Fix util::ostringstream, fix pretty-printing, stub out new globals

luprex/cpp/drv/driver-common.cpp

@@ -158,7 +158,8 @@ class Driver {
             drvutil::ostringstream oss;
             std::string err = drvutil::package_lua_source(".", &oss);
             if_error_print_and_exit(err);
-            engw.play_set_lua_source(&engw, oss.size(), oss.c_str());
+            std::string_view ossv = oss.view();
+            engw.play_set_lua_source(&engw, ossv.size(), ossv.data());
         }
     }
 
@@ -590,7 +591,8 @@ class Driver {
         if_error_print_and_exit(srcpakerr);
 
         // Initialize the engine.
-        engw.play_initialize(&engw, argc, argv, srcpak.size(), srcpak.c_str(), replaylogfn.c_str());
+        std::string_view srcpakv = srcpak.view();
+        engw.play_initialize(&engw, argc, argv, srcpakv.size(), srcpakv.data(), replaylogfn.c_str());
         if_error_print_and_exit(engw.error);
 
         // Set up listening ports.

luprex/cpp/drv/drvutil.hpp

@@ -68,23 +68,27 @@ double get_monotonic_clock();
 // without copying, use oss.size() and oss.c_str()
 //
 class ostringstream : public std::ostringstream {
-    class rstringbuf : public std::stringbuf {
+    class rstringbuf : public std::basic_stringbuf<char_type, traits_type, allocator_type> {
     public:
-        char *eback() { return std::streambuf::eback(); }
+        char *eback() const { return std::streambuf::eback(); }
+        char *pptr() const { return std::streambuf::pptr(); }
     };
-    rstringbuf rsbuf_;
+    rstringbuf rstringbuf_;
 public:
     ostringstream() {
-        std::basic_ostream<char>::rdbuf(&rsbuf_);
+        std::basic_ostream<char>::rdbuf(&rstringbuf_);
     }
-    size_t size() {
-        return tellp();
+    std::string_view view() const {
+        char *p = rstringbuf_.eback();
+        size_t size = rstringbuf_.pptr() - p;
+        return std::string_view(p, size);
     }
-    const char *c_str() {
-        return rsbuf_.eback();
+    std::string str() const {
+        return rstringbuf_.str();
     }
 };
 
+
 // Remove items from a vector that are marked for deletion.
 //
 template<class T>