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual std::string Custom600Headers() const APT_OVERRIDE;
+
+   /** \brief Create a new pkgAcqMetaSig. */
+   pkgAcqMetaSig(pkgAcquire * const Owner, pkgAcqMetaClearSig * const TransactionManager,
+	 IndexTarget const &Target, pkgAcqMetaIndex * const MetaIndex) APT_NONNULL(2, 3, 5);
+   virtual ~pkgAcqMetaSig();
+};
+									/*}}}*/
+/** \brief An item responsible for downloading clearsigned metaindexes	{{{*/
+class APT_HIDDEN pkgAcqMetaClearSig : public pkgAcqMetaIndex
+{
+   void * const d;
+   IndexTarget const DetachedDataTarget;
+
+ public:
+   /** \brief A package-system-specific parser for the meta-index file. */
+   metaIndex *MetaIndexParser;
+   metaIndex *LastMetaIndexParser;
+
+   virtual void Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual std::string Custom600Headers() const APT_OVERRIDE;
+   virtual bool VerifyDone(std::string const &Message, pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual void Done(std::string const &Message, HashStringList const &Hashes,
+		     pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual void Finished() APT_OVERRIDE;
+
+   /** \brief Starts downloading the individual index files.
+    *
+    *  \param verify If \b true, only indices whose expected hashsum
+    *  can be determined from the meta-index will be downloaded, and
+    *  the hashsums of indices will be checked (reporting
+    *  #StatAuthError if there is a mismatch).  If verify is \b false,
+    *  no hashsum checking will be performed.
+    */
+   void QueueIndexes(bool const verify);
+
+   /** \brief Create a new pkgAcqMetaClearSig. */
+   pkgAcqMetaClearSig(pkgAcquire * const Owner,
+		IndexTarget const &ClearsignedTarget,
+		IndexTarget const &DetachedDataTarget,
+		IndexTarget const &DetachedSigTarget,
+		metaIndex * const MetaIndexParser);
+   virtual ~pkgAcqMetaClearSig();
+};
+									/*}}}*/
+/** \brief Common base class for all classes that deal with fetching indexes	{{{*/
+class APT_HIDDEN pkgAcqBaseIndex : public pkgAcqTransactionItem
+{
+   void * const d;
+
+ public:
+   /** \brief Get the full pathname of the final file for the current URI */
+   virtual std::string GetFinalFilename() const APT_OVERRIDE;
+   virtual void Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+
+   pkgAcqBaseIndex(pkgAcquire * const Owner, pkgAcqMetaClearSig * const TransactionManager,
+                   IndexTarget const &Target) APT_NONNULL(2, 3);
+   virtual ~pkgAcqBaseIndex();
+};
+									/*}}}*/
+/** \brief An acquire item that is responsible for fetching an index	{{{
+ *  file (e.g., Packages or Sources).
+ *
+ *  \sa pkgAcqDiffIndex, pkgAcqIndexDiffs, pkgAcqIndexTrans
+ *
+ *  \todo Why does pkgAcqIndex have protected members?
+ */
+class APT_HIDDEN pkgAcqIndex : public pkgAcqBaseIndex
+{
+   void * const d;
+
+   protected:
+
+   /** \brief The stages the method goes through
+    *
+    *  The method first downloads the indexfile, then its decompressed (or
+    *  copied) and verified
+    */
+   enum AllStages {
+      STAGE_DOWNLOAD,
+      STAGE_DECOMPRESS_AND_VERIFY,
+   };
+   AllStages Stage;
+
+   /** \brief Handle what needs to be done when the download is done */
+   void StageDownloadDone(std::string const &Message);
+
+   /** \brief Handle what needs to be done when the decompression/copy is
+    *         done
+    */
+   void StageDecompressDone();
+
+   /** \brief If \b set, this partially downloaded file will be
+    *  removed when the download completes.
+    */
+   std::string EraseFileName;
+
+   /** \brief The compression-related file extensions that are being
+    *  added to the downloaded file one by one if first fails (e.g., "gz bz2").
