1 /*
2 * Copyright 2016, 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 <err.h>
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <string.h>
21
22 #include <limits>
23 #include <string_view>
24 #include <thread>
25
26 #include <android-base/file.h>
27 #include <android-base/logging.h>
28 #include <android-base/parseint.h>
29 #include <android-base/unique_fd.h>
30 #include <debuggerd/client.h>
31 #include <procinfo/process.h>
32 #include "util.h"
33
34 using android::base::unique_fd;
35
usage(int exit_code)36 static void usage(int exit_code) {
37 fprintf(stderr, "usage: debuggerd [-bj] PID\n");
38 fprintf(stderr, "\n");
39 fprintf(stderr, "-b, --backtrace just a backtrace rather than a full tombstone\n");
40 fprintf(stderr, "-j collect java traces\n");
41 _exit(exit_code);
42 }
43
spawn_redirect_thread(unique_fd fd)44 static std::thread spawn_redirect_thread(unique_fd fd) {
45 return std::thread([fd{ std::move(fd) }]() {
46 while (true) {
47 char buf[BUFSIZ];
48 ssize_t rc = TEMP_FAILURE_RETRY(read(fd.get(), buf, sizeof(buf)));
49 if (rc <= 0) {
50 return;
51 }
52
53 if (!android::base::WriteFully(STDOUT_FILENO, buf, rc)) {
54 return;
55 }
56 }
57 });
58 }
59
main(int argc,char * argv[])60 int main(int argc, char* argv[]) {
61 if (argc <= 1) usage(0);
62 if (argc > 3) usage(1);
63
64 DebuggerdDumpType dump_type = kDebuggerdTombstone;
65
66 if (argc == 3) {
67 std::string_view flag = argv[1];
68 if (flag == "-b" || flag == "--backtrace") {
69 dump_type = kDebuggerdNativeBacktrace;
70 } else if (flag == "-j") {
71 dump_type = kDebuggerdJavaBacktrace;
72 } else {
73 usage(1);
74 }
75 }
76
77 pid_t pid;
78 if (!android::base::ParseInt(argv[argc - 1], &pid, 1, std::numeric_limits<pid_t>::max())) {
79 usage(1);
80 }
81
82 if (getuid() != 0) {
83 errx(1, "root is required");
84 }
85
86 // Check to see if the process exists and that we can actually send a signal to it.
87 android::procinfo::ProcessInfo proc_info;
88 if (!android::procinfo::GetProcessInfo(pid, &proc_info)) {
89 err(1, "failed to fetch info for process %d", pid);
90 }
91
92 if (proc_info.state == android::procinfo::kProcessStateZombie) {
93 errx(1, "process %d is a zombie", pid);
94 }
95
96 // Send a signal to the main thread pid, not a side thread. The signal
97 // handler always sets the crashing tid to the main thread pid when sent this
98 // signal. This is to avoid a problem where the signal is sent to a process,
99 // but happens on a side thread and the intercept mismatches since it
100 // is looking for the main thread pid, not the tid of this random thread.
101 // See b/194346289 for extra details.
102 if (kill(proc_info.pid, 0) != 0) {
103 if (pid == proc_info.pid) {
104 err(1, "cannot send signal to process %d", pid);
105 } else {
106 err(1, "cannot send signal to main thread %d (requested thread %d)", proc_info.pid, pid);
107 }
108 }
109
110 unique_fd piperead, pipewrite;
111 if (!Pipe(&piperead, &pipewrite)) {
112 err(1, "failed to create pipe");
113 }
114
115 std::thread redirect_thread = spawn_redirect_thread(std::move(piperead));
116 if (!debuggerd_trigger_dump(proc_info.pid, dump_type, 0, std::move(pipewrite))) {
117 redirect_thread.join();
118 if (pid == proc_info.pid) {
119 errx(1, "failed to dump process %d", pid);
120 } else {
121 errx(1, "failed to dump main thread %d (requested thread %d)", proc_info.pid, pid);
122 }
123 }
124
125 redirect_thread.join();
126 return 0;
127 }
128