fix: --print-uris removes authentication

The constructors of our (clear)sign-acquire-items move a pre-existent
file for error-recovery away, which gets restored or discarded later as
the acquire progresses, but --print-uris never really starts the
acquire process, so the files aren't restored (as they should).

To fix this both get a destructor which checks for signs of acquire
doing anything and if it hasn't the file is restored.

Note that these virtual destructors theoretically break the API, but
only with classes extending the sign-acquire-items and nobody does this,
as it would be insane for library users to fiddle with Acquire
internals – and these classes are internals.

Closes: 719263

2 files changed, 29 insertions, 4 deletions

diff --git a/apt-pkg/acquire-item.cc b/apt-pkg/acquire-item.cc
index 7bcdf285b..95dadcd6d 100644
--- a/apt-pkg/acquire-item.cc
+++ b/apt-pkg/acquire-item.cc
@@ -1067,8 +1067,7 @@ pkgAcqMetaSig::pkgAcqMetaSig(pkgAcquire *Owner,				/*{{{*/
       
    string Final = _config->FindDir("Dir::State::lists");
    Final += URItoFileName(RealURI);
-   struct stat Buf;
-   if (stat(Final.c_str(),&Buf) == 0)
+   if (RealFileExists(Final) == true)
    {
       // File was already in place.  It needs to be re-downloaded/verified
       // because Release might have changed, we do give it a differnt
@@ -1082,6 +1081,19 @@ pkgAcqMetaSig::pkgAcqMetaSig(pkgAcquire *Owner,				/*{{{*/
    QueueURI(Desc);
 }
 									/*}}}*/
+pkgAcqMetaSig::~pkgAcqMetaSig()						/*{{{*/
+{
+   // if the file was never queued undo file-changes done in the constructor
+   if (QueueCounter == 1 && Status == StatIdle && FileSize == 0 && Complete == false &&
+	 LastGoodSig.empty() == false)
+   {
+      string const Final = _config->FindDir("Dir::State::lists") + URItoFileName(RealURI);
+      if (RealFileExists(Final) == false && RealFileExists(LastGoodSig) == true)
+	 Rename(LastGoodSig, Final);
+   }
+
+}
+									/*}}}*/
 // pkgAcqMetaSig::Custom600Headers - Insert custom request headers	/*{{{*/
 // ---------------------------------------------------------------------
 /* The only header we use is the last-modified header. */
@@ -1595,14 +1607,25 @@ pkgAcqMetaClearSig::pkgAcqMetaClearSig(pkgAcquire *Owner,		/*{{{*/
 
    // keep the old InRelease around in case of transistent network errors
    string const Final = _config->FindDir("Dir::State::lists") + URItoFileName(RealURI);
-   struct stat Buf;
-   if (stat(Final.c_str(),&Buf) == 0)
+   if (RealFileExists(Final) == true)
    {
       string const LastGoodSig = DestFile + ".reverify";
       Rename(Final,LastGoodSig);
    }
 }
 									/*}}}*/
+pkgAcqMetaClearSig::~pkgAcqMetaClearSig()				/*{{{*/
+{
+   // if the file was never queued undo file-changes done in the constructor
+   if (QueueCounter == 1 && Status == StatIdle && FileSize == 0 && Complete == false)
+   {
+      string const Final = _config->FindDir("Dir::State::lists") + URItoFileName(RealURI);
+      string const LastGoodSig = DestFile + ".reverify";
+      if (RealFileExists(Final) == false && RealFileExists(LastGoodSig) == true)
+	 Rename(LastGoodSig, Final);
+   }
+}
+									/*}}}*/
 // pkgAcqMetaClearSig::Custom600Headers - Insert custom request headers	/*{{{*/
 // ---------------------------------------------------------------------
 // FIXME: this can go away once the InRelease file is used widely
diff --git a/apt-pkg/acquire-item.h b/apt-pkg/acquire-item.h
index 51d539450..10c855e63 100644
--- a/apt-pkg/acquire-item.h
+++ b/apt-pkg/acquire-item.h
@@ -774,6 +774,7 @@ class pkgAcqMetaSig : public pkgAcquire::Item
 		 std::string MetaIndexURI, std::string MetaIndexURIDesc, std::string MetaIndexShortDesc,
 		 const std::vector<struct IndexTarget*>* IndexTargets,
 		 indexRecords* MetaIndexParser);
+   virtual ~pkgAcqMetaSig();
 };
 									/*}}}*/
 /** \brief An item that is responsible for downloading the meta-index	{{{
@@ -904,6 +905,7 @@ public:
 		std::string const &MetaSigURI, std::string const &MetaSigURIDesc, std::string const &MetaSigShortDesc,
 		const std::vector<struct IndexTarget*>* IndexTargets,
 		indexRecords* MetaIndexParser);
+   virtual ~pkgAcqMetaClearSig();
 };
 									/*}}}*/
 /** \brief An item that is responsible for fetching a package file.	{{{