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platform_system_core/debuggerd/debuggerd.c
Andy McFadden 424e07fcf6 Reduce suicidal tendencies 
Some changes to debuggerd:

(1) Send a SIGSTOP to the target process before doing any of the
PTRACE_ATTACH work.  This causes the threads that weren't hit by
the signal to stop moving, which seems to get rid of the "ptrace
detach failed: No such process" problems that result in missed
stack traces and debuggerd self-immolation.

(2) SIGPIPE was in the list of "interesting" signals caught by
debugger_signal_handler(), but debuggerd didn't recognize it, and
you'd get "unexpected signal 13" complaints.  It's now in the list.

(3) Fixed a bit-rotted XLOG.

Change-Id: I33297ea6b09ce450671c07dc25846f684afbf480
2012-03-08 15:42:30 -08:00

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/* 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 <sys/ptrace.h>
#include <sys/wait.h>
#include <sys/exec_elf.h>
#include <sys/stat.h>
#include <sys/poll.h>
#include <cutils/sockets.h>
#include <cutils/logd.h>
#include <cutils/logger.h>
#include <cutils/properties.h>
#include <corkscrew/backtrace.h>
#include <linux/input.h>
#include <private/android_filesystem_config.h>
#include "getevent.h"
#include "machine.h"
#include "utility.h"
#define ANDROID_LOG_INFO 4
static void dump_build_info(int tfd)
{
char fingerprint[PROPERTY_VALUE_MAX];
property_get("ro.build.fingerprint", fingerprint, "unknown");
_LOG(tfd, false, "Build fingerprint: '%s'\n", fingerprint);
}
static const char *get_signame(int sig)
{
switch(sig) {
case SIGILL: return "SIGILL";
case SIGABRT: return "SIGABRT";
case SIGBUS: return "SIGBUS";
case SIGFPE: return "SIGFPE";
case SIGSEGV: return "SIGSEGV";
case SIGPIPE: return "SIGPIPE";
case SIGSTKFLT: return "SIGSTKFLT";
case SIGSTOP: return "SIGSTOP";
default: return "?";
}
}
static const char *get_sigcode(int signo, int code)
{
switch (signo) {
case SIGILL:
switch (code) {
case ILL_ILLOPC: return "ILL_ILLOPC";
case ILL_ILLOPN: return "ILL_ILLOPN";
case ILL_ILLADR: return "ILL_ILLADR";
case ILL_ILLTRP: return "ILL_ILLTRP";
case ILL_PRVOPC: return "ILL_PRVOPC";
case ILL_PRVREG: return "ILL_PRVREG";
case ILL_COPROC: return "ILL_COPROC";
case ILL_BADSTK: return "ILL_BADSTK";
}
break;
case SIGBUS:
switch (code) {
case BUS_ADRALN: return "BUS_ADRALN";
case BUS_ADRERR: return "BUS_ADRERR";
case BUS_OBJERR: return "BUS_OBJERR";
}
break;
case SIGFPE:
switch (code) {
case FPE_INTDIV: return "FPE_INTDIV";
case FPE_INTOVF: return "FPE_INTOVF";
case FPE_FLTDIV: return "FPE_FLTDIV";
case FPE_FLTOVF: return "FPE_FLTOVF";
case FPE_FLTUND: return "FPE_FLTUND";
case FPE_FLTRES: return "FPE_FLTRES";
case FPE_FLTINV: return "FPE_FLTINV";
case FPE_FLTSUB: return "FPE_FLTSUB";
}
break;
case SIGSEGV:
switch (code) {
case SEGV_MAPERR: return "SEGV_MAPERR";
case SEGV_ACCERR: return "SEGV_ACCERR";
}
break;
}
return "?";
}
static void dump_fault_addr(int tfd, pid_t tid, int sig)
{
siginfo_t si;
memset(&si, 0, sizeof(si));
if(ptrace(PTRACE_GETSIGINFO, tid, 0, &si)){
_LOG(tfd, false, "cannot get siginfo: %s\n", strerror(errno));
} else if (signal_has_address(sig)) {
_LOG(tfd, false, "signal %d (%s), code %d (%s), fault addr %08x\n",
sig, get_signame(sig),
si.si_code, get_sigcode(sig, si.si_code),
(uintptr_t) si.si_addr);
} else {
_LOG(tfd, false, "signal %d (%s), code %d (%s), fault addr --------\n",
sig, get_signame(sig), si.si_code, get_sigcode(sig, si.si_code));
}
}
static void dump_crash_banner(int tfd, pid_t pid, pid_t tid, int sig)
