cdsa/cdsa_utilities/fdsel.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 // fdsel - select-style file descriptor set management
  21 //
  22 #include "fdsel.h"
  23
  24
  25 namespace Security {
  26 namespace UnixPlusPlus {
  27
  28
  29 //
  30 // Throw the bitvectors away on destruction
  31 //
  32 FDSet::~FDSet()
  33 {
  34     delete mBits;
  35     delete mUseBits;
  36 }
  37
  38
  39 //
  40 // Given the old and desired new sizes (in fd_mask words), grow
  41 // the bitvectors. New storage is zero filled. Note that we preserve
  42 // the mUseBits vector, so this is safe to do during a post-select scan.
  43 // This function cannot shrink the bitmaps.
  44 //
  45 void FDSet::grow(int oldWords, int newWords)
  46 {
  47     assert(oldWords < newWords);
  48     grow(mBits, oldWords, newWords);
  49     grow(mUseBits, oldWords, newWords);
  50 }
  51
  52 void FDSet::grow(fd_mask * &bits, int oldWords, int newWords)
  53 {
  54     fd_mask *newBits = new fd_mask[newWords];
  55     memcpy(newBits, bits, oldWords * sizeof(fd_mask));
  56     memset(newBits + oldWords, 0, (newWords - oldWords) * sizeof(fd_mask));
  57     delete [] bits;
  58     bits = newBits;
  59 }
  60
  61
  62 //
  63 // Set or clear a single bit in the map.
  64 // No check for overflow is perfomed.
  65 //
  66 void FDSet::set(int fd, bool on)
  67 {
  68     if (on) {
  69         FD_SET(fd, (fd_set *)mBits);
  70     } else {
  71         FD_CLR(fd, (fd_set *)mBits);
  72         FD_CLR(fd, (fd_set *)mUseBits);
  73     }
  74 }
  75
  76
  77 //
  78 // Copy only the first words fd_mask words from mBits to mUseBits
  79 // and return that for select(2) use.
  80 //
  81 fd_set *FDSet::make(int words)
  82 {
  83     //@@@ if empty -> return NULL (but check caller for [] use)
  84     memcpy(mUseBits, mBits, words * sizeof(fd_mask));
  85     return (fd_set *)mUseBits;
  86 }
  87
  88
  89 }       // end namespace IPPlusPlus
  90 }       // end namespace Security