1649e7ee5b
And fix old style casts. Change-Id: I37e7a3e3fd852528ea76f02d967c7bd8cd5b06c9
307 lines
9.8 KiB
C++
307 lines
9.8 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "linker.h"
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#include <errno.h>
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#include <inttypes.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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#include <sys/prctl.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <unistd.h>
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extern "C" int tgkill(int tgid, int tid, int sig);
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// Crash actions have to be sent to the proper debuggerd.
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// On 64 bit systems, the 32 bit debuggerd is named differently.
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#if defined(TARGET_IS_64_BIT) && !defined(__LP64__)
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#define DEBUGGER_SOCKET_NAME "android:debuggerd32"
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#else
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#define DEBUGGER_SOCKET_NAME "android:debuggerd"
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#endif
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enum debugger_action_t {
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// dump a crash
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DEBUGGER_ACTION_CRASH,
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// dump a tombstone file
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DEBUGGER_ACTION_DUMP_TOMBSTONE,
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// dump a backtrace only back to the socket
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DEBUGGER_ACTION_DUMP_BACKTRACE,
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};
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/* message sent over the socket */
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struct __attribute__((packed)) debugger_msg_t {
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int32_t action;
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pid_t tid;
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uint64_t abort_msg_address;
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int32_t original_si_code;
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};
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// see man(2) prctl, specifically the section about PR_GET_NAME
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#define MAX_TASK_NAME_LEN (16)
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static int socket_abstract_client(const char* name, int type) {
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sockaddr_un addr;
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// Test with length +1 for the *initial* '\0'.
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size_t namelen = strlen(name);
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if ((namelen + 1) > sizeof(addr.sun_path)) {
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errno = EINVAL;
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return -1;
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}
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// This is used for abstract socket namespace, we need
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// an initial '\0' at the start of the Unix socket path.
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//
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// Note: The path in this case is *not* supposed to be
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// '\0'-terminated. ("man 7 unix" for the gory details.)
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memset(&addr, 0, sizeof(addr));
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addr.sun_family = AF_LOCAL;
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addr.sun_path[0] = 0;
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memcpy(addr.sun_path + 1, name, namelen);
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socklen_t alen = namelen + offsetof(sockaddr_un, sun_path) + 1;
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int s = socket(AF_LOCAL, type, 0);
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if (s == -1) {
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return -1;
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}
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int rc = TEMP_FAILURE_RETRY(connect(s, reinterpret_cast<sockaddr*>(&addr), alen));
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if (rc == -1) {
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close(s);
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return -1;
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}
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return s;
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}
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/*
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* Writes a summary of the signal to the log file. We do this so that, if
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* for some reason we're not able to contact debuggerd, there is still some
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* indication of the failure in the log.
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*
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* We could be here as a result of native heap corruption, or while a
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* mutex is being held, so we don't want to use any libc functions that
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* could allocate memory or hold a lock.
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*/
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static void log_signal_summary(int signum, const siginfo_t* info) {
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const char* signal_name = "???";
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bool has_address = false;
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switch (signum) {
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case SIGABRT:
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signal_name = "SIGABRT";
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break;
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case SIGBUS:
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signal_name = "SIGBUS";
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has_address = true;
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break;
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case SIGFPE:
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signal_name = "SIGFPE";
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has_address = true;
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break;
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case SIGILL:
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signal_name = "SIGILL";
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has_address = true;
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break;
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case SIGPIPE:
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signal_name = "SIGPIPE";
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break;
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case SIGSEGV:
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signal_name = "SIGSEGV";
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has_address = true;
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break;
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#if defined(SIGSTKFLT)
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case SIGSTKFLT:
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signal_name = "SIGSTKFLT";
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break;
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#endif
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case SIGTRAP:
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signal_name = "SIGTRAP";
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break;
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}
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char thread_name[MAX_TASK_NAME_LEN + 1]; // one more for termination
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if (prctl(PR_GET_NAME, reinterpret_cast<unsigned long>(thread_name), 0, 0, 0) != 0) {
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strcpy(thread_name, "<name unknown>");
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} else {
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// short names are null terminated by prctl, but the man page
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// implies that 16 byte names are not.
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thread_name[MAX_TASK_NAME_LEN] = 0;
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}
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// "info" will be null if the siginfo_t information was not available.
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// Many signals don't have an address or a code.
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char code_desc[32]; // ", code -6"
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char addr_desc[32]; // ", fault addr 0x1234"
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addr_desc[0] = code_desc[0] = 0;
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if (info != nullptr) {
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// For a rethrown signal, this si_code will be right and the one debuggerd shows will
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// always be SI_TKILL.
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__libc_format_buffer(code_desc, sizeof(code_desc), ", code %d", info->si_code);
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if (has_address) {
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__libc_format_buffer(addr_desc, sizeof(addr_desc), ", fault addr %p", info->si_addr);
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}
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}
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__libc_format_log(ANDROID_LOG_FATAL, "libc",
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"Fatal signal %d (%s)%s%s in tid %d (%s)",
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signum, signal_name, code_desc, addr_desc, gettid(), thread_name);
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}
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/*
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* Returns true if the handler for signal "signum" has SA_SIGINFO set.