+    */
+   std::string CompressionExtensions;
+
+   /** \brief The actual compression extension currently used */
+   std::string CurrentCompressionExtension;
+
+   /** \brief Do the changes needed to fetch via AptByHash (if needed) */
+   void InitByHashIfNeeded();
+
+   /** \brief Get the full pathname of the final file for the current URI */
+   virtual std::string GetFinalFilename() const APT_OVERRIDE;
+
+   virtual bool TransactionState(TransactionStates const state) APT_OVERRIDE;
+
+   public:
+   // Specialized action members
+   virtual void Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual void Done(std::string const &Message, HashStringList const &Hashes,
+		     pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual std::string Custom600Headers() const APT_OVERRIDE;
+   virtual std::string DescURI() const APT_OVERRIDE {return Desc.URI;};
+   virtual std::string GetMetaKey() const APT_OVERRIDE;
+
+   pkgAcqIndex(pkgAcquire * const Owner, pkgAcqMetaClearSig * const TransactionManager,
+               IndexTarget const &Target, bool const Derived = false) APT_NONNULL(2, 3);
+   virtual ~pkgAcqIndex();
+
+   protected:
+   APT_HIDDEN void Init(std::string const &URI, std::string const &URIDesc,
+             std::string const &ShortDesc);
+   APT_HIDDEN bool CommonFailed(std::string const &TargetURI,
+				std::string const &Message, pkgAcquire::MethodConfig const *const Cnf);
+};
+									/*}}}*/
+struct APT_HIDDEN DiffInfo {						/*{{{*/
+   /** The filename of the diff. */
+   std::string file;
+
+   /** The hashes of the file after the diff is applied */
+   HashStringList result_hashes;
+
+   /** The hashes of the diff */
+   HashStringList patch_hashes;
+
+   /** The hashes of the compressed diff */
+   HashStringList download_hashes;
+};
+									/*}}}*/
+/** \brief An item that is responsible for fetching an index file of	{{{
+ *  package list diffs and starting the package list's download.
+ *
+ *  This item downloads the Index file and parses it, then enqueues
+ *  additional downloads of either the individual patches (using
+ *  pkgAcqIndexDiffs) or the entire Packages file (using pkgAcqIndex).
+ *
+ *  \sa pkgAcqIndexDiffs, pkgAcqIndex
+ */
+class APT_HIDDEN pkgAcqDiffIndex : public pkgAcqIndex
+{
+   void * const d;
+   std::vector<pkgAcqIndexMergeDiffs*> * diffs;
+   std::vector<DiffInfo> available_patches;
+   bool pdiff_merge;
+
+ protected:
+   /** \brief If \b true, debugging information will be written to std::clog. */
+   bool Debug;
+
+   /** \brief Get the full pathname of the final file for the current URI */
+   virtual std::string GetFinalFilename() const APT_OVERRIDE;
+
+   virtual bool QueueURI(pkgAcquire::ItemDesc &Item) APT_OVERRIDE;
+
+   virtual bool TransactionState(TransactionStates const state) APT_OVERRIDE;
+ public:
+   // Specialized action members
+   virtual void Failed(std::string const &Message, pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual bool VerifyDone(std::string const &Message, pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual void Done(std::string const &Message, HashStringList const &Hashes,
+		     pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual std::string DescURI() const APT_OVERRIDE {return Target.URI + "Index";};
+   virtual std::string GetMetaKey() const APT_OVERRIDE;
+
+   /** \brief Parse the Index file for a set of Packages diffs.
+    *
+    *  Parses the Index file and creates additional download items as
+    *  necessary.
+    *
+    *  \param IndexDiffFile The name of the Index file.
+    *
+    *  \return \b true if the Index file was successfully parsed, \b
+    *  false otherwise.
+    */
+   bool ParseDiffIndex(std::string const &IndexDiffFile);
+
+   /** \brief Create a new pkgAcqDiffIndex.
+    *
+    *  \param Owner The Acquire object that owns this item.
+    *
+    *  \param URI The URI of the list file to download.
+    *
+    *  \param URIDesc A long description of the list file to download.
+    *
+    *  \param ShortDesc A short description of the list file to download.
+    */
+   pkgAcqDiffIndex(pkgAcquire * const Owner, pkgAcqMetaClearSig * const TransactionManager,
+                   IndexTarget const &Target) APT_NONNULL(2, 3);
+   virtual ~pkgAcqDiffIndex();
+ private:
+   APT_HIDDEN void QueueOnIMSHit() const;
+};
+									/*}}}*/
+/** \brief An item that is responsible for fetching client-merge patches {{{
+ *  that need to be applied to a given package index file.
+ *
+ *  Instead of downloading and applying each patch one by one like its
+ *  sister #pkgAcqIndexDiffs this class will download all patches at once
+ *  and call rred with all the patches downloaded once. Rred will then
+ *  merge and apply them in one go, which should be a lot faster – but is
+ *  incompatible with server-based merges of patches like reprepro can do.
