Security-55163.44.tar.gz

[apple/security.git] / libsecurity_utilities / lib / buffers.h

diff --git a/libsecurity_utilities/lib/buffers.h b/libsecurity_utilities/lib/buffers.h
new file mode 100644 (file)
index 0000000..65a0eef
--- /dev/null
+++ b/libsecurity_utilities/lib/buffers.h
@@ -0,0 +1,162 @@
+/*
+ * Copyright (c) 2000-2001,2003-2004 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@
+ */
+
+
+//
+// buffer - simple data buffers with convenience
+//
+#ifndef _H_BUFFER
+#define _H_BUFFER
+
+#include <security_utilities/utilities.h>
+#include <cstdarg>
+#include <limits.h>
+
+
+namespace Security {
+
+
+class Buffer {
+public:
+    Buffer(size_t size);                       // allocate empty buffer
+    ~Buffer();
+    
+    static Buffer reader(void *base, size_t size, bool owned = false)
+    { return Buffer(base, size, true, owned); }
+    static Buffer writer(void *base, size_t size, bool owned = false)
+    { return Buffer(base, size, false, owned); }
+    
+    size_t available(bool heavy = false) const
+    { return heavy ? ((mTop - mEnd) + (mStart - mBase)): (mTop - mEnd); }
+    bool isFull(bool heavy = false) const
+    { return heavy ? (mEnd == mTop && mStart == mBase) : (mEnd == mTop); }
+    bool isEmpty() const               { return mStart == mEnd; }
+
+    size_t length() const              { return mEnd - mStart; }
+    void *data()                               { assert(mStart == mBase); return mStart; }
+    
+    void clear()                               { mStart = mEnd = mBase; }
+    
+protected:
+    // private constructor with full flexibility
+    Buffer(void *base, size_t size, bool filled, bool owned = false);
+    
+    // perform expensive realignment to coalesce freespace
+    size_t shuffle(size_t needed = UINT_MAX);
+    
+    // perform cheap adjustments after data was taken out
+    void adjustGet()
+    {
+        if (isEmpty()) // empty buffer. Reset pointers to base
+            mStart = mEnd = mBase;
+    }
+    
+public:
+    // elementary put: copy mode
+    size_t put(const void *data, size_t length)
+    {
+        if (length > available())
+            length = shuffle(length);
+        memcpy(mEnd, data, length);
+        mEnd += length;
+        return length;
+    }
+
+    // elementary put: locate mode. Remember that each can shuffle memory
+    template <class T> void locatePut(T * &addr, size_t &length)
+    {
+        if (length > available())
+            length = shuffle(length);
+        addr = reinterpret_cast<T *>(mEnd);
+    }
+    
+    void usePut(size_t length)
+    {
+        assert(length <= available());
+        mEnd += length;
+    }
+    
+    // elementary get: locate mode
+    template <class T> void locateGet(T * &addr, size_t &length)
+    {
+        if (length > size_t(mEnd - mStart))
+            length = mEnd - mStart;
+        addr = reinterpret_cast<T *>(mStart);
+    }
+    
+    void useGet(size_t length)
+    {
+        assert(length <= this->length());
+        mStart += length;
+        adjustGet();
+    }
+    
+    //
+    // I/O via FileDescoid objects
+    //
+    template <class IO>
+    size_t read(IO &io, size_t length)
+    {
+        if (length > available())
+            length = shuffle(length);
+        size_t bytesRead = io.read(mEnd, length);
+        mEnd += bytesRead;
+        return bytesRead;
+    }
+    
+    template <class IO>
+    size_t write(IO &io, size_t length)
+    {
+        length = min(this->length(), length);
+        size_t bytesWritten = io.write(mStart, length);
+        mStart += bytesWritten;
+        adjustGet();
+        return bytesWritten;
+    }
+
+    template <class IO> size_t read(IO &io, bool heavy = false)
+    { return read(io, available(heavy)); }
+    
+    template <class IO> size_t write(IO &io)
+    { return write(io, length()); }
+
+    // printf-style output to a buffer
+    void printf(const char *format, ...);
+    void vprintf(const char *format, va_list args);
+
+    // memory ownership
+    void own()         { mOwningMemory = true; }
+    
+private:
+    char *const mBase;                 // base pointer
+    char *const mTop;                  // end pointer + 1
+    char *mStart;                              // start of used area
+    char *mEnd;                                        // end of used area + 1
+    bool mOwningMemory;                        // true if we own the memory (free on destruction)
+};
+
+
+}      // end namespace Security
+
+
+#endif //_H_BUFFER