Merge "Fix off by 4 error handling eh_frame hdr."
diff --git a/debuggerd/handler/debuggerd_fallback.cpp b/debuggerd/handler/debuggerd_fallback.cpp
index 5fddddc..364fca5 100644
--- a/debuggerd/handler/debuggerd_fallback.cpp
+++ b/debuggerd/handler/debuggerd_fallback.cpp
@@ -55,7 +55,7 @@
 using android::base::unique_fd;
 using unwindstack::Regs;
 
-extern "C" void __linker_enable_fallback_allocator();
+extern "C" bool __linker_enable_fallback_allocator();
 extern "C" void __linker_disable_fallback_allocator();
 
 // This is incredibly sketchy to do inside of a signal handler, especially when libbacktrace
@@ -65,7 +65,11 @@
 // This isn't the default method of dumping because it can fail in cases such as address space
 // exhaustion.
 static void debuggerd_fallback_trace(int output_fd, ucontext_t* ucontext) {
-  __linker_enable_fallback_allocator();
+  if (!__linker_enable_fallback_allocator()) {
+    async_safe_format_log(ANDROID_LOG_ERROR, "libc", "fallback allocator already in use");
+    return;
+  }
+
   {
     std::unique_ptr<Regs> regs;
 
@@ -84,7 +88,11 @@
 
 static void debuggerd_fallback_tombstone(int output_fd, ucontext_t* ucontext, siginfo_t* siginfo,
                                          void* abort_message) {
-  __linker_enable_fallback_allocator();
+  if (!__linker_enable_fallback_allocator()) {
+    async_safe_format_log(ANDROID_LOG_ERROR, "libc", "fallback allocator already in use");
+    return;
+  }
+
   engrave_tombstone_ucontext(output_fd, reinterpret_cast<uintptr_t>(abort_message), siginfo,
                              ucontext);
   __linker_disable_fallback_allocator();
@@ -116,7 +124,7 @@
   closedir(dir);
 }
 
-static bool forward_output(int src_fd, int dst_fd) {
+static bool forward_output(int src_fd, int dst_fd, pid_t expected_tid) {
   // Make sure the thread actually got the signal.
   struct pollfd pfd = {
     .fd = src_fd, .events = POLLIN,
@@ -127,6 +135,18 @@
     return false;
   }
 
+  pid_t tid;
+  if (TEMP_FAILURE_RETRY(read(src_fd, &tid, sizeof(tid))) != sizeof(tid)) {
+    async_safe_format_log(ANDROID_LOG_ERROR, "libc", "failed to read tid");
+    return false;
+  }
+
+  if (tid != expected_tid) {
+    async_safe_format_log(ANDROID_LOG_ERROR, "libc", "received tid %d, expected %d", tid,
+                          expected_tid);
+    return false;
+  }
+
   while (true) {
     char buf[512];
     ssize_t rc = TEMP_FAILURE_RETRY(read(src_fd, buf, sizeof(buf)));
@@ -144,16 +164,54 @@
   }
 }
 
+struct __attribute__((__packed__)) packed_thread_output {
+  int32_t tid;
+  int32_t fd;
+};
+
+static uint64_t pack_thread_fd(pid_t tid, int fd) {
+  packed_thread_output packed = {.tid = tid, .fd = fd};
+  uint64_t result;
+  static_assert(sizeof(packed) == sizeof(result));
+  memcpy(&result, &packed, sizeof(packed));
+  return result;
+}
+
+static std::pair<pid_t, int> unpack_thread_fd(uint64_t value) {
+  packed_thread_output result;
+  memcpy(&result, &value, sizeof(value));
+  return std::make_pair(result.tid, result.fd);
+}
+
 static void trace_handler(siginfo_t* info, ucontext_t* ucontext) {
-  static std::atomic<int> trace_output_fd(-1);
+  static std::atomic<uint64_t> trace_output(pack_thread_fd(-1, -1));
 
   if (info->si_value.sival_int == ~0) {
     // Asked to dump by the original signal recipient.
-    debuggerd_fallback_trace(trace_output_fd, ucontext);
+    uint64_t val = trace_output.load();
+    auto [tid, fd] = unpack_thread_fd(val);
+    if (tid != gettid()) {
+      // We received some other thread's info request?
+      async_safe_format_log(ANDROID_LOG_ERROR, "libc",
+                            "thread %d received output fd for thread %d?", gettid(), tid);
+      return;
+    }
 
