1 /*
2 * Copyright (C) 2022 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <errno.h>
18 #include <stdint.h>
19 #include <stdio.h>
20 #include <sys/ptrace.h>
21 #include <sys/types.h>
22 #include <sys/wait.h>
23 #include <time.h>
24 #include <unistd.h>
25
26 #include "PidUtils.h"
27
28 namespace unwindstack {
29
Exited(pid_t pid)30 static bool Exited(pid_t pid) {
31 int status;
32 pid_t wait_pid = waitpid(pid, &status, WNOHANG);
33 if (wait_pid != pid) {
34 return false;
35 }
36
37 if (WIFEXITED(status)) {
38 fprintf(stderr, "%d died: Process exited with code %d\n", pid, WEXITSTATUS(status));
39 } else if (WIFSIGNALED(status)) {
40 fprintf(stderr, "%d died: Process exited due to signal %d\n", pid, WTERMSIG(status));
41 } else {
42 fprintf(stderr, "%d died: Process finished for unknown reason\n", pid);
43 }
44 return true;
45 }
46
Quiesce(pid_t pid)47 bool Quiesce(pid_t pid) {
48 siginfo_t si;
49 // Wait for up to 10 seconds.
50 for (time_t start_time = time(nullptr); time(nullptr) - start_time < 10;) {
51 if (ptrace(PTRACE_GETSIGINFO, pid, 0, &si) == 0) {
52 return true;
53 }
54 if (errno != ESRCH) {
55 if (errno == EINVAL) {
56 // The process is in group-stop state, so try and kick the
57 // process out of that state.
58 if (ptrace(PTRACE_LISTEN, pid, 0, 0) == -1) {
59 // Cannot recover from this, so just pretend it worked and see
60 // if we can unwind.
61 return true;
62 }
63 } else {
64 perror("ptrace getsiginfo failed");
65 return false;
66 }
67 }
68 usleep(5000);
69 }
70 fprintf(stderr, "%d: Did not quiesce in 10 seconds\n", pid);
71 return false;
72 }
73
Attach(pid_t pid)74 bool Attach(pid_t pid) {
75 // Wait up to 45 seconds to attach.
76 for (time_t start_time = time(nullptr); time(nullptr) - start_time < 45;) {
77 if (ptrace(PTRACE_ATTACH, pid, 0, 0) == 0) {
78 break;
79 }
80 if (errno != ESRCH) {
81 perror("Failed to attach");
82 return false;
83 }
84 usleep(5000);
85 }
86
87 if (Quiesce(pid)) {
88 return true;
89 }
90
91 if (ptrace(PTRACE_DETACH, pid, 0, 0) == -1) {
92 perror("Failed to detach");
93 }
94 return false;
95 }
96
Detach(pid_t pid)97 bool Detach(pid_t pid) {
98 if (ptrace(PTRACE_DETACH, pid, 0, 0) == -1) {
99 perror("ptrace detach failed");
100 return false;
101 }
102 return true;
103 }
104
105 static constexpr time_t kMaxWaitTimeSeconds = 30;
106
WaitForPidState(pid_t pid,const std::function<PidRunEnum ()> & state_check_func)107 bool WaitForPidState(pid_t pid, const std::function<PidRunEnum()>& state_check_func) {
108 PidRunEnum status = PID_RUN_KEEP_GOING;
109 for (time_t start_time = time(nullptr);
110 time(nullptr) - start_time < kMaxWaitTimeSeconds && status == PID_RUN_KEEP_GOING;) {
111 if (Attach(pid)) {
112 status = state_check_func();
113 if (status == PID_RUN_PASS) {
114 return true;
115 }
116
117 if (!Detach(pid)) {
118 return false;
119 }
120 } else if (Exited(pid)) {
121 return false;
122 }
123 usleep(5000);
124 }
125 if (status == PID_RUN_KEEP_GOING) {
126 fprintf(stderr, "Timed out waiting for pid %d to be ready\n", pid);
127 }
128 return status == PID_RUN_PASS;
129 }
130
WaitForPidStateAfterAttach(pid_t pid,const std::function<PidRunEnum ()> & state_check_func)131 bool WaitForPidStateAfterAttach(pid_t pid, const std::function<PidRunEnum()>& state_check_func) {
132 PidRunEnum status;
133 time_t start_time = time(nullptr);
134 do {
135 status = state_check_func();
136 if (status == PID_RUN_PASS) {
137 return true;
138 }
139 if (!Detach(pid)) {
140 return false;
141 }
142 usleep(5000);
143 } while (time(nullptr) - start_time < kMaxWaitTimeSeconds && status == PID_RUN_KEEP_GOING &&
144 Attach(pid));
145 if (status == PID_RUN_KEEP_GOING) {
146 fprintf(stderr, "Timed out waiting for pid %d to be ready\n", pid);
147 }
148 return status == PID_RUN_PASS;
149 }
150
151 } // namespace unwindstack
152