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am 8abf44c4: Merge "Make libc signal handler output more like debuggerd."

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* commit '8abf44c415bb3b02b6a3198196c92266442a0c32':
  Make libc signal handler output more like debuggerd.
This commit is contained in:
Elliott Hughes 2014-04-21 13:41:35 +00:00 committed by Android Git Automerger
commit a3d82df005
1 changed files with 171 additions and 148 deletions
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319
linker/debugger.cpp
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@ -29,6 +29,7 @@
#include "linker.h"
#include <errno.h>
#include <inttypes.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
@ -47,12 +48,12 @@ extern "C" int tgkill(int tgid, int tid, int sig);
#endif
enum debugger_action_t {
// dump a crash
DEBUGGER_ACTION_CRASH,
// dump a tombstone file
DEBUGGER_ACTION_DUMP_TOMBSTONE,
// dump a backtrace only back to the socket
DEBUGGER_ACTION_DUMP_BACKTRACE,
// dump a crash
DEBUGGER_ACTION_CRASH,
// dump a tombstone file
DEBUGGER_ACTION_DUMP_TOMBSTONE,
// dump a backtrace only back to the socket
DEBUGGER_ACTION_DUMP_BACKTRACE,
};
/* message sent over the socket */
@ -69,40 +70,39 @@ struct debugger_msg_t {
#define MAX_TASK_NAME_LEN (16)
static int socket_abstract_client(const char* name, int type) {
sockaddr_un addr;
sockaddr_un addr;
// Test with length +1 for the *initial* '\0'.
size_t namelen = strlen(name);
if ((namelen + 1) > sizeof(addr.sun_path)) {
errno = EINVAL;
return -1;
}
// Test with length +1 for the *initial* '\0'.
size_t namelen = strlen(name);
if ((namelen + 1) > sizeof(addr.sun_path)) {
errno = EINVAL;
return -1;
}
/* This is used for abstract socket namespace, we need
* an initial '\0' at the start of the Unix socket path.
*
* Note: The path in this case is *not* supposed to be
* '\0'-terminated. ("man 7 unix" for the gory details.)
*/
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_LOCAL;
addr.sun_path[0] = 0;
memcpy(addr.sun_path + 1, name, namelen);
// This is used for abstract socket namespace, we need
// an initial '\0' at the start of the Unix socket path.
//
// Note: The path in this case is *not* supposed to be
// '\0'-terminated. ("man 7 unix" for the gory details.)
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_LOCAL;
addr.sun_path[0] = 0;
memcpy(addr.sun_path + 1, name, namelen);
socklen_t alen = namelen + offsetof(sockaddr_un, sun_path) + 1;
socklen_t alen = namelen + offsetof(sockaddr_un, sun_path) + 1;
int s = socket(AF_LOCAL, type, 0);
if (s == -1) {
return -1;
}
int s = socket(AF_LOCAL, type, 0);
if (s == -1) {
return -1;
}
int rc = TEMP_FAILURE_RETRY(connect(s, reinterpret_cast<sockaddr*>(&addr), alen));
if (rc == -1) {
close(s);
return -1;
}
int rc = TEMP_FAILURE_RETRY(connect(s, reinterpret_cast<sockaddr*>(&addr), alen));
if (rc == -1) {
close(s);
return -1;
}
return s;
return s;
}
/*
@ -115,65 +115,88 @@ static int socket_abstract_client(const char* name, int type) {
* could allocate memory or hold a lock.
*/
static void log_signal_summary(int signum, const siginfo_t* info) {
const char* signal_name;
switch (signum) {
case SIGILL: signal_name = "SIGILL"; break;
case SIGABRT: signal_name = "SIGABRT"; break;
case SIGBUS: signal_name = "SIGBUS"; break;
case SIGFPE: signal_name = "SIGFPE"; break;
case SIGSEGV: signal_name = "SIGSEGV"; break;
const char* signal_name = "???";
bool has_address = false;
switch (signum) {
case SIGILL:
signal_name = "SIGILL";
has_address = true;
break;
case SIGABRT:
signal_name = "SIGABRT";
break;
case SIGBUS:
signal_name = "SIGBUS";
has_address = true;
break;
case SIGFPE:
signal_name = "SIGFPE";
has_address = true;
break;
case SIGSEGV:
signal_name = "SIGSEGV";
has_address = true;
break;
#if defined(SIGSTKFLT)
case SIGSTKFLT: signal_name = "SIGSTKFLT"; break;
case SIGSTKFLT:
signal_name = "SIGSTKFLT";
break;
#endif
case SIGPIPE: signal_name = "SIGPIPE"; break;
default: signal_name = "???"; break;
}
case SIGPIPE:
signal_name = "SIGPIPE";
break;
}
char thread_name[MAX_TASK_NAME_LEN + 1]; // one more for termination
if (prctl(PR_GET_NAME, (unsigned long)thread_name, 0, 0, 0) != 0) {
strcpy(thread_name, "<name unknown>");
} else {
// short names are null terminated by prctl, but the man page
// implies that 16 byte names are not.
