Rewrite libbacktrace using C++.
The old code was essentially trying to be C++ in C and was awkward. This
change makes it all objects with a thin layer that C code can use.
There is a C++ backtrace object that is not very useful, this code will
replace it.
This change also includes moving the backtrace test to a gtest, and adding
coverage of all major functionality.
Bug: 8410085
Change-Id: Iae0f1b09b3dd60395f71ed66010c1ea5cdd37841
diff --git a/libbacktrace/UnwindPtrace.cpp b/libbacktrace/UnwindPtrace.cpp
new file mode 100644
index 0000000..628caa0
--- /dev/null
+++ b/libbacktrace/UnwindPtrace.cpp
@@ -0,0 +1,136 @@
+/*
+ * 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 <backtrace/backtrace.h>
+
+#include <sys/types.h>
+#include <string.h>
+
+#include <cutils/log.h>
+
+#include <libunwind.h>
+#include <libunwind-ptrace.h>
+
+#include "UnwindPtrace.h"
+
+UnwindPtrace::UnwindPtrace() : addr_space_(NULL), upt_info_(NULL) {
+}
+
+UnwindPtrace::~UnwindPtrace() {
+ if (upt_info_) {
+ _UPT_destroy(upt_info_);
+ upt_info_ = NULL;
+ }
+ if (addr_space_) {
+ unw_destroy_addr_space(addr_space_);
+ addr_space_ = NULL;
+ }
+}
+
+bool UnwindPtrace::Unwind(size_t num_ignore_frames) {
+ addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
+ if (!addr_space_) {
+ ALOGW("UnwindPtrace::Unwind: unw_create_addr_space failed.\n");
+ return false;
+ }
+
+ upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(backtrace_obj_->Tid()));
+ if (!upt_info_) {
+ ALOGW("UnwindPtrace::Unwind: Failed to create upt info.\n");
+ return false;
+ }
+
+ backtrace_t* backtrace = GetBacktraceData();
+ backtrace->num_frames = 0;
+
+ unw_cursor_t cursor;
+ int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
+ if (ret < 0) {
+ ALOGW("UnwindPtrace::Unwind: unw_init_remote failed %d\n", ret);
+ return false;
+ }
+
+ do {
+ unw_word_t pc;
+ ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
+ if (ret < 0) {
+ ALOGW("UnwindPtrace::Unwind: Failed to read IP %d\n", ret);
+ break;
+ }
+ unw_word_t sp;
+ ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
+ if (ret < 0) {
+ ALOGW("UnwindPtrace::Unwind: Failed to read SP %d\n", ret);
+ break;
+ }
+
+ if (num_ignore_frames == 0) {
+ size_t num_frames = backtrace->num_frames;
+ backtrace_frame_data_t* frame = &backtrace->frames[num_frames];
+ frame->pc = static_cast<uintptr_t>(pc);
+ frame->sp = static_cast<uintptr_t>(sp);
+ frame->stack_size = 0;
+ frame->map_name = NULL;
+ frame->map_offset = 0;
+ frame->func_name = NULL;
+ frame->func_offset = 0;
+
+ if (num_frames > 0) {
+ backtrace_frame_data_t* prev = &backtrace->frames[num_frames-1];
+ prev->stack_size = frame->sp - prev->sp;
+ }
+
+ std::string func_name = backtrace_obj_->GetFunctionName(frame->pc, &frame->func_offset);
+ if (!func_name.empty()) {
+ frame->func_name = strdup(func_name.c_str());
+ }
+
+ uintptr_t map_start;
+ frame->map_name = backtrace_obj_->GetMapName(frame->pc, &map_start);
+ if (frame->map_name) {
+ frame->map_offset = frame->pc - map_start;
+ }
+
+ backtrace->num_frames++;
+ } else {
+ num_ignore_frames--;
+ }
+ ret = unw_step (&cursor);
+ } while (ret > 0 && backtrace->num_frames < MAX_BACKTRACE_FRAMES);
+
+ return true;
+}
+
+std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
+ *offset = 0;
+ char buf[512];
+ unw_word_t value;
+ if (unw_get_proc_name_by_ip(addr_space_, pc, buf, sizeof(buf), &value,
+ upt_info_) >= 0 && buf[0] != '\0') {
+ *offset = static_cast<uintptr_t>(value);
+ return buf;
+ }
+ return "";
+}
+
+//-------------------------------------------------------------------------
+// C++ object creation function.
+//-------------------------------------------------------------------------
+Backtrace* CreatePtraceObj(pid_t pid, pid_t tid) {
+ return new BacktracePtrace(new UnwindPtrace(), pid, tid);
+}