Add backtrace()

1 files changed, 101 insertions, 0 deletions

diff --git a/libbutl/backtrace.cxx b/libbutl/backtrace.cxx
new file mode 100644
index 0000000..7a8d615
--- /dev/null
+++ b/libbutl/backtrace.cxx
@@ -0,0 +1,101 @@
+// file      : libbutl/backtrace.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef __cpp_modules_ts
+#include <libbutl/backtrace.mxx>
+#endif
+
+// We only enable backtrace during bootstrap if we can do it without any
+// complications of the build scripts/makefiles.
+//
+// With glibc linking with -rdynamic gives (non-static) function names.
+// FreeBSD requires explicitly linking -lexecinfo.
+//
+#ifndef BUILD2_BOOTSTRAP
+#  if defined(__linux__) || \
+      defined(__APPLE__) || \
+      defined(__FreeBSD__)
+#    define LIBBUTL_BACKTRACE
+#  endif
+#else
+#  if defined(__linux__) || \
+      defined(__APPLE__)
+#    define LIBBUTL_BACKTRACE
+#  endif
+#endif
+
+#ifdef LIBBUTL_BACKTRACE
+#  include <stdlib.h>   // free()
+#  include <execinfo.h>
+#endif
+
+#include <cassert>
+
+#ifndef __cpp_lib_modules_ts
+#include <string>
+
+#ifdef LIBBUTL_BACKTRACE
+#  include <memory>  // unique_ptr
+#  include <cstddef> // size_t
+#endif
+
+#include <exception>
+#endif
+
+// Other includes.
+
+#ifdef __cpp_modules_ts
+module butl.backtrace;
+
+// Only imports additional to interface.
+#ifdef __clang__
+#ifdef __cpp_lib_modules_ts
+import std.core;
+#endif
+#endif
+
+#endif
+
+using namespace std;
+
+namespace butl
+{
+  string
+  backtrace () noexcept
+  try
+  {
+    string r;
+
+#ifdef LIBBUTL_BACKTRACE
+
+    // Note: backtrace() returns int on Linux and MacOS and size_t on FreeBSD.
+    //
+    void* buf[1024];
+    auto n (::backtrace (buf, 1024));
+
+    assert (n >= 0);
+
+    char** fs (backtrace_symbols (buf, n)); // Note: returns NULL on error.
+
+    if (fs != nullptr)
+    {
+      unique_ptr<char*, void (*)(char**)> deleter (
+        fs, [] (char** s) {::free (s);});
+
+      for (size_t i (0); i != static_cast<size_t> (n); ++i)
+      {
+        r += fs[i];
+        r += '\n';
+      }
+    }
+
+#endif
+
+    return r;
+  }
+  catch (const std::exception&)
+  {
+    return string ();
+  }
+}