thread_name[MAX_TASK_NAME_LEN] = 0;
}
char thread_name[MAX_TASK_NAME_LEN + 1]; // one more for termination
if (prctl(PR_GET_NAME, (unsigned long)thread_name, 0, 0, 0) != 0) {
strcpy(thread_name, "<name unknown>");
} else {
// short names are null terminated by prctl, but the man page
// implies that 16 byte names are not.
thread_name[MAX_TASK_NAME_LEN] = 0;
}
// "info" will be NULL if the siginfo_t information was not available.
if (info != NULL) {
__libc_format_log(ANDROID_LOG_FATAL, "libc",
"Fatal signal %d (%s) at %p (code=%d), thread %d (%s)",
signum, signal_name, info->si_addr, info->si_code,
gettid(), thread_name);
} else {
__libc_format_log(ANDROID_LOG_FATAL, "libc",
"Fatal signal %d (%s), thread %d (%s)",
signum, signal_name, gettid(), thread_name);
// "info" will be NULL if the siginfo_t information was not available.
// Many signals don't have an address or a code.
char code_desc[32]; // ", code -6"
char addr_desc[32]; // ", fault addr 0x1234"
addr_desc[0] = code_desc[0] = 0;
if (info != NULL) {
// For a rethrown signal, this si_code will be right and the one debuggerd shows will
// always be SI_TKILL.
snprintf(code_desc, sizeof(code_desc), ", code %d", info->si_code);
if (has_address) {
snprintf(addr_desc, sizeof(addr_desc), ", fault addr %p", info->si_addr);
}
}
__libc_format_log(ANDROID_LOG_FATAL, "libc",
"Fatal signal %d (%s)%s%s in tid %d (%s)",
signum, signal_name, code_desc, addr_desc, gettid(), thread_name);
}
/*
* Returns true if the handler for signal "signum" has SA_SIGINFO set.
*/
static bool have_siginfo(int signum) {
struct sigaction old_action, new_action;
struct sigaction old_action, new_action;
memset(&new_action, 0, sizeof(new_action));
new_action.sa_handler = SIG_DFL;
new_action.sa_flags = SA_RESTART;
sigemptyset(&new_action.sa_mask);
memset(&new_action, 0, sizeof(new_action));
new_action.sa_handler = SIG_DFL;
new_action.sa_flags = SA_RESTART;
sigemptyset(&new_action.sa_mask);
if (sigaction(signum, &new_action, &old_action) < 0) {
__libc_format_log(ANDROID_LOG_WARN, "libc", "Failed testing for SA_SIGINFO: %s",
strerror(errno));
return false;
}
bool result = (old_action.sa_flags & SA_SIGINFO) != 0;
if (sigaction(signum, &new_action, &old_action) < 0) {
__libc_format_log(ANDROID_LOG_WARN, "libc", "Failed testing for SA_SIGINFO: %s",
strerror(errno));
return false;
}
bool result = (old_action.sa_flags & SA_SIGINFO) != 0;
if (sigaction(signum, &old_action, NULL) == -1) {
__libc_format_log(ANDROID_LOG_WARN, "libc", "Restore failed in test for SA_SIGINFO: %s",
strerror(errno));
}
return result;
if (sigaction(signum, &old_action, NULL) == -1) {
__libc_format_log(ANDROID_LOG_WARN, "libc", "Restore failed in test for SA_SIGINFO: %s",
strerror(errno));
}
return result;
}
/*
@ -181,87 +204,87 @@ static bool have_siginfo(int signum) {
* we crash.
*/
void debuggerd_signal_handler(int signal_number, siginfo_t* info, void*) {
// It's possible somebody cleared the SA_SIGINFO flag, which would mean
// our "info" arg holds an undefined value.
if (!have_siginfo(signal_number)) {
info = NULL;
// It's possible somebody cleared the SA_SIGINFO flag, which would mean
// our "info" arg holds an undefined value.
if (!have_siginfo(signal_number)) {
info = NULL;
}
log_signal_summary(signal_number, info);
int s = socket_abstract_client(DEBUGGER_SOCKET_NAME, SOCK_STREAM);
if (s != -1) {
// debuggerd knows our pid from the credentials on the
// local socket but we need to tell it the tid of the crashing thread.
