ENH: Add compression support

Source/cmGeneratedFileStream.cxx

@@ -26,6 +26,10 @@
 # include <sys/stat.h>
 #endif
 
+#if defined(CMAKE_BUILD_WITH_CMAKE)
+# include <cmzlib/zlib.h>
+#endif
+
 //----------------------------------------------------------------------------
 cmGeneratedFileStream::cmGeneratedFileStream():
   cmGeneratedFileStreamBase(), Stream()
@@ -81,12 +85,19 @@ void cmGeneratedFileStream::SetCopyIfDifferent(bool copy_if_different)
   m_CopyIfDifferent = copy_if_different;
 }
 
+//----------------------------------------------------------------------------
+void cmGeneratedFileStream::SetCompression(bool compression)
+{
+  m_Compress = compression;
+}
+
 //----------------------------------------------------------------------------
 cmGeneratedFileStreamBase::cmGeneratedFileStreamBase():
   m_Name(),
   m_TempName(),
   m_CopyIfDifferent(false),
-  m_Okay(false)
+  m_Okay(false),
+  m_Compress(false)
 {
 }
 
@@ -95,7 +106,8 @@ cmGeneratedFileStreamBase::cmGeneratedFileStreamBase(const char* name):
   m_Name(name),
   m_TempName(name),
   m_CopyIfDifferent(false),
-  m_Okay(false)
+  m_Okay(false),
+  m_Compress(false)
 {
   // Create the name of the temporary file.
   m_TempName += ".tmp";
@@ -107,24 +119,41 @@ cmGeneratedFileStreamBase::cmGeneratedFileStreamBase(const char* name):
 //----------------------------------------------------------------------------
 cmGeneratedFileStreamBase::~cmGeneratedFileStreamBase()
 {
+  std::string resname = m_Name;
+  if ( m_Compress )
+    {
+    resname += ".gz";
+    }
+
   // Only consider replacing the destination file if no error
   // occurred.
   if(m_Okay &&
     (!m_CopyIfDifferent ||
-      cmSystemTools::FilesDiffer(m_TempName.c_str(), m_Name.c_str())))
+     cmSystemTools::FilesDiffer(m_TempName.c_str(), resname.c_str())))
     {
     // The destination is to be replaced.  Rename the temporary to the
     // destination atomically.
-    this->RenameFile(m_TempName.c_str(), m_Name.c_str());
+    if ( m_Compress )
+      {
+      std::string gzname = m_TempName + ".temp.gz";
+      if ( this->CompressFile(m_TempName.c_str(), gzname.c_str()) )
+        {
+        this->RenameFile(gzname.c_str(), resname.c_str());
+        }
+      cmSystemTools::RemoveFile(gzname.c_str());
       }
     else
       {
-    // The destination was not replaced.  Just delete the temporary
-    // file.
-    cmSystemTools::RemoveFile(m_TempName.c_str());
+      this->RenameFile(m_TempName.c_str(), resname.c_str());
       }
     }
 
+  // Else, the destination was not replaced.
+  //
+  // Always delete the temporary file. We never want it to stay around.
+  cmSystemTools::RemoveFile(m_TempName.c_str());
+}
+
 //----------------------------------------------------------------------------
 void cmGeneratedFileStreamBase::Open(const char* name)
 {
@@ -139,6 +168,41 @@ void cmGeneratedFileStreamBase::Open(const char* name)
   cmSystemTools::RemoveFile(m_TempName.c_str());
 }
 
+//----------------------------------------------------------------------------
+int cmGeneratedFileStreamBase::CompressFile(const char* oldname,
+                                            const char* newname)
+{
+#ifdef CMAKE_BUILD_WITH_CMAKE
+  gzFile gf = cm_zlib_gzopen(newname, "w");
+  if ( !gf )
+    {
+    return 0;
+    }
+  FILE* ifs = fopen(oldname, "r");
+  if ( !ifs )
+    {
+    return 0;
+    }
+  size_t res;
+  const size_t BUFFER_SIZE = 1024;
+  char buffer[BUFFER_SIZE];
+  while ( (res = fread(buffer, 1, BUFFER_SIZE, ifs)) > 0 )
+    {
+    if ( !cm_zlib_gzwrite(gf, buffer, res) )
+      {
+      fclose(ifs);
+      cm_zlib_gzclose(gf);
+      return 0;
+      }
+    }
+  fclose(ifs);
+  cm_zlib_gzclose(gf);
+  return 1;
+#else
+  return 0;
+#endif
+}
+
 //----------------------------------------------------------------------------
 int cmGeneratedFileStreamBase::RenameFile(const char* oldname,
                                           const char* newname)

Source/cmGeneratedFileStream.h

@@ -41,6 +41,9 @@ protected:
   // Internal file replacement implementation.
   int RenameFile(const char* oldname, const char* newname);
 
+  // Internal file compression implementation.
+  int CompressFile(const char* oldname, const char* newname);
+
   // The name of the final destination file for the output.
   std::string m_Name;
 
@@ -52,6 +55,9 @@ protected:
 
   // Whether the destination file should be replaced.
   bool m_Okay;
+
+  // Whether the destionation file is compressed
+  bool m_Compress;
 };
 
 /** \class cmGeneratedFileStream
@@ -103,6 +109,11 @@ public:
    * Set whether copy-if-different is done.
    */
   void SetCopyIfDifferent(bool copy_if_different);
+
+  /**
+   * Set whether compression is done.
+   */
+  void SetCompression(bool compression);
 };
 
 #endif