+ *
+ *  \sa pkgAcqDiffIndex, pkgAcqIndex
+ */
+class APT_HIDDEN pkgAcqIndexMergeDiffs : public pkgAcqBaseIndex
+{
+   protected:
+
+   /** \brief If \b true, debugging output will be written to
+    *  std::clog.
+    */
+   bool Debug;
+
+   /** \brief information about the current patch */
+   struct DiffInfo const patch;
+
+   /** \brief list of all download items for the patches */
+   std::vector<pkgAcqIndexMergeDiffs*> const * const allPatches;
+
+   /** The current status of this patch. */
+   enum DiffState
+   {
+      /** \brief The diff is currently being fetched. */
+      StateFetchDiff,
+
+      /** \brief The diff is currently being applied. */
+      StateApplyDiff,
+
+      /** \brief the work with this diff is done */
+      StateDoneDiff,
+
+      /** \brief something bad happened and fallback was triggered */
+      StateErrorDiff
+   } State;
+
+   public:
+   /** \brief Called when the patch file failed to be downloaded.
+    *
+    *  This method will fall back to downloading the whole index file
+    *  outright; its arguments are ignored.
+    */
+   virtual void Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual void Done(std::string const &Message, HashStringList const &Hashes,
+	 pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual std::string Custom600Headers() const APT_OVERRIDE;
+   virtual std::string DescURI() const APT_OVERRIDE {return Target.URI + "Index";};
+   virtual HashStringList GetExpectedHashes() const APT_OVERRIDE;
+   virtual bool HashesRequired() const APT_OVERRIDE;
+   virtual bool AcquireByHash() const APT_OVERRIDE;
+
+   /** \brief Create an index merge-diff item.
+    *
+    *  \param Owner The pkgAcquire object that owns this item.
+    *  \param TransactionManager responsible for this item
+    *  \param Target we intend to built via pdiff patching
+    *  \param baseURI is the URI used for the Index, but stripped down to Target
+    *  \param DiffInfo of the patch in question
+    *  \param patch contains infos about the patch this item is supposed
+    *  to download which were read from the index
+    *  \param allPatches contains all related items so that each item can
+    *  check if it was the last one to complete the download step
+    */
+   pkgAcqIndexMergeDiffs(pkgAcquire *const Owner, pkgAcqMetaClearSig *const TransactionManager,
+			 IndexTarget const &Target, DiffInfo const &patch,
+			 std::vector<pkgAcqIndexMergeDiffs *> const *const allPatches) APT_NONNULL(2, 3, 6);
+   virtual ~pkgAcqIndexMergeDiffs();
+};
+									/*}}}*/
+/** \brief An item that is responsible for fetching server-merge patches {{{
+ *  that need to be applied to a given package index file.
+ *
+ *  After downloading and applying a single patch, this item will
+ *  enqueue a new pkgAcqIndexDiffs to download and apply the remaining
+ *  patches.  If no patch can be found that applies to an intermediate
+ *  file or if one of the patches cannot be downloaded, falls back to
+ *  downloading the entire package index file using pkgAcqIndex.
+ *
+ *  \sa pkgAcqDiffIndex, pkgAcqIndex
+ */
+class APT_HIDDEN pkgAcqIndexDiffs : public pkgAcqBaseIndex
+{
+   private:
+
+   /** \brief Queue up the next diff download.
+    *
+    *  Search for the next available diff that applies to the file
+    *  that currently exists on disk, and enqueue it by calling
+    *  QueueURI().
+    *
+    *  \return \b true if an applicable diff was found, \b false
+    *  otherwise.
+    */
+   APT_HIDDEN bool QueueNextDiff();
+
+   /** \brief Handle tasks that must be performed after the item
+    *  finishes downloading.
+    *
+    *  Dequeues the item and checks the resulting file's hashsums
+    *  against ExpectedHashes after the last patch was applied.
+    *  There is no need to check the md5/sha1 after a "normal" 
+    *  patch because QueueNextDiff() will check the sha1 later.
+    *
+    *  \param allDone If \b true, the file was entirely reconstructed,
+    *  and its md5sum is verified. 
+    */
+   APT_HIDDEN void Finish(bool const allDone=false);
+
+   protected:
+
+   /** \brief If \b true, debugging output will be written to
+    *  std::clog.
+    */
+   bool Debug;
+
+   /** The patches that remain to be downloaded, including the patch
+    *  being downloaded right now.  This list should be ordered so
+    *  that each diff appears before any diff that depends on it.
