OSX/libsecurity_utilities/lib/selector.cpp

   1 /*
   2  * Copyright (c) 2000-2001,2003-2004,2011,2014 Apple Inc. All Rights Reserved.
   3  *
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   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,
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  18  * Please see the License for the specific language governing rights and
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  23
  24
  25 //
  26 // selector - I/O stream multiplexing
  27 //
  28 #include "selector.h"
  29 #include <security_utilities/errors.h>
  30 #include <security_utilities/debugging.h>
  31 #include <algorithm>    // min/max
  32
  33
  34 namespace Security {
  35 namespace UnixPlusPlus {
  36
  37
  38 //
  39 // construct a Selector object.
  40 //
  41 Selector::Selector() : fdMin(INT_MAX), fdMax(-1)
  42 {
  43     // initially allocate room for FD_SETSIZE file descriptors (usually good enough)
  44     fdSetSize = FD_SETSIZE / NFDBITS;
  45     inSet.grow(0, fdSetSize);
  46     outSet.grow(0, fdSetSize);
  47     errSet.grow(0, fdSetSize);
  48 }
  49
  50 Selector::~Selector()
  51 { }
  52
  53
  54 //
  55 // Add a Client to a Selector
  56 //
  57 void Selector::add(int fd, Client &client, Type type)
  58 {
  59     // plausibility checks
  60     assert(!client.isActive());         // one Selector per client, and no re-adding
  61     assert(fd >= 0);
  62
  63     secdebug("selector", "add client %p fd %d type=%d", &client, fd, type);
  64
  65     // grow FDSets if needed
  66     unsigned int pos = fd / NFDBITS;
  67     if (pos >= fdSetSize) {
  68         int newSize = (fd - 1) / NFDBITS + 2;   // as much as needed + 1 spare word
  69         inSet.grow(fdSetSize, newSize);
  70         outSet.grow(fdSetSize, newSize);
  71         errSet.grow(fdSetSize, newSize);
  72     }
  73
  74     // adjust boundaries
  75     if (fd < fdMin)
  76         fdMin = fd;
  77     if (fd > fdMax)
  78         fdMax = fd;
  79
  80     // add client
  81     Client * &slot = clientMap[fd];
  82     assert(!slot);
  83     slot = &client;
  84     client.mFd = fd;
  85     client.mSelector = this;
  86     client.mEvents = type;
  87     set(fd, type);
  88 }
  89
  90
  91 //
  92 // Remove a Client from a Selector
  93 //
  94 void Selector::remove(int fd)
  95 {
  96     // sanity checks
  97     assert(fd >= 0);
  98     ClientMap::iterator it = clientMap.find(fd);
  99     assert(it != clientMap.end());
 100     assert(it->second->mSelector == this);
 101
 102     secdebug("selector", "remove client %p fd %d", it->second, fd);
 103
 104     // remove from FDSets
 105     set(fd, none);
 106
 107     // remove client
 108     it->second->mSelector = NULL;
 109     clientMap.erase(it);
 110
 111     // recompute fdMin/fdMax if needed
 112     if (isEmpty()) {
 113         fdMin = INT_MAX;
 114         fdMax = -1;
 115     } else if (fd == fdMin) {
 116         fdMin = clientMap.begin()->first;
 117     } else if (fd == fdMax) {
 118         fdMax = clientMap.rbegin()->first;
 119     }
 120 }
 121
 122
 123 //
 124 // Adjust the FDSets for a single given Client according to a new event Type mask.
 125 //
 126 void Selector::set(int fd, Type type)
 127 {
 128     assert(fd >= 0);
 129     inSet.set(fd, type & input);
 130     outSet.set(fd, type & output);
 131     errSet.set(fd, type & critical);
 132     secdebug("selector", "fd %d notifications 0x%x", fd, type);
 133 }
 134
 135
 136 void Selector::operator () ()
 137 {
 138     if (!clientMap.empty())
 139         singleStep(0);
 140 }
 141
 142
 143 void Selector::operator () (Time::Absolute stopTime)
 144 {
 145     if (!clientMap.empty())
 146         singleStep(stopTime - Time::now());
 147 }
 148
 149
 150 //
 151 // Perform a single pass through the Selector and notify all clients
 152 // that have selected I/O pending at this time.
 153 // There is not time limit on how long this may take; if the clients
 154 // are well written, it won't be too long.
 155 //
 156 void Selector::singleStep(Time::Interval maxWait)
 157 {
 158     assert(!clientMap.empty());
 159     secdebug("selector", "select(%d) [%d-%d] for %ld clients",
 160         fdMax + 1, fdMin, fdMax, clientMap.size());
 161     for (;;) {  // pseudo-loop - only retries
 162         struct timeval duration = maxWait.timevalInterval();
 163 #if defined(__APPLE__)
 164         // ad-hoc fix: MacOS X's BSD rejects times of more than 100E6 seconds
 165         if (duration.tv_sec > 100000000)
 166             duration.tv_sec = 100000000;
 167 #endif
 168         const int size = FDSet::words(fdMax);           // number of active words in sets
 169         switch (int hits = ::select(fdMax + 1,
 170                 inSet.make(size), outSet.make(size), errSet.make(size),
 171                 &duration)) {
 172         case -1:                // error
 173             if (errno == EINTR)
 174                 continue;
 175             secdebug("selector", "select failed: errno=%d", errno);
 176             UnixError::throwMe();
 177         case 0:                 // no events
 178             secdebug("selector", "select returned nothing");
 179             return;
 180         default:                // some events
 181             secdebug("selector", "%d pending descriptors", hits);
 182             //@@@ This could be optimized as a word-merge scan.
 183             //@@@ The typical case doesn't benefit from this though, though browsers might
 184             //@@@ and integrated servers definitely would.
 185             for (int fd = fdMin; fd <= fdMax && hits > 0; fd++) {
 186                 int types = 0;
 187                 if (inSet[fd])  types |= input;
 188                 if (outSet[fd]) types |= output;
 189                 if (errSet[fd]) types |= critical;
 190                 if (types) {
 191                     secdebug("selector", "notify fd %d client %p type %d",
 192                         fd, clientMap[fd], types);
 193                     clientMap[fd]->notify(fd, types);
 194                     hits--;
 195                 }
 196             }
 197             return;
 198         }
 199     }
 200 }
 201
 202
 203 }       // end namespace IPPlusPlus
 204 }       // end namespace Security