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/Backtrace.cpp b/libbacktrace/Backtrace.cpp
new file mode 100644
index 0000000..eca1c3d
--- /dev/null
+++ b/libbacktrace/Backtrace.cpp
@@ -0,0 +1,312 @@
+/*
+ * 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.
+ */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#define __STDC_FORMAT_MACROS
+#include <inttypes.h>
+
+#include <string>
+
+#include <backtrace/Backtrace.h>
+#include <cutils/log.h>
+
+#include "Backtrace.h"
+#include "thread_utils.h"
+
+//-------------------------------------------------------------------------
+// BacktraceImpl functions.
+//-------------------------------------------------------------------------
+backtrace_t* BacktraceImpl::GetBacktraceData() {
+ return &backtrace_obj_->backtrace_;
+}
+
+//-------------------------------------------------------------------------
+// Backtrace functions.
+//-------------------------------------------------------------------------
+Backtrace::Backtrace(BacktraceImpl* impl) : impl_(impl), map_info_(NULL) {
+ impl_->SetParent(this);
+ backtrace_.num_frames = 0;
+ backtrace_.pid = -1;
+ backtrace_.tid = -1;
+}
+
+Backtrace::~Backtrace() {
+ for (size_t i = 0; i < NumFrames(); i++) {
+ if (backtrace_.frames[i].func_name) {
+ free(backtrace_.frames[i].func_name);
+ backtrace_.frames[i].func_name = NULL;
+ }
+ }
+
+ if (map_info_) {
+ backtrace_destroy_map_info_list(map_info_);
+ map_info_ = NULL;
+ }
+
+ if (impl_) {
+ delete impl_;
+ impl_ = NULL;
+ }
+}
+
+bool Backtrace::Unwind(size_t num_ignore_frames) {
+ return impl_->Unwind(num_ignore_frames);
+}
+
+__BEGIN_DECLS
+extern char* __cxa_demangle (const char* mangled, char* buf, size_t* len,
+ int* status);
+__END_DECLS
+
+std::string Backtrace::GetFunctionName(uintptr_t pc, uintptr_t* offset) {
+ std::string func_name = impl_->GetFunctionNameRaw(pc, offset);
+ if (!func_name.empty()) {
+#if defined(__APPLE__)
+ // Mac OS' __cxa_demangle demangles "f" as "float"; last tested on 10.7.
+ if (symbol_name[0] != '_') {
+ return func_name;
+ }
+#endif
+ char* name = __cxa_demangle(func_name.c_str(), 0, 0, 0);
+ if (name) {
+ func_name = name;
+ free(name);
+ }
+ }
+ return func_name;
+}
+
+bool Backtrace::VerifyReadWordArgs(uintptr_t ptr, uint32_t* out_value) {
+ if (ptr & 3) {
+ ALOGW("Backtrace::verifyReadWordArgs: invalid pointer %p", (void*)ptr);
+ *out_value = (uint32_t)-1;
+ return false;
+ }
+ return true;
+}
+
+const char* Backtrace::GetMapName(uintptr_t pc, uintptr_t* map_start) {
+ const backtrace_map_info_t* map_info = FindMapInfo(pc);
+ if (map_info) {
+ if (map_start) {
+ *map_start = map_info->start;
+ }
+ return map_info->name;
+ }
+ return NULL;
+}
+
+const backtrace_map_info_t* Backtrace::FindMapInfo(uintptr_t ptr) {
+ return backtrace_find_map_info(map_info_, ptr);
+}
+
+std::string Backtrace::FormatFrameData(size_t frame_num) {
+ backtrace_frame_data_t* frame = &backtrace_.frames[frame_num];
+ const char* map_name;
+ if (frame->map_name) {
+ map_name = frame->map_name;
+ } else {
+ map_name = "<unknown>";
+ }
+ uintptr_t relative_pc;
+ if (frame->map_offset) {
+ relative_pc = frame->map_offset;
+ } else {
+ relative_pc = frame->pc;
+ }
+
+ char buf[512];
+ if (frame->func_name && frame->func_offset) {
+ snprintf(buf, sizeof(buf), "#%02zu pc %0*" PRIxPTR " %s (%s+%" PRIuPTR ")",
+ frame_num, (int)sizeof(uintptr_t)*2, relative_pc, map_name,
+ frame->func_name, frame->func_offset);
+ } else if (frame->func_name) {
+ snprintf(buf, sizeof(buf), "#%02zu pc %0*" PRIxPTR " %s (%s)", frame_num,
+ (int)sizeof(uintptr_t)*2, relative_pc, map_name, frame->func_name);
+ } else {
+ snprintf(buf, sizeof(buf), "#%02zu pc %0*" PRIxPTR " %s", frame_num,
+ (int)sizeof(uintptr_t)*2, relative_pc, map_name);
+ }
+
+ return buf;
+}
+
+//-------------------------------------------------------------------------
+// BacktraceCurrent functions.
