Use the same function for logging dynlib errors on all platforms

Reduces the amount of #ifdefs scattered all over the code, thereby
simplifying the code.

The function was renamed from Error() to ReportError() to emphasize what
its purpose is.

Error messages logged on *nix are now a bit more verbose, as they are
prefixed with our own description text, which were earlier omitted on
platforms using the dlxxx() API.

include/wx/dynlib.h

@@ -357,11 +357,9 @@ protected:
     // common part of GetSymbol() and HasSymbol()
     void* DoGetSymbol(const wxString& name, bool* success = NULL) const;
 
-#ifdef HAVE_DLERROR
-    // log the error after a dlxxx() function failure
-    static void Error();
-#endif // HAVE_DLERROR
-
+    // log the error after an OS dynamic library function failure
+    static void ReportError(const wxString& msg,
+                            const wxString& name = wxString());
 
     // the handle to DLL or NULL
     wxDllType m_handle;

src/common/dynlib.cpp

@@ -86,11 +86,7 @@ bool wxDynamicLibrary::Load(const wxString& libnameOrig, int flags)
 
     if ( m_handle == 0 && !(flags & wxDL_QUIET) )
     {
-#ifdef HAVE_DLERROR
-        Error();
-#else
-        wxLogSysError(_("Failed to load shared library '%s'"), libname.c_str());
-#endif
+        ReportError(_("Failed to load shared library '%s'"), libname);
     }
 
     return IsLoaded();
@@ -114,12 +110,8 @@ void *wxDynamicLibrary::GetSymbol(const wxString& name, bool *success) const
     void *symbol = DoGetSymbol(name, success);
     if ( !symbol )
     {
-#ifdef HAVE_DLERROR
-        Error();
-#else
-        wxLogSysError(_("Couldn't find symbol '%s' in a dynamic library"),
+        ReportError(_("Couldn't find symbol '%s' in a dynamic library"),
                     name.c_str());
-#endif
     }
 
     return symbol;

src/msw/dlmsw.cpp

@@ -145,6 +145,31 @@ wxDllType wxDynamicLibrary::GetProgramHandle()
     return (wxDllType)::GetModuleHandle(NULL);
 }
 
+// ----------------------------------------------------------------------------
+// error handling
+// ----------------------------------------------------------------------------
+
+/* static */
+void wxDynamicLibrary::ReportError(const wxString& message, const wxString& name)
+{
+    wxString msg(message);
+    if ( name.IsEmpty() && msg.Find("%s") == wxNOT_FOUND )
+        msg += "%s";
+    // msg needs a %s for the name
+    wxASSERT(msg.Find("%s") != wxNOT_FOUND);
+
+    const unsigned long code = wxSysErrorCode();
+    wxString errMsg = wxSysErrorMsgStr(code);
+
+    // The error message (specifically code==193) may contain a
+    // placeholder '%1' which stands for the filename.
+    errMsg.Replace("%1", name, false);
+
+    // Mimic the output of wxLogSysError(), but use our pre-processed
+    // errMsg.
+    wxLogError(msg + " " + _("(error %d: %s)"), name, code, errMsg);
+}
+
 // ----------------------------------------------------------------------------
 // loading/unloading DLLs
 // ----------------------------------------------------------------------------

src/unix/dlunix.cpp

@@ -120,8 +120,8 @@ void wxDynamicLibrary::Unload(wxDllType handle)
 
 #if defined(USE_POSIX_DL_FUNCS) && defined(HAVE_DLERROR)
     if ( rc != 0 )
-        Error();
 #endif
+        ReportError(_("Failed to unload shared library"));
 }
 
 /* static */
@@ -145,20 +145,27 @@ void *wxDynamicLibrary::RawGetSymbol(wxDllType handle, const wxString& name)
 // error handling
 // ----------------------------------------------------------------------------
 
-#ifdef HAVE_DLERROR
-
 /* static */
-void wxDynamicLibrary::Error()
+void wxDynamicLibrary::ReportError(const wxString& message,
+                                   const wxString& name)
 {
+    wxString msg(message);
+    if ( name.IsEmpty() && msg.Find("%s") == wxNOT_FOUND )
+        msg += "%s";
+    // msg needs a %s for the name
+    wxASSERT(msg.Find("%s") != wxNOT_FOUND);
+#ifdef HAVE_DLERROR
     wxString err(dlerror());
 
     if ( err.empty() )
         err = _("Unknown dynamic library error");
 
-    wxLogError(wxT("%s"), err);
+    wxLogError(msg + wxT(": %s"), name, err);
+#else // !HAVE_DLERROR
+    wxLogSysError(msg, name);
+#endif // HAVE_DLERROR
 }
 
-#endif // HAVE_DLERROR
 
 // ----------------------------------------------------------------------------
 // listing loaded modules