Move to C++ for debuggerd.
This is part 1, only including the bare minimum changes because
our diff tool doesn't easily show differences when a file moves. This
also breaks it into a small chunk in case some other changes break things,
as unlikely as I think that will be.
Change-Id: Ib7a3e7a2cc1ac574d15b65fda23813ebcf5d31af
diff --git a/debuggerd/debuggerd.cpp b/debuggerd/debuggerd.cpp
new file mode 100644
index 0000000..a9f59c8
--- /dev/null
+++ b/debuggerd/debuggerd.cpp
@@ -0,0 +1,539 @@
+/* system/debuggerd/debuggerd.c
+**
+** Copyright 2006, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+** http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+
+#include <stdio.h>
+#include <errno.h>
+#include <signal.h>
+#include <pthread.h>
+#include <stdarg.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <time.h>
+
+#include <sys/ptrace.h>
+#include <sys/wait.h>
+#include <elf.h>
+#include <sys/stat.h>
+#include <sys/poll.h>
+
+#include <log/logd.h>
+#include <log/logger.h>
+
+#include <cutils/sockets.h>
+#include <cutils/properties.h>
+#include <cutils/debugger.h>
+
+#include <corkscrew/backtrace.h>
+
+#include <linux/input.h>
+
+#include <private/android_filesystem_config.h>
+
+#include "backtrace.h"
+#include "getevent.h"
+#include "tombstone.h"
+#include "utility.h"
+
+typedef struct {
+ debugger_action_t action;
+ pid_t pid, tid;
+ uid_t uid, gid;
+ uintptr_t abort_msg_address;
+} debugger_request_t;
+
+static int
+write_string(const char* file, const char* string)
+{
+ int len;
+ int fd;
+ ssize_t amt;
+ fd = open(file, O_RDWR);
+ len = strlen(string);
+ if (fd < 0)
+ return -errno;
+ amt = write(fd, string, len);
+ close(fd);
+ return amt >= 0 ? 0 : -errno;
+}
+
+static
+void init_debug_led(void)
+{
+ // trout leds
+ write_string("/sys/class/leds/red/brightness", "0");
+ write_string("/sys/class/leds/green/brightness", "0");
+ write_string("/sys/class/leds/blue/brightness", "0");
+ write_string("/sys/class/leds/red/device/blink", "0");
+ // sardine leds
+ write_string("/sys/class/leds/left/cadence", "0,0");
+}
+
+static
+void enable_debug_led(void)
+{
+ // trout leds
+ write_string("/sys/class/leds/red/brightness", "255");
+ // sardine leds
+ write_string("/sys/class/leds/left/cadence", "1,0");
+}
+
+static
+void disable_debug_led(void)
+{
+ // trout leds
+ write_string("/sys/class/leds/red/brightness", "0");
+ // sardine leds
+ write_string("/sys/class/leds/left/cadence", "0,0");
+}
+
+static void wait_for_user_action(pid_t pid) {
+ /* First log a helpful message */
+ LOG( "********************************************************\n"
+ "* Process %d has been suspended while crashing. To\n"
+ "* attach gdbserver for a gdb connection on port 5039\n"
+ "* and start gdbclient:\n"
+ "*\n"
+ "* gdbclient app_process :5039 %d\n"
+ "*\n"
+ "* Wait for gdb to start, then press HOME or VOLUME DOWN key\n"
+ "* to let the process continue crashing.\n"
+ "********************************************************\n",
+ pid, pid);
+
+ /* wait for HOME or VOLUME DOWN key */
+ if (init_getevent() == 0) {
+ int ms = 1200 / 10;
+ int dit = 1;
+ int dah = 3*dit;
+ int _ = -dit;
+ int ___ = 3*_;
+ int _______ = 7*_;
+ const int codes[] = {
+ dit,_,dit,_,dit,___,dah,_,dah,_,dah,___,dit,_,dit,_,dit,_______
+ };
+ size_t s = 0;
+ struct input_event e;
+ bool done = false;
+ init_debug_led();
+ enable_debug_led();
+ do {
+ int timeout = abs(codes[s]) * ms;
+ int res = get_event(&e, timeout);
+ if (res == 0) {
+ if (e.type == EV_KEY
+ && (e.code == KEY_HOME || e.code == KEY_VOLUMEDOWN)
+ && e.value == 0) {
+ done = true;
+ }
+ } else if (res == 1) {
+ if (++s >= sizeof(codes)/sizeof(*codes))
+ s = 0;
+ if (codes[s] > 0) {
+ enable_debug_led();
+ } else {
+ disable_debug_led();
+ }
+ }
+ } while (!done);
+ uninit_getevent();
+ }
+
+ /* don't forget to turn debug led off */
+ disable_debug_led();
