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/UnwindCurrent.cpp b/libbacktrace/UnwindCurrent.cpp
new file mode 100644
index 0000000..0280e93
--- /dev/null
+++ b/libbacktrace/UnwindCurrent.cpp
@@ -0,0 +1,222 @@
+/*
+ * 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 <sys/types.h>
+
+#include <cutils/log.h>
+
+#include <backtrace/backtrace.h>
+
+#define UNW_LOCAL_ONLY
+#include <libunwind.h>
+
+#include "UnwindCurrent.h"
+
+#if defined(__arm__)
+ #if !defined(__BIONIC_HAVE_UCONTEXT_T)
+ // The Current version of the Android <signal.h> doesn't define ucontext_t.
+ #include <asm/sigcontext.h> // Ensure 'struct sigcontext' is defined.
+
+ // Machine context at the time a signal was raised.
+ typedef struct ucontext {
+ uint32_t uc_flags;
+ struct ucontext* uc_link;
+ stack_t uc_stack;
+ struct sigcontext uc_mcontext;
+ uint32_t uc_sigmask;
+ } ucontext_t;
+ #endif // !__BIONIC_HAVE_UCONTEXT_T
+#endif // defined(__arm__)
+
+//-------------------------------------------------------------------------
+// UnwindCurrent functions.
+//-------------------------------------------------------------------------
+UnwindCurrent::UnwindCurrent() {
+}
+
+UnwindCurrent::~UnwindCurrent() {
+}
+
+bool UnwindCurrent::Unwind(size_t num_ignore_frames) {
+ int ret = unw_getcontext(&context_);
+ if (ret < 0) {
+ ALOGW("UnwindCurrent::Unwind: unw_getcontext failed %d\n", ret);
+ return false;
+ }
+ return UnwindFromContext(num_ignore_frames, true);
+}
+
+std::string UnwindCurrent::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
+ *offset = 0;
+ char buf[512];
+ unw_word_t value;
+ if (unw_get_proc_name_by_ip(unw_local_addr_space, pc, buf, sizeof(buf),
+ &value, &context_) >= 0 && buf[0] != '\0') {
+ *offset = static_cast<uintptr_t>(value);
+ return buf;
+ }
+ return "";
+}
+
+bool UnwindCurrent::UnwindFromContext(size_t num_ignore_frames, bool resolve) {
+ backtrace_t* backtrace = GetBacktraceData();
+ backtrace->num_frames = 0;
+
+ // The cursor structure is pretty large, do not put it on the stack.
+ unw_cursor_t* cursor = new unw_cursor_t;
+ int ret = unw_init_local(cursor, &context_);
+ if (ret < 0) {
+ ALOGW("UnwindCurrent::UnwindWithContext: unw_init_local failed %d\n", ret);
+ return false;
+ }
+
+ do {
+ unw_word_t pc;
+ ret = unw_get_reg(cursor, UNW_REG_IP, &pc);
+ if (ret < 0) {
+ ALOGW("UnwindCurrent::UnwindWithContext: 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("UnwindCurrent::UnwindWithContext: 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) {
+ // Set the stack size for the previous frame.
+ backtrace_frame_data_t* prev = &backtrace->frames[num_frames-1];
+ prev->stack_size = frame->sp - prev->sp;
+ }
+
+ if (resolve) {
+ 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);
+
+ delete cursor;
+ return true;
+}
+
+void UnwindCurrent::ExtractContext(void* sigcontext) {
+ unw_tdep_context_t* context = reinterpret_cast<unw_tdep_context_t*>(&context_);
+
+#if defined(__arm__)
+ const ucontext_t* uc = reinterpret_cast<const ucontext_t*>(sigcontext);
+
+ context->regs[0] = uc->uc_mcontext.arm_r0;
+ context->regs[1] = uc->uc_mcontext.arm_r1;
+ context->regs[2] = uc->uc_mcontext.arm_r2;
+ context->regs[3] = uc->uc_mcontext.arm_r3;
+ context->regs[4] = uc->uc_mcontext.arm_r4;
+ context->regs[5] = uc->uc_mcontext.arm_r5;
+ context->regs[6] = uc->uc_mcontext.arm_r6;
+ context->regs[7] = uc->uc_mcontext.arm_r7;
+ context->regs[8] = uc->uc_mcontext.arm_r8;
+ context->regs[9] = uc->uc_mcontext.arm_r9;
+ context->regs[10] = uc->uc_mcontext.arm_r10;
+ context->regs[11] = uc->uc_mcontext.arm_fp;
+ context->regs[12] = uc->uc_mcontext.arm_ip;
+ context->regs[13] = uc->uc_mcontext.arm_sp;
+ context->regs[14] = uc->uc_mcontext.arm_lr;
+ context->regs[15] = uc->uc_mcontext.arm_pc;
+
+#elif defined(__mips__)
+
+ typedef struct ucontext {
+ uint32_t sp;
+ uint32_t ra;
+ uint32_t pc;
+ } ucontext_t;
+
+ const ucontext_t* uc = (const ucontext_t*)sigcontext;
+
+ context->uc_mcontext.sp = uc->sp;
+ context->uc_mcontext.pc = uc->pc;
+ context->uc_mcontext.ra = uc->ra;
+#elif defined(__x86__)
+
+ #include <asm/sigcontext.h>
+ #include <asm/ucontext.h>
+ typedef struct ucontext ucontext_t;
+
+ const ucontext_t* uc = (const ucontext_t*)sigcontext;
+
+ context->uc_mcontext.gregs[REG_EBP] = uc->uc_mcontext.gregs[REG_EBP];
+ context->uc_mcontext.gregs[REG_ESP] = uc->uc_mcontext.gregs[REG_ESP];
+ context->uc_mcontext.gregs[REG_EIP] = uc->uc_mcontext.gregs[REG_EIP];
+#endif
+}
+
+//-------------------------------------------------------------------------
+// UnwindThread functions.
+//-------------------------------------------------------------------------
+UnwindThread::UnwindThread() {
+}
+
+UnwindThread::~UnwindThread() {
+}
+
+bool UnwindThread::Init() {
+ return true;
+}
+
+void UnwindThread::ThreadUnwind(
+ siginfo_t* /*siginfo*/, void* sigcontext, size_t num_ignore_frames) {
+ ExtractContext(sigcontext);
+ UnwindFromContext(num_ignore_frames, false);
+}
+
+//-------------------------------------------------------------------------
+// C++ object creation function.
+//-------------------------------------------------------------------------
+Backtrace* CreateCurrentObj() {
+ return new BacktraceCurrent(new UnwindCurrent());
+}
+
+Backtrace* CreateThreadObj(pid_t tid) {
+ UnwindThread* thread_obj = new UnwindThread();
+ return new BacktraceThread(thread_obj, thread_obj, tid);
+}