allow a method to request auxiliary files

If a method needs a file to operate like e.g. mirror needs to get a list
of mirrors before it can redirect the the actual requests to them. That
could easily be solved by moving the logic into libapt directly, but by
allowing a method to request other methods to do something we can keep
this logic contained in the method and allow e.g. also methods which
perform binary patching or similar things.

Previously they would need to implement their own acquire system inside
the existing one which in all likelyhood will not support the same
features and methods nor operate with similar security compared to what
we have already running 'above' the requesting method. That said, to
avoid methods producing conflicts with "proper" files we are downloading
a new directory is introduced to keep the auxiliary files in.

[The message magic number 351 is a tribute to the german Grundgesetz
article 35 paragraph 1 which defines that all authorities of the
state(s) help each other on request.]

1 files changed, 19 insertions, 0 deletions

diff --git a/apt-pkg/acquire-item.h b/apt-pkg/acquire-item.h
index cf227d1b5..46d79df92 100644
--- a/apt-pkg/acquire-item.h
+++ b/apt-pkg/acquire-item.h
@@ -1238,6 +1238,25 @@ class pkgAcqFile : public pkgAcquire::Item
    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