debuggerd: make sure that we kill the process after dumping.
Bug: http://b/27367422
Change-Id: Icd704b1effd558904975cfc524714b51917a653f
diff --git a/debuggerd/debuggerd.cpp b/debuggerd/debuggerd.cpp
index ac1c58c..b191954 100644
--- a/debuggerd/debuggerd.cpp
+++ b/debuggerd/debuggerd.cpp
@@ -449,18 +449,11 @@
return true;
}
-static bool fork_signal_sender(int* in_fd, int* out_fd, pid_t* sender_pid, pid_t target_pid) {
- int input_pipe[2];
- int output_pipe[2];
- if (pipe(input_pipe) != 0) {
- ALOGE("debuggerd: failed to create input pipe for signal sender: %s", strerror(errno));
- return false;
- }
-
- if (pipe(output_pipe) != 0) {
- close(input_pipe[0]);
- close(input_pipe[1]);
- ALOGE("debuggerd: failed to create output pipe for signal sender: %s", strerror(errno));
+// Fork a process that listens for signals to send, or 0, to exit.
+static bool fork_signal_sender(int* out_fd, pid_t* sender_pid, pid_t target_pid) {
+ int sfd[2];
+ if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, sfd) != 0) {
+ ALOGE("debuggerd: failed to create socketpair for signal sender: %s", strerror(errno));
return false;
}
@@ -469,40 +462,42 @@
ALOGE("debuggerd: failed to initialize signal sender: fork failed: %s", strerror(errno));
return false;
} else if (fork_pid == 0) {
- close(input_pipe[1]);
- close(output_pipe[0]);
- auto wait = [=]() {
- char buf[1];
- if (TEMP_FAILURE_RETRY(read(input_pipe[0], buf, 1)) != 1) {
- ALOGE("debuggerd: signal sender failed to read from pipe");
+ close(sfd[1]);
+
+ while (true) {
+ int signal;
+ int rc = TEMP_FAILURE_RETRY(read(sfd[0], &signal, sizeof(signal)));
+ if (rc < 0) {
+ ALOGE("debuggerd: signal sender failed to read from socket");
+ kill(target_pid, SIGKILL);
+ exit(1);
+ } else if (rc != sizeof(signal)) {
+ ALOGE("debuggerd: signal sender read unexpected number of bytes: %d", rc);
+ kill(target_pid, SIGKILL);
exit(1);
}
- };
- auto notify_done = [=]() {
- if (TEMP_FAILURE_RETRY(write(output_pipe[1], "", 1)) != 1) {
- ALOGE("debuggerd: signal sender failed to write to pipe");
+
+ // Report success after sending a signal, or before exiting.
+ int err = 0;
+ if (signal != 0) {
+ if (kill(target_pid, signal) != 0) {
+ err = errno;
+ }
+ }
+
+ if (TEMP_FAILURE_RETRY(write(sfd[0], &err, sizeof(err))) < 0) {
+ ALOGE("debuggerd: signal sender failed to write: %s", strerror(errno));
+ kill(target_pid, SIGKILL);
exit(1);
}
- };
- wait();
- if (kill(target_pid, SIGSTOP) != 0) {
- ALOGE("debuggerd: failed to stop target '%d': %s", target_pid, strerror(errno));
+ if (signal == 0) {
+ exit(0);
+ }
}
- notify_done();
-
- wait();
- if (kill(target_pid, SIGCONT) != 0) {
- ALOGE("debuggerd: failed to resume target '%d': %s", target_pid, strerror(errno));
- }
- notify_done();
-
- exit(0);
} else {
- close(input_pipe[0]);
- close(output_pipe[1]);
- *in_fd = input_pipe[1];
- *out_fd = output_pipe[0];
+ close(sfd[0]);
+ *out_fd = sfd[1];
*sender_pid = fork_pid;
return true;
}
@@ -588,9 +583,15 @@
// Don't attach to the sibling threads if we want to attach gdb.
// Supposedly, it makes the process less reliable.
bool attach_gdb = should_attach_gdb(&request);
- int signal_in_fd = -1;
- int signal_out_fd = -1;
+ int signal_fd = -1;
pid_t signal_pid = 0;
+
+ // Fork a process that stays root, and listens on a pipe to pause and resume the target.
