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 <thread>
24
25 #include <android-base/file.h>
26 #include <android-base/logging.h>
27 #include <android-base/parseint.h>
28 #include <android-base/unique_fd.h>
29 #include <debuggerd/client.h>
30 #include <procinfo/process.h>
31 #include "util.h"
32
33 using android::base::unique_fd;
34
usage(int exit_code)35 static void usage(int exit_code) {
36 fprintf(stderr, "usage: debuggerd [-b] PID\n");
37 fprintf(stderr, "\n");
38 fprintf(stderr, "-b, --backtrace just a backtrace rather than a full tombstone\n");
39 _exit(exit_code);
40 }
41
spawn_redirect_thread(unique_fd fd)42 static std::thread spawn_redirect_thread(unique_fd fd) {
43 return std::thread([fd{ std::move(fd) }]() {
44 while (true) {
45 char buf[BUFSIZ];
46 ssize_t rc = TEMP_FAILURE_RETRY(read(fd.get(), buf, sizeof(buf)));
47 if (rc <= 0) {
48 return;
49 }
50
51 if (!android::base::WriteFully(STDOUT_FILENO, buf, rc)) {
52 return;
53 }
54 }
55 });
56 }
57
main(int argc,char * argv[])58 int main(int argc, char* argv[]) {
59 if (argc <= 1) usage(0);
60 if (argc > 3) usage(1);
61 if (argc == 3 && strcmp(argv[1], "-b") != 0 && strcmp(argv[1], "--backtrace") != 0) usage(1);
62 bool backtrace_only = argc == 3;
63
64 pid_t pid;
65 if (!android::base::ParseInt(argv[argc - 1], &pid, 1, std::numeric_limits<pid_t>::max())) {
66 usage(1);
67 }
68
69 if (getuid() != 0) {
70 errx(1, "root is required");
71 }
72
73 // Check to see if the process exists and that we can actually send a signal to it.
74 android::procinfo::ProcessInfo proc_info;
75 if (!android::procinfo::GetProcessInfo(pid, &proc_info)) {
76 err(1, "failed to fetch info for process %d", pid);
77 }
78
79 if (proc_info.state == android::procinfo::kProcessStateZombie) {
80 errx(1, "process %d is a zombie", pid);
81 }
82
83 if (kill(pid, 0) != 0) {
84 err(1, "cannot send signal to process %d", pid);
85 }
86
87 unique_fd piperead, pipewrite;
88 if (!Pipe(&piperead, &pipewrite)) {
89 err(1, "failed to create pipe");
90 }
91
92 std::thread redirect_thread = spawn_redirect_thread(std::move(piperead));
93 if (!debuggerd_trigger_dump(pid, backtrace_only ? kDebuggerdNativeBacktrace : kDebuggerdTombstone,
94 0, std::move(pipewrite))) {
95 redirect_thread.join();
96 errx(1, "failed to dump process %d", pid);
97 }
98
99 redirect_thread.join();
100 return 0;
101 }
102