OSX/libsecurity_utilities/lib/fdsel.cpp

   1 /*
   2  * Copyright (c) 2000-2001,2004,2011,2014 Apple Inc. All Rights Reserved.
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   6  * This file contains Original Code and/or Modifications of Original Code
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   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
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  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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  23
  24
  25 //
  26 // fdsel - select-style file descriptor set management
  27 //
  28 #include "fdsel.h"
  29
  30
  31 namespace Security {
  32 namespace UnixPlusPlus {
  33
  34
  35 //
  36 // Throw the bitvectors away on destruction
  37 //
  38 FDSet::~FDSet()
  39 {
  40     delete mBits;
  41     delete mUseBits;
  42 }
  43
  44
  45 //
  46 // Given the old and desired new sizes (in fd_mask words), grow
  47 // the bitvectors. New storage is zero filled. Note that we preserve
  48 // the mUseBits vector, so this is safe to do during a post-select scan.
  49 // This function cannot shrink the bitmaps.
  50 //
  51 void FDSet::grow(int oldWords, int newWords)
  52 {
  53     assert(oldWords < newWords);
  54     grow(mBits, oldWords, newWords);
  55     grow(mUseBits, oldWords, newWords);
  56 }
  57
  58 void FDSet::grow(fd_mask * &bits, int oldWords, int newWords)
  59 {
  60     fd_mask *newBits = new fd_mask[newWords];
  61     memcpy(newBits, bits, oldWords * sizeof(fd_mask));
  62     memset(newBits + oldWords, 0, (newWords - oldWords) * sizeof(fd_mask));
  63     delete [] bits;
  64     bits = newBits;
  65 }
  66
  67
  68 //
  69 // Set or clear a single bit in the map.
  70 // No check for overflow is perfomed.
  71 //
  72 void FDSet::set(int fd, bool on)
  73 {
  74     if (on) {
  75         FD_SET(fd, (fd_set *)mBits);
  76     } else {
  77         FD_CLR(fd, (fd_set *)mBits);
  78         FD_CLR(fd, (fd_set *)mUseBits);
  79     }
  80 }
  81
  82
  83 //
  84 // Copy only the first words fd_mask words from mBits to mUseBits
  85 // and return that for select(2) use.
  86 //
  87 fd_set *FDSet::make(int words)
  88 {
  89     //@@@ if empty -> return NULL (but check caller for [] use)
  90     memcpy(mUseBits, mBits, words * sizeof(fd_mask));
  91     return (fd_set *)mUseBits;
  92 }
  93
  94
  95 }       // end namespace IPPlusPlus
  96 }       // end namespace Security