Include the map name when dumping memory around a register.

Bug: http://b/19590178
Test: ran tests, ran crasher
Change-Id: Ib9afa34c860d8732ef1943eb4decd0b7c8fb55fd

3 files changed, 15 insertions, 4 deletions

diff --git a/libbacktrace/Backtrace.cpp b/libbacktrace/Backtrace.cpp
index dec241c3c..6445a7c51 100644
--- a/libbacktrace/Backtrace.cpp
+++ b/libbacktrace/Backtrace.cpp
@@ -85,14 +85,12 @@ std::string Backtrace::FormatFrameData(size_t frame_num) {
 std::string Backtrace::FormatFrameData(const backtrace_frame_data_t* frame) {
   std::string map_name;
   if (BacktraceMap::IsValid(frame->map)) {
+    map_name = frame->map.Name();
     if (!frame->map.name.empty()) {
-      map_name = frame->map.name.c_str();
       if (map_name[0] == '[' && map_name[map_name.size() - 1] == ']') {
         map_name.resize(map_name.size() - 1);
         map_name += StringPrintf(":%" PRIPTR "]", frame->map.start);
       }
-    } else {
-      map_name = StringPrintf("<anonymous:%" PRIPTR ">", frame->map.start);
     }
   } else {
     map_name = "<unknown>";
diff --git a/libbacktrace/BacktraceMap.cpp b/libbacktrace/BacktraceMap.cpp
index c8a500cee..bdae14062 100644
--- a/libbacktrace/BacktraceMap.cpp
+++ b/libbacktrace/BacktraceMap.cpp
@@ -24,11 +24,21 @@
 
 #include <log/log.h>
 
-#include <backtrace/backtrace_constants.h>
+#include <android-base/stringprintf.h>
+#include <backtrace/Backtrace.h>
 #include <backtrace/BacktraceMap.h>
+#include <backtrace/backtrace_constants.h>
 
 #include "thread_utils.h"
 
+using android::base::StringPrintf;
+
+std::string backtrace_map_t::Name() const {
+  if (!name.empty()) return name;
+  if (start == 0 && end == 0) return "";
+  return StringPrintf("<anonymous:%" PRIPTR ">", start);
+}
+
 BacktraceMap::BacktraceMap(pid_t pid) : pid_(pid) {
   if (pid_ < 0) {
     pid_ = getpid();
diff --git a/libbacktrace/include/backtrace/BacktraceMap.h b/libbacktrace/include/backtrace/BacktraceMap.h
index e19c41396..7b26079cc 100644
--- a/libbacktrace/include/backtrace/BacktraceMap.h
+++ b/libbacktrace/include/backtrace/BacktraceMap.h
@@ -48,6 +48,9 @@ struct backtrace_map_t {
   uint64_t load_bias = 0;
   int flags = 0;
   std::string name;
+
+  // Returns `name` if non-empty, or `<anonymous:0x...>` otherwise.
+  std::string Name() const;
 };
 
 namespace unwindstack {