+ LOG("debuggerd resuming process %d", pid);
+}
+
+static int get_process_info(pid_t tid, pid_t* out_pid, uid_t* out_uid, uid_t* out_gid) {
+ char path[64];
+ snprintf(path, sizeof(path), "/proc/%d/status", tid);
+
+ FILE* fp = fopen(path, "r");
+ if (!fp) {
+ return -1;
+ }
+
+ int fields = 0;
+ char line[1024];
+ while (fgets(line, sizeof(line), fp)) {
+ size_t len = strlen(line);
+ if (len > 6 && !memcmp(line, "Tgid:\t", 6)) {
+ *out_pid = atoi(line + 6);
+ fields |= 1;
+ } else if (len > 5 && !memcmp(line, "Uid:\t", 5)) {
+ *out_uid = atoi(line + 5);
+ fields |= 2;
+ } else if (len > 5 && !memcmp(line, "Gid:\t", 5)) {
+ *out_gid = atoi(line + 5);
+ fields |= 4;
+ }
+ }
+ fclose(fp);
+ return fields == 7 ? 0 : -1;
+}
+
+static int read_request(int fd, debugger_request_t* out_request) {
+ struct ucred cr;
+ int len = sizeof(cr);
+ int status = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
+ if (status != 0) {
+ LOG("cannot get credentials\n");
+ return -1;
+ }
+
+ XLOG("reading tid\n");
+ fcntl(fd, F_SETFL, O_NONBLOCK);
+
+ struct pollfd pollfds[1];
+ pollfds[0].fd = fd;
+ pollfds[0].events = POLLIN;
+ pollfds[0].revents = 0;
+ status = TEMP_FAILURE_RETRY(poll(pollfds, 1, 3000));
+ if (status != 1) {
+ LOG("timed out reading tid (from pid=%d uid=%d)\n", cr.pid, cr.uid);
+ return -1;
+ }
+
+ debugger_msg_t msg;
+ memset(&msg, 0, sizeof(msg));
+ status = TEMP_FAILURE_RETRY(read(fd, &msg, sizeof(msg)));
+ if (status < 0) {
+ LOG("read failure? %s (pid=%d uid=%d)\n",
+ strerror(errno), cr.pid, cr.uid);
+ return -1;
+ }
+ if (status == sizeof(debugger_msg_t)) {
+ XLOG("crash request of size %d abort_msg_address=%#08x\n", status, msg.abort_msg_address);
+ } else {
+ LOG("invalid crash request of size %d (from pid=%d uid=%d)\n",
+ status, cr.pid, cr.uid);
+ return -1;
+ }
+
+ out_request->action = msg.action;
+ out_request->tid = msg.tid;
+ out_request->pid = cr.pid;
+ out_request->uid = cr.uid;
+ out_request->gid = cr.gid;
+ out_request->abort_msg_address = msg.abort_msg_address;
+
+ if (msg.action == DEBUGGER_ACTION_CRASH) {
+ /* Ensure that the tid reported by the crashing process is valid. */
+ char buf[64];
+ struct stat s;
+ snprintf(buf, sizeof buf, "/proc/%d/task/%d", out_request->pid, out_request->tid);
+ if(stat(buf, &s)) {
+ LOG("tid %d does not exist in pid %d. ignoring debug request\n",
+ out_request->tid, out_request->pid);
+ return -1;
+ }
+ } else if (cr.uid == 0
+ || (cr.uid == AID_SYSTEM && msg.action == DEBUGGER_ACTION_DUMP_BACKTRACE)) {
+ /* Only root or system can ask us to attach to any process and dump it explicitly.
+ * However, system is only allowed to collect backtraces but cannot dump tombstones. */
+ status = get_process_info(out_request->tid, &out_request->pid,
+ &out_request->uid, &out_request->gid);
+ if (status < 0) {
+ LOG("tid %d does not exist. ignoring explicit dump request\n",
+ out_request->tid);
+ return -1;
+ }
+ } else {
+ /* No one else is allowed to dump arbitrary processes. */
+ return -1;
+ }
+ return 0;
+}
+
+static bool should_attach_gdb(debugger_request_t* request) {
+ if (request->action == DEBUGGER_ACTION_CRASH) {
+ char value[PROPERTY_VALUE_MAX];
+ property_get("debug.db.uid", value, "-1");
+ int debug_uid = atoi(value);
+ return debug_uid >= 0 && request->uid <= (uid_t)debug_uid;
+ }
+ return false;
+}
+
+static void handle_request(int fd) {
+ XLOG("handle_request(%d)\n", fd);
+
+ debugger_request_t request;
+ memset(&request, 0, sizeof(request));
+ int status = read_request(fd, &request);
+ if (!status) {
+ XLOG("BOOM: pid=%d uid=%d gid=%d tid=%d\n",
+ request.pid, request.uid, request.gid, request.tid);
+
+ /* At this point, the thread that made the request is blocked in
+ * a read() call. If the thread has crashed, then this gives us
+ * time to PTRACE_ATTACH to it before it has a chance to really fault.
