Changing IMkvReadableWriter to IMkvWriteEOFReader

Changing the IMkvReadableWriter interface to IMkvWriteEOFReader.
Also changing the default implementation.

Change-Id: Id37ffd7ef0af2ff7a392fb4fb0b1b134664ab20f

Makefile

@@ -2,7 +2,7 @@ CXX       := g++
 CXXFLAGS  := -W -Wall -g
 LIBWEBMA  := libwebm.a
 LIBWEBMSO := libwebm.so
-WEBMOBJS  := mkvparser.o mkvreader.o mkvmuxer.o mkvmuxerutil.o mkvwriter.o mkvreadablewriter.o
+WEBMOBJS  := mkvparser.o mkvreader.o mkvmuxer.o mkvmuxerutil.o mkvwriter.o mkvwriteeofreader.o
 OBJSA     := $(WEBMOBJS:.o=_a.o)
 OBJSSO    := $(WEBMOBJS:.o=_so.o)
 OBJECTS1  := sample.o

mkvmuxer.cpp

@@ -7,7 +7,7 @@
 // be found in the AUTHORS file in the root of the source tree.
 
 #include "mkvmuxer.hpp"
-#include "mkvreadablewriter.hpp"
+#include "mkvwriteeofreader.hpp"
 
 #include <cstdio>
 #include <cstdlib>
@@ -91,7 +91,7 @@ bool WriteEbmlHeader(IMkvWriter* writer) {
   return true;
 }
 
-bool ChunkedCopy(mkvmuxer::IMkvReadableWriter* source,
+bool ChunkedCopy(mkvmuxer::IMkvWriteEOFReader* source,
                  mkvmuxer::IMkvWriter* dst,
                  mkvmuxer::int64 start, int64 size) {
   // TODO(vigneshv): Check if this is a reasonable value.
@@ -2091,7 +2091,7 @@ bool Segment::Init(IMkvWriter* ptr_writer) {
   return segment_info_.Init();
 }
 
-bool Segment::WriteCuesBeforeClusters(IMkvReadableWriter* ptr_writer) {
+bool Segment::WriteCuesBeforeClusters(IMkvWriteEOFReader* ptr_writer) {
   if (!ptr_writer || writer_cluster_ || writer_cues_ || writer_header_) {
     return false;
   }

mkvmuxer.hpp

@@ -51,11 +51,15 @@ class IMkvWriter {
   LIBWEBM_DISALLOW_COPY_AND_ASSIGN(IMkvWriter);
 };
 
-class IMkvReadableWriter : public IMkvWriter {
+// Classes implementing this interface should adhere to the following rule:
+// - There can be any number of calls to Write().
+// - Once the first call to Read() occurs, no more Write()'s are allowed.
+// - Write() should return error if there has been a call to Read() before.
+class IMkvWriteEOFReader : public IMkvWriter {
  public:
-  virtual int Read(long long position, long length,
-                   unsigned char* buffer) = 0;
-  virtual int Length(long long* total, long long* available) = 0;
+  // Reads data of size |length| starting from the offset of |position| into
+  // |buffer|.
+  virtual int Read(int64 position, int32 length, uint8* buffer) = 0;
 };
 
 // Writes out the EBML header for a WebM file. This function must be called
@@ -63,7 +67,7 @@ class IMkvReadableWriter : public IMkvWriter {
 bool WriteEbmlHeader(IMkvWriter* writer);
 
 // Copies in Chunk from source to destination between the given byte positions
-bool ChunkedCopy(IMkvReadableWriter* source, IMkvWriter* dst,
+bool ChunkedCopy(IMkvWriteEOFReader* source, IMkvWriter* dst,
                  int64 start, int64 size);
 
 ///////////////////////////////////////////////////////////////
@@ -943,9 +947,10 @@ class Segment {
   bool Init(IMkvWriter* ptr_writer);
 
   // This function must be called before Init() if Cues are to be written before
-  // the Clusters. Input parameter is a IMkvReadableWriter object which supports
-  // both writing and reading.
-  bool WriteCuesBeforeClusters(IMkvReadableWriter* ptr_writer);
+  // the Clusters. Input parameter is a IMkvWriteEOFReader object, which is to
+  // be used as the temporary storage, while moving the Cues before the
+  // Clusters.
+  bool WriteCuesBeforeClusters(IMkvWriteEOFReader* ptr_writer);
 
   // Adds a generic track to the segment.  Returns the newly-allocated
   // track object (which is owned by the segment) on success, NULL on
@@ -1249,7 +1254,7 @@ class Segment {
 
   // Pointer to actual writer object and temp writer object
   IMkvWriter* writer_;
-  IMkvReadableWriter* writer_temp_;
+  IMkvWriteEOFReader* writer_temp_;
 
   LIBWEBM_DISALLOW_COPY_AND_ASSIGN(Segment);
 };

mkvwriteeofreader.cpp

@@ -6,7 +6,7 @@
 // in the file PATENTS.  All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 
-#include "mkvreadablewriter.hpp"
+#include "mkvwriteeofreader.hpp"
 
 #ifdef _MSC_VER
 #include <share.h>  // for _SH_DENYWR
@@ -17,15 +17,16 @@
 
 namespace mkvmuxer {
 
-MkvReadableWriter::MkvReadableWriter() : file_(NULL) {
+MkvWriteEOFReader::MkvWriteEOFReader() : file_(NULL),
+                                             writes_allowed_(true) {
 }
 
-MkvReadableWriter::~MkvReadableWriter() {
+MkvWriteEOFReader::~MkvWriteEOFReader() {
   Close();
 }
 