-    int tmp = trace_output_fd.load();
-    trace_output_fd.store(-1);
-    close(tmp);
+    if (!trace_output.compare_exchange_strong(val, pack_thread_fd(-1, -1))) {
+      // Presumably, the timeout in forward_output expired, and the main thread moved on.
+      // If this happened, the main thread closed our fd for us, so just return.
+      async_safe_format_log(ANDROID_LOG_ERROR, "libc", "cmpxchg for thread %d failed", gettid());
+      return;
+    }
+
+    // Write our tid to the output fd to let the main thread know that we're working.
+    if (TEMP_FAILURE_RETRY(write(fd, &tid, sizeof(tid))) == sizeof(tid)) {
+      debuggerd_fallback_trace(fd, ucontext);
+    } else {
+      async_safe_format_log(ANDROID_LOG_ERROR, "libc", "failed to write to output fd");
+    }
+
+    close(fd);
     return;
   }
 
@@ -189,7 +247,14 @@
           return false;
         }
 
-        trace_output_fd.store(pipe_write.get());
+        uint64_t expected = pack_thread_fd(-1, -1);
+        if (!trace_output.compare_exchange_strong(expected,
+                                                  pack_thread_fd(tid, pipe_write.release()))) {
+          auto [tid, fd] = unpack_thread_fd(expected);
+          async_safe_format_log(ANDROID_LOG_ERROR, "libc",
+                                "thread %d is already outputting to fd %d?", tid, fd);
+          return false;
+        }
 
         siginfo_t siginfo = {};
         siginfo.si_code = SI_QUEUE;
@@ -203,12 +268,20 @@
           return false;
         }
 
-        bool success = forward_output(pipe_read.get(), output_fd);
-        if (success) {
-          // The signaled thread has closed trace_output_fd already.
-          (void)pipe_write.release();
-        } else {
-          trace_output_fd.store(-1);
+        bool success = forward_output(pipe_read.get(), output_fd, tid);
+        if (!success) {
+          async_safe_format_log(ANDROID_LOG_ERROR, "libc",
+                                "timeout expired while waiting for thread %d to dump", tid);
+        }
+
+        // Regardless of whether the poll succeeds, check to see if the thread took fd ownership.
+        uint64_t post_wait = trace_output.exchange(pack_thread_fd(-1, -1));
+        if (post_wait != pack_thread_fd(-1, -1)) {
+          auto [tid, fd] = unpack_thread_fd(post_wait);
+          if (fd != -1) {
+            async_safe_format_log(ANDROID_LOG_ERROR, "libc", "closing fd %d for thread %d", fd, tid);
+            close(fd);
+          }
         }
 
         return true;
diff --git a/demangle/DemangleTest.cpp b/demangle/DemangleTest.cpp
index 46a6f76..1787031 100644
--- a/demangle/DemangleTest.cpp
+++ b/demangle/DemangleTest.cpp
@@ -509,6 +509,29 @@
   ASSERT_EQ("_ZTH_N3oneE", demangler.Parse("_ZTH_N3oneE"));
 }
 
+TEST(DemangleTest, r_value_reference) {
+  Demangler demangler;
+  ASSERT_EQ(
+      "android::SurfaceComposerClient::Transaction::merge(android::SurfaceComposerClient::"
+      "Transaction&&)",
+      demangler.Parse("_ZN7android21SurfaceComposerClient11Transaction5mergeEOS1_"));
+}
+
+TEST(DemangleTest, initial_St) {
+  Demangler demangler;
+  EXPECT_EQ("std::state", demangler.Parse("_ZSt5state"));
+  EXPECT_EQ("std::_In::ward", demangler.Parse("_ZNSt3_In4wardE"));
+  EXPECT_EQ("std::__terminate(void (*)())", demangler.Parse("_ZSt11__terminatePFvvE"));
+}
+
+TEST(DemangleTest, cfi) {
+  Demangler demangler;
+  EXPECT_EQ("nfa_sys_ptim_timer_update(tPTIM_CB*)",
+            demangler.Parse("_Z25nfa_sys_ptim_timer_updateP8tPTIM_CB"));
+  EXPECT_EQ("nfa_sys_ptim_timer_update(tPTIM_CB*) [clone .cfi]",
+            demangler.Parse("_Z25nfa_sys_ptim_timer_updateP8tPTIM_CB.cfi"));
+}
+
 TEST(DemangleTest, demangle) {
   std::string str;
 
diff --git a/demangle/Demangler.cpp b/demangle/Demangler.cpp
index af2816c..7a3aa81 100644
--- a/demangle/Demangler.cpp
+++ b/demangle/Demangler.cpp
@@ -580,6 +580,10 @@
     }
     return name + 1;
 
+  case 'O':
+    cur_state_.suffixes.push_back("&&");
+    return name + 1;
+
   case 'K':
   case 'V': {
     const char* suffix;
@@ -701,6 +705,9 @@
         cur_state_.str.clear();
       }
       return name;
+    } else if (strcmp(name, ".cfi") == 0) {
+      function_suffix_ += " [clone .cfi]";
+      return name + 4;
     }
   }
   return nullptr;
@@ -816,6 +823,16 @@
     return name + 1;
   }
 
