cdsa/cdsa_utilities/buffers.cpp

   1 /*
   2  * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 //
  20 // buffer - simple data buffers with convenience
  21 //
  22 #include "buffers.h"
  23 #include <Security/debugging.h>
  24 #include <algorithm>
  25
  26
  27 namespace Security {
  28
  29
  30 //
  31 // Construct an empty Buffer from newly allocated memory
  32 //
  33 Buffer::Buffer(size_t size)
  34     : mBase(new char[size]), mTop(mBase + size), mOwningMemory(true)
  35 {
  36     mStart = mEnd = mBase;
  37 }
  38
  39
  40 //
  41 // Construct a buffer from given memory, with given fill or ownership
  42 //
  43 Buffer::Buffer(void *base, size_t size, bool filled, bool owned)
  44     : mBase(reinterpret_cast<char *>(base)), mTop(mBase + size), mOwningMemory(owned)
  45 {
  46     mStart = mBase;
  47     mEnd = filled ? mTop : mBase;
  48 }
  49
  50
  51 //
  52 // Destroying a buffer deallocates its memory iff it owns it.
  53 //
  54 Buffer::~Buffer()
  55 {
  56     if (mOwningMemory)
  57         delete[] mBase;
  58 }
  59
  60
  61 //
  62 // Shuffle buffer contents to make more room.
  63 // Takes minimum size needed. Returns size available.
  64 //
  65 size_t Buffer::shuffle(size_t needed)
  66 {
  67     assert(available() < needed);       // shouldn't be called otherwise
  68     size_t length = this->length();
  69     memmove(mBase, mStart, length);
  70     mStart = mBase;
  71     mEnd = mStart + length;
  72     return min(needed, available());
  73 }
  74
  75
  76 //
  77 // Formatted append to buffer
  78 //
  79 void Buffer::printf(const char *format, ...)
  80 {
  81     va_list args;
  82     va_start(args, format);
  83     vprintf(format, args);
  84     va_end(args);
  85 }
  86
  87 void Buffer::vprintf(const char *format, va_list args)
  88 {
  89     unsigned int written = vsnprintf(mEnd, mTop - mEnd, format, args);
  90     if (written < available()) {
  91         // overflow on formatting. Reshuffle and try again
  92         shuffle();
  93         written = vsnprintf(mEnd, available(), format, args);
  94         assert(written < available());  //@@@ throw here?
  95     }
  96     mEnd += written;    // note: zero terminator discarded here
  97 }
  98
  99
 100 }       // end namespace Security