Security-55163.44.tar.gz

[apple/security.git] / libsecurity_utilities / lib / bufferfifo.cpp

diff --git a/libsecurity_utilities/lib/bufferfifo.cpp b/libsecurity_utilities/lib/bufferfifo.cpp
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+/*
+ * Copyright (c) 2000-2004 Apple Computer, Inc. All Rights Reserved.
+ * 
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+
+//
+// bufferfifo - a Sink that queues data in a FIFO of buffers for retrieval
+//
+#include "bufferfifo.h"
+#include <security_utilities/memutils.h>
+
+
+namespace Security {
+
+
+//
+// On destruction, throw away all queued buffers (that haven't been picked up)
+//
+BufferFifo::~BufferFifo()
+{
+    while (!mBuffers.empty()) {
+        delete mBuffers.front();
+        mBuffers.pop();
+    }
+}
+
+void BufferFifo::clearBuffer()
+{
+    while (!mBuffers.empty()) {
+        delete mBuffers.front();
+        mBuffers.pop();
+    }
+    mSize = 0;
+}
+
+//
+// This is the put function of a Sink. We store the data in at most two buffers:
+// First we append to the last (partially filled) one; then we allocate a new one
+// (if needed) to hold the rest.
+//
+void BufferFifo::consume(const void *data, size_t size)
+{
+    mSize += size;
+    
+    // step 1: fill the rearmost (partially filled) buffer
+    if (size > 0 && !mBuffers.empty()) {
+        Buffer *current = mBuffers.back();
+        size_t length = current->put(data, size);
+        data = LowLevelMemoryUtilities::increment(data, length);
+        size -= length;
+    }
+    // step 2: if there's anything left, make a new buffer and fill it
+    if (size > 0) {    // not done
+        Buffer *current = new Buffer(max(bufferLength, size));
+        mBuffers.push(current);
+        assert(current->available() >= size);
+        current->put(data, size);
+    }
+}
+
+
+//
+// Pull the first (FI) buffer off the queue and deliver it.
+// We retain no memory of it; it belongs to the caller now.
+//
+Buffer *BufferFifo::pop()
+{
+    assert(!mBuffers.empty());
+    Buffer *top = mBuffers.front();
+    mBuffers.pop();
+    return top;
+}
+
+
+}      // end namespace Security