+  if (*name == 'S') {
+    name++;
+    if (*name == 't') {
+      function_name_ = "std::";
+      name++;
+    } else {
+      return nullptr;
+    }
+  }
+
   if (std::isdigit(*name)) {
     name = GetStringFromLength(name, &function_name_);
   } else if (*name == 'L' && std::isdigit(name[1])) {
diff --git a/libunwindstack/Unwinder.cpp b/libunwindstack/Unwinder.cpp
index 644bfa8..dfd7b18 100644
--- a/libunwindstack/Unwinder.cpp
+++ b/libunwindstack/Unwinder.cpp
@@ -175,6 +175,8 @@
       if (regs_->dex_pc() != 0) {
         // Add a frame to represent the dex file.
         FillInDexFrame();
+        // Clear the dex pc so that we don't repeat this frame later.
+        regs_->set_dex_pc(0);
       }
 
       FillInFrame(map_info, elf, adjusted_rel_pc, adjusted_pc);
diff --git a/libunwindstack/tests/UnwinderTest.cpp b/libunwindstack/tests/UnwinderTest.cpp
index 09c6e04..7358ae6 100644
--- a/libunwindstack/tests/UnwinderTest.cpp
+++ b/libunwindstack/tests/UnwinderTest.cpp
@@ -752,6 +752,64 @@
   EXPECT_EQ(PROT_READ | PROT_WRITE, frame->map_flags);
 }
 
+TEST_F(UnwinderTest, dex_pc_multiple_frames) {
+  ElfInterfaceFake::FakePushFunctionData(FunctionData("Frame0", 0));
+  ElfInterfaceFake::FakePushFunctionData(FunctionData("Frame1", 1));
+  regs_.FakeSetPc(0x1000);
+  regs_.FakeSetSp(0x10000);
+  regs_.FakeSetDexPc(0xa3400);
+  ElfInterfaceFake::FakePushStepData(StepData(0x33402, 0x10010, false));
+  ElfInterfaceFake::FakePushStepData(StepData(0, 0, true));
+
+  Unwinder unwinder(64, &maps_, &regs_, process_memory_);
+  unwinder.Unwind();
+  EXPECT_EQ(ERROR_NONE, unwinder.LastErrorCode());
+
+  ASSERT_EQ(3U, unwinder.NumFrames());
+
+  auto* frame = &unwinder.frames()[0];
+  EXPECT_EQ(0U, frame->num);
+  EXPECT_EQ(0x400U, frame->rel_pc);
+  EXPECT_EQ(0xa3400U, frame->pc);
+  EXPECT_EQ(0x10000U, frame->sp);
+  EXPECT_EQ("", frame->function_name);
+  EXPECT_EQ(0U, frame->function_offset);
+  EXPECT_EQ("/fake/fake.vdex", frame->map_name);
+  EXPECT_EQ(0U, frame->map_offset);
+  EXPECT_EQ(0xa3000U, frame->map_start);
+  EXPECT_EQ(0xa4000U, frame->map_end);
+  EXPECT_EQ(0U, frame->map_load_bias);
+  EXPECT_EQ(PROT_READ | PROT_WRITE | PROT_EXEC, frame->map_flags);
+
+  frame = &unwinder.frames()[1];
+  EXPECT_EQ(1U, frame->num);
+  EXPECT_EQ(0U, frame->rel_pc);
+  EXPECT_EQ(0x1000U, frame->pc);
+  EXPECT_EQ(0x10000U, frame->sp);
+  EXPECT_EQ("Frame0", frame->function_name);
+  EXPECT_EQ(0U, frame->function_offset);
+  EXPECT_EQ("/system/fake/libc.so", frame->map_name);
+  EXPECT_EQ(0U, frame->map_offset);
+  EXPECT_EQ(0x1000U, frame->map_start);
+  EXPECT_EQ(0x8000U, frame->map_end);
+  EXPECT_EQ(0U, frame->map_load_bias);
+  EXPECT_EQ(PROT_READ | PROT_WRITE, frame->map_flags);
+
+  frame = &unwinder.frames()[2];
+  EXPECT_EQ(2U, frame->num);
+  EXPECT_EQ(0x400U, frame->rel_pc);
+  EXPECT_EQ(0x33400U, frame->pc);
+  EXPECT_EQ(0x10010U, frame->sp);
+  EXPECT_EQ("Frame1", frame->function_name);
+  EXPECT_EQ(1U, frame->function_offset);
+  EXPECT_EQ("/fake/compressed.so", frame->map_name);
+  EXPECT_EQ(0U, frame->map_offset);
+  EXPECT_EQ(0x33000U, frame->map_start);
+  EXPECT_EQ(0x34000U, frame->map_end);
+  EXPECT_EQ(0U, frame->map_load_bias);
+  EXPECT_EQ(PROT_READ | PROT_WRITE, frame->map_flags);
+}
+
 // Verify format frame code.
 TEST_F(UnwinderTest, format_frame_static) {
   FrameData frame;