1 files changed, 141 insertions, 0 deletions
diff --git a/Source/cmGeneratedFileStream.h b/Source/cmGeneratedFileStream.h
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+++ b/Source/cmGeneratedFileStream.h
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+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cmGeneratedFileStream_h
+#define cmGeneratedFileStream_h
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include "cm_codecvt.hxx"
+#include "cmsys/FStream.hxx"
+#include <string>
+
+// This is the first base class of cmGeneratedFileStream.  It will be
+// created before and destroyed after the ofstream portion and can
+// therefore be used to manage the temporary file.
+class cmGeneratedFileStreamBase
+{
+protected:
+  // This constructor does not prepare the temporary file.  The open
+  // method must be used.
+  cmGeneratedFileStreamBase();
+
+  // This constructor prepares the temporary output file.
+  cmGeneratedFileStreamBase(const char* name);
+
+  // The destructor renames the temporary output file to the real name.
+  ~cmGeneratedFileStreamBase();
+
+  // Internal methods to handle the temporary file.  Open is always
+  // called before the real stream is opened.  Close is always called
+  // after the real stream is closed and Okay is set to whether the
+  // real stream was still valid for writing when it was closed.
+  void Open(const char* name);
+  bool Close();
+
+  // 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 Name;
+
+  // The name of the temporary file.
+  std::string TempName;
+
+  // Whether to do a copy-if-different.
+  bool CopyIfDifferent;
+
+  // Whether the real file stream was valid when it was closed.
+  bool Okay;
+
+  // Whether the destination file is compressed
+  bool Compress;
+
+  // Whether the destination file is compressed
+  bool CompressExtraExtension;
+};
+
+/** \class cmGeneratedFileStream
+ * \brief Output stream for generated files.
+ *
+ * File generation should be atomic so that if CMake is killed then a
+ * generated file is either the original version or the complete new
+ * version.  This stream is used to make sure file generation is
+ * atomic.  Optionally the output file is only replaced if its
+ * contents have changed to prevent the file modification time from
+ * being updated.
+ */
+class cmGeneratedFileStream : private cmGeneratedFileStreamBase,
+                              public cmsys::ofstream
+{
+public:
+  typedef cmsys::ofstream Stream;
+  typedef codecvt::Encoding Encoding;
+
+  /**
+   * This constructor prepares a default stream.  The open method must
+   * be used before writing to the stream.
+   */
+  cmGeneratedFileStream(Encoding encoding = codecvt::None);
+
+  /**
+   * This constructor takes the name of the file to be generated.  It
+   * automatically generates a name for the temporary file.  If the
+   * file cannot be opened an error message is produced unless the
+   * second argument is set to true.
+   */
+  cmGeneratedFileStream(const char* name, bool quiet = false,
+                        Encoding encoding = codecvt::None);
+
+  /**
+   * The destructor checks the stream status to be sure the temporary
+   * file was successfully written before allowing the original to be
+   * replaced.
+   */
+  ~cmGeneratedFileStream() override;
+
+  /**
+   * Open an output file by name.  This should be used only with a
+   * non-open stream.  It automatically generates a name for the
+   * temporary file.  If the file cannot be opened an error message is
+   * produced unless the second argument is set to true.
+   */
+  cmGeneratedFileStream& Open(const char* name, bool quiet = false,
+                              bool binaryFlag = false);
+
+  /**
+   * Close the output file.  This should be used only with an open
+   * stream.  The temporary file is atomically renamed to the
+   * destionation file if the stream is still valid when this method
+   * is called.
+   */
+  bool Close();
+
+  /**
+   * Set whether copy-if-different is done.
+   */
+  void SetCopyIfDifferent(bool copy_if_different);
+
+  /**
+   * Set whether compression is done.
+   */
+  void SetCompression(bool compression);
+
+  /**
+   * Set whether compression has extra extension
+   */
+  void SetCompressionExtraExtension(bool ext);
+
+  /**
+   * Set name of the file that will hold the actual output. This method allows
+   * the output file to be changed during the use of cmGeneratedFileStream.
+   */
+  void SetName(const std::string& fname);
+
+private:
+  cmGeneratedFileStream(cmGeneratedFileStream const&); // not implemented
+};
+
+#endif