Initial commit

common/rdr/ZlibOutStream.cxx

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+/* Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
+ * Copyright (C) 2011 D. R. Commander.  All Rights Reserved.
+ * 
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+#include <stdio.h>
+
+#include <rdr/ZlibOutStream.h>
+#include <rdr/Exception.h>
+
+#include <zlib.h>
+
+#undef ZLIBOUT_DEBUG
+
+using namespace rdr;
+
+enum { DEFAULT_BUF_SIZE = 16384 };
+
+ZlibOutStream::ZlibOutStream(OutStream* os, int bufSize_, int compressLevel)
+  : underlying(os), compressionLevel(compressLevel), newLevel(compressLevel),
+    bufSize(bufSize_ ? bufSize_ : DEFAULT_BUF_SIZE), offset(0)
+{
+  zs = new z_stream;
+  zs->zalloc    = Z_NULL;
+  zs->zfree     = Z_NULL;
+  zs->opaque    = Z_NULL;
+  zs->next_in   = Z_NULL;
+  zs->avail_in  = 0;
+  if (deflateInit(zs, compressLevel) != Z_OK) {
+    delete zs;
+    throw Exception("ZlibOutStream: deflateInit failed");
+  }
+  ptr = start = new U8[bufSize];
+  end = start + bufSize;
+}
+
+ZlibOutStream::~ZlibOutStream()
+{
+  try {
+    flush();
+  } catch (Exception&) {
+  }
+  delete [] start;
+  deflateEnd(zs);
+  delete zs;
+}
+
+void ZlibOutStream::setUnderlying(OutStream* os)
+{
+  underlying = os;
+}
+
+void ZlibOutStream::setCompressionLevel(int level)
+{
+  if (level < -1 || level > 9)
+    level = -1;                 // Z_DEFAULT_COMPRESSION
+
+  newLevel = level;
+}
+
+int ZlibOutStream::length()
+{
+  return offset + ptr - start;
+}
+
+void ZlibOutStream::flush()
+{
+  checkCompressionLevel();
+
+  zs->next_in = start;
+  zs->avail_in = ptr - start;
+
+#ifdef ZLIBOUT_DEBUG
+  fprintf(stderr,"zos flush: avail_in %d\n",zs->avail_in);
+#endif
+
+  // Force out everything from the zlib encoder
+  deflate(Z_SYNC_FLUSH);
+
+  offset += ptr - start;
+  ptr = start;
+}
+
+int ZlibOutStream::overrun(int itemSize, int nItems)
+{
+#ifdef ZLIBOUT_DEBUG
+  fprintf(stderr,"zos overrun\n");
+#endif
+
+  if (itemSize > bufSize)
+    throw Exception("ZlibOutStream overrun: max itemSize exceeded");
+
+  checkCompressionLevel();
+
+  while (end - ptr < itemSize) {
+    zs->next_in = start;
+    zs->avail_in = ptr - start;
+
+    deflate(Z_NO_FLUSH);
+
+    // output buffer not full
+
+    if (zs->avail_in == 0) {
+      offset += ptr - start;
+      ptr = start;
+    } else {
+      // but didn't consume all the data?  try shifting what's left to the
+      // start of the buffer.
+      fprintf(stderr,"z out buf not full, but in data not consumed\n");
+      memmove(start, zs->next_in, ptr - zs->next_in);
+      offset += zs->next_in - start;
+      ptr -= zs->next_in - start;
+    }
+  }
+
+  if (itemSize * nItems > end - ptr)
+    nItems = (end - ptr) / itemSize;
+
+  return nItems;
+}
+
+void ZlibOutStream::deflate(int flush)
+{
+  int rc;
+
+  if (!underlying)
+    throw Exception("ZlibOutStream: underlying OutStream has not been set");
+
+  if ((flush == Z_NO_FLUSH) && (zs->avail_in == 0))
+    return;
+
+  do {
+    underlying->check(1);
+    zs->next_out = underlying->getptr();
+    zs->avail_out = underlying->getend() - underlying->getptr();
+
+#ifdef ZLIBOUT_DEBUG
+    fprintf(stderr,"zos: calling deflate, avail_in %d, avail_out %d\n",
+            zs->avail_in,zs->avail_out);
+#endif
+
+    rc = ::deflate(zs, flush);
+    if (rc != Z_OK) {
+      // Silly zlib returns an error if you try to flush something twice
+      if ((rc == Z_BUF_ERROR) && (flush != Z_NO_FLUSH))
+        break;
+
+      throw Exception("ZlibOutStream: deflate failed");
+    }
+
+#ifdef ZLIBOUT_DEBUG
+    fprintf(stderr,"zos: after deflate: %d bytes\n",
+            zs->next_out-underlying->getptr());
+#endif
+
+    underlying->setptr(zs->next_out);
+  } while (zs->avail_out == 0);
+}
+
+void ZlibOutStream::checkCompressionLevel()
+{
+  int rc;
+
+  if (newLevel != compressionLevel) {
+#ifdef ZLIBOUT_DEBUG
+    fprintf(stderr,"zos change: avail_in %d\n",zs->avail_in);
+#endif
+
+    // zlib is just horribly stupid. It does an implicit flush on
+    // parameter changes, but the flush it does is not one that forces
+    // out all the data. And since you cannot flush things again, we
+    // cannot force out our data after the parameter change. Hence we
+    // need to do a more proper flush here first.
+    deflate(Z_SYNC_FLUSH);
+
+    rc = deflateParams (zs, newLevel, Z_DEFAULT_STRATEGY);
+    if (rc != Z_OK) {
+      // The implicit flush can result in this error, caused by the
+      // explicit flush we did above. It should be safe to ignore though
+      // as the first flush should have left things in a stable state...
+      if (rc != Z_BUF_ERROR)
+        throw Exception("ZlibOutStream: deflateParams failed");
+    }
+
+    compressionLevel = newLevel;
+  }
+}