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/*
* Copyright (C) 2013 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 "libbacktrace"
#include <errno.h>
#include <stdlib.h>
#include <sys/ptrace.h>
#include <inttypes.h>
#include <cutils/log.h>
#include <backtrace/backtrace.h>
#include "common.h"
bool backtrace_read_word(const backtrace_t* backtrace, uintptr_t ptr,
uint32_t* out_value) {
if (ptr & 3) {
ALOGW("backtrace_read_word: invalid pointer %p", (void*)ptr);
*out_value = (uint32_t)-1;
return false;
}
// Check if reading from the current process, or a different process.
if (backtrace->tid < 0) {
const backtrace_map_info_t* map_info = backtrace_find_map_info(backtrace->map_info_list, ptr);
if (map_info && map_info->is_readable) {
*out_value = *(uint32_t*)ptr;
return true;
} else {
ALOGW("backtrace_read_word: pointer %p not in a readbale map", (void*)ptr);
*out_value = (uint32_t)-1;
return false;
}
} else {
#if defined(__APPLE__)
ALOGW("read_word: MacOS does not support reading from another pid.\n");
return false;
#else
// ptrace() returns -1 and sets errno when the operation fails.
// To disambiguate -1 from a valid result, we clear errno beforehand.
errno = 0;
*out_value = ptrace(PTRACE_PEEKTEXT, backtrace->tid, (void*)ptr, NULL);
if (*out_value == (uint32_t)-1 && errno) {
ALOGW("try_get_word: invalid pointer 0x%08x reading from tid %d, "
"ptrace() errno=%d", ptr, backtrace->tid, errno);
return false;
}
return true;
}
#endif
}
const char *backtrace_get_map_info(
const backtrace_t* backtrace, uintptr_t pc, uintptr_t* start_pc) {
const backtrace_map_info_t* map_info = backtrace_find_map_info(backtrace->map_info_list, pc);
if (map_info) {
if (start_pc) {
*start_pc = map_info->start;
}
return map_info->name;
}
return NULL;
}
void backtrace_format_frame_data(
const backtrace_frame_data_t* frame, size_t frame_num, char *buf, size_t buf_size) {
uintptr_t relative_pc;
const char* map_name;
if (frame->map_name) {
map_name = frame->map_name;
} else {
map_name = "<unknown>";
}
if (frame->map_offset) {
relative_pc = frame->map_offset;
} else {
relative_pc = frame->pc;
}
if (frame->proc_name && frame->proc_offset) {
snprintf(buf, buf_size, "#%02zu pc %0*" PRIxPTR " %s (%s+%" PRIuPTR ")",
frame_num, (int)sizeof(uintptr_t)*2, relative_pc, map_name,
frame->proc_name, frame->proc_offset);
} else if (frame->proc_name) {
snprintf(buf, buf_size, "#%02zu pc %0*" PRIxPTR " %s (%s)", frame_num,
(int)sizeof(uintptr_t)*2, relative_pc, map_name, frame->proc_name);
} else {
snprintf(buf, buf_size, "#%02zu pc %0*" PRIxPTR " %s", frame_num,
(int)sizeof(uintptr_t)*2, relative_pc, map_name);
}
}
void free_frame_data(backtrace_t* backtrace) {
for (size_t i = 0; i < backtrace->num_frames; i++) {
if (backtrace->frames[i].proc_name) {
free(backtrace->frames[i].proc_name);
}
}
backtrace->num_frames = 0;
}
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