Move ConstrainedStreamBuf into separate file

components/CMakeLists.txt

@@ -206,7 +206,7 @@ IF(NOT WIN32 AND NOT APPLE)
 ENDIF()
 add_component_dir (files
     linuxpath androidpath windowspath macospath fixedpath multidircollection collections configurationmanager
-    lowlevelfile constrainedfilestream memorystream hash configfileparser openfile
+    lowlevelfile constrainedfilestream memorystream hash configfileparser openfile constrainedfilestreambuf
     )
 
 add_component_dir (compiler

components/files/constrainedfilestream.cpp

@@ -1,109 +1,8 @@
 #include "constrainedfilestream.hpp"
 
-#include <streambuf>
-#include <algorithm>
-
-#include "lowlevelfile.hpp"
-
-namespace
-{
-// somewhat arbitrary though 64KB buffers didn't seem to improve performance any
-const size_t sBufferSize = 8192;
-}
-
 namespace Files
 {
-    class ConstrainedFileStreamBuf : public std::streambuf
+    ConstrainedFileStream::ConstrainedFileStream(std::unique_ptr<ConstrainedFileStreamBuf> buf)
-    {
-
-        size_t mOrigin;
-        size_t mSize;
-
-        LowLevelFile mFile;
-
-        char mBuffer[sBufferSize]{0};
-
-    public:
-        ConstrainedFileStreamBuf(const std::string &fname, size_t start, size_t length)
-        {
-            mFile.open (fname.c_str ());
-            mSize  = length != std::numeric_limits<std::size_t>::max() ? length : mFile.size () - start;
-
-            if (start != 0)
-                mFile.seek(start);
-
-            setg(nullptr,nullptr,nullptr);
-
-            mOrigin = start;
-        }
-
-        int_type underflow() override
-        {
-            if(gptr() == egptr())
-            {
-                size_t toRead = std::min((mOrigin+mSize)-(mFile.tell()), sBufferSize);
-                // Read in the next chunk of data, and set the read pointers on success
-                // Failure will throw exception in LowLevelFile
-                size_t got = mFile.read(mBuffer, toRead);
-                setg(&mBuffer[0], &mBuffer[0], &mBuffer[0]+got);
-            }
-            if(gptr() == egptr())
-                return traits_type::eof();
-
-            return traits_type::to_int_type(*gptr());
-        }
-
-        pos_type seekoff(off_type offset, std::ios_base::seekdir whence, std::ios_base::openmode mode) override
-        {
-            if((mode&std::ios_base::out) || !(mode&std::ios_base::in))
-                return traits_type::eof();
-
-            // new file position, relative to mOrigin
-            size_t newPos;
-            switch (whence)
-            {
-                case std::ios_base::beg:
-                    newPos = offset;
-                    break;
-                case std::ios_base::cur:
-                    newPos = (mFile.tell() - mOrigin - (egptr() - gptr())) + offset;
-                    break;
-                case std::ios_base::end:
-                    newPos = mSize + offset;
-                    break;
-                default:
-                    return traits_type::eof();
-            }
-
-            if (newPos > mSize)
-                return traits_type::eof();
-
-            mFile.seek(mOrigin+newPos);
-
-            // Clear read pointers so underflow() gets called on the next read attempt.
-            setg(nullptr, nullptr, nullptr);
-
-            return newPos;
-        }
-
-        pos_type seekpos(pos_type pos, std::ios_base::openmode mode) override
-        {
-            if((mode&std::ios_base::out) || !(mode&std::ios_base::in))
-                return traits_type::eof();
-
-            if ((size_t)pos > mSize)
-                return traits_type::eof();
-
-            mFile.seek(mOrigin + pos);
-
-            // Clear read pointers so underflow() gets called on the next read attempt.
-            setg(nullptr, nullptr, nullptr);
-            return pos;
-        }
-
-    };
-
-    ConstrainedFileStream::ConstrainedFileStream(std::unique_ptr<std::streambuf> buf)
         : std::istream(buf.get())
         , mBuf(std::move(buf))
     {

components/files/constrainedfilestream.hpp

@@ -1,6 +1,8 @@
 #ifndef OPENMW_CONSTRAINEDFILESTREAM_H
 #define OPENMW_CONSTRAINEDFILESTREAM_H
 
+#include "constrainedfilestreambuf.hpp"
+
 #include <istream>
 #include <memory>
 #include <limits>
@@ -10,14 +12,13 @@ namespace Files
 {
 
