hphp/runtime/base/data-walker.cpp

   1 /*
   2    +----------------------------------------------------------------------+
   3    | HipHop for PHP                                                       |
   4    +----------------------------------------------------------------------+
   5    | Copyright (c) 2010-present Facebook, Inc. (http://www.facebook.com)  |
   6    +----------------------------------------------------------------------+
   7    | This source file is subject to version 3.01 of the PHP license,      |
   8    | that is bundled with this package in the file LICENSE, and is        |
   9    | available through the world-wide-web at the following url:           |
  10    | http://www.php.net/license/3_01.txt                                  |
  11    | If you did not receive a copy of the PHP license and are unable to   |
  12    | obtain it through the world-wide-web, please send a note to          |
  13    | license@php.net so we can mail you a copy immediately.               |
  14    +----------------------------------------------------------------------+
  15 */
  16 #include "hphp/runtime/base/data-walker.h"
  17
  18 #include "hphp/runtime/base/array-data.h"
  19 #include "hphp/runtime/base/object-data.h"
  20 #include "hphp/runtime/base/type-variant.h"
  21 #include "hphp/runtime/base/array-iterator.h"
  22 #include "hphp/runtime/base/collections.h"
  23
  24 namespace HPHP {
  25
  26 //////////////////////////////////////////////////////////////////////
  27
  28 void DataWalker::traverseData(ArrayData* data,
  29                               DataFeature& features,
  30                               PointerSet& visited) const {
  31   for (ArrayIter iter(data); iter; ++iter) {
  32     auto const rval = iter.secondRval();
  33
  34     if (rval.type() == KindOfRef &&
  35         rval.val().pref->isReferenced()) {
  36       if (markVisited(rval.val().pref->var(), features, visited)) {
  37         if (canStopWalk(features)) return;
  38         continue; // don't recurse forever; we already went down this path
  39       }
  40       // Right now consider it circular even if the referenced variant only
  41       // showed up in one spot.  This could be revisted later.
  42       features.isCircular = true;
  43       if (canStopWalk(features)) return;
  44     }
  45
  46     auto const inner = tvToCell(rval);
  47     // cheap enough, do it always
  48     features.hasRefCountReference = isRefcountedType(inner.type());
  49     if (inner.type() == KindOfObject) {
  50       features.hasObjectOrResource = true;
  51       traverseData(inner.val().pobj, features, visited);
  52     } else if (isArrayLikeType(inner.type())) {
  53       traverseData(inner.val().parr, features, visited);
  54     } else if (inner.type() == KindOfResource) {
  55       features.hasObjectOrResource = true;
  56     }
  57     if (canStopWalk(features)) return;
  58   }
  59 }
  60
  61 void DataWalker::traverseData(
  62     ObjectData* data,
  63     DataFeature& features,
  64     PointerSet& visited) const {
  65   objectFeature(data, features, visited);
  66   if (markVisited(data, features, visited)) {
  67     return; // avoid infinite recursion
  68   }
  69   if (!canStopWalk(features)) {
  70     traverseData(data->toArray().get(), features, visited);
  71   }
  72 }
  73
  74 inline bool DataWalker::markVisited(
  75     void* pvar,
  76     DataFeature& features,
  77     PointerSet& visited) const {
  78   if (!visited.insert(pvar).second) {
  79     features.isCircular = true;
  80     return true;
  81   }
  82   return false;
  83 }
  84
  85 inline void DataWalker::objectFeature(ObjectData* pobj, DataFeature& features,
  86                                       PointerSet& /*visited*/) const {
  87   if (pobj->isCollection()) return;
  88   if ((m_features & LookupFeature::DetectSerializable) &&
  89        pobj->instanceof(SystemLib::s_SerializableClass)) {
  90     features.hasSerializable = true;
  91   }
  92 }
  93
  94 inline bool DataWalker::canStopWalk(DataFeature& features) const {
  95   auto refCountCheck =
  96     features.hasRefCountReference ||
  97     !(m_features & LookupFeature::RefCountedReference);
  98   auto objectCheck =
  99     features.hasObjectOrResource ||
 100     !(m_features & LookupFeature::HasObjectOrResource);
 101   auto defaultChecks = features.isCircular || features.hasSerializable;
 102   return refCountCheck && objectCheck && defaultChecks;
 103 }
 104
 105 //////////////////////////////////////////////////////////////////////
 106
 107 }