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Side by Side Diff: mojo/edk/system/handle_table.cc

Issue 623883002: Revert "Move mojo edk into mojo/edk" (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Created 6 years, 2 months ago
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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/edk/system/handle_table.h"
6
7 #include "base/logging.h"
8 #include "base/macros.h"
9 #include "mojo/edk/system/constants.h"
10 #include "mojo/edk/system/dispatcher.h"
11
12 namespace mojo {
13 namespace system {
14
15 HandleTable::Entry::Entry() : busy(false) {
16 }
17
18 HandleTable::Entry::Entry(const scoped_refptr<Dispatcher>& dispatcher)
19 : dispatcher(dispatcher), busy(false) {
20 }
21
22 HandleTable::Entry::~Entry() {
23 DCHECK(!busy);
24 }
25
26 HandleTable::HandleTable() : next_handle_(MOJO_HANDLE_INVALID + 1) {
27 }
28
29 HandleTable::~HandleTable() {
30 // This should usually not be reached (the only instance should be owned by
31 // the singleton |Core|, which lives forever), except in tests.
32 }
33
34 Dispatcher* HandleTable::GetDispatcher(MojoHandle handle) {
35 DCHECK_NE(handle, MOJO_HANDLE_INVALID);
36
37 HandleToEntryMap::iterator it = handle_to_entry_map_.find(handle);
38 if (it == handle_to_entry_map_.end())
39 return nullptr;
40 return it->second.dispatcher.get();
41 }
42
43 MojoResult HandleTable::GetAndRemoveDispatcher(
44 MojoHandle handle,
45 scoped_refptr<Dispatcher>* dispatcher) {
46 DCHECK_NE(handle, MOJO_HANDLE_INVALID);
47 DCHECK(dispatcher);
48
49 HandleToEntryMap::iterator it = handle_to_entry_map_.find(handle);
50 if (it == handle_to_entry_map_.end())
51 return MOJO_RESULT_INVALID_ARGUMENT;
52 if (it->second.busy)
53 return MOJO_RESULT_BUSY;
54 *dispatcher = it->second.dispatcher;
55 handle_to_entry_map_.erase(it);
56
57 return MOJO_RESULT_OK;
58 }
59
60 MojoHandle HandleTable::AddDispatcher(
61 const scoped_refptr<Dispatcher>& dispatcher) {
62 if (handle_to_entry_map_.size() >= kMaxHandleTableSize)
63 return MOJO_HANDLE_INVALID;
64 return AddDispatcherNoSizeCheck(dispatcher);
65 }
66
67 std::pair<MojoHandle, MojoHandle> HandleTable::AddDispatcherPair(
68 const scoped_refptr<Dispatcher>& dispatcher0,
69 const scoped_refptr<Dispatcher>& dispatcher1) {
70 if (handle_to_entry_map_.size() + 1 >= kMaxHandleTableSize)
71 return std::make_pair(MOJO_HANDLE_INVALID, MOJO_HANDLE_INVALID);
72 return std::make_pair(AddDispatcherNoSizeCheck(dispatcher0),
73 AddDispatcherNoSizeCheck(dispatcher1));
74 }
75
76 bool HandleTable::AddDispatcherVector(const DispatcherVector& dispatchers,
77 MojoHandle* handles) {
78 DCHECK_LE(dispatchers.size(), kMaxMessageNumHandles);
79 DCHECK(handles);
80 // TODO(vtl): |std::numeric_limits<size_t>::max()| isn't a compile-time
81 // expression in C++03.
82 static_assert(
83 static_cast<uint64_t>(kMaxHandleTableSize) + kMaxMessageNumHandles <
84 (sizeof(size_t) == 8 ? kuint64max
85 : static_cast<uint64_t>(kuint32max)),
86 "Addition may overflow");
87
88 if (handle_to_entry_map_.size() + dispatchers.size() > kMaxHandleTableSize)
89 return false;
90
91 for (size_t i = 0; i < dispatchers.size(); i++) {
92 if (dispatchers[i].get()) {
93 handles[i] = AddDispatcherNoSizeCheck(dispatchers[i]);
94 } else {
95 LOG(WARNING) << "Invalid dispatcher at index " << i;
96 handles[i] = MOJO_HANDLE_INVALID;
97 }
98 }
99 return true;
100 }
101
102 MojoResult HandleTable::MarkBusyAndStartTransport(
103 MojoHandle disallowed_handle,
104 const MojoHandle* handles,
105 uint32_t num_handles,
106 std::vector<DispatcherTransport>* transports) {
107 DCHECK_NE(disallowed_handle, MOJO_HANDLE_INVALID);
108 DCHECK(handles);
109 DCHECK_LE(num_handles, kMaxMessageNumHandles);
110 DCHECK(transports);
111 DCHECK_EQ(transports->size(), num_handles);
112
113 std::vector<Entry*> entries(num_handles);
114
115 // First verify all the handles and get their dispatchers.
116 uint32_t i;
117 MojoResult error_result = MOJO_RESULT_INTERNAL;
118 for (i = 0; i < num_handles; i++) {
119 // Sending your own handle is not allowed (and, for consistency, returns
120 // "busy").
121 if (handles[i] == disallowed_handle) {
122 error_result = MOJO_RESULT_BUSY;
123 break;
124 }
125
126 HandleToEntryMap::iterator it = handle_to_entry_map_.find(handles[i]);
127 if (it == handle_to_entry_map_.end()) {
128 error_result = MOJO_RESULT_INVALID_ARGUMENT;
129 break;
130 }
131
132 entries[i] = &it->second;
133 if (entries[i]->busy) {
134 error_result = MOJO_RESULT_BUSY;
135 break;
136 }
137 // Note: By marking the handle as busy here, we're also preventing the
138 // same handle from being sent multiple times in the same message.
139 entries[i]->busy = true;
140
141 // Try to start the transport.
142 DispatcherTransport transport =
143 Dispatcher::HandleTableAccess::TryStartTransport(
144 entries[i]->dispatcher.get());
145 if (!transport.is_valid()) {
146 // Only log for Debug builds, since this is not a problem with the system
147 // code, but with user code.
148 DLOG(WARNING) << "Likely race condition in user code detected: attempt "
149 "to transfer handle " << handles[i]
150 << " while it is in use on a different thread";
151
152 // Unset the busy flag (since it won't be unset below).
153 entries[i]->busy = false;
154 error_result = MOJO_RESULT_BUSY;
155 break;
156 }
157
158 // Check if the dispatcher is busy (e.g., in a two-phase read/write).
159 // (Note that this must be done after the dispatcher's lock is acquired.)
160 if (transport.IsBusy()) {
161 // Unset the busy flag and end the transport (since it won't be done
162 // below).
163 entries[i]->busy = false;
164 transport.End();
165 error_result = MOJO_RESULT_BUSY;
166 break;
167 }
168
169 // Hang on to the transport (which we'll need to end the transport).
170 (*transports)[i] = transport;
171 }
172 if (i < num_handles) {
173 DCHECK_NE(error_result, MOJO_RESULT_INTERNAL);
174
175 // Unset the busy flags and release the locks.
176 for (uint32_t j = 0; j < i; j++) {
177 DCHECK(entries[j]->busy);
178 entries[j]->busy = false;
179 (*transports)[j].End();
180 }
181 return error_result;
182 }
183
184 return MOJO_RESULT_OK;
185 }
186
187 MojoHandle HandleTable::AddDispatcherNoSizeCheck(
188 const scoped_refptr<Dispatcher>& dispatcher) {
189 DCHECK(dispatcher.get());
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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