Add input and output classes for streaming compression.

enc/streams.cc

@@ -0,0 +1,126 @@
+// Copyright 2009 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Convience routines to make Brotli I/O classes from some memory containers and
+// files.
+
+#include "./streams.h"
+
+#include <assert.h>
+#include <string.h>
+
+namespace brotli {
+
+BrotliMemOut::BrotliMemOut(void* buf, int len)
+    : buf_(buf),
+      len_(len),
+      pos_(0) {}
+
+void BrotliMemOut::Reset(void* buf, int len) {
+  buf_ = buf;
+  len_ = len;
+  pos_ = 0;
+}
+
+// Brotli output routine: copy n bytes to the output buffer.
+bool BrotliMemOut::Write(const void *buf, size_t n) {
+  if (n + pos_ > len_)
+    return false;
+  char* p = reinterpret_cast<char*>(buf_) + pos_;
+  memcpy(p, buf, n);
+  pos_ += n;
+  return true;
+}
+
+BrotliStringOut::BrotliStringOut(std::string* buf, int max_size)
+    : buf_(buf),
+      max_size_(max_size) {
+  assert(buf->empty());
+}
+
+void BrotliStringOut::Reset(std::string* buf, int max_size) {
+  buf_ = buf;
+  max_size_ = max_size;
+}
+
+// Brotli output routine: add n bytes to a string.
+bool BrotliStringOut::Write(const void *buf, size_t n) {
+  if (buf_->size() + n > max_size_)
+    return false;
+  buf_->append(static_cast<const char*>(buf), n);
+  return true;
+}
+
+BrotliMemIn::BrotliMemIn(const void* buf, int len)
+    : buf_(buf),
+      len_(len),
+      pos_(0) {}
+
+void BrotliMemIn::Reset(const void* buf, int len) {
+  buf_ = buf;
+  len_ = len;
+  pos_ = 0;
+}
+
+// Brotli input routine: read the next chunk of memory.
+const void* BrotliMemIn::Read(size_t n, size_t* output) {
+  if (pos_ == len_) {
+    return NULL;
+  }
+  if (n > len_ - pos_)
+    n = len_ - pos_;
+  const char* p = reinterpret_cast<const char*>(buf_) + pos_;
+  pos_ += n;
+  *output = n;
+  return p;
+}
+
+BrotliFileIn::BrotliFileIn(FILE* f, size_t max_read_size)
+    : f_(f),
+      buf_(malloc(max_read_size)),
+      buf_size_(max_read_size) {}
+
+BrotliFileIn::~BrotliFileIn() {
+  if (buf_) free(buf_);
+}
+
+const void* BrotliFileIn::Read(size_t n, size_t* bytes_read) {
+  if (buf_ == NULL) {
+    *bytes_read = 0;
+    return NULL;
+  }
+  if (n > buf_size_) {
+    n = buf_size_;
+  } else if (n == 0) {
+    return feof(f_) ? NULL : buf_;
+  }
+  *bytes_read = fread(buf_, 1, n, f_);
+  if (*bytes_read == 0) {
+    return NULL;
+  } else {
+    return buf_;
+  }
+}
+
+BrotliFileOut::BrotliFileOut(FILE* f) : f_(f) {}
+
+bool BrotliFileOut::Write(const void* buf, size_t n) {
+  if (fwrite(buf, n, 1, f_) != 1) {
+    return false;
+  }
+  return true;
+}
+
+
+}  // namespace brotli

enc/streams.h

@@ -0,0 +1,129 @@
+// Copyright 2009 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Input and output classes for streaming brotli compression.
+
+#ifndef BROTLI_ENC_STREAMS_H_
+#define BROTLI_ENC_STREAMS_H_
+
+#include <stddef.h>
+#include <stdio.h>
+#include <string>
+
+namespace brotli {
+
+// Input interface for the compression routines.
+class BrotliIn {
+ public:
+  virtual ~BrotliIn() {}
+
+  // Return a pointer to the next block of input of at most n bytes.
+  // Return the actual length in *nread.
+  // At end of data, return NULL. Don't return NULL if there is more data
+  // to read, even if called with n == 0.
+  // Read will only be called if some of its bytes are needed.
+  virtual const void* Read(size_t n, size_t* nread) = 0;
+};
+
+// Output interface for the compression routines.
+class BrotliOut {
+ public:
+  virtual ~BrotliOut() {}
+
+  // Write n bytes of data from buf.
+  // Return true if all written, false otherwise.
+  virtual bool Write(const void *buf, size_t n) = 0;
+};
+
+// Adapter class to make BrotliIn objects from raw memory.
+class BrotliMemIn : public BrotliIn {
+ public:
+  BrotliMemIn(const void* buf, int len);
+
+  void Reset(const void* buf, int len);
+
+  // returns the amount of data consumed
+  int position() const { return pos_; }
+
+  const void* Read(size_t n, size_t* OUTPUT) override;
+
+ private:
+  const void* buf_;  // start of input buffer
+  int len_;  // length of input
+  int pos_;  // current read position within input
+};
+
+// Adapter class to make BrotliOut objects from raw memory.
+class BrotliMemOut : public BrotliOut {
+ public:
+  BrotliMemOut(void* buf, int len);
+
+  void Reset(void* buf, int len);
+
+  // returns the amount of data written
+  int position() const { return pos_; }
+
+  bool Write(const void* buf, size_t n) override;
+
+ private:
+  void* buf_;  // start of output buffer
+  int len_;  // length of output
+  int pos_;  // current write position within output
+};
+
+// Adapter class to make BrotliOut objects from a string.
+class BrotliStringOut : public BrotliOut {
+ public:
+  // Create a writer that appends its data to buf.
+  // buf->size() will grow to at most max_size
+  // buf is expected to be empty when constructing BrotliStringOut.
+  BrotliStringOut(std::string* buf, int max_size);
+
+  void Reset(std::string* buf, int max_len);
+
+  bool Write(const void* buf, size_t n) override;
+
+ private:
+  std::string* buf_;  // start of output buffer
+  int max_size_;  // max length of output
+};
+
+// Adapter class to make BrotliIn object from a file.
+class BrotliFileIn : public BrotliIn {
+ public:
+  BrotliFileIn(FILE* f, size_t max_read_size);
+  ~BrotliFileIn() override;
+
+  const void* Read(size_t n, size_t* bytes_read) override;
+
+ private:
+  FILE* f_;
+  void* buf_;
+  size_t buf_size_;
+};
+
+// Adapter class to make BrotliOut object from a file.
+class BrotliFileOut : public BrotliOut {
+ public:
+  explicit BrotliFileOut(FILE* f);
+
+  bool Write(const void* buf, size_t n) override;
+ private:
+  FILE* f_;
+};
+
+
+}  // namespace brotli
+
+#endif  // BROTLI_ENC_STREAMS_H_