Deprecate modification of Pipe objects

This is a feature that is hairy to implement and really makes
application code confusing.

4 files changed, 44 insertions, 29 deletions

diff --git a/src/lib/filters/filter.h b/src/lib/filters/filter.h
index 8cd045f6e..773552b77 100644
--- a/src/lib/filters/filter.h
+++ b/src/lib/filters/filter.h
@@ -139,7 +139,7 @@ class BOTAN_PUBLIC_API(2,0) Filter
       Filter* get_next() const;
 
       secure_vector<uint8_t> m_write_queue;
-      std::vector<Filter*> m_next;
+      std::vector<Filter*> m_next; // not owned
       size_t m_port_num, m_filter_owns;
 
       // true if filter belongs to a pipe --> prohibit filter sharing!
diff --git a/src/lib/filters/pipe.cpp b/src/lib/filters/pipe.cpp
index 09ebd2165..51f2cace5 100644
--- a/src/lib/filters/pipe.cpp
+++ b/src/lib/filters/pipe.cpp
@@ -30,13 +30,9 @@ class Null_Filter final : public Filter
 /*
 * Pipe Constructor
 */
-Pipe::Pipe(Filter* f1, Filter* f2, Filter* f3, Filter* f4)
+Pipe::Pipe(Filter* f1, Filter* f2, Filter* f3, Filter* f4) :
+   Pipe({f1,f2,f3,f4})
    {
-   init();
-   append(f1);
-   append(f2);
-   append(f3);
-   append(f4);
    }
 
 /*
@@ -47,7 +43,7 @@ Pipe::Pipe(std::initializer_list<Filter*> args)
    init();
 
    for(auto i = args.begin(); i != args.end(); ++i)
-      append(*i);
+      do_append(*i);
    }
 
 /*
@@ -213,13 +209,16 @@ void Pipe::clear_endpoints(Filter* f)
       }
    }
 
+void Pipe::append(Filter* filter)
+   {
+   do_append(filter);
+   }
+
 /*
 * Append a Filter to the Pipe
 */
-void Pipe::append(Filter* filter)
+void Pipe::do_append(Filter* filter)
    {
-   if(m_inside_msg)
-      throw Invalid_State("Cannot append to a Pipe while it is processing");
    if(!filter)
       return;
    if(dynamic_cast<SecureQueue*>(filter))
@@ -227,6 +226,9 @@ void Pipe::append(Filter* filter)
    if(filter->m_owned)
       throw Invalid_Argument("Filters cannot be shared among multiple Pipes");
 
+   if(m_inside_msg)
+      throw Invalid_State("Cannot append to a Pipe while it is processing");
+
    filter->m_owned = true;
 
    if(!m_pipe) m_pipe = filter;
@@ -267,16 +269,12 @@ void Pipe::pop()
    if(m_pipe->total_ports() > 1)
       throw Invalid_State("Cannot pop off a Filter with multiple ports");
 
-   Filter* f = m_pipe;
-   size_t owns = f->owns();
-   m_pipe = m_pipe->m_next[0];
-   delete f;
+   size_t to_remove = m_pipe->owns() + 1;
 
-   while(owns--)
+   while(to_remove--)
       {
-      f = m_pipe;
+      std::unique_ptr<Filter> to_destroy(m_pipe);
       m_pipe = m_pipe->m_next[0];
-      delete f;
       }
    }
 
diff --git a/src/lib/filters/pipe.h b/src/lib/filters/pipe.h
index 8dcb1e95c..060b5c1ca 100644
--- a/src/lib/filters/pipe.h
+++ b/src/lib/filters/pipe.h
@@ -271,22 +271,26 @@ class BOTAN_PUBLIC_API(2,0) Pipe final : public DataSource
       * Insert a new filter at the front of the pipe
       * @param filt the new filter to insert
       */
+      BOTAN_DEPRECATED("Runtime modification of Pipe deprecated")
       void prepend(Filter* filt);
 