{
char data[1024];
char *x = 0;
FILE *fp;
sprintf(data, "/proc/%d/cmdline", pid);
fp = fopen(data, "r");
if(fp) {
x = fgets(data, 1024, fp);
fclose(fp);
}
_LOG(tfd, false,
"*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
dump_build_info(tfd);
_LOG(tfd, false, "pid: %d, tid: %d >>> %s <<<\n",
pid, tid, x ? x : "UNKNOWN");
if(sig) {
dump_fault_addr(tfd, tid, sig);
}
}
/* Return true if some thread is not detached cleanly */
static bool dump_sibling_thread_report(const ptrace_context_t* context,
int tfd, pid_t pid, pid_t tid) {
char task_path[64];
snprintf(task_path, sizeof(task_path), "/proc/%d/task", pid);
DIR* d = opendir(task_path);
/* Bail early if cannot open the task directory */
if (d == NULL) {
XLOG("Cannot open /proc/%d/task\n", pid);
return false;
}
bool detach_failed = false;
struct dirent *de;
while ((de = readdir(d)) != NULL) {
pid_t new_tid;
/* Ignore "." and ".." */
if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, "..")) {
continue;
}
new_tid = atoi(de->d_name);
/* The main thread at fault has been handled individually */
if (new_tid == tid) {
continue;
}
/* Skip this thread if cannot ptrace it */
if (ptrace(PTRACE_ATTACH, new_tid, 0, 0) < 0) {
continue;
}
_LOG(tfd, true, "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
_LOG(tfd, true, "pid: %d, tid: %d\n", pid, new_tid);
dump_thread(context, tfd, new_tid, false);
if (ptrace(PTRACE_DETACH, new_tid, 0, 0) != 0) {
LOG("ptrace detach from %d failed: %s\n", new_tid, strerror(errno));
detach_failed = true;
}
}
closedir(d);
return detach_failed;
}
/*
* Reads the contents of the specified log device, filters out the entries
* that don't match the specified pid, and writes them to the tombstone file.
*
* If "tailOnly" is set, we only print the last few lines.
*/
static void dump_log_file(int tfd, pid_t pid, const char* filename,
bool tailOnly)
{
bool first = true;
/* circular buffer, for "tailOnly" mode */
const int kShortLogMaxLines = 5;
const int kShortLogLineLen = 256;
char shortLog[kShortLogMaxLines][kShortLogLineLen];
int shortLogCount = 0;
int shortLogNext = 0;
int logfd = open(filename, O_RDONLY | O_NONBLOCK);
if (logfd < 0) {
XLOG("Unable to open %s: %s\n", filename, strerror(errno));
return;
}
union {
unsigned char buf[LOGGER_ENTRY_MAX_LEN + 1];
struct logger_entry entry;
} log_entry;
while (true) {
ssize_t actual = read(logfd, log_entry.buf, LOGGER_ENTRY_MAX_LEN);
if (actual < 0) {
if (errno == EINTR) {
/* interrupted by signal, retry */
continue;
} else if (errno == EAGAIN) {
/* non-blocking EOF; we're done */
break;
} else {
_LOG(tfd, true, "Error while reading log: %s\n",
strerror(errno));
break;
}
} else if (actual == 0) {
_LOG(tfd, true, "Got zero bytes while reading log: %s\n",
strerror(errno));
break;
}
/*
* NOTE: if you XLOG something here, this will spin forever,
* because you will be writing as fast as you're reading. Any
* high-frequency debug diagnostics should just be written to
* the tombstone file.
*/
struct logger_entry* entry = &log_entry.entry;
if (entry->pid != (int32_t) pid) {
/* wrong pid, ignore */
continue;
}
if (first) {
_LOG(tfd, true, "--------- %slog %s\n",
tailOnly ? "tail end of " : "", filename);
first = false;
}
/*
* Msg format is: <priority:1><tag:N>\0<message:N>\0
*
* We want to display it in the same format as "logcat -v threadtime"
* (although in this case the pid is redundant).
*
* TODO: scan for line breaks ('\n') and display each text line
* on a separate line, prefixed with the header, like logcat does.
