protect file_priority functions from being called on torrents without metadata

docs/manual.rst

@@ -2084,6 +2084,10 @@ Whenever a file priority is changed, all other piece priorities are reset
 to match the file priorities. In order to maintain sepcial priorities for
 particular pieces, ``piece_priority`` has to be called again for those pieces.
 
+You cannot set the file priorities on a torrent that does not yet
+have metadata or a torrent that is a seed. ``file_priority(int, int)`` and
+``prioritize_files()`` are both no-ops for such torrents.
+
 file_progress()
 ---------------
 

include/libtorrent/lazy_entry.hpp

@@ -53,6 +53,18 @@ namespace libtorrent
 	// return 0 = success
 	TORRENT_EXPORT int lazy_bdecode(char const* start, char const* end, lazy_entry& ret, int depth_limit = 1000);
 
+	struct pascal_string
+	{
+		pascal_string(char const* p, int l): len(l), ptr(p) {}
+		int len;
+		char const* ptr;
+		bool operator<(pascal_string const& rhs) const
+		{
+			return memcmp(ptr, rhs.ptr, (std::min)(len, rhs.len)) < 0
+				|| len < rhs.len;
+		}
+	};
+
 	struct TORRENT_EXPORT lazy_entry
 	{
 		enum entry_type_t
@@ -100,6 +112,12 @@ namespace libtorrent
 			return m_data.start;
 		}
 
+		pascal_string string_pstr() const
+		{
+			TORRENT_ASSERT(m_type == string_t);
+			return pascal_string(m_data.start, m_size);
+		}
+
 		std::string string_value() const
 		{
 			TORRENT_ASSERT(m_type == string_t);
@@ -228,6 +246,10 @@ namespace libtorrent
 		// in the original buffer they are based on
 		char const* m_begin;
 		char const* m_end;
+
+		// non-copyable
+		lazy_entry(lazy_entry const&);
+		lazy_entry const& operator=(lazy_entry const&);
 	};
 
 	TORRENT_EXPORT std::string print_entry(lazy_entry const& e, bool single_line = false);

src/torrent.cpp

@@ -2617,6 +2617,10 @@ namespace libtorrent
 	void torrent::set_file_priority(int index, int prio)
 	{
 		INVARIANT_CHECK;
+
+		// this call is only valid on torrents with metadata
+		if (!valid_metadata() || is_seed()) return;
+
 		TORRENT_ASSERT(index < m_torrent_file->num_files());
 		TORRENT_ASSERT(index >= 0);
 		if (m_file_priority[index] == prio) return;
@@ -2626,6 +2630,9 @@ namespace libtorrent
 	
 	int torrent::file_priority(int index) const
 	{
+		// this call is only valid on torrents with metadata
+		if (!valid_metadata()) return 1;
+
 		TORRENT_ASSERT(index < m_torrent_file->num_files());
 		TORRENT_ASSERT(index >= 0);
 		return m_file_priority[index];

src/torrent_info.cpp

@@ -303,6 +303,17 @@ namespace libtorrent
 		return true;
 	}
 
+	struct pascal_string
+	{
+		int len;
+		char const* ptr;
+		bool operator<(pascal_string const& rhs) const
+		{
+			return memcmp(ptr, rhs.ptr, (std::min)(len, rhs.len)) < 0
+				|| len < rhs.len;
+		}
+	};
+
 	bool extract_files(lazy_entry const& list, file_storage& target
 		, std::string const& root_dir)
 	{
@@ -313,6 +324,9 @@ namespace libtorrent
 			if (!extract_single_file(*list.list_at(i), e, root_dir))
 				return false;
 			int cnt = 0;
+			std::set<pascal_string> files;
+			pascal_string = 
+			while (!files.insert(path).second)
 			for (file_storage::iterator k = target.begin()
 				, end(target.end()); k != end; ++k)
 			{