1 files changed, 169 insertions, 0 deletions
diff --git a/xpcom/io/nsSegmentedBuffer.cpp b/xpcom/io/nsSegmentedBuffer.cpp
new file mode 100644
index 000000000..ab42a73c7
--- /dev/null
+++ b/xpcom/io/nsSegmentedBuffer.cpp
@@ -0,0 +1,169 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsSegmentedBuffer.h"
+#include "nsMemory.h"
+
+nsresult
+nsSegmentedBuffer::Init(uint32_t aSegmentSize, uint32_t aMaxSize)
+{
+  if (mSegmentArrayCount != 0) {
+    return NS_ERROR_FAILURE;  // initialized more than once
+  }
+  mSegmentSize = aSegmentSize;
+  mMaxSize = aMaxSize;
+#if 0 // testing...
+  mSegmentArrayCount = 2;
+#else
+  mSegmentArrayCount = NS_SEGMENTARRAY_INITIAL_COUNT;
+#endif
+  return NS_OK;
+}
+
+char*
+nsSegmentedBuffer::AppendNewSegment()
+{
+  if (GetSize() >= mMaxSize) {
+    return nullptr;
+  }
+
+  if (!mSegmentArray) {
+    uint32_t bytes = mSegmentArrayCount * sizeof(char*);
+    mSegmentArray = (char**)moz_xmalloc(bytes);
+    if (!mSegmentArray) {
+      return nullptr;
+    }
+    memset(mSegmentArray, 0, bytes);
+  }
+
+  if (IsFull()) {
+    uint32_t newArraySize = mSegmentArrayCount * 2;
+    uint32_t bytes = newArraySize * sizeof(char*);
+    char** newSegArray = (char**)moz_xrealloc(mSegmentArray, bytes);
+    if (!newSegArray) {
+      return nullptr;
+    }
+    mSegmentArray = newSegArray;
+    // copy wrapped content to new extension
+    if (mFirstSegmentIndex > mLastSegmentIndex) {
+      // deal with wrap around case
+      memcpy(&mSegmentArray[mSegmentArrayCount],
+             mSegmentArray,
+             mLastSegmentIndex * sizeof(char*));
+      memset(mSegmentArray, 0, mLastSegmentIndex * sizeof(char*));
+      mLastSegmentIndex += mSegmentArrayCount;
+      memset(&mSegmentArray[mLastSegmentIndex], 0,
+             (newArraySize - mLastSegmentIndex) * sizeof(char*));
+    } else {
+      memset(&mSegmentArray[mLastSegmentIndex], 0,
+             (newArraySize - mLastSegmentIndex) * sizeof(char*));
+    }
+    mSegmentArrayCount = newArraySize;
+  }
+
+  char* seg = (char*)malloc(mSegmentSize);
+  if (!seg) {
+    return nullptr;
+  }
+  mSegmentArray[mLastSegmentIndex] = seg;
+  mLastSegmentIndex = ModSegArraySize(mLastSegmentIndex + 1);
+  return seg;
+}
+
+bool
+nsSegmentedBuffer::DeleteFirstSegment()
+{
+  NS_ASSERTION(mSegmentArray[mFirstSegmentIndex] != nullptr, "deleting bad segment");
+  free(mSegmentArray[mFirstSegmentIndex]);
+  mSegmentArray[mFirstSegmentIndex] = nullptr;
+  int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
+  if (mFirstSegmentIndex == last) {
+    mLastSegmentIndex = last;
+    return true;
+  } else {
+    mFirstSegmentIndex = ModSegArraySize(mFirstSegmentIndex + 1);
+    return false;
+  }
+}
+
+bool
+nsSegmentedBuffer::DeleteLastSegment()
+{
+  int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
+  NS_ASSERTION(mSegmentArray[last] != nullptr, "deleting bad segment");
+  free(mSegmentArray[last]);
+  mSegmentArray[last] = nullptr;
+  mLastSegmentIndex = last;
+  return (bool)(mLastSegmentIndex == mFirstSegmentIndex);
+}
+
+bool
+nsSegmentedBuffer::ReallocLastSegment(size_t aNewSize)
+{
+  int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
+  NS_ASSERTION(mSegmentArray[last] != nullptr, "realloc'ing bad segment");
+  char* newSegment = (char*)realloc(mSegmentArray[last], aNewSize);
+  if (newSegment) {
+    mSegmentArray[last] = newSegment;
+    return true;
+  }
+  return false;
+}
+
+void
+nsSegmentedBuffer::Empty()
+{
+  if (mSegmentArray) {
+    for (uint32_t i = 0; i < mSegmentArrayCount; i++) {
+      if (mSegmentArray[i]) {
+        free(mSegmentArray[i]);
+      }
+    }
+    free(mSegmentArray);
+    mSegmentArray = nullptr;
+  }
+  mSegmentArrayCount = NS_SEGMENTARRAY_INITIAL_COUNT;
+  mFirstSegmentIndex = mLastSegmentIndex = 0;
+}
+
+#if 0
+void
+TestSegmentedBuffer()
+{
+  nsSegmentedBuffer* buf = new nsSegmentedBuffer();
+  NS_ASSERTION(buf, "out of memory");
+  buf->Init(4, 16);
+  char* seg;
+  bool empty;
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(empty, "DeleteFirstSegment failed");
+  delete buf;
+}
+#endif
+
+////////////////////////////////////////////////////////////////////////////////