Add full support for initing registers.

- Fixes a few bugs in untested functionality.
- Add tests for the way the register handling code is used.
- Fix a few tests that were not reaping child processes.

Bug: 23762183

Test: Ran unit tests on host (32 bit and 64 bit).
Test: Ran unit tests on angler (32 bit and 64 bit).
Change-Id: I573d6617b4f1561f6e8494d7213c52086d112d97
diff --git a/libunwindstack/tests/UnwindTest.cpp b/libunwindstack/tests/UnwindTest.cpp
new file mode 100644
index 0000000..7497b65
--- /dev/null
+++ b/libunwindstack/tests/UnwindTest.cpp
@@ -0,0 +1,233 @@
+/*
+ * Copyright (C) 2017 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 <string.h>
+
+#include <signal.h>
+#include <stdint.h>
+#include <sys/ptrace.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include <gtest/gtest.h>
+
+#include <atomic>
+#include <memory>
+#include <sstream>
+#include <string>
+#include <thread>
+
+#include "Elf.h"
+#include "MapInfo.h"
+#include "Maps.h"
+#include "Memory.h"
+#include "Regs.h"
+#include "RegsGetLocal.h"
+
+static std::atomic_bool g_ready(false);
+static volatile bool g_ready_for_remote = false;
+static std::atomic_bool g_finish(false);
+static std::atomic_uintptr_t g_ucontext;
+
+static void Signal(int, siginfo_t*, void* sigcontext) {
+  g_ucontext = reinterpret_cast<uintptr_t>(sigcontext);
+  while (!g_finish.load()) {
+  }
+}
+
+static std::string ErrorMsg(const char** function_names, size_t index,
+                            std::stringstream& unwind_stream) {
+  return std::string(
+             "Unwind completed without finding all frames\n"
+             "  Looking for function: ") +
+         function_names[index] + "\n" + "Unwind data:\n" + unwind_stream.str();
+}
+
+static void VerifyUnwind(pid_t pid, Memory* memory, Maps* maps, Regs* regs) {
+  const char* function_names[] = {
+      "InnerFunction", "MiddleFunction", "OuterFunction",
+  };
+  size_t function_name_index = 0;
+
+  std::stringstream unwind_stream;
+  unwind_stream << std::hex;
+  for (size_t frame_num = 0; frame_num < 64; frame_num++) {
+    ASSERT_NE(0U, regs->pc()) << ErrorMsg(function_names, function_name_index, unwind_stream);
+    MapInfo* map_info = maps->Find(regs->pc());
+    ASSERT_TRUE(map_info != nullptr) << ErrorMsg(function_names, function_name_index, unwind_stream);
+
+    Elf* elf = map_info->GetElf(pid, true);
+    uint64_t rel_pc = regs->GetRelPc(elf, map_info);
+    uint64_t adjusted_rel_pc = rel_pc;
+    if (frame_num != 0) {
+      adjusted_rel_pc = regs->GetAdjustedPc(rel_pc, elf);
+    }
+    unwind_stream << "  PC: 0x" << regs->pc() << " Rel: 0x" << adjusted_rel_pc;
+    unwind_stream << " Map: ";
+    if (!map_info->name.empty()) {
+      unwind_stream << map_info->name;
+    } else {
+      unwind_stream << " anonymous";
+    }
+    unwind_stream << "<" << map_info->start << "-" << map_info->end << ">";
+
+    std::string name;
+    uint64_t func_offset;
+    if (elf->GetFunctionName(adjusted_rel_pc, &name, &func_offset)) {
+      if (name == function_names[function_name_index]) {
+        function_name_index++;
+        if (function_name_index == sizeof(function_names) / sizeof(const char*)) {
+          return;
+        }
+      }
+      unwind_stream << " " << name;
+    }
+    unwind_stream << "\n";
+    ASSERT_TRUE(elf->Step(rel_pc + map_info->elf_offset, regs, memory))
+        << ErrorMsg(function_names, function_name_index, unwind_stream);
+  }
+  ASSERT_TRUE(false) << ErrorMsg(function_names, function_name_index, unwind_stream);