+//-------------------------------------------------------------------------
+BacktraceCurrent::BacktraceCurrent(BacktraceImpl* impl) : Backtrace(impl) {
+ map_info_ = backtrace_create_map_info_list(-1);
+
+ backtrace_.pid = getpid();
+}
+
+BacktraceCurrent::~BacktraceCurrent() {
+}
+
+bool BacktraceCurrent::ReadWord(uintptr_t ptr, uint32_t* out_value) {
+ if (!VerifyReadWordArgs(ptr, out_value)) {
+ return false;
+ }
+
+ const backtrace_map_info_t* map_info = FindMapInfo(ptr);
+ if (map_info && map_info->is_readable) {
+ *out_value = *reinterpret_cast<uint32_t*>(ptr);
+ return true;
+ } else {
+ ALOGW("BacktraceCurrent::readWord: pointer %p not in a readbale map", reinterpret_cast<void*>(ptr));
+ *out_value = static_cast<uint32_t>(-1);
+ return false;
+ }
+}
+
+//-------------------------------------------------------------------------
+// BacktracePtrace functions.
+//-------------------------------------------------------------------------
+BacktracePtrace::BacktracePtrace(BacktraceImpl* impl, pid_t pid, pid_t tid)
+ : Backtrace(impl) {
+ map_info_ = backtrace_create_map_info_list(tid);
+
+ backtrace_.pid = pid;
+ backtrace_.tid = tid;
+}
+
+BacktracePtrace::~BacktracePtrace() {
+}
+
+bool BacktracePtrace::ReadWord(uintptr_t ptr, uint32_t* out_value) {
+ if (!VerifyReadWordArgs(ptr, out_value)) {
+ return false;
+ }
+
+#if defined(__APPLE__)
+ ALOGW("BacktracePtrace::readWord: 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, Tid(), reinterpret_cast<void*>(ptr), NULL);
+ if (*out_value == static_cast<uint32_t>(-1) && errno) {
+ ALOGW("BacktracePtrace::readWord: invalid pointer 0x%08x reading from tid %d, "
+ "ptrace() errno=%d", ptr, Tid(), errno);
+ return false;
+ }
+ return true;
+#endif
+}
+
+Backtrace* Backtrace::Create(pid_t pid, pid_t tid) {
+ if (pid < 0 || pid == getpid()) {
+ if (tid < 0 || tid == gettid()) {
+ return CreateCurrentObj();
+ } else {
+ return CreateThreadObj(tid);
+ }
+ } else if (tid < 0) {
+ return CreatePtraceObj(pid, pid);
+ } else {
+ return CreatePtraceObj(pid, tid);
+ }
+}
+
+//-------------------------------------------------------------------------
+// Common interface functions.
+//-------------------------------------------------------------------------
+bool backtrace_create_context(
+ backtrace_context_t* context, pid_t pid, pid_t tid, size_t num_ignore_frames) {
+ Backtrace* backtrace = Backtrace::Create(pid, tid);
+ if (!backtrace) {
+ return false;
+ }
+ if (!backtrace->Unwind(num_ignore_frames)) {
+ delete backtrace;
+ return false;
+ }
+
+ context->data = backtrace;
+ context->backtrace = backtrace->GetBacktrace();
+ return true;
+}
+
+void backtrace_destroy_context(backtrace_context_t* context) {
+ if (context->data) {
+ Backtrace* backtrace = reinterpret_cast<Backtrace*>(context->data);
+ delete backtrace;
+ context->data = NULL;
+ }
+ context->backtrace = NULL;
+}
+
+const backtrace_t* backtrace_get_data(backtrace_context_t* context) {
+ if (context && context->data) {
+ Backtrace* backtrace = reinterpret_cast<Backtrace*>(context->data);
+ return backtrace->GetBacktrace();
+ }
+ return NULL;
+}
+
+bool backtrace_read_word(const backtrace_context_t* context, uintptr_t ptr, uint32_t* value) {
+ if (context->data) {
+ Backtrace* backtrace = reinterpret_cast<Backtrace*>(context->data);
+ return backtrace->ReadWord(ptr, value);
+ }
+ return true;
+}
+
+const char* backtrace_get_map_name(const backtrace_context_t* context, uintptr_t pc, uintptr_t* map_start) {
+ if (context->data) {
+ Backtrace* backtrace = reinterpret_cast<Backtrace*>(context->data);
+ return backtrace->GetMapName(pc, map_start);
+ }
+ return NULL;
+}
+
+char* backtrace_get_func_name(const backtrace_context_t* context, uintptr_t pc, uintptr_t* func_offset) {
+ if (context->data) {
+ Backtrace* backtrace = reinterpret_cast<Backtrace*>(context->data);
+ std::string func_name = backtrace->GetFunctionName(pc, func_offset);
+ if (!func_name.empty()) {
+ return strdup(func_name.c_str());
+ }
+ }
+ return NULL;
+}
+
+void backtrace_format_frame_data(
+ const backtrace_context_t* context, size_t frame_num, char* buf,
+ size_t buf_size) {
+ if (buf_size == 0 || buf == NULL) {
+ ALOGW("backtrace_format_frame_data: bad call buf %p buf_size %zu\n",
+ buf, buf_size);
+ return;
+ }
+ if (context->data) {
+ Backtrace* backtrace = reinterpret_cast<Backtrace*>(context->data);
+ std::string line = backtrace->FormatFrameData(frame_num);
+ if (line.size() > buf_size) {
+ memcpy(buf, line.c_str(), buf_size-1);
+ buf[buf_size] = '\0';
+ } else {
+ memcpy(buf, line.c_str(), line.size()+1);
+ }
+ }
+}