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Issue 1427643010: win: Explain the CreateFile() client-side pipe-opening loop (Closed) Base URL: https://chromium.googlesource.com/crashpad/crashpad@master
Patch Set: Fix TransactNamedPipe() logging Created 5 years, 1 month ago
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1 // Copyright 2015 The Crashpad Authors. All rights reserved. 1 // Copyright 2015 The Crashpad Authors. All rights reserved.
2 // 2 //
3 // Licensed under the Apache License, Version 2.0 (the "License"); 3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License. 4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at 5 // You may obtain a copy of the License at
6 // 6 //
7 // http://www.apache.org/licenses/LICENSE-2.0 7 // http://www.apache.org/licenses/LICENSE-2.0
8 // 8 //
9 // Unless required by applicable law or agreed to in writing, software 9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS, 10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and 12 // See the License for the specific language governing permissions and
13 // limitations under the License. 13 // limitations under the License.
14 14
15 #include "util/win/registration_protocol_win.h" 15 #include "util/win/registration_protocol_win.h"
16 16
17 #include <windows.h> 17 #include <windows.h>
18 18
19 #include "base/logging.h" 19 #include "base/logging.h"
20 #include "util/win/scoped_handle.h" 20 #include "util/win/scoped_handle.h"
21 21
22 namespace crashpad { 22 namespace crashpad {
23 23
24 bool SendToCrashHandlerServer(const base::string16& pipe_name, 24 bool SendToCrashHandlerServer(const base::string16& pipe_name,
25 const crashpad::ClientToServerMessage& message, 25 const crashpad::ClientToServerMessage& message,
26 crashpad::ServerToClientMessage* response) { 26 crashpad::ServerToClientMessage* response) {
27 int tries = 0; 27 // Retry CreateFile() in a loop. If the handler isn’t actively waiting in
28 for (;;) { 28 // ConnectNamedPipe() on a pipe instance because it’s busy doing something
29 // else, CreateFile() will fail with ERROR_PIPE_BUSY. WaitNamedPipe() waits
30 // until a pipe instance is ready, but there’s no way to wait for this
31 // condition and atomically open the client side of the pipe in a single
32 // operation. CallNamedPipe() implements similar retry logic to this, also in
33 // user-mode code.
scottmg 2015/11/10 20:02:20 You could maybe also note that this means we don't
Mark Mentovai 2015/11/10 20:12:19 scottmg wrote:
34 for (int tries = 0;;) {
29 ScopedFileHANDLE pipe( 35 ScopedFileHANDLE pipe(
30 CreateFile(pipe_name.c_str(), 36 CreateFile(pipe_name.c_str(),
31 GENERIC_READ | GENERIC_WRITE, 37 GENERIC_READ | GENERIC_WRITE,
32 0, 38 0,
33 nullptr, 39 nullptr,
34 OPEN_EXISTING, 40 OPEN_EXISTING,
35 SECURITY_SQOS_PRESENT | SECURITY_IDENTIFICATION, 41 SECURITY_SQOS_PRESENT | SECURITY_IDENTIFICATION,
36 nullptr)); 42 nullptr));
37 if (!pipe.is_valid()) { 43 if (!pipe.is_valid()) {
38 if (++tries == 5 || GetLastError() != ERROR_PIPE_BUSY) { 44 if (++tries == 5 || GetLastError() != ERROR_PIPE_BUSY) {
(...skipping 19 matching lines...) Expand all
58 BOOL result = TransactNamedPipe( 64 BOOL result = TransactNamedPipe(
59 pipe.get(), 65 pipe.get(),
60 // This is [in], but is incorrectly declared non-const. 66 // This is [in], but is incorrectly declared non-const.
61 const_cast<crashpad::ClientToServerMessage*>(&message), 67 const_cast<crashpad::ClientToServerMessage*>(&message),
62 sizeof(message), 68 sizeof(message),
63 response, 69 response,
64 sizeof(*response), 70 sizeof(*response),
65 &bytes_read, 71 &bytes_read,
66 nullptr); 72 nullptr);
67 if (!result) { 73 if (!result) {
74 PLOG(ERROR) << "TransactNamedPipe";
75 return false;
76 }
77 if (bytes_read != sizeof(*response)) {
68 LOG(ERROR) << "TransactNamedPipe: expected " << sizeof(*response) 78 LOG(ERROR) << "TransactNamedPipe: expected " << sizeof(*response)
scottmg 2015/11/10 20:02:19 Duh, oops.
69 << ", observed " << bytes_read; 79 << ", observed " << bytes_read;
70 return false; 80 return false;
71 } 81 }
72 if (bytes_read != sizeof(*response)) {
73 LOG(ERROR) << "TransactNamedPipe read incorrect number of bytes";
74 return false;
75 }
76 return true; 82 return true;
77 } 83 }
78 } 84 }
79 85
80 } // namespace crashpad 86 } // namespace crashpad
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