+ if (!fork_signal_sender(&signal_fd, &signal_pid, request.pid)) {
+ ALOGE("debuggerd: failed to fork signal sender");
+ exit(1);
+ }
+
if (attach_gdb) {
// Open all of the input devices we need to listen for VOLUMEDOWN before dropping privileges.
if (init_getevent() != 0) {
@@ -598,19 +599,21 @@
attach_gdb = false;
}
- // Fork a process that stays root, and listens on a pipe to pause and resume the target.
- if (!fork_signal_sender(&signal_in_fd, &signal_out_fd, &signal_pid, request.pid)) {
- attach_gdb = false;
- }
}
- auto notify_signal_sender = [=]() {
- char buf[1];
- if (TEMP_FAILURE_RETRY(write(signal_in_fd, "", 1)) != 1) {
+ auto send_signal = [=](int signal) {
+ int error;
+ if (TEMP_FAILURE_RETRY(write(signal_fd, &signal, sizeof(signal))) < 0) {
ALOGE("debuggerd: failed to notify signal process: %s", strerror(errno));
- } else if (TEMP_FAILURE_RETRY(read(signal_out_fd, buf, 1)) != 1) {
+ return false;
+ } else if (TEMP_FAILURE_RETRY(read(signal_fd, &error, sizeof(error))) < 0) {
ALOGE("debuggerd: failed to read response from signal process: %s", strerror(errno));
+ return false;
+ } else if (error != 0) {
+ errno = error;
+ return false;
}
+ return true;
};
std::set<pid_t> siblings;
@@ -624,19 +627,25 @@
bool succeeded = false;
// Now that we've done everything that requires privileges, we can drop them.
- if (drop_privileges()) {
- succeeded = perform_dump(request, fd, tombstone_fd, backtrace_map.get(), siblings);
- if (succeeded) {
- if (request.action == DEBUGGER_ACTION_DUMP_TOMBSTONE) {
- if (!tombstone_path.empty()) {
- write(fd, tombstone_path.c_str(), tombstone_path.length());
- }
+ if (!drop_privileges()) {
+ ALOGE("debuggerd: failed to drop privileges, exiting");
+ _exit(1);
+ }
+
+ succeeded = perform_dump(request, fd, tombstone_fd, backtrace_map.get(), siblings);
+ if (succeeded) {
+ if (request.action == DEBUGGER_ACTION_DUMP_TOMBSTONE) {
+ if (!tombstone_path.empty()) {
+ write(fd, tombstone_path.c_str(), tombstone_path.length());
}
}
+ }
- if (attach_gdb) {
- // Tell the signal process to send SIGSTOP to the target.
- notify_signal_sender();
+ if (attach_gdb) {
+ // Tell the signal process to send SIGSTOP to the target.
+ if (!send_signal(SIGSTOP)) {
+ ALOGE("debuggerd: failed to stop process for gdb attach: %s", strerror(errno));
+ attach_gdb = false;
}
}
@@ -648,17 +657,32 @@
ptrace(PTRACE_DETACH, sibling, 0, 0);
}
+ // Send the signal back to the process if it crashed and we're not waiting for gdb.
+ if (!attach_gdb && request.action == DEBUGGER_ACTION_CRASH) {
+ // TODO: Send the same signal that triggered the dump, so that shell says "Segmentation fault"
+ // instead of "Killed"?
+ if (!send_signal(SIGKILL)) {
+ ALOGE("debuggerd: failed to kill process %d: %s", request.pid, strerror(errno));
+ }
+ }
+
// Wait for gdb, if requested.
if (attach_gdb && succeeded) {
wait_for_user_action(request);
// Tell the signal process to send SIGCONT to the target.
- notify_signal_sender();
+ if (!send_signal(SIGCONT)) {
+ ALOGE("debuggerd: failed to resume process %d: %s", request.pid, strerror(errno));
+ }
uninit_getevent();
- waitpid(signal_pid, nullptr, 0);
}
+ if (!send_signal(0)) {
+ ALOGE("debuggerd: failed to notify signal sender to finish");
+ kill(signal_pid, SIGKILL);
+ }
+ waitpid(signal_pid, nullptr, 0);
exit(!succeeded);
}