+    *
+    *  \todo These are indexed by sha1sum; why not use some sort of
+    *  dictionary instead of relying on ordering and stripping them
+    *  off the front?
+    */
+   std::vector<DiffInfo> available_patches;
+
+   /** The current status of this patch. */
+   enum DiffState
+   {
+	 /** \brief The diff is currently being fetched. */
+	 StateFetchDiff,
+
+	 /** \brief The diff is currently being applied. */
+	 StateApplyDiff
+   } State;
+
+   public:
+
+   /** \brief Called when the patch file failed to be downloaded.
+    *
+    *  This method will fall back to downloading the whole index file
+    *  outright; its arguments are ignored.
+    */
+   virtual void Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+
+   virtual void Done(std::string const &Message, HashStringList const &Hashes,
+		     pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual std::string Custom600Headers() const APT_OVERRIDE;
+   virtual std::string DescURI() const APT_OVERRIDE {return Target.URI + "IndexDiffs";};
+   virtual HashStringList GetExpectedHashes() const APT_OVERRIDE;
+   virtual bool HashesRequired() const APT_OVERRIDE;
+   virtual bool AcquireByHash() const APT_OVERRIDE;
+
+   /** \brief Create an index diff item.
+    *
+    *  After filling in its basic fields, this invokes Finish(true) if
+    *  \a diffs is empty, or QueueNextDiff() otherwise.
+    *
+    *  \param Owner The pkgAcquire object that owns this item.
+    *  \param TransactionManager responsible for this item
+    *  \param Target we want to built via pdiff patching
+    *  \param baseURI is the URI used for the Index, but stripped down to Target
+    *  \param diffs The remaining diffs from the index of diffs.  They
+    *  should be ordered so that each diff appears before any diff
+    *  that depends on it.
+    */
+   pkgAcqIndexDiffs(pkgAcquire *const Owner, pkgAcqMetaClearSig *const TransactionManager,
+		    IndexTarget const &Target,
+		    std::vector<DiffInfo> const &diffs = std::vector<DiffInfo>()) APT_NONNULL(2, 3);
+   virtual ~pkgAcqIndexDiffs();
+};
+									/*}}}*/
+/** \brief An item that is responsible for fetching a package file.	{{{
+ *
+ *  If the package file already exists in the cache, nothing will be
+ *  done.
+ */
+class APT_PUBLIC pkgAcqArchive : public pkgAcquire::Item
+{
+   void * const d;
+
+   bool LocalSource;
+   HashStringList ExpectedHashes;
+
+   protected:
+   /** \brief The package version being fetched. */
+   pkgCache::VerIterator Version;
+
+   /** \brief The list of sources from which to pick archives to
+    *  download this package from.
+    */
+   pkgSourceList *Sources;
+
+   /** \brief A package records object, used to look up the file
+    *  corresponding to each version of the package.
+    */
+   pkgRecords *Recs;
+
+   /** \brief A location in which the actual filename of the package
+    *  should be stored.
+    */
+   std::string &StoreFilename;
+
+   /** \brief \b true if this version file is being downloaded from a
+    *  trusted source.
+    */
+   bool Trusted;
+
+   /** \brief Queue up the next available file for this version. */
+   bool QueueNext();
+
+   /** \brief Get the full pathname of the final file for the current URI */
+   virtual std::string GetFinalFilename() const APT_OVERRIDE;
+
+   public:
+
+   virtual void Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual void Done(std::string const &Message, HashStringList const &Hashes,
+		     pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual std::string DescURI() const APT_OVERRIDE;
+   virtual std::string ShortDesc() const APT_OVERRIDE;
+   virtual void Finished() APT_OVERRIDE;
+   virtual bool IsTrusted() const APT_OVERRIDE;
+   virtual HashStringList GetExpectedHashes() const APT_OVERRIDE;
+   virtual bool HashesRequired() const APT_OVERRIDE;
+
+   /** \brief Create a new pkgAcqArchive.
+    *
+    *  \param Owner The pkgAcquire object with which this item is
+    *  associated.
+    *
+    *  \param Sources The sources from which to download version
+    *  files.
+    *
+    *  \param Recs A package records object, used to look up the file
+    *  corresponding to each version of the package.
+    *
+    *  \param Version The package version to download.
+    *
+    *  \param[out] StoreFilename A location in which the actual filename of
+    *  the package should be stored.  It will be set to a guessed
+    *  basename in the constructor, and filled in with a fully
+    *  qualified filename once the download finishes.
