Create a single backtrace library.
This library will be used to abstract away getting backtrace
data from how it is implemented. This is the first step to
replacing libcorkscrew with libunwind.
Bug: 8410085
Change-Id: Ie8f159e96a055d378e1ddc72d40239fba4cf52b7
diff --git a/libbacktrace/common.c b/libbacktrace/common.c
new file mode 100644
index 0000000..20786f4
--- /dev/null
+++ b/libbacktrace/common.c
@@ -0,0 +1,113 @@
+/*
+ * 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;
+}