Add backtrace_string and export to libmemunreachable

Add backtrace_string to convert a malloc_debug backtrace to a string.
Also move the backtrace functions to libc_malloc_debug_backtrace so that
libmemunreachable can reuse them.

Bug: 27208635
(cherry picked from commit 2c75991359df165ca7cc7a6213fb227c0b5ed87c)

Change-Id: Ia93aaf010fbce1ace058439427066ea2dfd8bd13

diff --git a/libc/bionic/libc_logging.cpp b/libc/bionic/libc_logging.cpp
index 67bb052..fffaea8 100644 (file)
--- a/libc/bionic/libc_logging.cpp
+++ b/libc/bionic/libc_logging.cpp
@@ -548,7 +548,7 @@ struct log_time { // Wire format
   uint32_t tv_nsec;
 };
 
-static int __libc_write_log(int priority, const char* tag, const char* msg) {
+int __libc_write_log(int priority, const char* tag, const char* msg) {
   int main_log_fd = __libc_open_log_socket();
   if (main_log_fd == -1) {
     // Try stderr instead.

diff --git a/libc/malloc_debug/Android.mk b/libc/malloc_debug/Android.mk
index 3eb0790..fb36643 100644 (file)
--- a/libc/malloc_debug/Android.mk
+++ b/libc/malloc_debug/Android.mk
@@ -11,6 +11,38 @@ libc_malloc_debug_src_files := \
     TrackData.cpp \
 
 # ==============================================================
+# libc_malloc_debug_backtrace.a
+# ==============================================================
+# Used by libmemunreachable
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := libc_malloc_debug_backtrace
+
+LOCAL_SRC_FILES := \
+    backtrace.cpp \
+    MapData.cpp \
+
+LOCAL_CXX_STL := libc++_static
+
+LOCAL_STATIC_LIBRARIES += \
+    libc_logging \
+
+LOCAL_C_INCLUDES += bionic/libc
+LOCAL_EXPORT_C_INCLUDE_DIRS += $(LOCAL_PATH)
+
+LOCAL_SANITIZE := never
+LOCAL_NATIVE_COVERAGE := false
+
+# -Wno-error=format-zero-length needed for gcc to compile.
+LOCAL_CFLAGS := \
+    -Wall \
+    -Werror \
+    -fno-stack-protector \
+    -Wno-error=format-zero-length \
+
+include $(BUILD_STATIC_LIBRARY)
+
+# ==============================================================
 # libc_malloc_debug.so
 # ==============================================================
 include $(CLEAR_VARS)
@@ -19,16 +51,17 @@ LOCAL_MODULE := libc_malloc_debug
 
 LOCAL_SRC_FILES := \
     $(libc_malloc_debug_src_files) \
-    backtrace.cpp \
-    MapData.cpp \
 
-LOCAL_CXX_STL := none
+LOCAL_CXX_STL := libc++_static
 
 # Only need this for arm since libc++ uses its own unwind code that
 # doesn't mix with the other default unwind code.
 LOCAL_STATIC_LIBRARIES_arm := libunwind_llvm
 
-LOCAL_STATIC_LIBRARIES += libc++abi libc++_static libc_logging
+LOCAL_STATIC_LIBRARIES += \
+    libc_malloc_debug_backtrace \
+    libc_logging \
+
 LOCAL_LDFLAGS_32 := -Wl,--version-script,$(LOCAL_PATH)/exported32.map
 LOCAL_LDFLAGS_64 := -Wl,--version-script,$(LOCAL_PATH)/exported64.map
 LOCAL_ALLOW_UNDEFINED_SYMBOLS := true

diff --git a/libc/malloc_debug/MapData.cpp b/libc/malloc_debug/MapData.cpp
index ce2b999..c38362b 100644 (file)
--- a/libc/malloc_debug/MapData.cpp
+++ b/libc/malloc_debug/MapData.cpp
@@ -36,7 +36,6 @@
 
 #include <vector>
 
-#include "debug_disable.h"
 #include "MapData.h"
 
 // Format of /proc/<PID>/maps:
@@ -112,8 +111,6 @@ static void read_loadbase(MapEntry* entry) {
 }
 
 bool MapData::Initialize() {
-  ScopedDisableDebugCalls disable;
-
   FILE* fp = fopen("/proc/self/maps", "re");
   if (fp == nullptr) {
     return false;
@@ -141,8 +138,6 @@ MapData* MapData::Create() {
 }
 
 MapData::~MapData() {
-  ScopedDisableDebugCalls disable;
-
   for (auto* entry : entries_) {
     delete entry;
   }

diff --git a/libc/malloc_debug/backtrace.cpp b/libc/malloc_debug/backtrace.cpp
index 8549dc4..716e672 100644 (file)
--- a/libc/malloc_debug/backtrace.cpp
+++ b/libc/malloc_debug/backtrace.cpp
@@ -37,7 +37,6 @@
 #include <unwind.h>
 
 #include "backtrace.h"
-#include "debug_disable.h"
 #include "debug_log.h"
 #include "MapData.h"
 
