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/*
* Copyright 2008, 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.
*/
#define LOG_TAG "DEBUG"
#include "utility.h"
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <unistd.h>
#include <string>
#include <android-base/stringprintf.h>
#include <backtrace/Backtrace.h>
#include <log/log.h>
// Whitelist output desired in the logcat output.
bool is_allowed_in_logcat(enum logtype ltype) {
if ((ltype == HEADER)
|| (ltype == REGISTERS)
|| (ltype == BACKTRACE)) {
return true;
}
return false;
}
__attribute__((__weak__, visibility("default")))
void _LOG(log_t* log, enum logtype ltype, const char* fmt, ...) {
bool write_to_tombstone = (log->tfd != -1);
bool write_to_logcat = is_allowed_in_logcat(ltype)
&& log->crashed_tid != -1
&& log->current_tid != -1
&& (log->crashed_tid == log->current_tid);
char buf[512];
va_list ap;
va_start(ap, fmt);
vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
size_t len = strlen(buf);
if (len <= 0) {
return;
}
if (write_to_tombstone) {
TEMP_FAILURE_RETRY(write(log->tfd, buf, len));
}
if (write_to_logcat) {
__android_log_buf_write(LOG_ID_CRASH, ANDROID_LOG_FATAL, LOG_TAG, buf);
if (log->amfd_data != nullptr) {
*log->amfd_data += buf;
}
}
}
bool wait_for_signal(pid_t tid, siginfo_t* siginfo) {
while (true) {
int status;
pid_t n = TEMP_FAILURE_RETRY(waitpid(tid, &status, __WALL));
if (n == -1) {
ALOGE("waitpid failed: tid %d, %s", tid, strerror(errno));
return false;
} else if (n == tid) {
if (WIFSTOPPED(status)) {
if (ptrace(PTRACE_GETSIGINFO, tid, nullptr, siginfo) != 0) {
ALOGE("PTRACE_GETSIGINFO failed: %s", strerror(errno));
return false;
}
return true;
} else {
ALOGE("unexpected waitpid response: n=%d, status=%08x\n", n, status);
// This is the only circumstance under which we can allow a detach
// to fail with ESRCH, which indicates the tid has exited.
return false;
}
}
}
}
#define MEMORY_BYTES_TO_DUMP 256
#define MEMORY_BYTES_PER_LINE 16
void dump_memory(log_t* log, Backtrace* backtrace, uintptr_t addr, const char* fmt, ...) {
std::string log_msg;
va_list ap;
va_start(ap, fmt);
android::base::StringAppendV(&log_msg, fmt, ap);
va_end(ap);
// Align the address to sizeof(long) and start 32 bytes before the address.
addr &= ~(sizeof(long) - 1);
if (addr >= 4128) {
addr -= 32;
}
// Don't bother if the address looks too low, or looks too high.
if (addr < 4096 ||
#if defined(__LP64__)
addr > 0x4000000000000000UL - MEMORY_BYTES_TO_DUMP) {
#else
addr > 0xffff0000 - MEMORY_BYTES_TO_DUMP) {
#endif
return;
}
_LOG(log, logtype::MEMORY, "\n%s\n", log_msg.c_str());
// Dump 256 bytes
uintptr_t data[MEMORY_BYTES_TO_DUMP/sizeof(uintptr_t)];
memset(data, 0, MEMORY_BYTES_TO_DUMP);
size_t bytes = backtrace->Read(addr, reinterpret_cast<uint8_t*>(data), sizeof(data));
if (bytes % sizeof(uintptr_t) != 0) {
// This should never happen, but just in case.
ALOGE("Bytes read %zu, is not a multiple of %zu", bytes, sizeof(uintptr_t));
bytes &= ~(sizeof(uintptr_t) - 1);
}
uintptr_t start = 0;
bool skip_2nd_read = false;
if (bytes == 0) {
// In this case, we might want to try another read at the beginning of
// the next page only if it's within the amount of memory we would have
// read.
size_t page_size = sysconf(_SC_PAGE_SIZE);
start = ((addr + (page_size - 1)) & ~(page_size - 1)) - addr;
if (start == 0 || start >= MEMORY_BYTES_TO_DUMP) {
skip_2nd_read = true;
}
}
if (bytes < MEMORY_BYTES_TO_DUMP && !skip_2nd_read) {
// Try to do one more read. This could happen if a read crosses a map,
// but the maps do not have any break between them. Or it could happen
// if reading from an unreadable map, but the read would cross back
// into a readable map. Only requires one extra read because a map has
// to contain at least one page, and the total number of bytes to dump
// is smaller than a page.
size_t bytes2 = backtrace->Read(addr + start + bytes, reinterpret_cast<uint8_t*>(data) + bytes,
sizeof(data) - bytes - start);
bytes += bytes2;
if (bytes2 > 0 && bytes % sizeof(uintptr_t) != 0) {
// This should never happen, but we'll try and continue any way.
ALOGE("Bytes after second read %zu, is not a multiple of %zu", bytes, sizeof(uintptr_t));
bytes &= ~(sizeof(uintptr_t) - 1);
}
}
// Dump the code around memory as:
// addr contents ascii
// 0000000000008d34 ef000000e8bd0090 e1b00000512fff1e ............../Q
// 0000000000008d44 ea00b1f9e92d0090 e3a070fcef000000 ......-..p......
// On 32-bit machines, there are still 16 bytes per line but addresses and
// words are of course presented differently.
uintptr_t* data_ptr = data;
size_t current = 0;
size_t total_bytes = start + bytes;
for (size_t line = 0; line < MEMORY_BYTES_TO_DUMP / MEMORY_BYTES_PER_LINE; line++) {
std::string logline;
android::base::StringAppendF(&logline, " %" PRIPTR, addr);
addr += MEMORY_BYTES_PER_LINE;
std::string ascii;
for (size_t i = 0; i < MEMORY_BYTES_PER_LINE / sizeof(uintptr_t); i++) {
if (current >= start && current + sizeof(uintptr_t) <= total_bytes) {
android::base::StringAppendF(&logline, " %" PRIPTR, *data_ptr);
// Fill out the ascii string from the data.
uint8_t* ptr = reinterpret_cast<uint8_t*>(data_ptr);
for (size_t val = 0; val < sizeof(uintptr_t); val++, ptr++) {
if (*ptr >= 0x20 && *ptr < 0x7f) {
ascii += *ptr;
} else {
ascii += '.';
}
}
data_ptr++;
} else {
logline += ' ' + std::string(sizeof(uintptr_t) * 2, '-');
ascii += std::string(sizeof(uintptr_t), '.');
}
current += sizeof(uintptr_t);
}
_LOG(log, logtype::MEMORY, "%s %s\n", logline.c_str(), ascii.c_str());
}
}
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