Improved error messages from plugins (#1031)

# Description
Issue a warning message with plugins that fails to load.

src/dlite-mapping-plugins.c

@@ -132,11 +132,12 @@ const DLiteMappingPlugin *dlite_mapping_plugin_get(const char *name)
 {
   const DLiteMappingPlugin *api;
   PluginInfo *info;
+  int code = dliteMappingError;
 
   if (!(info = get_mapping_plugin_info())) return NULL;
-  if ((api = (DLiteMappingPlugin *)plugin_get_api(info, name))) return api;
+  if ((api = (DLiteMappingPlugin *)plugin_get_api(info, name, code))) return api;
   load_mapping_plugins();
-  if ((api = (DLiteMappingPlugin *)plugin_get_api(info, name))) return api;
+  if ((api = (DLiteMappingPlugin *)plugin_get_api(info, name, code))) return api;
 #ifdef WITH_PYTHON
   if ((api = dlite_python_mapping_get_api(name))) return api;
 #endif

src/dlite-storage-plugins.c

@@ -110,9 +110,10 @@ const DLiteStoragePlugin *dlite_storage_plugin_get(const char *name)
   if (!(info = get_storage_plugin_info())) return NULL;
 
   /* Return plugin if it is loaded */
- ErrTry:  // silence errors
-  api = (const DLiteStoragePlugin *)plugin_get_api(info, name);
- ErrOther:  // hmm, we should update plugins.c to produce more specific errors
+ ErrTry:  // silence dliteStorageLoadError
+  api = (const DLiteStoragePlugin *)plugin_get_api(info, name,
+                                                   dliteStorageLoadError);
+ ErrCatch(dliteStorageLoadError):
   break;
  ErrEnd;
   if (api) return api;
@@ -125,9 +126,10 @@ const DLiteStoragePlugin *dlite_storage_plugin_get(const char *name)
       plugin_load_all(info);
       memcpy(g->storage_plugin_path_hash, hash, sizeof(hash));
 
-     ErrTry:  // silence errors
-      api = (const DLiteStoragePlugin *)plugin_get_api(info, name);
-     ErrOther:  // update plugins.c to produce more specific errors
+     ErrTry:  // silence dliteStorageLoadError
+      api = (const DLiteStoragePlugin *)plugin_get_api(info, name,
+                                                       dliteStorageLoadError);
+      ErrCatch(dliteStorageLoadError):
       break;
      ErrEnd;
       if (api) return api;
@@ -179,12 +181,25 @@ const DLiteStoragePlugin *dlite_storage_plugin_get(const char *name)
       }
     }
 
-    if (n <= 1)
+    if (n <= 1) {
       m += asnpprintf(&buf, &size, m,
-                      "   Are the required Python packages installed or %s\n"
-                      "   DLITE_STORAGE_PLUGIN_DIRS or "
-                      "DLITE_PYTHON_STORAGE_PLUGIN_DIRS\n"
-                      "   environment variables set?", submsg);
+                      "   If the plugin is listed above, but could not be "
+                      "loaded, it may be an\n"
+                      "   error in the plugin. Are the required Python "
+                      "packages installed?\n");
+    }
+    if (!getenv("DLITE_PYDEBUG")) {
+      r = asnpprintf(&buf, &size, m,
+                     "   Please rerun with the DLITE_PYDEBUG environment "
+                     "variable set.\n");
+      if (r >= 0) m += r;
+    }
+    r = asnpprintf(&buf, &size, m,
+                   "   If the plugin is not listed above, it may not be "
+                   "in the search path.\n"
+                   "   Are the %sDLITE_STORAGE_PLUGIN_DIRS or "
+                   "DLITE_PYTHON_STORAGE_PLUGIN_DIRS\n"
+                   "   environment variables set?", submsg);
     errx(dliteStorageOpenError, "%s", buf);
 #endif
     free(buf);

src/pyembed/dlite-pyembed.c

@@ -321,6 +321,7 @@ int dlite_pyembed_errmsg(char *errmsg, size_t errlen)
   PyErr_Fetch(&type, &value, &tb);
   if (!type) return 0;
   PyErr_NormalizeException(&type, &value, &tb);
+  if (!tb) PyException_SetTraceback(value, tb);
 
   /* Try to create a error message from Python using the treaceback package */
   if (errmsg) {
@@ -624,6 +625,8 @@ PyObject *dlite_pyembed_load_plugins(FUPaths *paths, PyObject *baseclass,
   PyObject *subclassnames=NULL;
   FUIter *iter;
   int i;
+  FILE *fp=NULL;
+  size_t errors_pos=0;
   char errors[4098] = "";
 
   dlite_errclr();
@@ -655,12 +658,9 @@ PyObject *dlite_pyembed_load_plugins(FUPaths *paths, PyObject *baseclass,
 
     if ((stem = fu_stem(path))) {
       int stat;
-      FILE *fp=NULL;
       PyObject *plugindict;
 
       if (!(plugindict = dlite_python_plugindict(stem))) goto fail;
-      //if (!(plugindict = dlite_python_dlitedict())) goto fail;
-
       if (!(ppath = PyUnicode_FromString(path)))
         FAIL1("cannot create Python string from path: '%s'", path);
       stat = PyDict_SetItemString(plugindict, "__file__", ppath);
@@ -679,17 +679,29 @@ PyObject *dlite_pyembed_load_plugins(FUPaths *paths, PyObject *baseclass,
           PyObject *ret = PyRun_File(fp, path, Py_file_input, plugindict,
                                      plugindict);
           if (!ret) {
-
             if (failed_paths && failed_len) {
               char **new = strlst_append(*failed_paths, failed_len, path);
               if (!new) FAIL("allocation failure");
               *failed_paths = new;
             }
 