// debuggerd will be paranoid and verify that we sent a tid
// that's actually in our process.
debugger_msg_t msg;
msg.action = DEBUGGER_ACTION_CRASH;
msg.tid = gettid();
msg.abort_msg_address = reinterpret_cast<uintptr_t>(gAbortMessage);
int ret = TEMP_FAILURE_RETRY(write(s, &msg, sizeof(msg)));
if (ret == sizeof(msg)) {
// If the write failed, there is no point trying to read a response.
char debuggerd_ack;
ret = TEMP_FAILURE_RETRY(read(s, &debuggerd_ack, 1));
int saved_errno = errno;
notify_gdb_of_libraries();
errno = saved_errno;
}
log_signal_summary(signal_number, info);
int s = socket_abstract_client(DEBUGGER_SOCKET_NAME, SOCK_STREAM);
if (s != -1) {
// debuggerd knows our pid from the credentials on the
// local socket but we need to tell it the tid of the crashing thread.
// debuggerd will be paranoid and verify that we sent a tid
// that's actually in our process.
debugger_msg_t msg;
msg.action = DEBUGGER_ACTION_CRASH;
msg.tid = gettid();
msg.abort_msg_address = reinterpret_cast<uintptr_t>(gAbortMessage);
int ret = TEMP_FAILURE_RETRY(write(s, &msg, sizeof(msg)));
if (ret == sizeof(msg)) {
// If the write failed, there is no point trying to read a response.
char debuggerd_ack;
ret = TEMP_FAILURE_RETRY(read(s, &debuggerd_ack, 1));
int saved_errno = errno;
notify_gdb_of_libraries();
errno = saved_errno;
}
if (ret < 0) {
// read or write failed -- broken connection?
__libc_format_log(ANDROID_LOG_FATAL, "libc", "Failed while talking to debuggerd: %s",
strerror(errno));
}
close(s);
} else {
// socket failed; maybe process ran out of fds?
__libc_format_log(ANDROID_LOG_FATAL, "libc", "Unable to open connection to debuggerd: %s",
strerror(errno));
if (ret < 0) {
// read or write failed -- broken connection?
__libc_format_log(ANDROID_LOG_FATAL, "libc", "Failed while talking to debuggerd: %s",
strerror(errno));
}
// Remove our net so we fault for real when we return.
signal(signal_number, SIG_DFL);
close(s);
} else {
// socket failed; maybe process ran out of fds?
__libc_format_log(ANDROID_LOG_FATAL, "libc", "Unable to open connection to debuggerd: %s",
strerror(errno));
}
// These signals are not re-thrown when we resume. This means that
// crashing due to (say) SIGPIPE doesn't work the way you'd expect it
// to. We work around this by throwing them manually. We don't want
// to do this for *all* signals because it'll screw up the address for
// faults like SIGSEGV.
switch (signal_number) {
case SIGABRT:
case SIGFPE:
case SIGPIPE:
// Remove our net so we fault for real when we return.
signal(signal_number, SIG_DFL);
// These signals are not re-thrown when we resume. This means that
// crashing due to (say) SIGPIPE doesn't work the way you'd expect it
// to. We work around this by throwing them manually. We don't want
// to do this for *all* signals because it'll screw up the address for
// faults like SIGSEGV.
switch (signal_number) {
case SIGABRT:
case SIGFPE:
case SIGPIPE:
#if defined(SIGSTKFLT)
case SIGSTKFLT:
case SIGSTKFLT:
#endif
tgkill(getpid(), gettid(), signal_number);
break;
default: // SIGILL, SIGBUS, SIGSEGV
break;
}
tgkill(getpid(), gettid(), signal_number);
break;
default: // SIGILL, SIGBUS, SIGSEGV
break;
}
}
void debuggerd_init() {
struct sigaction action;
memset(&action, 0, sizeof(action));
sigemptyset(&action.sa_mask);
action.sa_sigaction = debuggerd_signal_handler;
action.sa_flags = SA_RESTART | SA_SIGINFO;
struct sigaction action;
memset(&action, 0, sizeof(action));
sigemptyset(&action.sa_mask);
action.sa_sigaction = debuggerd_signal_handler;
action.sa_flags = SA_RESTART | SA_SIGINFO;
// Use the alternate signal stack if available so we can catch stack overflows.
action.sa_flags |= SA_ONSTACK;
// Use the alternate signal stack if available so we can catch stack overflows.
action.sa_flags |= SA_ONSTACK;
sigaction(SIGABRT, &action, NULL);
sigaction(SIGBUS, &action, NULL);
sigaction(SIGFPE, &action, NULL);
sigaction(SIGILL, &action, NULL);
sigaction(SIGPIPE, &action, NULL);
sigaction(SIGSEGV, &action, NULL);
sigaction(SIGABRT, &action, NULL);
sigaction(SIGBUS, &action, NULL);
sigaction(SIGFPE, &action, NULL);
sigaction(SIGILL, &action, NULL);
sigaction(SIGPIPE, &action, NULL);
sigaction(SIGSEGV, &action, NULL);
#if defined(SIGSTKFLT)
sigaction(SIGSTKFLT, &action, NULL);
sigaction(SIGSTKFLT, &action, NULL);
#endif
sigaction(SIGTRAP, &action, NULL);
sigaction(SIGTRAP, &action, NULL);
}