*/
static const char* kPrioChars = "!.VDIWEFS";
unsigned char prio = entry->msg[0];
char* tag = entry->msg + 1;
char* msg = tag + strlen(tag) + 1;
/* consume any trailing newlines */
char* eatnl = msg + strlen(msg) - 1;
while (eatnl >= msg && *eatnl == '\n') {
*eatnl-- = '\0';
}
char prioChar = (prio < strlen(kPrioChars) ? kPrioChars[prio] : '?');
char timeBuf[32];
time_t sec = (time_t) entry->sec;
struct tm tmBuf;
struct tm* ptm;
ptm = localtime_r(&sec, &tmBuf);
strftime(timeBuf, sizeof(timeBuf), "%m-%d %H:%M:%S", ptm);
if (tailOnly) {
snprintf(shortLog[shortLogNext], kShortLogLineLen,
"%s.%03d %5d %5d %c %-8s: %s",
timeBuf, entry->nsec / 1000000, entry->pid, entry->tid,
prioChar, tag, msg);
shortLogNext = (shortLogNext + 1) % kShortLogMaxLines;
shortLogCount++;
} else {
_LOG(tfd, true, "%s.%03d %5d %5d %c %-8s: %s\n",
timeBuf, entry->nsec / 1000000, entry->pid, entry->tid,
prioChar, tag, msg);
}
}
if (tailOnly) {
int i;
/*
* If we filled the buffer, we want to start at "next", which has
* the oldest entry. If we didn't, we want to start at zero.
*/
if (shortLogCount < kShortLogMaxLines) {
shortLogNext = 0;
} else {
shortLogCount = kShortLogMaxLines; /* cap at window size */
}
for (i = 0; i < shortLogCount; i++) {
_LOG(tfd, true, "%s\n", shortLog[shortLogNext]);
shortLogNext = (shortLogNext + 1) % kShortLogMaxLines;
}
}
close(logfd);
}
/*
* Dumps the logs generated by the specified pid to the tombstone, from both
* "system" and "main" log devices. Ideally we'd interleave the output.
*/
static void dump_logs(int tfd, pid_t pid, bool tailOnly)
{
dump_log_file(tfd, pid, "/dev/log/system", tailOnly);
dump_log_file(tfd, pid, "/dev/log/main", tailOnly);
}
/*
* Dumps all information about the specified pid to the tombstone.
*/
static bool dump_crash(int tfd, pid_t pid, pid_t tid, int signal,
bool dump_sibling_threads)
{
/* don't copy log messages to tombstone unless this is a dev device */
char value[PROPERTY_VALUE_MAX];
property_get("ro.debuggable", value, "0");
bool wantLogs = (value[0] == '1');
dump_crash_banner(tfd, pid, tid, signal);
ptrace_context_t* context = load_ptrace_context(tid);
dump_thread(context, tfd, tid, true);
if (wantLogs) {
dump_logs(tfd, pid, true);
}
bool detach_failed = false;
if (dump_sibling_threads) {
detach_failed = dump_sibling_thread_report(context, tfd, pid, tid);
}
free_ptrace_context(context);
if (wantLogs) {
dump_logs(tfd, pid, false);
}
return detach_failed;
}
#define MAX_TOMBSTONES 10
#define typecheck(x,y) { \
typeof(x) __dummy1; \
typeof(y) __dummy2; \
(void)(&__dummy1 == &__dummy2); }
#define TOMBSTONE_DIR "/data/tombstones"
/*
* find_and_open_tombstone - find an available tombstone slot, if any, of the
* form tombstone_XX where XX is 00 to MAX_TOMBSTONES-1, inclusive. If no
* file is available, we reuse the least-recently-modified file.
*
* Returns the path of the tombstone file, allocated using malloc(). Caller must free() it.
*/
static char* find_and_open_tombstone(int* fd)
{
unsigned long mtime = ULONG_MAX;
struct stat sb;
/*
* XXX: Our stat.st_mtime isn't time_t. If it changes, as it probably ought
* to, our logic breaks. This check will generate a warning if that happens.
*/
typecheck(mtime, sb.st_mtime);
/*
* In a single wolf-like pass, find an available slot and, in case none
* exist, find and record the least-recently-modified file.
