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| 1 // Copyright 2014 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #include "mojo/system/handle_table.h" |
| 6 |
| 7 #include "base/basictypes.h" |
| 8 #include "base/logging.h" |
| 9 #include "mojo/system/constants.h" |
| 10 #include "mojo/system/dispatcher.h" |
| 11 |
| 12 namespace mojo { |
| 13 namespace system { |
| 14 |
| 15 HandleTable::Entry::Entry() |
| 16 : busy(false) { |
| 17 } |
| 18 |
| 19 HandleTable::Entry::Entry(const scoped_refptr<Dispatcher>& dispatcher) |
| 20 : dispatcher(dispatcher), |
| 21 busy(false) { |
| 22 } |
| 23 |
| 24 HandleTable::Entry::~Entry() { |
| 25 DCHECK(!busy); |
| 26 } |
| 27 |
| 28 HandleTable::HandleTable() |
| 29 : next_handle_(MOJO_HANDLE_INVALID + 1) { |
| 30 } |
| 31 |
| 32 HandleTable::~HandleTable() { |
| 33 // This should usually not be reached (the only instance should be owned by |
| 34 // the singleton |CoreImpl|, which lives forever), except in tests. |
| 35 } |
| 36 |
| 37 Dispatcher* HandleTable::GetDispatcher(MojoHandle handle) { |
| 38 DCHECK_NE(handle, MOJO_HANDLE_INVALID); |
| 39 |
| 40 HandleToEntryMap::iterator it = handle_to_entry_map_.find(handle); |
| 41 if (it == handle_to_entry_map_.end()) |
| 42 return NULL; |
| 43 return it->second.dispatcher; |
| 44 } |
| 45 |
| 46 MojoResult HandleTable::GetAndRemoveDispatcher( |
| 47 MojoHandle handle, |
| 48 scoped_refptr<Dispatcher>* dispatcher) { |
| 49 DCHECK_NE(handle, MOJO_HANDLE_INVALID); |
| 50 DCHECK(dispatcher); |
| 51 |
| 52 HandleToEntryMap::iterator it = handle_to_entry_map_.find(handle); |
| 53 if (it == handle_to_entry_map_.end()) |
| 54 return MOJO_RESULT_INVALID_ARGUMENT; |
| 55 if (it->second.busy) |
| 56 return MOJO_RESULT_BUSY; |
| 57 *dispatcher = it->second.dispatcher; |
| 58 handle_to_entry_map_.erase(it); |
| 59 |
| 60 return MOJO_RESULT_OK; |
| 61 } |
| 62 |
| 63 MojoHandle HandleTable::AddDispatcher( |
| 64 const scoped_refptr<Dispatcher>& dispatcher) { |
| 65 if (handle_to_entry_map_.size() >= kMaxHandleTableSize) |
| 66 return MOJO_HANDLE_INVALID; |
| 67 return AddDispatcherNoSizeCheck(dispatcher); |
| 68 } |
| 69 |
| 70 std::pair<MojoHandle, MojoHandle> HandleTable::AddDispatcherPair( |
| 71 const scoped_refptr<Dispatcher>& dispatcher0, |
| 72 const scoped_refptr<Dispatcher>& dispatcher1) { |
| 73 if (handle_to_entry_map_.size() + 1 >= kMaxHandleTableSize) |
| 74 return std::make_pair(MOJO_HANDLE_INVALID, MOJO_HANDLE_INVALID); |
| 75 return std::make_pair(AddDispatcherNoSizeCheck(dispatcher0), |
| 76 AddDispatcherNoSizeCheck(dispatcher1)); |
| 77 } |
| 78 |
| 79 bool HandleTable::AddDispatcherVector( |
| 80 const std::vector<scoped_refptr<Dispatcher> >& dispatchers, |
| 81 MojoHandle* handles) { |
| 82 DCHECK_LE(dispatchers.size(), kMaxMessageNumHandles); |
| 83 DCHECK(handles); |
| 84 // TODO(vtl): |std::numeric_limits<size_t>::max()| isn't a compile-time |
| 85 // expression in C++03. |
| 86 COMPILE_ASSERT( |
| 87 static_cast<uint64_t>(kMaxHandleTableSize) + kMaxMessageNumHandles < |
| 88 (sizeof(size_t) == 8 ? kuint64max : |
| 89 static_cast<uint64_t>(kuint32max)), |
| 90 addition_may_overflow); |
| 91 |
| 92 if (handle_to_entry_map_.size() + dispatchers.size() > kMaxHandleTableSize) |
| 93 return false; |
| 94 |
| 95 for (size_t i = 0; i < dispatchers.size(); i++) { |
| 96 if (dispatchers[i]) { |
| 97 handles[i] = AddDispatcherNoSizeCheck(dispatchers[i]); |
| 98 } else { |
| 99 LOG(WARNING) << "Invalid dispatcher at index " << i; |
| 100 handles[i] = MOJO_HANDLE_INVALID; |
| 101 } |
| 102 } |
| 103 return true; |
| 104 } |
| 105 |
| 106 MojoResult HandleTable::MarkBusyAndStartTransport( |
| 107 MojoHandle disallowed_handle, |
| 108 const MojoHandle* handles, |
| 109 uint32_t num_handles, |
| 110 std::vector<DispatcherTransport>* transports) { |
| 111 DCHECK_NE(disallowed_handle, MOJO_HANDLE_INVALID); |
| 112 DCHECK(handles); |
| 113 DCHECK_LE(num_handles, kMaxMessageNumHandles); |
| 114 DCHECK(transports); |
| 115 |
| 116 std::vector<Entry*> entries(num_handles); |
| 117 |
| 118 // First verify all the handles and get their dispatchers. |
| 119 uint32_t i; |
| 120 MojoResult error_result = MOJO_RESULT_INTERNAL; |
