1 // Copyright 2015 The Chromium OS 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 "brillo/process_reaper.h"
6
7 #include <sys/signalfd.h>
8 #include <sys/types.h>
9 #include <sys/wait.h>
10
11 #include <utility>
12
13 #include <base/bind.h>
14 #include <base/posix/eintr_wrapper.h>
15 #include <brillo/asynchronous_signal_handler.h>
16 #include <brillo/location_logging.h>
17
18 namespace brillo {
19
~ProcessReaper()20 ProcessReaper::~ProcessReaper() {
21 Unregister();
22 }
23
Register(AsynchronousSignalHandlerInterface * async_signal_handler)24 void ProcessReaper::Register(
25 AsynchronousSignalHandlerInterface* async_signal_handler) {
26 CHECK(!async_signal_handler_);
27 async_signal_handler_ = async_signal_handler;
28 async_signal_handler->RegisterHandler(
29 SIGCHLD,
30 base::Bind(&ProcessReaper::HandleSIGCHLD, base::Unretained(this)));
31 }
32
Unregister()33 void ProcessReaper::Unregister() {
34 if (!async_signal_handler_)
35 return;
36 async_signal_handler_->UnregisterHandler(SIGCHLD);
37 async_signal_handler_ = nullptr;
38 }
39
WatchForChild(const base::Location & from_here,pid_t pid,ChildCallback callback)40 bool ProcessReaper::WatchForChild(const base::Location& from_here,
41 pid_t pid,
42 ChildCallback callback) {
43 if (watched_processes_.find(pid) != watched_processes_.end())
44 return false;
45 watched_processes_.emplace(
46 pid, WatchedProcess{from_here, std::move(callback)});
47 return true;
48 }
49
ForgetChild(pid_t pid)50 bool ProcessReaper::ForgetChild(pid_t pid) {
51 return watched_processes_.erase(pid) != 0;
52 }
53
HandleSIGCHLD(const struct signalfd_siginfo &)54 bool ProcessReaper::HandleSIGCHLD(
55 const struct signalfd_siginfo& /* sigfd_info */) {
56 // One SIGCHLD may correspond to multiple terminated children, so ignore
57 // sigfd_info and reap any available children.
58 while (true) {
59 siginfo_t info;
60 info.si_pid = 0;
61 int rc = HANDLE_EINTR(waitid(P_ALL, 0, &info, WNOHANG | WEXITED));
62
63 if (rc == -1) {
64 if (errno != ECHILD) {
65 PLOG(ERROR) << "waitid failed";
66 }
67 break;
68 }
69
70 if (info.si_pid == 0) {
71 break;
72 }
73
74 auto proc = watched_processes_.find(info.si_pid);
75 if (proc == watched_processes_.end()) {
76 LOG(INFO) << "Untracked process " << info.si_pid
77 << " terminated with status " << info.si_status
78 << " (code = " << info.si_code << ")";
79 } else {
80 DVLOG_LOC(proc->second.location, 1)
81 << "Process " << info.si_pid << " terminated with status "
82 << info.si_status << " (code = " << info.si_code << ")";
83 ChildCallback callback = std::move(proc->second.callback);
84 watched_processes_.erase(proc);
85 std::move(callback).Run(info);
86 }
87 }
88
89 // Return false to indicate that our handler should not be uninstalled.
90 return false;
91 }
92
93 } // namespace brillo
94