*/
char path[128];
int oldest = 0;
for (int i = 0; i < MAX_TOMBSTONES; i++) {
snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", i);
if (!stat(path, &sb)) {
if (sb.st_mtime < mtime) {
oldest = i;
mtime = sb.st_mtime;
}
continue;
}
if (errno != ENOENT)
continue;
*fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0600);
if (*fd < 0)
continue; /* raced ? */
fchown(*fd, AID_SYSTEM, AID_SYSTEM);
return strdup(path);
}
/* we didn't find an available file, so we clobber the oldest one */
snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", oldest);
*fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
if (*fd < 0) {
LOG("failed to open tombstone file '%s': %s\n", path, strerror(errno));
return NULL;
}
fchown(*fd, AID_SYSTEM, AID_SYSTEM);
return strdup(path);
}
/* Return true if some thread is not detached cleanly */
static char* engrave_tombstone(pid_t pid, pid_t tid, int signal, bool dump_sibling_threads,
bool* detach_failed)
{
mkdir(TOMBSTONE_DIR, 0755);
chown(TOMBSTONE_DIR, AID_SYSTEM, AID_SYSTEM);
int fd;
char* path = find_and_open_tombstone(&fd);
if (!path) {
*detach_failed = false;
return NULL;
}
*detach_failed = dump_crash(fd, pid, tid, signal, dump_sibling_threads);
close(fd);
return path;
}
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 signed char 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((int)(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 wait_for_signal(pid_t tid, int* total_sleep_time_usec) {
const int sleep_time_usec = 200000; /* 0.2 seconds */
const int max_total_sleep_usec = 3000000; /* 3 seconds */
for (;;) {
int status;
pid_t n = waitpid(tid, &status, __WALL | WNOHANG);
if (n < 0) {
if(errno == EAGAIN) continue;
LOG("waitpid failed: %s\n", strerror(errno));
return -1;
} else if (n > 0) {
XLOG("waitpid: n=%d status=%08x\n", n, status);
if (WIFSTOPPED(status)) {
return WSTOPSIG(status);
} else {
LOG("unexpected waitpid response: n=%d, status=%08x\n", n, status);
return -1;
}
}
if (*total_sleep_time_usec > max_total_sleep_usec) {
LOG("timed out waiting for tid=%d to die\n", tid);
return -1;
}
/* not ready yet */
XLOG("not ready yet\n");
usleep(sleep_time_usec);
*total_sleep_time_usec += sleep_time_usec;
}
}
enum {
REQUEST_TYPE_CRASH,
REQUEST_TYPE_DUMP,
};
typedef struct {
int type;
pid_t pid, tid;
uid_t uid, gid;
} request_t;
static int read_request(int fd, 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\n");
return -1;
}
status = TEMP_FAILURE_RETRY(read(fd, &out_request->tid, sizeof(pid_t)));
if (status < 0) {
LOG("read failure? %s\n", strerror(errno));
return -1;
}
if (status != sizeof(pid_t)) {
LOG("invalid crash request of size %d\n", status);
return -1;
}
if (out_request->tid < 0 && cr.uid == 0) {
/* Root can ask us to attach to any process and dump it explicitly. */
out_request->type = REQUEST_TYPE_DUMP;
out_request->tid = -out_request->tid;
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;
}
return 0;
}
/* Ensure that the tid reported by the crashing process is valid. */
out_request->type = REQUEST_TYPE_CRASH;
out_request->pid = cr.pid;
out_request->uid = cr.uid;
out_request->gid = cr.gid;
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;
}
return 0;
}
static bool should_attach_gdb(request_t* request) {
if (request->type == REQUEST_TYPE_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);
request_t 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);
char response = 0;
if (TEMP_FAILURE_RETRY(write(fd, &response, 1)) != 1) {
LOG("failed responding to client: %s\n", strerror(errno));
} else {
char* tombstone_path = NULL;
if (request.type != REQUEST_TYPE_DUMP) {
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.type == REQUEST_TYPE_DUMP) {
XLOG("stopped -- dumping\n");
tombstone_path = engrave_tombstone(request.pid, request.tid,
signal, true, &detach_failed);
} 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:
case SIGSTKFLT: {
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, !attach_gdb, &detach_failed);
break;
}
default:
XLOG("stopped -- unexpected signal\n");
LOG("process stopped due to unexpected signal %d\n", signal);
break;
}
break;
}
if (request.type == REQUEST_TYPE_DUMP) {
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);
signal(SIGPIPE, SIG_DFL);
signal(SIGSTKFLT, SIG_DFL);
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("android:debuggerd",
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) {
fprintf(stdout, "Sending request to dump task %d.\n", tid);
int fd = socket_local_client("android:debuggerd",
ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
if (fd < 0) {
fputs("Error opening local socket to debuggerd.\n", stderr);
return 1;
}
pid_t request = -tid;
write(fd, &request, sizeof(pid_t));
if (read(fd, &request, 1) != 1) {
/* did not get expected reply, debuggerd must have closed the socket */
fputs("Error sending request. Did not receive reply from debuggerd.\n", stderr);
} else {
char tombstone_path[PATH_MAX];
ssize_t n = read(fd, &tombstone_path, sizeof(tombstone_path) - 1);
if (n <= 0) {
fputs("Error dumping process. Check log for details.\n", stderr);
} else {
tombstone_path[n] = '\0';
fprintf(stderr, "Tombstone written to: %s\n", tombstone_path);
}
}
close(fd);
return 0;
}
int main(int argc, char** argv) {
if (argc == 2) {
pid_t tid = atoi(argv[1]);
if (!tid) {
fputs("Usage: [<tid>]\n"
"\n"
"If tid specified, sends a request to debuggerd to dump that task.\n"
"Otherwise, starts the debuggerd server.\n", stderr);
return 1;
}
return do_explicit_dump(tid);
}
return do_server();
}
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