@@ -65,8 +64,6 @@ static _Unwind_Reason_Code find_current_map(__unwind_context* context, void*) {
 }
 
 void backtrace_startup() {
-  ScopedDisableDebugCalls disable;
-
   g_map_data = MapData::Create();
   if (g_map_data) {
     _Unwind_Backtrace(find_current_map, nullptr);
@@ -74,8 +71,6 @@ void backtrace_startup() {
 }
 
 void backtrace_shutdown() {
-  ScopedDisableDebugCalls disable;
-
   delete g_map_data;
   g_map_data = nullptr;
 }
@@ -136,15 +131,13 @@ static _Unwind_Reason_Code trace_function(__unwind_context* context, void* arg)
 }
 
 size_t backtrace_get(uintptr_t* frames, size_t frame_count) {
-  ScopedDisableDebugCalls disable;
-
   stack_crawl_state_t state(frames, frame_count);
   _Unwind_Backtrace(trace_function, &state);
   return state.cur_frame;
 }
 
-void backtrace_log(const uintptr_t* frames, size_t frame_count) {
-  ScopedDisableDebugCalls disable;
+std::string backtrace_string(const uintptr_t* frames, size_t frame_count) {
+  std::string str;
 
   for (size_t frame_num = 0; frame_num < frame_count; frame_num++) {
     uintptr_t offset = 0;
@@ -165,15 +158,25 @@ void backtrace_log(const uintptr_t* frames, size_t frame_count) {
     if (soname == nullptr) {
       soname = "<unknown>";
     }
+    char buf[1024];
     if (symbol != nullptr) {
       char* demangled_symbol = __cxa_demangle(symbol, nullptr, nullptr, nullptr);
       const char* best_name = (demangled_symbol != nullptr) ? demangled_symbol : symbol;
 
-      error_log("          #%02zd  pc %" PAD_PTR "  %s (%s+%" PRIuPTR ")",
-                frame_num, rel_pc, soname, best_name, frames[frame_num] - offset);
+      __libc_format_buffer(buf, sizeof(buf),
+          "          #%02zd  pc %" PAD_PTR "  %s (%s+%" PRIuPTR ")\n", frame_num,
+          rel_pc, soname, best_name, frames[frame_num] - offset);
       free(demangled_symbol);
     } else {
-      error_log("          #%02zd  pc %" PAD_PTR "  %s", frame_num, rel_pc, soname);
+      __libc_format_buffer(buf, sizeof(buf),
+          "          #%02zd  pc %" PAD_PTR "  %s\n", frame_num, rel_pc, soname);
     }
+    str += buf;
   }
+
+  return str;
+}
+
+void backtrace_log(const uintptr_t* frames, size_t frame_count) {
+  error_log_string(backtrace_string(frames, frame_count).c_str());
 }

diff --git a/libc/malloc_debug/backtrace.h b/libc/malloc_debug/backtrace.h
index 9e01009..f570873 100644 (file)
--- a/libc/malloc_debug/backtrace.h
+++ b/libc/malloc_debug/backtrace.h
@@ -32,9 +32,12 @@
 #include <stdint.h>
 #include <sys/cdefs.h>
 
+#include <string>
+
 void backtrace_startup();
 void backtrace_shutdown();
 size_t backtrace_get(uintptr_t* frames, size_t frame_count);
 void backtrace_log(const uintptr_t* frames, size_t frame_count);
+std::string backtrace_string(const uintptr_t* frames, size_t frame_count);
 
 #endif // MALLOC_DEBUG_BACKTRACE_H

diff --git a/libc/malloc_debug/debug_log.h b/libc/malloc_debug/debug_log.h
index 67f584d..4df0408 100644 (file)
--- a/libc/malloc_debug/debug_log.h
+++ b/libc/malloc_debug/debug_log.h
@@ -38,6 +38,8 @@
     __libc_format_log(ANDROID_LOG_DEBUG, "malloc_debug", (format), ##__VA_ARGS__ )
 #define error_log(format, ...)  \
     __libc_format_log(ANDROID_LOG_ERROR, "malloc_debug", (format), ##__VA_ARGS__ )
+#define error_log_string(str)  \
+    __libc_write_log(ANDROID_LOG_ERROR, "malloc_debug", (str))
 #define info_log(format, ...)  \
     __libc_format_log(ANDROID_LOG_INFO, "malloc_debug", (format), ##__VA_ARGS__ )
 

diff --git a/libc/malloc_debug/malloc_debug.cpp b/libc/malloc_debug/malloc_debug.cpp
index e079c7e..aa6f5f7 100644 (file)
--- a/libc/malloc_debug/malloc_debug.cpp
+++ b/libc/malloc_debug/malloc_debug.cpp
@@ -223,10 +223,10 @@ void debug_finalize() {
     g_debug->track->DisplayLeaks(*g_debug);
   }
 
-  backtrace_shutdown();
-
   DebugDisableSet(true);
 
+  backtrace_shutdown();
+
   delete g_debug;
   g_debug = nullptr;
 

diff --git a/libc/private/libc_logging.h b/libc/private/libc_logging.h
index da2192b..e389565 100644 (file)
--- a/libc/private/libc_logging.h
+++ b/libc/private/libc_logging.h
@@ -101,6 +101,8 @@ __LIBC_HIDDEN__ int __libc_format_log(int priority, const char* tag, const char*
 __LIBC_HIDDEN__ int __libc_format_log_va_list(int priority, const char* tag, const char* format,
                                               va_list ap);
 
+__LIBC_HIDDEN__ int __libc_write_log(int priority, const char* tag, const char* msg);
+
 //
 // Event logging.
 //