+    */
+   pkgAcqArchive(pkgAcquire * const Owner,pkgSourceList * const Sources,
+		 pkgRecords * const Recs,pkgCache::VerIterator const &Version,
+		 std::string &StoreFilename);
+   virtual ~pkgAcqArchive();
+};
+									/*}}}*/
+/** \brief Retrieve the changelog for the given version			{{{
+ *
+ *  Downloads the changelog to a temporary file it will also remove again
+ *  while it is deconstructed or downloads it to a named location.
+ */
+class APT_PUBLIC pkgAcqChangelog : public pkgAcquire::Item
+{
+   class Private;
+   Private * const d;
+   std::string TemporaryDirectory;
+   std::string const SrcName;
+   std::string const SrcVersion;
+
+   public:
+   // we will never have hashes for changelogs.
+   // If you need verified ones, download the deb and extract the changelog.
+   virtual HashStringList GetExpectedHashes() const APT_OVERRIDE { return HashStringList(); }
+   virtual bool HashesRequired() const APT_OVERRIDE { return false; }
+
+   // Specialized action members
+   virtual void Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual void Done(std::string const &Message, HashStringList const &CalcHashes,
+		     pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual std::string DescURI() const APT_OVERRIDE {return Desc.URI;};
+
+   /** returns the URI to the changelog of this version
+    *
+    * @param Ver is the version to get the changelog for
+    * @return the URI which will be used to acquire the changelog
+    */
+   static std::string URI(pkgCache::VerIterator const &Ver);
+
+   /** returns the URI to the changelog of this version
+    *
+    *  \param Rls is the Release file the package comes from
+    *  \param Component in which the package resides, can be empty
+    *  \param SrcName is the source package name
+    *  \param SrcVersion is the source package version
+    * @return the URI which will be used to acquire the changelog
+    */
+   static std::string URI(pkgCache::RlsFileIterator const &Rls,
+	 char const * const Component, char const * const SrcName,
+	 char const * const SrcVersion);
+
+   /** returns the URI to the changelog of this version
+    *
+    *  \param Template URI where @CHANGEPATH@ has to be filled in
+    *  \param Component in which the package resides, can be empty
+    *  \param SrcName is the source package name
+    *  \param SrcVersion is the source package version
+    * @return the URI which will be used to acquire the changelog
+    */
+   static std::string URI(std::string const &Template,
+	 char const * const Component, char const * const SrcName,
+	 char const * const SrcVersion);
+
+   /** returns the URI template for this release file
+    *
+    *  \param Rls is a Release file
+    * @return the URI template to use for this release file
+    */
+   static std::string URITemplate(pkgCache::RlsFileIterator const &Rls);
+
+   /** \brief Create a new pkgAcqChangelog object.
+    *
+    *  \param Owner The pkgAcquire object with which this object is
+    *  associated.
+    *  \param Ver is the version to get the changelog for
+    *  \param DestDir The directory the file should be downloaded into.
+    *  Will be an autocreated (and cleaned up) temporary directory if not set.
+    *  \param DestFilename The filename the file should have in #DestDir
+    *  Defaults to sourcepackagename.changelog if not set.
+    */
+   pkgAcqChangelog(pkgAcquire * const Owner, pkgCache::VerIterator const &Ver,
+	 std::string const &DestDir="", std::string const &DestFilename="");
+
+   /** \brief Create a new pkgAcqChangelog object.
+    *
+    *  \param Owner The pkgAcquire object with which this object is
+    *  associated.
+    *  \param Rls is the Release file the package comes from
+    *  \param Component in which the package resides, can be empty
+    *  \param SrcName is the source package name
+    *  \param SrcVersion is the source package version
+    *  \param DestDir The directory the file should be downloaded into.
+    *  Will be an autocreated (and cleaned up) temporary directory if not set.
+    *  \param DestFilename The filename the file should have in #DestDir
+    *  Defaults to sourcepackagename.changelog if not set.
+    */
+   pkgAcqChangelog(pkgAcquire * const Owner, pkgCache::RlsFileIterator const &Rls,
+	 char const * const Component, char const * const SrcName, char const * const SrcVersion,
+	 std::string const &DestDir="", std::string const &DestFilename="");
+
+   /** \brief Create a new pkgAcqChangelog object.
+    *
+    *  \param Owner The pkgAcquire object with which this object is
+    *  associated.
