debuggerd: fork the signal sender once.
Bug: http://b/27427439
Change-Id: I6294ff68a150bc9950a300264c31d2141307ac66
diff --git a/debuggerd/debuggerd.cpp b/debuggerd/debuggerd.cpp
index eabbb9a..b6c2f8a 100644
--- a/debuggerd/debuggerd.cpp
+++ b/debuggerd/debuggerd.cpp
@@ -15,21 +15,20 @@
*/
#include <dirent.h>
+#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
-#include <sys/types.h>
-#include <time.h>
-
-#include <elf.h>
#include <sys/poll.h>
#include <sys/prctl.h>
#include <sys/ptrace.h>
#include <sys/stat.h>
+#include <sys/types.h>
#include <sys/wait.h>
+#include <time.h>
#include <set>
@@ -48,6 +47,7 @@
#include "backtrace.h"
#include "getevent.h"
+#include "signal_sender.h"
#include "tombstone.h"
#include "utility.h"
@@ -422,7 +422,7 @@
// this we get a lot of "ptrace detach failed:
// No such process".
*crash_signal = signal;
- kill(request.pid, SIGSTOP);
+ send_signal(request.pid, 0, SIGSTOP);
engrave_tombstone(tombstone_fd, backtrace_map, request.pid, request.tid, siblings, signal,
request.original_si_code, request.abort_msg_address);
break;
@@ -451,60 +451,6 @@
return true;
}
-// 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;
- }
-
- pid_t fork_pid = fork();
- if (fork_pid == -1) {
- ALOGE("debuggerd: failed to initialize signal sender: fork failed: %s", strerror(errno));
- return false;
- } else if (fork_pid == 0) {
- 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);
- }
-
- // 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);
- }
-
- if (signal == 0) {
- exit(0);
- }
- }
- } else {
- close(sfd[0]);
- *out_fd = sfd[1];
- *sender_pid = fork_pid;
- return true;
- }
-}
-
static void handle_request(int fd) {
ALOGV("handle_request(%d)\n", fd);
@@ -585,15 +531,6 @@
// 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_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) {
@@ -603,21 +540,6 @@
}
- 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));
- 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;
if (!attach_gdb) {
ptrace_siblings(request.pid, request.tid, siblings);
@@ -646,7 +568,7 @@
if (attach_gdb) {
// Tell the signal process to send SIGSTOP to the target.
- if (!send_signal(SIGSTOP)) {
+ if (!send_signal(request.pid, 0, SIGSTOP)) {
ALOGE("debuggerd: failed to stop process for gdb attach: %s", strerror(errno));
attach_gdb = false;
}
@@ -662,7 +584,7 @@
// 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) {
- if (!send_signal(crash_signal)) {
+ if (!send_signal(request.pid, request.tid, crash_signal)) {
ALOGE("debuggerd: failed to kill process %d: %s", request.pid, strerror(errno));
}
}
@@ -672,18 +594,13 @@
wait_for_user_action(request);
// Tell the signal process to send SIGCONT to the target.
- if (!send_signal(SIGCONT)) {
+ if (!send_signal(request.pid, 0, SIGCONT)) {
ALOGE("debuggerd: failed to resume process %d: %s", request.pid, strerror(errno));
}
uninit_getevent();
}
- if (!send_signal(0)) {
- ALOGE("debuggerd: failed to notify signal sender to finish");
- kill(signal_pid, SIGKILL);
- }
- waitpid(signal_pid, nullptr, 0);
exit(!succeeded);
}
@@ -714,6 +631,12 @@
SOCK_STREAM | SOCK_CLOEXEC);
if (s == -1) return 1;
+ // Fork a process that stays root, and listens on a pipe to pause and resume the target.
+ if (!start_signal_sender()) {
+ ALOGE("debuggerd: failed to fork signal sender");
+ return 1;
+ }
+
ALOGI("debuggerd: starting\n");
for (;;) {