commit 5cfb4a9c6dfaed4cd1f600fc0c3258fd9eb8e60a
author Christopher Ferris <cferris@google.com> Mon Nov 30 13:36:08 2015 -0800
committer Christopher Ferris <cferris@google.com> Mon Nov 30 14:39:52 2015 -0800
tree 6d1f0dba7c6f9401641ad4775dc99a93fd8724af
parent fe347dfaf5227fadad1fbb259cce34867aee85e9

Change the way some maps are printed.

Before, an anonymous map wound up printing the pc as relative.
Unfortunately, this meant that it was impossible to tell the actual
pc. The new code prints the map name as <anonymous:map_start> and
still prints the pc as relative.

In addition, add the start of the map for map names that begin with a
'[' character.

Bug: 25844836
Change-Id: Ie0b6149dde258fe13f0e5a3e5739d85374512f4b

libbacktrace/Backtrace.cpp

diff --git a/libbacktrace/Backtrace.cpp b/libbacktrace/Backtrace.cpp
index 9ead452..555e8cf 100644
--- a/libbacktrace/Backtrace.cpp
+++ b/libbacktrace/Backtrace.cpp
@@ -93,16 +93,26 @@
 }
 
 std::string Backtrace::FormatFrameData(const backtrace_frame_data_t* frame) {
-  const char* map_name;
-  if (BacktraceMap::IsValid(frame->map) && !frame->map.name.empty()) {
-    map_name = frame->map.name.c_str();
+  uintptr_t relative_pc;
+  std::string map_name;
+  if (BacktraceMap::IsValid(frame->map)) {
+    relative_pc = BacktraceMap::GetRelativePc(frame->map, frame->pc);
+    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>";
+    relative_pc = frame->pc;
   }
 
-  uintptr_t relative_pc = BacktraceMap::GetRelativePc(frame->map, frame->pc);
-
-  std::string line(StringPrintf("#%02zu pc %" PRIPTR "  %s", frame->num, relative_pc, map_name));
+  std::string line(StringPrintf("#%02zu pc %" PRIPTR "  ", frame->num, relative_pc));
+  line += map_name;
   // Special handling for non-zero offset maps, we need to print that
   // information.
   if (frame->map.offset != 0) {

libbacktrace/backtrace_test.cpp

diff --git a/libbacktrace/backtrace_test.cpp b/libbacktrace/backtrace_test.cpp
index 9ebd639..ce04817 100644
--- a/libbacktrace/backtrace_test.cpp
+++ b/libbacktrace/backtrace_test.cpp
@@ -775,16 +775,29 @@
             backtrace->FormatFrameData(&frame));
 
   // Check map name empty, but exists.
-  frame.map.start = 1;
-  frame.map.end = 1;
+  frame.pc = 0xb0020;
+  frame.map.start = 0xb0000;
+  frame.map.end = 0xbffff;
   frame.map.load_base = 0;
 #if defined(__LP64__)
-  EXPECT_EQ("#01 pc 0000000000000001  <unknown>",
+  EXPECT_EQ("#01 pc 0000000000000020  <anonymous:00000000000b0000>",
 #else
-  EXPECT_EQ("#01 pc 00000001  <unknown>",
+  EXPECT_EQ("#01 pc 00000020  <anonymous:000b0000>",
 #endif
             backtrace->FormatFrameData(&frame));
 
+  // Check map name begins with a [.
+  frame.pc = 0xc0020;
+  frame.map.start = 0xc0000;
+  frame.map.end = 0xcffff;
+  frame.map.load_base = 0;
+  frame.map.name = "[anon:thread signal stack]";
+#if defined(__LP64__)
+  EXPECT_EQ("#01 pc 0000000000000020  [anon:thread signal stack:00000000000c0000]",
+#else
+  EXPECT_EQ("#01 pc 00000020  [anon:thread signal stack:000c0000]",
+#endif
+            backtrace->FormatFrameData(&frame));
 
   // Check relative pc is set and map name is set.
   frame.pc = 0x12345679;