 /// A file stream constrained to a specific region in the file, specified by the 'start' and 'length' parameters.
-class ConstrainedFileStream : public std::istream
+class ConstrainedFileStream final : public std::istream
 {
 public:
-    ConstrainedFileStream(std::unique_ptr<std::streambuf> buf);
+    explicit ConstrainedFileStream(std::unique_ptr<ConstrainedFileStreamBuf> buf);
-    virtual ~ConstrainedFileStream() {};
 
 private:
-    std::unique_ptr<std::streambuf> mBuf;
+    std::unique_ptr<ConstrainedFileStreamBuf> mBuf;
 };
 
 typedef std::shared_ptr<std::istream> IStreamPtr;

components/files/constrainedfilestreambuf.cpp

@@ -0,0 +1,83 @@
+#include "constrainedfilestreambuf.hpp"
+
+#include <algorithm>
+#include <limits>
+
+namespace Files
+{
+    ConstrainedFileStreamBuf::ConstrainedFileStreamBuf(const std::string& fname, std::size_t start, std::size_t length)
+        : mOrigin(start)
+    {
+        mFile.open(fname.c_str());
+        mSize  = length != std::numeric_limits<std::size_t>::max() ? length : mFile.size () - start;
+
+        if (start != 0)
+            mFile.seek(start);
+
+        setg(nullptr, nullptr, nullptr);
+    }
+
+    std::streambuf::int_type ConstrainedFileStreamBuf::underflow()
+    {
+        if (gptr() == egptr())
+        {
+            const std::size_t toRead = std::min((mOrigin + mSize) - (mFile.tell()), sizeof(mBuffer));
+            // Read in the next chunk of data, and set the read pointers on success
+            // Failure will throw exception in LowLevelFile
+            const std::size_t got = mFile.read(mBuffer, toRead);
+            setg(&mBuffer[0], &mBuffer[0], &mBuffer[0] + got);
+        }
+        if (gptr() == egptr())
+            return traits_type::eof();
+
+        return traits_type::to_int_type(*gptr());
+    }
+
+    std::streambuf::pos_type ConstrainedFileStreamBuf::seekoff(off_type offset, std::ios_base::seekdir whence, std::ios_base::openmode mode)
+    {
+        if ((mode & std::ios_base::out) || !(mode & std::ios_base::in))
+            return traits_type::eof();
+
+        // new file position, relative to mOrigin
+        size_t newPos;
+        switch (whence)
+        {
+            case std::ios_base::beg:
+                newPos = offset;
+                break;
+            case std::ios_base::cur:
+                newPos = (mFile.tell() - mOrigin - (egptr() - gptr())) + offset;
+                break;
+            case std::ios_base::end:
+                newPos = mSize + offset;
+                break;
+            default:
+                return traits_type::eof();
+        }
+
+        if (newPos > mSize)
+            return traits_type::eof();
+
+        mFile.seek(mOrigin + newPos);
+
+        // Clear read pointers so underflow() gets called on the next read attempt.
+        setg(nullptr, nullptr, nullptr);
+
+        return newPos;
+    }
+
+    std::streambuf::pos_type ConstrainedFileStreamBuf::seekpos(pos_type pos, std::ios_base::openmode mode)
+    {
+        if ((mode & std::ios_base::out) || !(mode & std::ios_base::in))
+            return traits_type::eof();
+
+        if (static_cast<std::size_t>(pos) > mSize)
+            return traits_type::eof();
+
+        mFile.seek(mOrigin + pos);
+
+        // Clear read pointers so underflow() gets called on the next read attempt.
+        setg(nullptr, nullptr, nullptr);
+        return pos;
+    }
+}

components/files/constrainedfilestreambuf.hpp

@@ -0,0 +1,30 @@
+#ifndef OPENMW_CONSTRAINEDFILESTREAMBUF_H
+#define OPENMW_CONSTRAINEDFILESTREAMBUF_H
+
+#include "lowlevelfile.hpp"
+
+#include <streambuf>
+
+namespace Files
+{
+    /// A file streambuf constrained to a specific region in the file, specified by the 'start' and 'length' parameters.
+    class ConstrainedFileStreamBuf final : public std::streambuf
+    {
+    public:
+        ConstrainedFileStreamBuf(const std::string& fname, std::size_t start, std::size_t length);
+
+        int_type underflow() final;
+
+        pos_type seekoff(off_type offset, std::ios_base::seekdir whence, std::ios_base::openmode mode) final;
+
+        pos_type seekpos(pos_type pos, std::ios_base::openmode mode) final;
+
+    private:
+        std::size_t mOrigin;
+        std::size_t mSize;
+        LowLevelFile mFile;
+        char mBuffer[8192]{0};
+    };
+}
+
+#endif