1 files changed, 209 insertions, 0 deletions
diff --git a/xpcom/io/SlicedInputStream.cpp b/xpcom/io/SlicedInputStream.cpp
new file mode 100644
index 000000000..7d5fc2b05
--- /dev/null
+++ b/xpcom/io/SlicedInputStream.cpp
@@ -0,0 +1,209 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 "SlicedInputStream.h"
+#include "nsISeekableStream.h"
+#include "nsStreamUtils.h"
+
+NS_IMPL_ISUPPORTS(SlicedInputStream, nsIInputStream,
+                  nsICloneableInputStream, nsIAsyncInputStream)
+
+SlicedInputStream::SlicedInputStream(nsIInputStream* aInputStream,
+                                     uint64_t aStart, uint64_t aLength)
+  : mInputStream(aInputStream)
+  , mStart(aStart)
+  , mLength(aLength)
+  , mCurPos(0)
+  , mClosed(false)
+{
+  MOZ_ASSERT(aInputStream);
+}
+
+SlicedInputStream::~SlicedInputStream()
+{}
+
+NS_IMETHODIMP
+SlicedInputStream::Close()
+{
+  mClosed = true;
+  return NS_OK;
+}
+
+// nsIInputStream interface
+
+NS_IMETHODIMP
+SlicedInputStream::Available(uint64_t* aLength)
+{
+  if (mClosed) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  nsresult rv = mInputStream->Available(aLength);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  // Let's remove extra length from the end.
+  if (*aLength + mCurPos > mStart + mLength) {
+    *aLength -= XPCOM_MIN(*aLength, (*aLength + mCurPos) - (mStart + mLength));
+  }
+
+  // Let's remove extra length from the begin.
+  if (mCurPos < mStart) {
+    *aLength -= XPCOM_MIN(*aLength, mStart - mCurPos);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SlicedInputStream::Read(char* aBuffer, uint32_t aCount, uint32_t* aReadCount)
+{
+  return ReadSegments(NS_CopySegmentToBuffer, aBuffer, aCount, aReadCount);
+}
+
+NS_IMETHODIMP
+SlicedInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                                uint32_t aCount, uint32_t *aResult)
+{
+  uint32_t result;
+
+  if (!aResult) {
+    aResult = &result;
+  }
+
+  *aResult = 0;
+
+  if (mClosed) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  if (mCurPos < mStart) {
+    nsCOMPtr<nsISeekableStream> seekableStream =
+      do_QueryInterface(mInputStream);
+    if (seekableStream) {
+      nsresult rv = seekableStream->Seek(nsISeekableStream::NS_SEEK_SET,
+                                         mStart);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
+
+      mCurPos = mStart;
+    } else {
+      char buf[4096];
+      while (mCurPos < mStart) {
+	uint32_t bytesRead;
+	uint64_t bufCount = XPCOM_MIN(mStart - mCurPos, (uint64_t)sizeof(buf));
+	nsresult rv = mInputStream->Read(buf, bufCount, &bytesRead);
+	if (NS_WARN_IF(NS_FAILED(rv)) || bytesRead == 0) {
+	  return rv;
+	}
+
+         mCurPos += bytesRead;
+      }
+    }
+  }
+
+  // Let's reduce aCount in case it's too big.
+  if (mCurPos + aCount > mStart + mLength) {
+    aCount = mStart + mLength - mCurPos;
+  }
+
+  char buf[4096];
+  while (mCurPos < mStart + mLength && *aResult < aCount) {
+    uint32_t bytesRead;
+    uint64_t bufCount = XPCOM_MIN(aCount - *aResult, (uint32_t)sizeof(buf));
+    nsresult rv = mInputStream->Read(buf, bufCount, &bytesRead);
+    if (NS_WARN_IF(NS_FAILED(rv)) || bytesRead == 0) {
+      return rv;
+    }
+
+    mCurPos += bytesRead;
+
+    uint32_t bytesWritten = 0;
+    while (bytesWritten < bytesRead) {
+      uint32_t writerCount = 0;
+      rv = aWriter(this, aClosure, buf + bytesWritten, *aResult,
+                   bytesRead - bytesWritten, &writerCount);
+      if (NS_FAILED(rv) || writerCount == 0) {
+	return NS_OK;
+      }
+
+      MOZ_ASSERT(writerCount <= bytesRead - bytesWritten);
+      bytesWritten += writerCount;
+      *aResult += writerCount;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SlicedInputStream::IsNonBlocking(bool* aNonBlocking)
+{
+  return mInputStream->IsNonBlocking(aNonBlocking);
+}
+
+// nsICloneableInputStream interface
+
+NS_IMETHODIMP
+SlicedInputStream::GetCloneable(bool* aCloneable)
+{
+  *aCloneable = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+SlicedInputStream::Clone(nsIInputStream** aResult)
+{
+  nsCOMPtr<nsIInputStream> clonedStream;
+  nsCOMPtr<nsIInputStream> replacementStream;
+
+  nsresult rv = NS_CloneInputStream(mInputStream, getter_AddRefs(clonedStream),
+                                    getter_AddRefs(replacementStream));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  if (replacementStream) {
+    mInputStream = replacementStream.forget();
+  }
+
+  nsCOMPtr<nsIInputStream> sis =
+    new SlicedInputStream(clonedStream, mStart, mLength);
+
+  sis.forget(aResult);
+  return NS_OK;
+}
+
+// nsIAsyncInputStream interface
+
+NS_IMETHODIMP
+SlicedInputStream::CloseWithStatus(nsresult aStatus)
+{
+  nsCOMPtr<nsIAsyncInputStream> asyncStream =
+    do_QueryInterface(mInputStream);
+  if (!asyncStream) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return asyncStream->CloseWithStatus(aStatus);
+}
+
+NS_IMETHODIMP
+SlicedInputStream::AsyncWait(nsIInputStreamCallback* aCallback,
+                             uint32_t aFlags,
+                             uint32_t aRequestedCount,
+                             nsIEventTarget* aEventTarget)
+{
+  nsCOMPtr<nsIAsyncInputStream> asyncStream =
+    do_QueryInterface(mInputStream);
+  if (!asyncStream) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return asyncStream->AsyncWait(aCallback, aFlags, aRequestedCount,
+                                aEventTarget);
+}