Add caching of build id in MapInfo object.

Change the GetBuildID function to return a std::string.
Added benchmark to check how long it takes to get the build id from
a file versus an elf object.
Added a way to get an elf without passing in a valid process_memory and
added tests for this.

Test: New unit tests.
Change-Id: I3029019767e0181c758d611fe635bc1bf72d6e8e

1 files changed, 2 insertions, 2 deletions

diff --git a/libunwindstack/tools/unwind_info.cpp b/libunwindstack/tools/unwind_info.cpp
index 3f2dfb07d..3f5b88ba8 100644
--- a/libunwindstack/tools/unwind_info.cpp
+++ b/libunwindstack/tools/unwind_info.cpp
@@ -123,8 +123,8 @@ int GetElfInfo(const char* file, uint64_t offset) {
     printf("Soname: %s\n", soname.c_str());
   }
 
-  std::string build_id;
-  if (elf.GetBuildID(&build_id)) {
+  std::string build_id = elf.GetBuildID();
+  if (!build_id.empty()) {
     printf("Build ID: ");
     for (size_t i = 0; i < build_id.size(); ++i) {
       printf("%02hhx", build_id[i]);