Remove Transform base class

With sufficient squinting, Transform provided an abstract base
interface that covered both cipher modes and compression algorithms.
However it mapped on neither of them particularly well. In addition
this API had the same problem that has made me dislike the Pipe/Filter
API: given a Transform&, what does it do when you put bits in? Maybe
it encrypts. Maybe it compresses. It's a floor wax and a dessert topping!

Currently the Cipher_Mode interface is left mostly unchanged, with the
APIs previously on Transform just moved down the type hierarchy.  I
think there are some definite improvements possible here, wrt handling
of in-place encryption, but left for a later commit.

The compression API is split into two types, Compression_Algorithm and
Decompression_Algorithm. Compression_Algorithm's start() call takes
the compression level, allowing varying compressions with a single
object. And flushing the compression state is moved to a bool param on
`Compression_Algorithm::update`. All the nonsense WRT compression
algorithms having zero length nonces, input granularity rules, etc
as a result of using the Transform interface goes away.

2 files changed, 49 insertions, 41 deletions

diff --git a/src/cli/compress.cpp b/src/cli/compress.cpp
index c573eaa20..d5b2c4736 100644
--- a/src/cli/compress.cpp
+++ b/src/cli/compress.cpp
@@ -6,42 +6,13 @@
 
 #include "cli.h"
 
-#include <botan/transform.h>
-
 #if defined(BOTAN_HAS_COMPRESSION)
   #include <botan/compression.h>
 #endif
 
 namespace Botan_CLI {
 
-namespace {
-
-void do_compress(Botan::Transform& comp,
-                 std::ifstream& in,
-                 std::ostream& out,
-                 size_t buf_size)
-   {
-   Botan::secure_vector<uint8_t> buf;
-
-   comp.start();
-
-   while(in.good())
-      {
-      buf.resize(buf_size);
-      in.read(reinterpret_cast<char*>(&buf[0]), buf.size());
-      buf.resize(in.gcount());
-
-      comp.update(buf);
-
-      out.write(reinterpret_cast<const char*>(&buf[0]), buf.size());
-      }
-
-   buf.clear();
-   comp.finish(buf);
-   out.write(reinterpret_cast<const char*>(&buf[0]), buf.size());
-   }
-
-}
+#if defined(BOTAN_HAS_COMPRESSION)
 
 class Compress final : public Command
    {
@@ -70,12 +41,12 @@ class Compress final : public Command
       void go() override
          {
          const std::string comp_type = get_arg("type");
+         const size_t buf_size = get_arg_sz("buf-size");
+         const size_t comp_level = get_arg_sz("level");
 
-         std::unique_ptr<Botan::Transform> compress;
+         std::unique_ptr<Botan::Compression_Algorithm> compress;
 
-#if defined(BOTAN_HAS_COMPRESSION)
-         compress.reset(Botan::make_compressor(comp_type, get_arg_sz("level")));
-#endif
+         compress.reset(Botan::make_compressor(comp_type));
 
          if(!compress)
             {
@@ -97,7 +68,25 @@ class Compress final : public Command
             throw CLI_IO_Error("writing", out_file);
             }
 
-         do_compress(*compress, in, out, get_arg_sz("buf-size"));
+         Botan::secure_vector<uint8_t> buf;
+
+         compress->start(comp_level);
+
+         while(in.good())
+            {
+            buf.resize(buf_size);
+            in.read(reinterpret_cast<char*>(&buf[0]), buf.size());
+            buf.resize(in.gcount());
+
+            compress->update(buf);
+
+            out.write(reinterpret_cast<const char*>(&buf[0]), buf.size());
+            }
+
+         buf.clear();
+         compress->finish(buf);
+         out.write(reinterpret_cast<const char*>(&buf[0]), buf.size());
+         out.close();
          }
    };
 
@@ -122,6 +111,7 @@ class Decompress final : public Command
 
       void go() override
          {
+         const size_t buf_size = get_arg_sz("buf-size");
          const std::string in_file = get_arg("file");
          std::string out_file, suffix;
          parse_extension(in_file, out_file, suffix);
@@ -131,11 +121,9 @@ class Decompress final : public Command
          if(!in.good())
             throw CLI_IO_Error("reading", in_file);
 
-         std::unique_ptr<Botan::Transform> decompress;
+         std::unique_ptr<Botan::Decompression_Algorithm> decompress;
 
-#if defined(BOTAN_HAS_COMPRESSION)
          decompress.reset(Botan::make_decompressor(suffix));
-#endif
 
          if(!decompress)
             throw CLI_Error_Unsupported("Decompression", suffix);
@@ -144,10 +132,30 @@ class Decompress final : public Command
          if(!out.good())
             throw CLI_IO_Error("writing", out_file);
 
-         do_compress(*decompress, in, out, get_arg_sz("buf-size"));
+         Botan::secure_vector<uint8_t> buf;
+
+         decompress->start();
+
+         while(in.good())
+            {
+            buf.resize(buf_size);
+            in.read(reinterpret_cast<char*>(&buf[0]), buf.size());
+            buf.resize(in.gcount());
+
+            decompress->update(buf);
+
+            out.write(reinterpret_cast<const char*>(&buf[0]), buf.size());
+            }
+
+         buf.clear();
+         decompress->finish(buf);
+         out.write(reinterpret_cast<const char*>(&buf[0]), buf.size());
+         out.close();
          }
    };
 
 BOTAN_REGISTER_COMMAND("decompress", Decompress);
 
+#endif
+
 }
diff --git a/src/cli/speed.cpp b/src/cli/speed.cpp
index c767b2a55..595b4bd20 100644
--- a/src/cli/speed.cpp
+++ b/src/cli/speed.cpp
@@ -613,13 +613,13 @@ class Speed final : public Command
             timer.run([&] { srcs.poll_just(accum, src); });
 
 #if defined(BOTAN_HAS_COMPRESSION)
-            std::unique_ptr<Botan::Compressor_Transform> comp(Botan::make_compressor("zlib", 9));
+            std::unique_ptr<Botan::Compression_Algorithm> comp(Botan::make_compressor("zlib"));
             Botan::secure_vector<uint8_t> compressed;
 
             if(comp)
                {
                compressed.assign(entropy.begin(), entropy.end());
-               comp->start();
+               comp->start(9);
                comp->finish(compressed);
                }
 #endif