commit ab63124cd9a1a3211504f30667a0bf56d0cac6b7
author Christopher Ferris <cferris@google.com> Tue May 10 16:13:02 2022 -0700
committer Christopher Ferris <cferris@google.com> Tue May 10 17:19:12 2022 -0700
tree d24088342830cae2b1c266a3ae40d50b7e98843f
parent 37a5303642a7779c80f236e54bcbb61c6419b55b

Use the new AndroidUnwinder object.

Replaces libbacktrace in CallStack. There is one small behavioral
change, the BuildId data is added to the unwinds.

Bug: 120606663

Test: All unit tests pass.
Test: Run the fuzzer for over an hour without any crashes.
Change-Id: Ic8a4247c515ce0d3cdc4d2cc15167d1948b15fa5

libutils/Android.bp

diff --git a/libutils/Android.bp b/libutils/Android.bp
index 1b29285..f663671 100644
--- a/libutils/Android.bp
+++ b/libutils/Android.bp
@@ -44,14 +44,6 @@
     export_include_dirs: ["include"],
 
     target: {
-        android: {
-            header_libs: ["libbacktrace_headers"],
-            export_header_lib_headers: ["libbacktrace_headers"],
-        },
-        host_linux: {
-            header_libs: ["libbacktrace_headers"],
-            export_header_lib_headers: ["libbacktrace_headers"],
-        },
         linux_bionic: {
             enabled: true,
         },
@@ -196,7 +188,7 @@
 
     shared_libs: [
         "libutils",
-        "libbacktrace",
+        "libunwindstack",
     ],
 
     target: {

libutils/CallStack.cpp

diff --git a/libutils/CallStack.cpp b/libutils/CallStack.cpp
index fe6f33d..f19ba6a 100644
--- a/libutils/CallStack.cpp
+++ b/libutils/CallStack.cpp
@@ -20,7 +20,7 @@
 #include <utils/Errors.h>
 #include <utils/Log.h>
 
-#include <backtrace/Backtrace.h>
+#include <unwindstack/AndroidUnwinder.h>
 
 #define CALLSTACK_WEAK  // Don't generate weak definitions.
 #include <utils/CallStack.h>
@@ -39,14 +39,25 @@
 }
 
 void CallStack::update(int32_t ignoreDepth, pid_t tid) {
+    if (ignoreDepth < 0) {
+        ignoreDepth = 0;
+    }
+
     mFrameLines.clear();
 
-    std::unique_ptr<Backtrace> backtrace(Backtrace::Create(BACKTRACE_CURRENT_PROCESS, tid));
-    if (!backtrace->Unwind(ignoreDepth)) {
-        ALOGW("%s: Failed to unwind callstack.", __FUNCTION__);
+    unwindstack::AndroidLocalUnwinder unwinder;
+    unwindstack::AndroidUnwinderData data;
+    std::optional<pid_t> tid_val;
+    if (tid != -1) {
+        *tid_val = tid;
     }
-    for (size_t i = 0; i < backtrace->NumFrames(); i++) {
-      mFrameLines.push_back(String8(backtrace->FormatFrameData(i).c_str()));
+    if (!unwinder.Unwind(tid_val, data)) {
+        ALOGW("%s: Failed to unwind callstack: %s", __FUNCTION__, data.GetErrorString().c_str());
+    }
+    for (size_t i = ignoreDepth; i < data.frames.size(); i++) {
+        auto& frame = data.frames[i];
+        frame.num -= ignoreDepth;
+        mFrameLines.push_back(String8(unwinder.FormatFrame(frame).c_str()));
     }
 }
 

libutils/include/utils/CallStack.h

diff --git a/libutils/include/utils/CallStack.h b/libutils/include/utils/CallStack.h
index 7a4a345..fe4d4f5 100644
--- a/libutils/include/utils/CallStack.h
+++ b/libutils/include/utils/CallStack.h
@@ -20,7 +20,6 @@
 #include <memory>
 
 #include <android/log.h>
-#include <backtrace/backtrace_constants.h>
 #include <utils/String8.h>
 #include <utils/Vector.h>
 
@@ -59,7 +58,7 @@
 
     // Immediately collect the stack traces for the specified thread.
     // The default is to dump the stack of the current call.
-    void update(int32_t ignoreDepth = 1, pid_t tid = BACKTRACE_CURRENT_THREAD);
+    void update(int32_t ignoreDepth = 1, pid_t tid = -1);
 
     // Dump a stack trace to the log using the supplied logtag.
     void log(const char* logtag,