+}
+
+// This test assumes that this code is compiled with optimizations turned
+// off. If this doesn't happen, then all of the calls will be optimized
+// away.
+extern "C" void InnerFunction(bool local) {
+  if (local) {
+    LocalMaps maps;
+    ASSERT_TRUE(maps.Parse());
+    std::unique_ptr<Regs> regs(Regs::CreateFromLocal());
+    RegsGetLocal(regs.get());
+    MemoryLocal memory;
+
+    VerifyUnwind(getpid(), &memory, &maps, regs.get());
+  } else {
+    g_ready_for_remote = true;
+    g_ready = true;
+    while (!g_finish.load()) {
+    }
+  }
+}
+
+extern "C" void MiddleFunction(bool local) {
+  InnerFunction(local);
+}
+
+extern "C" void OuterFunction(bool local) {
+  MiddleFunction(local);
+}
+
+TEST(UnwindTest, local) {
+  OuterFunction(true);
+}
+
+TEST(UnwindTest, remote) {
+  pid_t pid;
+  if ((pid = fork()) == 0) {
+    OuterFunction(false);
+    exit(0);
+  }
+  ASSERT_NE(-1, pid);
+
+  bool ready = false;
+  uint64_t addr = reinterpret_cast<uint64_t>(&g_ready_for_remote);
+  for (size_t i = 0; i < 100; i++) {
+    ASSERT_EQ(0, ptrace(PTRACE_ATTACH, pid, 0, 0));
+    for (size_t j = 0; j < 100; j++) {
+      siginfo_t si;
+      if (ptrace(PTRACE_GETSIGINFO, pid, 0, &si) == 0) {
+        // Check to see if process is ready to be unwound.
+        MemoryRemote memory(pid);
+        // Read the remote value to see if we are ready.
+        bool value;
+        if (memory.Read(addr, &value, sizeof(value)) && value) {
+          ready = true;
+          break;
+        }
+      }
+      usleep(1000);
+    }
+    if (ready) {
+      break;
+    }
+    ASSERT_EQ(0, ptrace(PTRACE_DETACH, pid, 0, 0));
+    usleep(1000);
+  }
+  ASSERT_TRUE(read) << "Timed out waiting for remote process to be ready.";
+
+  RemoteMaps maps(pid);
+  ASSERT_TRUE(maps.Parse());
+  MemoryRemote memory(pid);
+  uint32_t machine_type;
+  std::unique_ptr<Regs> regs(Regs::RemoteGet(pid, &machine_type));
+  ASSERT_TRUE(regs.get() != nullptr);
+
+  VerifyUnwind(pid, &memory, &maps, regs.get());
+
+  ASSERT_EQ(0, ptrace(PTRACE_DETACH, pid, 0, 0));
+
+  kill(pid, SIGKILL);
+  ASSERT_EQ(pid, wait(nullptr));
+}
+
+TEST(UnwindTest, from_context) {
+  std::atomic_int tid(0);
+  std::thread thread([&]() {
+    tid = syscall(__NR_gettid);
+    OuterFunction(false);
+  });
+
+  struct sigaction act, oldact;
+  memset(&act, 0, sizeof(act));
+  act.sa_sigaction = Signal;
+  act.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK;
+  ASSERT_EQ(0, sigaction(SIGUSR1, &act, &oldact));
+  // Wait for the tid to get set.
+  for (size_t i = 0; i < 100; i++) {
+    if (tid.load() != 0) {
+      break;
+    }
+    usleep(1000);
+  }
+  ASSERT_NE(0, tid.load());
+  // Portable tgkill method.
+  ASSERT_EQ(0, syscall(__NR_tgkill, getpid(), tid.load(), SIGUSR1)) << "Failed because "
+                                                                    << strerror(errno);
+
+  // Wait for context data.
+  void* ucontext;
+  for (size_t i = 0; i < 200; i++) {
+    ucontext = reinterpret_cast<void*>(g_ucontext.load());
+    if (ucontext != nullptr) {
+      break;
+    }
+    usleep(1000);
+  }
+  ASSERT_TRUE(ucontext != nullptr) << "Timed out waiting for thread to respond to signal.";
+
+  LocalMaps maps;
+  ASSERT_TRUE(maps.Parse());
+  std::unique_ptr<Regs> regs(Regs::CreateFromUcontext(Regs::GetMachineType(), ucontext));
+  MemoryLocal memory;
+
+  VerifyUnwind(tid.load(), &memory, &maps, regs.get());
+
+  ASSERT_EQ(0, sigaction(SIGUSR1, &oldact, nullptr));
+
+  g_finish = true;
+  thread.join();
+}