Add source info to backtrace

This patch recovers putting source code information in backtrace.
Previous solution was based on binutils but its license is not
acceptable. This patch uses elfutils library licensed under LGPL3.

Change-Id: I1df0a54ac0702f08d876728b535fd0e172efca17

diff --git a/packaging/cynara.spec b/packaging/cynara.spec
index f4e8d1a..3421fd9 100644 (file)
--- a/packaging/cynara.spec
+++ b/packaging/cynara.spec
@@ -35,6 +35,7 @@ BuildRequires: pkgconfig(libsystemd-journal)
 
 %if %{?build_type} == "DEBUG"
 
+BuildRequires: libdw-devel
 BuildRequires: pkgconfig(libunwind)
 
 %endif

diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index 8f99d0e..3de3909 100644 (file)
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -67,6 +67,7 @@ SET_TARGET_PROPERTIES(
 IF (CMAKE_BUILD_TYPE MATCHES "DEBUG")
 SET(CYNARA_DBG_LIBRARIES
     ${CYNARA_DEP_LIBRARIES}
+    dw
     )
 ENDIF (CMAKE_BUILD_TYPE MATCHES "DEBUG")
 

diff --git a/src/common/log/Backtrace.cpp b/src/common/log/Backtrace.cpp
index ca413b7..2fe2566 100644 (file)
--- a/src/common/log/Backtrace.cpp
+++ b/src/common/log/Backtrace.cpp
@@ -23,13 +23,14 @@
  */
 
 #include <cxxabi.h>
+#include <elfutils/libdw.h>
+#include <inttypes.h>
+#include <iostream>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
-#include <iostream>
 #include <sstream>
 
-#include <attributes/attributes.h>
 #include <log/log.h>
 
 #include "Backtrace.h"
@@ -41,19 +42,68 @@ Backtrace &Backtrace::getInstance(void) {
     return m_instance;
 }
 
-Backtrace::Backtrace() :
-        m_fileName(NULL),
-        m_functionName(NULL), m_lineNumber(0) {
+const Dwfl_Callbacks Backtrace::m_callbacks = {
+    dwfl_linux_proc_find_elf,
+    dwfl_standard_find_debuginfo,
+    nullptr,
+    nullptr,
+};
+
+Backtrace::Backtrace() {
+    init();
 }
 
 Backtrace::~Backtrace() {
+    dwfl_end(m_dwfl);
 }
 
-void Backtrace::getSourceInfo(unw_word_t proc_address UNUSED) {
-    // TODO: extract filename and line number for symbol at given address
-    m_fileName = "??";
-    m_functionName = "??";
-    m_lineNumber = 0;
+void Backtrace::init(void) {
+    m_dwfl = dwfl_begin(&m_callbacks);
+    if (m_dwfl == nullptr) {
+        LOGE("dwfl_begin failed! Source info won't be available in backtrace!");
+        return;
+    }
+
+    if (dwfl_linux_proc_report(m_dwfl, getpid())) {
+        LOGE("dwfl_linux_proc_report failed! Source info won't be available in backtrace!");
+        dwfl_end(m_dwfl);
+        m_dwfl = nullptr;
+    }
+}
+
+void Backtrace::getSourceInfo(unw_word_t address, std::string &fileName, int &lineNumber) {
+    fileName = "??";
+    lineNumber = 0;
+
+    if (m_dwfl == nullptr)
+        return;
+
+    Dwarf_Addr addr = static_cast<Dwarf_Addr>(address);
+
+    Dwfl_Module *module = dwfl_addrmodule(m_dwfl, addr);
+    if (module == nullptr)
+        return;
+
+    Dwfl_Line *line = dwfl_module_getsrc(module, addr);
+    if (line == nullptr)
+        return;
+
+    const char *src = dwfl_lineinfo(line, &addr, &lineNumber, nullptr, nullptr, nullptr);
+    if (src == nullptr)
+        return;
+
+    const char *compilationDirectory = "";
+    const char *compilationDirectorySeparator = "";
+
+    if (src[0] != '/') {
+        compilationDirectory = dwfl_line_comp_dir(line);
+        if (compilationDirectory != NULL)
+            compilationDirectorySeparator = "/";
+    }
+
+    std::ostringstream fileNameStream;
+    fileNameStream << compilationDirectory << compilationDirectorySeparator << src;
+    fileName = fileNameStream.str();
 }
 
 const std::string Backtrace::buildBacktrace(void) {
@@ -64,6 +114,8 @@ const std::string Backtrace::buildBacktrace(void) {
     char proc_name[BUFSIZ];
     unw_word_t offp;
     int status;
+    std::string fileName;
+    int  lineNumber;
 
     unw_getcontext(&uc);
     // get rid of previous function: Backtrace::getBacktrace
@@ -74,12 +126,12 @@ const std::string Backtrace::buildBacktrace(void) {
         unw_get_reg(&cursor, UNW_REG_SP, &sp);
         unw_get_proc_name(&cursor, proc_name, sizeof(proc_name), &offp);
         char *realname = abi::__cxa_demangle(proc_name, 0, 0, &status);
-        getSourceInfo(ip);
+        getSourceInfo(ip, fileName, lineNumber);
 
         backtrace << std::hex << "ip = 0x" <<  ip << ", sp = 0x" << sp
                   << ", " << (realname ? realname : proc_name)
-                  << ", " << m_fileName
-                  << ":" << std::dec << m_lineNumber << std::endl;
+                  << ", " << fileName
+                  << ":" << std::dec << lineNumber << std::endl;
 
         free(realname);
     }

diff --git a/src/common/log/Backtrace.h b/src/common/log/Backtrace.h
index c96f29d..55a0f48 100644 (file)
--- a/src/common/log/Backtrace.h
+++ b/src/common/log/Backtrace.h
@@ -26,6 +26,7 @@
 #define SRC_COMMON_LOG_BACKTRACE_H_
 
 #if defined(BUILD_TYPE_DEBUG) && !defined(CYNARA_NO_LOGS)
+#include <elfutils/libdwfl.h>
 #define UNW_LOCAL_ONLY
 #include <libunwind.h>
 #endif
@@ -52,15 +53,15 @@ private:
 
     void operator=(Backtrace const &) = delete;
 
+    void init(void);
     const std::string buildBacktrace(void);
+
 #if defined(BUILD_TYPE_DEBUG) && !defined(CYNARA_NO_LOGS)
-    void getSourceInfo(unw_word_t proc_address);
-#endif
+    void getSourceInfo(unw_word_t address, std::string &fileName, int &lineNumber);
 
-private:
-    const char *m_fileName;
-    const char *m_functionName;
-    unsigned int m_lineNumber;
+    Dwfl *m_dwfl;
+    static const Dwfl_Callbacks m_callbacks;
+#endif
 };
 
 } /* namespace Cynara */