       /**
       * Insert a new filter at the back of the pipe
       * @param filt the new filter to insert
       */
+      BOTAN_DEPRECATED("Runtime modification of Pipe deprecated")
       void append(Filter* filt);
 
       /**
       * Remove the first filter at the front of the pipe.
       */
+      BOTAN_DEPRECATED("Runtime modification of Pipe deprecated")
       void pop();
 
       /**
       * Reset this pipe to an empty pipe.
       */
+      BOTAN_DEPRECATED("Runtime modification of Pipe deprecated")
       void reset();
 
       /**
@@ -309,6 +313,7 @@ class BOTAN_PUBLIC_API(2,0) Pipe final : public DataSource
    private:
       void init();
       void destruct(Filter*);
+      void do_append(Filter* filt);
       void find_endpoints(Filter*);
       void clear_endpoints(Filter*);
 
diff --git a/src/tests/test_filters.cpp b/src/tests/test_filters.cpp
index d3993cce3..0fac1d4e3 100644
--- a/src/tests/test_filters.cpp
+++ b/src/tests/test_filters.cpp
@@ -7,6 +7,8 @@
 * Botan is released under the Simplified BSD License (see license.txt)
 */
 
+#define BOTAN_NO_DEPRECATED_WARNINGS
+
 #include "tests.h"
 
 #if defined(BOTAN_HAS_FILTERS)
@@ -194,20 +196,30 @@ class Filter_Tests final : public Test
          std::unique_ptr<Botan::Filter> queue_filter(new Botan::SecureQueue);
 
          // can't explicitly insert a queue into the pipe because they are implicit
-         result.test_throws("pipe error", "Invalid argument Pipe::append: SecureQueue cannot be used", [&]()
-            { pipe.append(queue_filter.get()); });
-         result.test_throws("pipe error", "Invalid argument Pipe::prepend: SecureQueue cannot be used", [&]()
-            { pipe.prepend(queue_filter.get()); });
+         result.test_throws("pipe error",
+                            "Invalid argument Pipe::append: SecureQueue cannot be used",
+                            [&]() { pipe.append(queue_filter.get()); });
+
+         result.test_throws("pipe error",
+                            "Invalid argument Pipe::prepend: SecureQueue cannot be used",
+                            [&]() { pipe.prepend(queue_filter.get()); });
 
          pipe.start_msg();
 
+         std::unique_ptr<Botan::Filter> filter(new Botan::BitBucket);
+
          // now inside a message, cannot modify pipe structure
-         result.test_throws("pipe error", "Cannot append to a Pipe while it is processing", [&]()
-            { pipe.append(nullptr); });
-         result.test_throws("pipe error", "Cannot prepend to a Pipe while it is processing", [&]()
-            { pipe.prepend(nullptr); });
-         result.test_throws("pipe error", "Cannot pop off a Pipe while it is processing", [&]()
-            { pipe.pop(); });
+         result.test_throws("pipe error",
+                            "Cannot append to a Pipe while it is processing",
+                            [&]() { pipe.append(filter.get()); });
+
+         result.test_throws("pipe error",
+                            "Cannot prepend to a Pipe while it is processing",
+                            [&]() { pipe.prepend(filter.get()); });
+
+         result.test_throws("pipe error",
+                            "Cannot pop off a Pipe while it is processing",
+                            [&]() { pipe.pop(); });
 
          pipe.end_msg();
 
@@ -247,7 +259,7 @@ class Filter_Tests final : public Test
          Test::Result result("Pipe");
 
 #if defined(BOTAN_HAS_SHA2_32)
-         Botan::Pipe pipe(new Botan::Hash_Filter("SHA-224"));
+         Botan::Pipe pipe(new Botan::Chain(new Botan::Hash_Filter("SHA-224"), new Botan::Hex_Encoder));
          pipe.pop();
          pipe.append(new Botan::Hash_Filter("SHA-256"));