Security-57031.1.35.tar.gz

[apple/security.git] / Security / libsecurity_utilities / lib / memstreams.h

diff --git a/Security/libsecurity_utilities/lib/memstreams.h b/Security/libsecurity_utilities/lib/memstreams.h
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+/*
+ * Copyright (c) 2000-2004,2011-2012,2014 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@
+ */
+
+
+//
+// memstreams - primitive memory block streaming support
+//
+#ifndef _H_MEMSTREAMS
+#define _H_MEMSTREAMS
+
+#include <stdint.h>
+#include <security_utilities/memutils.h>
+#include <security_utilities/endian.h>
+#include <security_utilities/errors.h>
+
+
+namespace Security
+{
+
+//
+// Encapsulate these very sharp tools in a separate namespace
+//
+namespace LowLevelMemoryUtilities
+{
+
+
+//
+// A simple utility for incremental creation of a contiguous memory block.
+//
+// Note that Writer and Writer::Counter go together. They use the same alignment
+// and padding rules, so Writer::Counter will correctly calculate total buffer
+// size for Writer, *presuming* that they are called in the same order.
+//
+// This layer allocates no memory; that's up to the caller (you).
+//
+// WARNING: There is no check for overflow. If you write too much, you will die.
+// Writer::Counter can tell you how much you need.
+//
+class Writer {
+private:
+       void *advance(size_t size)
+       {
+               void *here = alignUp(writePos);
+               writePos = increment(here, size);
+               return here;
+       }
+    
+public:    
+       Writer() { }
+       Writer(void *base) : writePos(base) { }
+       void operator = (void *base) { writePos = base; }
+
+       template <class T>
+       T *operator () (const T &obj)
+       { T *here = (T *)advance(sizeof(T)); *here = obj; return here; }
+
+       void *operator () (const void *addr, size_t size)
+       { void *here = advance(size); return memcpy(here, addr, size); }
+
+       char *operator () (const char *s)
+       { return (char *)(*this)(s, strlen(s) + 1); }
+       
+       void countedData(const void *data, size_t length)
+       { 
+        if (length > uint32_t(~0))
+            UnixError::throwMe(ERANGE);
+        Endian<uint32_t> temp = (uint32_t)length; (*this)(temp); (*this)(data, length); 
+    }
+       
+       template <class Data>
+       void countedData(const Data &data)
+       { countedData(data.data(), data.length()); }
+
+       class Counter;
+
+private:
+       void *writePos;                 // next byte address
+};
+
+class Writer::Counter {
+private:
+       void align() { totalSoFar = alignUp(totalSoFar); }
+
+public:
+       Counter() : totalSoFar(0) { }
+       operator size_t () { return totalSoFar; }
+
+       template <class T> size_t operator () (const T &) { align(); return totalSoFar += sizeof(T); }
+       size_t insert(size_t size) { align(); return totalSoFar += size; }
+       size_t operator () (const char *s) { align(); return totalSoFar += strlen(s) + 1; }
+       
+       void countedData(const void *, size_t length)
+       { insert(sizeof(length)); insert(length); }
+       
+       template <class Data>
+       void countedData(const Data &data)
+       { countedData(data.data(), data.length()); }
+
+private:
+       size_t totalSoFar;      // total size counted so far
+};
+
+
+//
+// The Reader counter-part for a Writer.
+// Again, Reader and Writer share alignment and representation rules, so what was
+// Written shall be Read again, just fine.
+//
+class Reader {
+private:
+    const void *advance(size_t size = 0)
+    {
+        const void *here = alignUp(readPos);
+        readPos = increment(here, size);
+        return here;
+    }
+
+public:
+    Reader() { }
+    Reader(const void *base) : readPos(base) { }
+    void operator = (const void *base) { readPos = base; }
+    
+    template <class T>
+    void operator () (T &obj) {        obj = *reinterpret_cast<const T *>(advance(sizeof(T))); }
+    void operator () (void *addr, size_t size) { memcpy(addr, advance(size), size); }
+    void operator () (const char * &s)
+    { s = reinterpret_cast<const char *>(advance()); advance(strlen(s) + 1); }
+    template <class T>
+    const T *get(size_t size)
+       { return reinterpret_cast<const T *>(advance(size)); }
+       
+       void countedData(const void * &data, size_t &length)
+       { Endian<uint32_t> temp; (*this)(temp); length = temp; data = advance(length); }
+
+private:
+       // Explicitly forbid some invocations that are likely to be wrong.
+       void operator () (char * &s);   // can't get writable string in-place
+    
+private:
+    const void *readPos;       // next byte address
+};
+
+
+} // end namespace LowLevelMemoryUtilities
+
+} // end namespace Security
+
+#endif //_H_MEMUTILS