Avoid program_invocation_name which is available only on Linux

Boss/Main.cpp

@@ -20,6 +20,8 @@
 # include "config.h"
 #endif
 
+std::string g_argv0;
+
 namespace Boss {
 
 class Main::Impl {
@@ -62,6 +64,7 @@ class Main::Impl {
 	      {
 		assert(argv.size() >= 1);
 		argv0 = argv[0];
+		g_argv0 = argv[0];
 		if (argv.size() >= 2) {
 			auto argv1 = argv[1];
 			if (argv1 == "--version" || argv1 == "-V")

Util/BacktraceException.hpp

@@ -6,8 +6,15 @@
 #include <iomanip>
 #include <memory>
 #include <sstream>
-#include <vector>
+#include <stdlib.h>
 #include <string.h>
+#include <string>
+
+#ifdef HAVE_CONFIG_H
+# include"config.h"
+#endif
+
+extern std::string g_argv0;
 
 namespace Util {
 
@@ -74,13 +81,29 @@ class BacktraceException : public T {
 		return oss.str();
 	}
 
+        std::string progname() const {
+		// This variable is set by the CLBOSS mainline.
+		if (!g_argv0.empty()) {
+			return g_argv0;
+		}
+
+		// When libclboss is linked with the unit tests the
+		// g_argv0 variable is not set and we need to use
+		// built-in versions
+#ifdef HAVE_GETPROGNAME
+		return getprogname();
+#else
+		return program_invocation_name;
+#endif
+	}
+
 	// Unfortunately there is no simple way to get a high quality
 	// backtrace using in-process libraries.  Instead for now we
 	// popen an addr2line process and use it's output.
 	std::string addr2line(void* addr) const {
 		char cmd[512];
 		snprintf(cmd, sizeof(cmd),
-			 "addr2line -C -f -p -e %s %p", program_invocation_name, addr);
+			 "addr2line -C -f -p -e %s %p", progname().c_str(), addr);
 
 		std::array<char, 128> buffer;
 		std::string result;

configure.ac

@@ -100,6 +100,21 @@ AC_LINK_IFELSE([AC_LANG_PROGRAM([[
 	AC_MSG_RESULT([no])
 ])
 
+# Check for getprogname()
+AC_MSG_CHECKING([for getprogname])
+AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+#include<stdlib.h>
+]], [[
+	const char* p = getprogname();
+	(void)p; // avoid warning about set but unused variable
+]])], [ #then
+	AC_DEFINE([HAVE_GETPROGNAME], [1],
+		  [Define to 1 if you have a getprogname function.])
+	AC_MSG_RESULT([yes])
+], [ #else
+	AC_MSG_RESULT([no])
+])
+
 AC_CONFIG_FILES([Makefile
 		 external/bitcoin-ripemd160/Makefile
 		 external/bitcoin-sha256/Makefile