commit cd546c11d679288d552d80b3e6caf965a9094c63
author Josh Gao <jmgao@google.com> Wed Oct 25 15:21:45 2017 -0700
committer Josh Gao <jmgao@google.com> Thu Oct 26 14:19:49 2017 -0700
tree 3e78e02b3af17a345e0ae63f776d20ec954a6f99
parent 972753e09411ab223d2ed5a70a2a99938f2785b1

libbacktrace: correctly number frames when skipping.

Correct for the number of skipped frames when unwinding with
libunwindstack.

Test: backtrace_test32  --gtest_filter="unwind_frame_skip_*"
Change-Id: I9528977104fde3c4ec792a6db1ada24ed571b867

libbacktrace/UnwindStack.cpp

diff --git a/libbacktrace/UnwindStack.cpp b/libbacktrace/UnwindStack.cpp
index c3f08c8..62e453f 100644
--- a/libbacktrace/UnwindStack.cpp
+++ b/libbacktrace/UnwindStack.cpp
@@ -64,7 +64,7 @@
     auto frame = &unwinder_frames[i];
     backtrace_frame_data_t* back_frame = &frames->at(cur_frame);
 
-    back_frame->num = frame->num;
+    back_frame->num = frame->num - num_ignore_frames;
 
     back_frame->rel_pc = frame->rel_pc;
     back_frame->pc = frame->pc;

libbacktrace/backtrace_test.cpp

diff --git a/libbacktrace/backtrace_test.cpp b/libbacktrace/backtrace_test.cpp
index e5eb9e3..c3e5da0 100644
--- a/libbacktrace/backtrace_test.cpp
+++ b/libbacktrace/backtrace_test.cpp
@@ -1844,6 +1844,22 @@
   UnwindThroughSignal(true, Backtrace::CreateNew, BacktraceMap::CreateNew);
 }
 
+static void TestFrameSkipNumbering(create_func_t create_func, map_create_func_t map_create_func) {
+  std::unique_ptr<BacktraceMap> map(map_create_func(getpid(), false));
+  std::unique_ptr<Backtrace> backtrace(create_func(getpid(), gettid(), map.get()));
+  backtrace->Unwind(1);
+  ASSERT_NE(0U, backtrace->NumFrames());
+  ASSERT_EQ(0U, backtrace->GetFrame(0)->num);
+}
+
+TEST(libbacktrace, unwind_frame_skip_numbering) {
+  TestFrameSkipNumbering(Backtrace::Create, BacktraceMap::Create);
+}
+
+TEST(libbacktrace, unwind_frame_skip_numbering_new) {
+  TestFrameSkipNumbering(Backtrace::CreateNew, BacktraceMap::CreateNew);
+}
+
 #if defined(ENABLE_PSS_TESTS)
 #include "GetPss.h"