commit 82f3bbdc25253ee299207acd22b074bbe39bf2c6
author Christopher Ferris <cferris@google.com> Tue Mar 14 15:22:26 2017 -0700
committer Christopher Ferris <cferris@google.com> Tue Mar 21 14:21:49 2017 -0700
tree b67e7819902938723b530108841a16059d6bf5f1
parent e87a826a1df1891d2819aa70d613f7f140b11953

Allow calling GetFunctionName before unwinding.

Some extra initialization needs to occur before calling the local/remote
GetFunctioneName.

Also, cleanup the test code a bit:

- Make all local functions static.
- Create a common function to create and finish remote processes.
- Remove unused function.
- Fix the formatting a bit by making it match clang format.

Test: Ran the unit tests.
Change-Id: I998bed1378d582df59fdf9263df6f208db5d795a

libbacktrace/UnwindPtrace.cpp

diff --git a/libbacktrace/UnwindPtrace.cpp b/libbacktrace/UnwindPtrace.cpp
index 306d2ac..5c73bd6 100644
--- a/libbacktrace/UnwindPtrace.cpp
+++ b/libbacktrace/UnwindPtrace.cpp
@@ -37,6 +37,7 @@
     _UPT_destroy(upt_info_);
     upt_info_ = nullptr;
   }
+
   if (addr_space_) {
     // Remove the map from the address space before destroying it.
     // It will be freed in the UnwindMap destructor.
@@ -47,18 +48,14 @@
   }
 }
 
-bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
-  if (GetMap() == nullptr) {
-    // Without a map object, we can't do anything.
-    error_ = BACKTRACE_UNWIND_ERROR_MAP_MISSING;
-    return false;
+bool UnwindPtrace::Init() {
+  if (upt_info_) {
+    return true;
   }
 
-  error_ = BACKTRACE_UNWIND_NO_ERROR;
-
-  if (ucontext) {
-    BACK_LOGW("Unwinding from a specified context not supported yet.");
-    error_ = BACKTRACE_UNWIND_ERROR_UNSUPPORTED_OPERATION;
+  if (addr_space_) {
+    // If somehow the addr_space_ gets initialized but upt_info_ doesn't,
+    // then that indicates there is some kind of failure.
     return false;
   }
 
@@ -79,6 +76,28 @@
     return false;
   }
 
+  return true;
+}
+
+bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
+  if (GetMap() == nullptr) {
+    // Without a map object, we can't do anything.
+    error_ = BACKTRACE_UNWIND_ERROR_MAP_MISSING;
+    return false;
+  }
+
+  error_ = BACKTRACE_UNWIND_NO_ERROR;
+
+  if (ucontext) {
+    BACK_LOGW("Unwinding from a specified context not supported yet.");
+    error_ = BACKTRACE_UNWIND_ERROR_UNSUPPORTED_OPERATION;
+    return false;
+  }
+
+  if (!Init()) {
+    return false;
+  }
+
   unw_cursor_t cursor;
   int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
   if (ret < 0) {
@@ -115,10 +134,10 @@
         prev->stack_size = frame->sp - prev->sp;
       }
 
-      frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
-
       FillInMap(frame->pc, &frame->map);
 
+      frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
+
       num_frames++;
     } else {
       num_ignore_frames--;
@@ -130,6 +149,10 @@
 }
 
 std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
+  if (!Init()) {
+    return "";
+  }
+
   *offset = 0;
   char buf[512];
   unw_word_t value;