+    *  \param URI is to be used to get the changelog
+    *  \param SrcName is the source package name
+    *  \param SrcVersion is the source package version
+    *  \param DestDir The directory the file should be downloaded into.
+    *  Will be an autocreated (and cleaned up) temporary directory if not set.
+    *  \param DestFilename The filename the file should have in #DestDir
+    *  Defaults to sourcepackagename.changelog if not set.
+    */
+   pkgAcqChangelog(pkgAcquire * const Owner, std::string const &URI,
+	 char const * const SrcName, char const * const SrcVersion,
+	 std::string const &DestDir="", std::string const &DestFilename="");
+
+   virtual ~pkgAcqChangelog();
+
+private:
+   APT_HIDDEN void Init(std::string const &DestDir, std::string const &DestFilename);
+};
+									/*}}}*/
+/** \brief Retrieve an arbitrary file to the current directory.		{{{
+ *
+ *  The file is retrieved even if it is accessed via a URL type that
+ *  normally is a NOP, such as "file".  If the download fails, the
+ *  partial file is renamed to get a ".FAILED" extension.
+ */
+class APT_PUBLIC pkgAcqFile : public pkgAcquire::Item
+{
+   void * const d;
+
+   /** \brief Should this file be considered a index file */
+   bool IsIndexFile;
+
+   HashStringList const ExpectedHashes;
+   public:
+   virtual HashStringList GetExpectedHashes() const APT_OVERRIDE;
+   virtual bool HashesRequired() const APT_OVERRIDE;
+
+   // Specialized action members
+   virtual void Done(std::string const &Message, HashStringList const &CalcHashes,
+		     pkgAcquire::MethodConfig const * const Cnf) APT_OVERRIDE;
+   virtual std::string DescURI() const APT_OVERRIDE {return Desc.URI;};
+   virtual std::string Custom600Headers() const APT_OVERRIDE;
+
+   /** \brief Create a new pkgAcqFile object.
+    *
+    *  \param Owner The pkgAcquire object with which this object is
+    *  associated.
+    *
+    *  \param URI The URI to download.
+    *
+    *  \param Hashes The hashsums of the file to download, if they are known;
+    *  otherwise empty list.
+    *
+    *  \param Size The size of the file to download, if it is known;
+    *  otherwise 0.
+    *
+    *  \param Desc A description of the file being downloaded.
+    *
+    *  \param ShortDesc A brief description of the file being
+    *  downloaded.
+    *
+    *  \param DestDir The directory the file should be downloaded into.
+    *
+    *  \param DestFilename The filename+path the file is downloaded to.
+    *
+    *  \param IsIndexFile The file is considered a IndexFile and cache-control
+    *                     headers like "cache-control: max-age=0" are send
+    *
+    * If DestFilename is empty, download to DestDir/\<basename\> if
+    * DestDir is non-empty, $CWD/\<basename\> otherwise.  If
+    * DestFilename is NOT empty, DestDir is ignored and DestFilename
+    * is the absolute name to which the file should be downloaded.
+    */
+
+   pkgAcqFile(pkgAcquire * const Owner, std::string const &URI, HashStringList const &Hashes, unsigned long long const Size,
+	      std::string const &Desc, std::string const &ShortDesc,
+	      std::string const &DestDir="", std::string const &DestFilename="",
+	      bool const IsIndexFile=false);
+   virtual ~pkgAcqFile();
+};
+									/*}}}*/
+class APT_HIDDEN pkgAcqAuxFile : public pkgAcqFile /*{{{*/
+{
+   pkgAcquire::Item *const Owner;
+   pkgAcquire::Worker *const Worker;
+   unsigned long long MaximumSize;
+
+   public:
+   virtual void Failed(std::string const &Message, pkgAcquire::MethodConfig const *const Cnf) APT_OVERRIDE;
+   virtual void Done(std::string const &Message, HashStringList const &CalcHashes,
+		     pkgAcquire::MethodConfig const *const Cnf) APT_OVERRIDE;
+   virtual std::string Custom600Headers() const APT_OVERRIDE;
+   virtual void Finished() APT_OVERRIDE;
+
+   pkgAcqAuxFile(pkgAcquire::Item *const Owner, pkgAcquire::Worker *const Worker,
+		 std::string const &ShortDesc, std::string const &Desc, std::string const &URI,
+		 HashStringList const &Hashes, unsigned long long const MaximumSize);
+   virtual ~pkgAcqAuxFile();
+};
+									/*}}}*/
+/** @} */
+
+#endif