| 121 for (i = 0; i < num_handles; i++) { |
| 122 // Sending your own handle is not allowed (and, for consistency, returns |
| 123 // "busy"). |
| 124 if (handles[i] == disallowed_handle) { |
| 125 error_result = MOJO_RESULT_BUSY; |
| 126 break; |
| 127 } |
| 128 |
| 129 HandleToEntryMap::iterator it = handle_to_entry_map_.find(handles[i]); |
| 130 if (it == handle_to_entry_map_.end()) { |
| 131 error_result = MOJO_RESULT_INVALID_ARGUMENT; |
| 132 break; |
| 133 } |
| 134 |
| 135 entries[i] = &it->second; |
| 136 if (entries[i]->busy) { |
| 137 error_result = MOJO_RESULT_BUSY; |
| 138 break; |
| 139 } |
| 140 // Note: By marking the handle as busy here, we're also preventing the |
| 141 // same handle from being sent multiple times in the same message. |
| 142 entries[i]->busy = true; |
| 143 |
| 144 // Try to start the transport. |
| 145 DispatcherTransport transport = |
| 146 Dispatcher::HandleTableAccess::TryStartTransport( |
| 147 entries[i]->dispatcher.get()); |
| 148 if (!transport.is_valid()) { |
| 149 // Unset the busy flag (since it won't be unset below). |
| 150 entries[i]->busy = false; |
| 151 error_result = MOJO_RESULT_BUSY; |
| 152 break; |
| 153 } |
| 154 |
| 155 // Check if the dispatcher is busy (e.g., in a two-phase read/write). |
| 156 // (Note that this must be done after the dispatcher's lock is acquired.) |
| 157 if (transport.IsBusy()) { |
| 158 // Unset the busy flag and end the transport (since it won't be done |
| 159 // below). |
| 160 entries[i]->busy = false; |
| 161 transport.End(); |
| 162 error_result = MOJO_RESULT_BUSY; |
| 163 break; |
| 164 } |
| 165 |
| 166 // Hang on to the transport (which we'll need to end the transport). |
| 167 (*transports)[i] = transport; |
| 168 } |
| 169 if (i < num_handles) { |
| 170 DCHECK_NE(error_result, MOJO_RESULT_INTERNAL); |
| 171 |
| 172 // Unset the busy flags and release the locks. |
| 173 for (uint32_t j = 0; j < i; j++) { |
| 174 DCHECK(entries[j]->busy); |
| 175 entries[j]->busy = false; |
| 176 (*transports)[j].End(); |
| 177 } |
| 178 return error_result; |
| 179 } |
| 180 |
| 181 return MOJO_RESULT_OK; |
| 182 } |
| 183 |
| 184 |
| 185 ////////////// |
| 186 |
| 187 MojoHandle HandleTable::AddDispatcherNoSizeCheck( |
| 188 const scoped_refptr<Dispatcher>& dispatcher) { |
| 189 DCHECK(dispatcher); |
| 190 DCHECK_LT(handle_to_entry_map_.size(), kMaxHandleTableSize); |
| 191 DCHECK_NE(next_handle_, MOJO_HANDLE_INVALID); |
| 192 |
| 193 // TODO(vtl): Maybe we want to do something different/smarter. (Or maybe try |
| 194 // assigning randomly?) |
| 195 while (handle_to_entry_map_.find(next_handle_) != |
| 196 handle_to_entry_map_.end()) { |
| 197 next_handle_++; |
| 198 if (next_handle_ == MOJO_HANDLE_INVALID) |
| 199 next_handle_++; |
| 200 } |
| 201 |
| 202 MojoHandle new_handle = next_handle_; |
| 203 handle_to_entry_map_[new_handle] = Entry(dispatcher); |
| 204 |
| 205 next_handle_++; |
| 206 if (next_handle_ == MOJO_HANDLE_INVALID) |
| 207 next_handle_++; |
| 208 |
| 209 return new_handle; |
| 210 } |
| 211 |
| 212 void HandleTable::RemoveBusyHandles(const MojoHandle* handles, |
| 213 uint32_t num_handles) { |
| 214 DCHECK(handles); |
| 215 DCHECK_LE(num_handles, kMaxMessageNumHandles); |
| 216 |
| 217 for (uint32_t i = 0; i < num_handles; i++) { |
| 218 HandleToEntryMap::iterator it = handle_to_entry_map_.find(handles[i]); |
| 219 DCHECK(it != handle_to_entry_map_.end()); |
| 220 DCHECK(it->second.busy); |
| 221 it->second.busy = false; // For the sake of a |DCHECK()|. |
| 222 handle_to_entry_map_.erase(it); |
| 223 } |
| 224 } |
| 225 |
| 226 void HandleTable::RestoreBusyHandles(const MojoHandle* handles, |
| 227 uint32_t num_handles) { |
| 228 DCHECK(handles); |
| 229 DCHECK_LE(num_handles, kMaxMessageNumHandles); |
| 230 |
| 231 for (uint32_t i = 0; i < num_handles; i++) { |
| 232 HandleToEntryMap::iterator it = handle_to_entry_map_.find(handles[i]); |
| 233 DCHECK(it != handle_to_entry_map_.end()); |
| 234 DCHECK(it->second.busy); |
| 235 it->second.busy = false; |
| 236 } |
| 237 } |
| 238 |
| 239 } // namespace system |
| 240 } // namespace mojo |
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