Security-57031.1.35.tar.gz

[apple/security.git] / Security / libsecurity_utilities / lib / buffers.cpp

diff --git a/Security/libsecurity_utilities/lib/buffers.cpp b/Security/libsecurity_utilities/lib/buffers.cpp
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+/*
+ * Copyright (c) 2000-2001,2003-2004,2011,2014 Apple 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@
+ */
+
+
+//
+// buffer - simple data buffers with convenience
+//
+#include "buffers.h"
+#include <security_utilities/debugging.h>
+#include <algorithm>
+
+
+namespace Security {
+
+
+//
+// Construct an empty Buffer from newly allocated memory
+//
+Buffer::Buffer(size_t size)
+    : mBase(new char[size]), mTop(mBase + size), mOwningMemory(true)
+{
+    mStart = mEnd = mBase;
+}
+
+
+//
+// Construct a buffer from given memory, with given fill or ownership
+//
+Buffer::Buffer(void *base, size_t size, bool filled, bool owned) 
+    : mBase(reinterpret_cast<char *>(base)), mTop(mBase + size), mOwningMemory(owned)
+{
+    mStart = mBase;
+    mEnd = filled ? mTop : mBase;
+}
+
+
+//
+// Destroying a buffer deallocates its memory iff it owns it.
+//
+Buffer::~Buffer()
+{
+    if (mOwningMemory)
+        delete[] mBase;
+}
+
+
+//
+// Shuffle buffer contents to make more room.
+// Takes minimum size needed. Returns size available.
+//
+size_t Buffer::shuffle(size_t needed)
+{
+    assert(available() < needed);      // shouldn't be called otherwise
+    size_t length = this->length();
+    memmove(mBase, mStart, length);
+    mStart = mBase;
+    mEnd = mStart + length;
+    return min(needed, available());
+}
+
+
+//
+// Formatted append to buffer
+//
+void Buffer::printf(const char *format, ...)
+{
+    va_list args;
+    va_start(args, format);
+    vprintf(format, args);
+    va_end(args);
+}
+
+void Buffer::vprintf(const char *format, va_list args)
+{
+    unsigned int written = vsnprintf(mEnd, mTop - mEnd, format, args);
+    if (written < available()) {
+        // overflow on formatting. Reshuffle and try again
+        shuffle();
+        written = vsnprintf(mEnd, available(), format, args);
+        assert(written < available()); //@@@ throw here?
+    }
+    mEnd += written;   // note: zero terminator discarded here
+}
+
+
+}      // end namespace Security