fail in CopyFile if the FileFds have error flag set

Testing for global PendingErrors in users of CopyFile is incorrect
in so far as unrelated errors will prevent us from copying perfectly
fine files and checking for the validity of the files is just better
in CopyFiles as it already checks if files are at least opened.

Add also a higher-level error message to the error stack if it fails.

apt-pkg/contrib/fileutl.cc

@@ -184,7 +184,8 @@ bool RunScripts(const char *Cnf)
 /* The caller is expected to set things so that failure causes erasure */
 bool CopyFile(FileFd &From,FileFd &To)
 {
-   if (From.IsOpen() == false || To.IsOpen() == false)
+   if (From.IsOpen() == false || To.IsOpen() == false ||
+	 From.Failed() == true || To.Failed() == true)
       return false;
    
    // Buffered copy between fds

apt-pkg/indexcopy.cc

@@ -544,11 +544,9 @@ bool SigVerify::CopyMetaIndex(string CDROM, string CDName,		/*{{{*/
       FileFd Rel;
       Target.Open(TargetF,FileFd::WriteAtomic);
       Rel.Open(prefix + file,FileFd::ReadOnly);
-      if (_error->PendingError() == true)
-	 return false;
       if (CopyFile(Rel,Target) == false)
-	 return false;
-   
+	 return _error->Error("Copying of '%s' for '%s' from '%s' failed", file.c_str(), CDName.c_str(), prefix.c_str());
+
       return true;
 }
 									/*}}}*/

debian/changelog

@@ -13,6 +13,7 @@ apt (0.9.8.3) UNRELEASED; urgency=low
   * set Fail flag in FileFd on all errors consistently
   * don't explicitly init ExtractTar InFd with invalid fd
   * OpenDescriptor should autoclose fd always on error (Closes: #704608)
+  * fail in CopyFile if the FileFds have error flag set
 
  -- David Kalnischkies <kalnischkies@gmail.com>  Sun, 09 Jun 2013 15:06:24 +0200