Correct buffering logic in compression filter. GH issue #93 pull #95

Found and fixed by Eric Cornelius <[email protected]>

2 files changed, 4 insertions, 3 deletions

diff --git a/src/lib/filters/comp_filter.cpp b/src/lib/filters/comp_filter.cpp
index 76c90d626..61ac16f38 100644
--- a/src/lib/filters/comp_filter.cpp
+++ b/src/lib/filters/comp_filter.cpp
@@ -20,9 +20,9 @@ Decompression_Filter::Decompression_Filter(const std::string& type, size_t bs) :
    {
    }
 
-Compression_Decompression_Filter::Compression_Decompression_Filter(Transform* transform, size_t bs)
+Compression_Decompression_Filter::Compression_Decompression_Filter(Transform* transform, size_t bs) :
+   m_buffersize(std::max<size_t>(256, bs)), m_buffer(m_buffersize)
    {
-   m_buffer.resize(std::min<size_t>(256, bs));
    m_transform.reset(dynamic_cast<Compressor_Transform*>(transform));
    if(!m_transform)
       throw std::invalid_argument("Transform " + transform->name() + " is not a compressor");
@@ -42,7 +42,7 @@ void Compression_Decompression_Filter::write(const byte input[], size_t input_le
    {
    while(input_length)
       {
-      const size_t take = std::min(m_buffer.size(), input_length);
+      const size_t take = std::min(m_buffersize, input_length);
       BOTAN_ASSERT(take > 0, "Consumed something");
 
       m_buffer.assign(input, input + take);
diff --git a/src/lib/filters/comp_filter.h b/src/lib/filters/comp_filter.h
index 503f25102..59d6f7185 100644
--- a/src/lib/filters/comp_filter.h
+++ b/src/lib/filters/comp_filter.h
@@ -33,6 +33,7 @@ class BOTAN_DLL Compression_Decompression_Filter : public Filter
       void flush();
    private:
       std::unique_ptr<Compressor_Transform> m_transform;
+      std::size_t m_buffersize;
       secure_vector<byte> m_buffer;
    };