+ *
+ * The PTRACE_ATTACH sends a SIGSTOP to the target process, but it
+ * won't necessarily have stopped by the time ptrace() returns. (We
+ * currently assume it does.) We write to the file descriptor to
+ * ensure that it can run as soon as we call PTRACE_CONT below.
+ * See details in bionic/libc/linker/debugger.c, in function
+ * debugger_signal_handler().
+ */
+ if (ptrace(PTRACE_ATTACH, request.tid, 0, 0)) {
+ LOG("ptrace attach failed: %s\n", strerror(errno));
+ } else {
+ bool detach_failed = false;
+ bool attach_gdb = should_attach_gdb(&request);
+ if (TEMP_FAILURE_RETRY(write(fd, "\0", 1)) != 1) {
+ LOG("failed responding to client: %s\n", strerror(errno));
+ } else {
+ char* tombstone_path = NULL;
+
+ if (request.action == DEBUGGER_ACTION_CRASH) {
+ close(fd);
+ fd = -1;
+ }
+
+ int total_sleep_time_usec = 0;
+ for (;;) {
+ int signal = wait_for_signal(request.tid, &total_sleep_time_usec);
+ if (signal < 0) {
+ break;
+ }
+
+ switch (signal) {
+ case SIGSTOP:
+ if (request.action == DEBUGGER_ACTION_DUMP_TOMBSTONE) {
+ XLOG("stopped -- dumping to tombstone\n");
+ tombstone_path = engrave_tombstone(request.pid, request.tid,
+ signal, request.abort_msg_address, true, true, &detach_failed,
+ &total_sleep_time_usec);
+ } else if (request.action == DEBUGGER_ACTION_DUMP_BACKTRACE) {
+ XLOG("stopped -- dumping to fd\n");
+ dump_backtrace(fd, -1,
+ request.pid, request.tid, &detach_failed,
+ &total_sleep_time_usec);
+ } else {
+ XLOG("stopped -- continuing\n");
+ status = ptrace(PTRACE_CONT, request.tid, 0, 0);
+ if (status) {
+ LOG("ptrace continue failed: %s\n", strerror(errno));
+ }
+ continue; /* loop again */
+ }
+ break;
+
+ case SIGILL:
+ case SIGABRT:
+ case SIGBUS:
+ case SIGFPE:
+ case SIGSEGV:
+ case SIGPIPE:
+#ifdef SIGSTKFLT
+ case SIGSTKFLT:
+#endif
+ {
+ XLOG("stopped -- fatal signal\n");
+ /*
+ * Send a SIGSTOP to the process to make all of
+ * the non-signaled threads stop moving. Without
+ * this we get a lot of "ptrace detach failed:
+ * No such process".
+ */
+ kill(request.pid, SIGSTOP);
+ /* don't dump sibling threads when attaching to GDB because it
+ * makes the process less reliable, apparently... */
+ tombstone_path = engrave_tombstone(request.pid, request.tid,
+ signal, request.abort_msg_address, !attach_gdb, false,
+ &detach_failed, &total_sleep_time_usec);
+ break;
+ }
+
+ default:
+ XLOG("stopped -- unexpected signal\n");
+ LOG("process stopped due to unexpected signal %d\n", signal);
+ break;
+ }
+ break;
+ }
+
+ if (request.action == DEBUGGER_ACTION_DUMP_TOMBSTONE) {
+ if (tombstone_path) {
+ write(fd, tombstone_path, strlen(tombstone_path));
+ }
+ close(fd);
+ fd = -1;
+ }
+ free(tombstone_path);
+ }
+
+ XLOG("detaching\n");
+ if (attach_gdb) {
+ /* stop the process so we can debug */
+ kill(request.pid, SIGSTOP);
+
+ /* detach so we can attach gdbserver */
+ if (ptrace(PTRACE_DETACH, request.tid, 0, 0)) {
+ LOG("ptrace detach from %d failed: %s\n", request.tid, strerror(errno));
+ detach_failed = true;
+ }
+
+ /*
+ * if debug.db.uid is set, its value indicates if we should wait
+ * for user action for the crashing process.