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*/
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static bool have_siginfo(int signum) {
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struct sigaction old_action, new_action;
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memset(&new_action, 0, sizeof(new_action));
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new_action.sa_handler = SIG_DFL;
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new_action.sa_flags = SA_RESTART;
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sigemptyset(&new_action.sa_mask);
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if (sigaction(signum, &new_action, &old_action) < 0) {
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__libc_format_log(ANDROID_LOG_WARN, "libc", "Failed testing for SA_SIGINFO: %s",
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strerror(errno));
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return false;
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}
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bool result = (old_action.sa_flags & SA_SIGINFO) != 0;
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if (sigaction(signum, &old_action, nullptr) == -1) {
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__libc_format_log(ANDROID_LOG_WARN, "libc", "Restore failed in test for SA_SIGINFO: %s",
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strerror(errno));
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}
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return result;
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}
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static void send_debuggerd_packet(siginfo_t* info) {
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if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0) {
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// process has disabled core dumps and PTRACE_ATTACH, and does not want to be dumped.
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// Honor that intention by not connecting to debuggerd and asking it
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// to dump our internal state.
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__libc_format_log(ANDROID_LOG_INFO, "libc",
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"Suppressing debuggerd output because prctl(PR_GET_DUMPABLE)==0");
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return;
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}
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int s = socket_abstract_client(DEBUGGER_SOCKET_NAME, SOCK_STREAM | SOCK_CLOEXEC);
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if (s == -1) {
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__libc_format_log(ANDROID_LOG_FATAL, "libc", "Unable to open connection to debuggerd: %s",
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strerror(errno));
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return;
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}
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// debuggerd knows our pid from the credentials on the
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// local socket but we need to tell it the tid of the crashing thread.
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// debuggerd will be paranoid and verify that we sent a tid
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// that's actually in our process.
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debugger_msg_t msg;
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msg.action = DEBUGGER_ACTION_CRASH;
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msg.tid = gettid();
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msg.abort_msg_address = reinterpret_cast<uintptr_t>(g_abort_message);
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msg.original_si_code = (info != nullptr) ? info->si_code : 0;
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int ret = TEMP_FAILURE_RETRY(write(s, &msg, sizeof(msg)));
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if (ret == sizeof(msg)) {
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char debuggerd_ack;
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ret = TEMP_FAILURE_RETRY(read(s, &debuggerd_ack, 1));
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int saved_errno = errno;
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notify_gdb_of_libraries();
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errno = saved_errno;
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} else {
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// read or write failed -- broken connection?
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__libc_format_log(ANDROID_LOG_FATAL, "libc", "Failed while talking to debuggerd: %s",
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strerror(errno));
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}
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close(s);
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}
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/*
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* Catches fatal signals so we can ask debuggerd to ptrace us before
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* we crash.
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*/
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static void debuggerd_signal_handler(int signal_number, siginfo_t* info, void*) {
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// It's possible somebody cleared the SA_SIGINFO flag, which would mean
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// our "info" arg holds an undefined value.
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if (!have_siginfo(signal_number)) {
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info = nullptr;
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}
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log_signal_summary(signal_number, info);
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send_debuggerd_packet(info);
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// Remove our net so we fault for real when we return.
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signal(signal_number, SIG_DFL);
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// These signals are not re-thrown when we resume. This means that
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// crashing due to (say) SIGPIPE doesn't work the way you'd expect it
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// to. We work around this by throwing them manually. We don't want
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// to do this for *all* signals because it'll screw up the si_addr for
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// faults like SIGSEGV. It does screw up the si_code, which is why we
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// passed that to debuggerd above.
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switch (signal_number) {
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case SIGABRT:
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case SIGFPE:
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case SIGPIPE:
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#if defined(SIGSTKFLT)
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case SIGSTKFLT:
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#endif
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case SIGTRAP:
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tgkill(getpid(), gettid(), signal_number);
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break;
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default: // SIGILL, SIGBUS, SIGSEGV
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break;
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}
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}
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__LIBC_HIDDEN__ void debuggerd_init() {
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struct sigaction action;
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memset(&action, 0, sizeof(action));
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sigemptyset(&action.sa_mask);
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action.sa_sigaction = debuggerd_signal_handler;
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action.sa_flags = SA_RESTART | SA_SIGINFO;
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// Use the alternate signal stack if available so we can catch stack overflows.
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action.sa_flags |= SA_ONSTACK;
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sigaction(SIGABRT, &action, nullptr);
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sigaction(SIGBUS, &action, nullptr);
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sigaction(SIGFPE, &action, nullptr);
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sigaction(SIGILL, &action, nullptr);
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sigaction(SIGPIPE, &action, nullptr);
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sigaction(SIGSEGV, &action, nullptr);
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#if defined(SIGSTKFLT)
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sigaction(SIGSTKFLT, &action, nullptr);
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#endif
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sigaction(SIGTRAP, &action, nullptr);
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}
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