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