-int32 MkvReadableWriter::Write(const void* buffer, uint32 length) {
-  if (file_ == NULL)
+int32 MkvWriteEOFReader::Write(const void* buffer, uint32 length) {
+  if (file_ == NULL || !writes_allowed_)
     return -1;
 
   if (length == 0)
@@ -39,7 +40,7 @@ int32 MkvReadableWriter::Write(const void* buffer, uint32 length) {
   return (bytes_written == length) ? 0 : -1;
 }
 
-bool MkvReadableWriter::Open(const char* filename, bool create_temp_file) {
+bool MkvWriteEOFReader::Open(const char* filename, bool create_temp_file) {
   if (filename == NULL && !create_temp_file)
     return false;
 
@@ -56,14 +57,14 @@ bool MkvReadableWriter::Open(const char* filename, bool create_temp_file) {
   return true;
 }
 
-void MkvReadableWriter::Close() {
+void MkvWriteEOFReader::Close() {
   if (file_ != NULL) {
     fclose(file_);
     file_ = NULL;
   }
 }
 
-int64 MkvReadableWriter::Position() const {
+int64 MkvWriteEOFReader::Position() const {
   if (file_ == NULL)
     return 0;
 
@@ -74,7 +75,7 @@ int64 MkvReadableWriter::Position() const {
 #endif
 }
 
-int32 MkvReadableWriter::Position(int64 position) {
+int32 MkvWriteEOFReader::Position(int64 position) {
   if (file_ == NULL)
     return -1;
 
@@ -85,20 +86,14 @@ int32 MkvReadableWriter::Position(int64 position) {
 #endif
 }
 
-bool MkvReadableWriter::Seekable() const {
+bool MkvWriteEOFReader::Seekable() const {
   return true;
 }
 
-void MkvReadableWriter::ElementStartNotify(uint64, int64) {
+void MkvWriteEOFReader::ElementStartNotify(uint64, int64) {
 }
 
-int MkvReadableWriter::Length(long long* total, long long* available) {
-    return 0;
-}
-
-int MkvReadableWriter::Read(long long offset,
-                          long len,
-                          unsigned char* buffer) {
+int MkvWriteEOFReader::Read(int64 offset, int32 len, uint8* buffer) {
   if (file_ == NULL)
     return -1;
 
@@ -108,6 +103,9 @@ int MkvReadableWriter::Read(long long offset,
   if (len < 0)
     return -1;
 
+  if (writes_allowed_)
+    writes_allowed_ = false;
+
   if (len == 0)
     return 0;
 

mkvwriteeofreader.hpp

@@ -6,8 +6,8 @@
 // in the file PATENTS.  All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 
-#ifndef MKVREADABLEWRITER_HPP
-#define MKVREADABLEWRITER_HPP
+#ifndef MKVWRITEEOFREADER_HPP
+#define MKVWRITEEOFREADER_HPP
 
 #include <stdio.h>
 
@@ -16,20 +16,19 @@
 
 namespace mkvmuxer {
 
-// Default implementation of the IMkvReadableWriter interface.
-class MkvReadableWriter : public IMkvReadableWriter {
+// Default implementation of the IMkvWriteEOFReader interface.
+class MkvWriteEOFReader : public IMkvWriteEOFReader {
  public:
-  MkvReadableWriter();
-  virtual ~MkvReadableWriter();
+  MkvWriteEOFReader();
+  virtual ~MkvWriteEOFReader();
 
-  // IMkvReadableWriter interface
+  // IMkvWriteEOFReader interface
   virtual int64 Position() const;
   virtual int32 Position(int64 position);
   virtual bool Seekable() const;
   virtual int32 Write(const void* buffer, uint32 length);
   virtual void ElementStartNotify(uint64 element_id, int64 position);
-  virtual int Read(long long position, long length, unsigned char* buffer);
-  virtual int Length(long long* total, long long* available);
+  virtual int Read(int64 position, int32 length, uint8* buffer);
 
   // Creates and opens a file for reading and writing. |filename| is the name of
   // the file to open. This function will overwrite the contents of |filename|.
@@ -45,9 +44,13 @@ class MkvReadableWriter : public IMkvReadableWriter {
   // File handle to output file.
   FILE* file_;
 
-  LIBWEBM_DISALLOW_COPY_AND_ASSIGN(MkvReadableWriter);
+  // Flag indicating if writes are allowed. Will be set to false on first call
+  // to Read().
+  bool writes_allowed_;
+
+  LIBWEBM_DISALLOW_COPY_AND_ASSIGN(MkvWriteEOFReader);
 };
 
 }  // end namespace mkvmuxer
 
-#endif  // MKVREADABLEWRITER_HPP
+#endif  // MKVWRITEEOFREADER_HPP

sample_muxer.cpp

@@ -18,7 +18,7 @@
 
 // libwebm muxer includes
 #include "mkvmuxer.hpp"
-#include "mkvreadablewriter.hpp"
+#include "mkvwriteeofreader.hpp"
 #include "mkvwriter.hpp"
 #include "mkvmuxerutil.hpp"
 
@@ -272,7 +272,7 @@ int main(int argc, char* argv[]) {
   // Set Segment element attributes
   mkvmuxer::Segment muxer_segment;
 
-  mkvmuxer::MkvReadableWriter writer_temp;
+  mkvmuxer::MkvWriteEOFReader writer_temp;
   if (cues_before_clusters) {
     if (!writer_temp.Open(NULL, true)) {
       printf("\n Filename is invalid or error while opening.\n");