+ * in this case, we log a message and turn the debug LED on
+ * waiting for a gdb connection (for instance)
+ */
+ wait_for_user_action(request.pid);
+ } else {
+ /* just detach */
+ if (ptrace(PTRACE_DETACH, request.tid, 0, 0)) {
+ LOG("ptrace detach from %d failed: %s\n", request.tid, strerror(errno));
+ detach_failed = true;
+ }
+ }
+
+ /* resume stopped process (so it can crash in peace). */
+ kill(request.pid, SIGCONT);
+
+ /* If we didn't successfully detach, we're still the parent, and the
+ * actual parent won't receive a death notification via wait(2). At this point
+ * there's not much we can do about that. */
+ if (detach_failed) {
+ LOG("debuggerd committing suicide to free the zombie!\n");
+ kill(getpid(), SIGKILL);
+ }
+ }
+
+ }
+ if (fd >= 0) {
+ close(fd);
+ }
+}
+
+static int do_server() {
+ int s;
+ struct sigaction act;
+ int logsocket = -1;
+
+ /*
+ * debuggerd crashes can't be reported to debuggerd. Reset all of the
+ * crash handlers.
+ */
+ signal(SIGILL, SIG_DFL);
+ signal(SIGABRT, SIG_DFL);
+ signal(SIGBUS, SIG_DFL);
+ signal(SIGFPE, SIG_DFL);
+ signal(SIGSEGV, SIG_DFL);
+#ifdef SIGSTKFLT
+ signal(SIGSTKFLT, SIG_DFL);
+#endif
+
+ // Ignore failed writes to closed sockets
+ signal(SIGPIPE, SIG_IGN);
+
+ logsocket = socket_local_client("logd",
+ ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_DGRAM);
+ if(logsocket < 0) {
+ logsocket = -1;
+ } else {
+ fcntl(logsocket, F_SETFD, FD_CLOEXEC);
+ }
+
+ act.sa_handler = SIG_DFL;
+ sigemptyset(&act.sa_mask);
+ sigaddset(&act.sa_mask,SIGCHLD);
+ act.sa_flags = SA_NOCLDWAIT;
+ sigaction(SIGCHLD, &act, 0);
+
+ s = socket_local_server(DEBUGGER_SOCKET_NAME,
+ ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
+ if(s < 0) return 1;
+ fcntl(s, F_SETFD, FD_CLOEXEC);
+
+ LOG("debuggerd: " __DATE__ " " __TIME__ "\n");
+
+ for(;;) {
+ struct sockaddr addr;
+ socklen_t alen;
+ int fd;
+
+ alen = sizeof(addr);
+ XLOG("waiting for connection\n");
+ fd = accept(s, &addr, &alen);
+ if(fd < 0) {
+ XLOG("accept failed: %s\n", strerror(errno));
+ continue;
+ }
+
+ fcntl(fd, F_SETFD, FD_CLOEXEC);
+
+ handle_request(fd);
+ }
+ return 0;
+}
+
+static int do_explicit_dump(pid_t tid, bool dump_backtrace) {
+ fprintf(stdout, "Sending request to dump task %d.\n", tid);
+
+ if (dump_backtrace) {
+ fflush(stdout);
+ if (dump_backtrace_to_file(tid, fileno(stdout)) < 0) {
+ fputs("Error dumping backtrace.\n", stderr);
+ return 1;
+ }
+ } else {
+ char tombstone_path[PATH_MAX];
+ if (dump_tombstone(tid, tombstone_path, sizeof(tombstone_path)) < 0) {
+ fputs("Error dumping tombstone.\n", stderr);
+ return 1;
+ }
+ fprintf(stderr, "Tombstone written to: %s\n", tombstone_path);
+ }
+ return 0;
+}
+
+static void usage() {
+ fputs("Usage: -b [<tid>]\n"
+ " -b dump backtrace to console, otherwise dump full tombstone file\n"
+ "\n"
+ "If tid specified, sends a request to debuggerd to dump that task.\n"
+ "Otherwise, starts the debuggerd server.\n", stderr);
+}
+
+int main(int argc, char** argv) {
+ if (argc == 1) {
+ return do_server();
+ }
+
+ bool dump_backtrace = false;
+ bool have_tid = false;
+ pid_t tid = 0;
+ for (int i = 1; i < argc; i++) {
+ if (!strcmp(argv[i], "-b")) {
+ dump_backtrace = true;
+ } else if (!have_tid) {
+ tid = atoi(argv[i]);
+ have_tid = true;
+ } else {
+ usage();
+ return 1;
+ }
+ }
+ if (!have_tid) {
+ usage();
+ return 1;
+ }
+ return do_explicit_dump(tid, dump_backtrace);
+}