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1 // Copyright 2015 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 <stdint.h>
6 
7 #include "base/logging.h"
8 #include "base/process/process_handle.h"
9 #include "build/build_config.h"
10 
11 namespace base {
12 
13 namespace {
14 bool g_have_unique_id = false;
15 uint32_t g_unique_id;
16 
17 // The process which set |g_unique_id|.
18 ProcessId g_procid;
19 
20 // Mangle IDs so that they are not accidentally used as PIDs, e.g. as an
21 // argument to kill or waitpid.
MangleProcessId(ProcessId process_id)22 uint32_t MangleProcessId(ProcessId process_id) {
23   // Add a large power of 10 so that the pid is still the pid is still readable
24   // inside the mangled id.
25   return static_cast<uint32_t>(process_id) + 1000000000U;
26 }
27 
28 }  // namespace
29 
GetUniqueIdForProcess()30 uint32_t GetUniqueIdForProcess() {
31   if (!g_have_unique_id) {
32     return MangleProcessId(GetCurrentProcId());
33   }
34 
35   // Make sure we are the same process that set |g_procid|. This check may have
36   // false negatives (if a process ID was reused) but should have no false
37   // positives.
38   DCHECK_EQ(GetCurrentProcId(), g_procid);
39   return g_unique_id;
40 }
41 
42 #if defined(OS_LINUX)
43 
InitUniqueIdForProcessInPidNamespace(ProcessId pid_outside_of_namespace)44 void InitUniqueIdForProcessInPidNamespace(ProcessId pid_outside_of_namespace) {
45   g_unique_id = MangleProcessId(pid_outside_of_namespace);
46   g_procid = GetCurrentProcId();
47   g_have_unique_id = true;
48 }
49 
50 #endif
51 
52 }  // namespace base
53