libsecurity_utilities/lib/buffers.cpp

   1 /*
   2  * Copyright (c) 2000-2001,2003-2004 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24
  25 //
  26 // buffer - simple data buffers with convenience
  27 //
  28 #include "buffers.h"
  29 #include <security_utilities/debugging.h>
  30 #include <algorithm>
  31
  32
  33 namespace Security {
  34
  35
  36 //
  37 // Construct an empty Buffer from newly allocated memory
  38 //
  39 Buffer::Buffer(size_t size)
  40     : mBase(new char[size]), mTop(mBase + size), mOwningMemory(true)
  41 {
  42     mStart = mEnd = mBase;
  43 }
  44
  45
  46 //
  47 // Construct a buffer from given memory, with given fill or ownership
  48 //
  49 Buffer::Buffer(void *base, size_t size, bool filled, bool owned)
  50     : mBase(reinterpret_cast<char *>(base)), mTop(mBase + size), mOwningMemory(owned)
  51 {
  52     mStart = mBase;
  53     mEnd = filled ? mTop : mBase;
  54 }
  55
  56
  57 //
  58 // Destroying a buffer deallocates its memory iff it owns it.
  59 //
  60 Buffer::~Buffer()
  61 {
  62     if (mOwningMemory)
  63         delete[] mBase;
  64 }
  65
  66
  67 //
  68 // Shuffle buffer contents to make more room.
  69 // Takes minimum size needed. Returns size available.
  70 //
  71 size_t Buffer::shuffle(size_t needed)
  72 {
  73     assert(available() < needed);       // shouldn't be called otherwise
  74     size_t length = this->length();
  75     memmove(mBase, mStart, length);
  76     mStart = mBase;
  77     mEnd = mStart + length;
  78     return min(needed, available());
  79 }
  80
  81
  82 //
  83 // Formatted append to buffer
  84 //
  85 void Buffer::printf(const char *format, ...)
  86 {
  87     va_list args;
  88     va_start(args, format);
  89     vprintf(format, args);
  90     va_end(args);
  91 }
  92
  93 void Buffer::vprintf(const char *format, va_list args)
  94 {
  95     unsigned int written = vsnprintf(mEnd, mTop - mEnd, format, args);
  96     if (written < available()) {
  97         // overflow on formatting. Reshuffle and try again
  98         shuffle();
  99         written = vsnprintf(mEnd, available(), format, args);
 100         assert(written < available());  //@@@ throw here?
 101     }
 102     mEnd += written;    // note: zero terminator discarded here
 103 }
 104
 105
 106 }       // end namespace Security