Add backtrace()

3 files changed, 163 insertions, 9 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 ();
+  }
+}
diff --git a/libbutl/backtrace.mxx b/libbutl/backtrace.mxx
new file mode 100644
index 0000000..25d0dcd
--- /dev/null
+++ b/libbutl/backtrace.mxx
@@ -0,0 +1,43 @@
+// file      : libbutl/backtrace.mxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef __cpp_modules_ts
+#pragma once
+#endif
+
+// C includes.
+
+#ifndef __cpp_lib_modules_ts
+#include <string>
+#endif
+
+// Other includes.
+
+#ifdef __cpp_modules_ts
+export module butl.backtrace;
+#ifdef __cpp_lib_modules_ts
+import std.core;
+#endif
+#endif
+
+#include <libbutl/export.hxx>
+
+LIBBUTL_MODEXPORT namespace butl
+{
+  // Return the calling thread's backtrace or empty string if this
+  // functionality is not supported or an error has occurred. The exact
+  // backtrace format is implementation-defined; it normally contains a line
+  // with the binary name, address in that binary, and, if available, the
+  // function name for each stack frame.
+  //
+  // Currently this functionality is only available on Linux, FreeBSD, and Mac
+  // OS. On the first two platforms the address can be mapped to the function
+  // name and, if built with debug info, to source location using the
+  // addr2line(1) utility:
+  //
+  // $ addr2line -f -C -e <binary> <addr>
+  //
+  LIBBUTL_SYMEXPORT std::string
+  backtrace () noexcept;
+}
diff --git a/libbutl/buildfile b/libbutl/buildfile
index 8e88402..feb2f96 100644
--- a/libbutl/buildfile
+++ b/libbutl/buildfile
@@ -16,7 +16,15 @@ lib{butl}: {hxx ixx txx cxx}{** -uuid-* +uuid-io -win32-utility} \
            hxx{**.hxx -uuid-*.hxx +uuid-io.hxx -win32-utility.hxx \
                -version.hxx} hxx{version}
 
-windows = ($cxx.target.class == 'windows')
+tclass = $cxx.target.class
+tsys   = $cxx.target.system
+
+linux   = ($tclass == 'linux')
+macos   = ($tclass == 'macos')
+windows = ($tclass == 'windows')
+freebsd = ($tsys == 'freebsd')
+
+mingw = ($tsys == 'mingw32')
 
 # Exclude these from compilation on non-Windows targets.
 #
@@ -30,17 +38,19 @@ lib{butl}: file{*.c *.h}
 
 # Platform-specific UUID implementations.
 #
-lib{butl}: cxx{uuid-linux}:   include = ($cxx.target.class  == 'linux')
-lib{butl}: cxx{uuid-macos}:   include = ($cxx.target.class  == 'macos')
+lib{butl}: cxx{uuid-linux}:   include = $linux
+lib{butl}: cxx{uuid-macos}:   include = $macos
 lib{butl}: cxx{uuid-windows}: include = $windows
-lib{butl}: cxx{uuid-freebsd}: include = ($cxx.target.system == 'freebsd')
+lib{butl}: cxx{uuid-freebsd}: include = $freebsd
 
-if ($cxx.target.class == 'linux')
+if $linux
   cxx.libs += -ldl
-elif ($cxx.target.class == 'macos')
+elif $macos
   cxx.libs += -framework CoreFoundation
-elif ($windows)
-  cxx.libs += ($cxx.target.system == 'mingw32' ? -lrpcrt4 : rpcrt4.lib)
+elif $windows
+  cxx.libs += ($mingw ? -lrpcrt4 : rpcrt4.lib)
+elif $freebsd
+  cxx.libs += -lexecinfo
 
 # Include the generated version header into the distribution (so that we don't
 # pick up an installed one) and don't remove it when cleaning in src (so that
@@ -63,7 +73,7 @@ objs{*} bmis{*}: cxx.poptions += -DLIBBUTL_SHARED_BUILD
 # Additional system libraries.
 #
 if $windows
-  cxx.libs += ($cxx.target.system == 'mingw32' ? -limagehlp : imagehlp.lib)
+  cxx.libs += ($mingw ? -limagehlp : imagehlp.lib)
 else
   cxx.libs += -lpthread