-            dlite_pyembed_errmsg(NULL, 0);
-            fclose(fp);
+            int m;
+            if (errors_pos < sizeof(errors) &&
+                (m = snprintf(errors+errors_pos, sizeof(errors)-errors_pos,
+                              "  - %s: (%s): ", stem, path)) > 0)
+              errors_pos += m;
+            if (errors_pos < sizeof(errors) &&
+                (m = dlite_pyembed_errmsg(errors+errors_pos,
+                                          sizeof(errors)-errors_pos)) > 0)
+              errors_pos += m;
+            if (errors_pos < sizeof(errors) &&
+                (m = snprintf(errors+errors_pos, sizeof(errors)-errors_pos,
+                              "\n")) > 0)
+              errors_pos += m;
           }
           Py_XDECREF(ret);
+          fclose(fp);
+          fp = NULL;
         }
       }
       free(stem);
@@ -698,11 +710,13 @@ PyObject *dlite_pyembed_load_plugins(FUPaths *paths, PyObject *baseclass,
   }
   if (fu_pathsiter_deinit(iter)) goto fail;
 
-  if (errors[0])
+  if (errors[0]) {
     dlite_warn("Could not load the following Python plugins:\n%s"
-               "   You might have to install corresponding python "
-               "package(s).\n",
+               "You may have to install missing python package(s).\n",
                errors);
+  }
+
+
 
   /* Append new subclasses to the list of Python plugins that will be
      returned */
@@ -729,6 +743,7 @@ PyObject *dlite_pyembed_load_plugins(FUPaths *paths, PyObject *baseclass,
  fail:
   Py_XDECREF(lst);
   Py_XDECREF(subclassnames);
+  if (fp) fclose(fp);
   return subclasses;
 }
 

src/utils/err.c

@@ -287,8 +287,9 @@ int _err_vformat(ErrLevel errlevel, int eval, int errnum, const char *file,
   if (errlevel >= errLevelError && tls->err_record->state)
     tls->err_record->reraise = eval;
 
-  /* If we are not within a ErrTry...ErrEnd clause */
+  /* Call error handler */
   if (!tls->err_record->prev) {
+    /* If we are not within a ErrTry...ErrEnd clause */
 
     /* ...call the error handler */
     if (handler) handler(tls->err_record);
@@ -309,6 +310,11 @@ int _err_vformat(ErrLevel errlevel, int eval, int errnum, const char *file,
       if (!handler) err_default_handler(tls->err_record);
       exit(eval);
     }
+
+  } else if (errlevel == errLevelWarn) {
+    /* Handle warnings within a ErrTry...ErrEnd clause */
+
+    if (handler) handler(tls->err_record);
   }
 
   /* Clear errno */

src/utils/plugin.c

@@ -180,13 +180,13 @@ static int register_plugin(PluginInfo *info, const PluginAPI *api,
   If `name` is NULL, all plugins matching `pattern` are registered and a
   pointer to latest successfully loaded API is returned.
 
-  If `emit_err` is non-zero, an error message will be emitted in case a
+  If `errcode` is non-zero, an error with this code will be emitted in case a
   named plugin cannot be loaded.
 
   Returns a pointer to the plugin API or NULL on error.
  */
 const PluginAPI *plugin_load(PluginInfo *info, const char *name,
-                             const char *pattern, int emit_err)
+                             const char *pattern, int errcode)
 {
   FUIter *iter=NULL;
   const char *filepath;
@@ -255,7 +255,7 @@ const PluginAPI *plugin_load(PluginInfo *info, const char *name,
     }
   }
   if (name) {
-    if (emit_err) errx(1, "no such api: \"%s\"", name);
+    if (errcode) errx(errcode, "no such plugin: \"%s\"", name);
     retval = NULL;
   } else {
     retval = loaded_api;
@@ -308,9 +308,11 @@ int plugin_has_api(PluginInfo *info, const char *name)
   any shared library.  If a plugin with the provided name is found, it
   is loaded, registered and returned.
 
+  If the plugin is not found, `err()` is called with `eval` set to `errcode`.
+
   Otherwise NULL is returned.
  */
-const PluginAPI *plugin_get_api(PluginInfo *info, const char *name)
+const PluginAPI *plugin_get_api(PluginInfo *info, const char *name, int errcode)
 {
   const PluginAPI *api=NULL;
   PluginAPI **p;
@@ -322,12 +324,11 @@ const PluginAPI *plugin_get_api(PluginInfo *info, const char *name)
 
   /* Load plugin from search path */
   if (!(pattern = malloc(strlen(name) + strlen(DSL_EXT) + 1)))
-    return err(1, "allocation failure"), NULL;
+    return err(pluginMemoryError, "allocation failure"), NULL;
   strcpy(pattern, name);
   strcat(pattern, DSL_EXT);
-  if (!(api = plugin_load(info, name, pattern, 0)) &&
-      !(api = plugin_load(info, name, "*" DSL_EXT, 1)))
-    err(1, "cannot find api: '%s'", name);
+  if (!(api = plugin_load(info, name, pattern, 0)))
+    api = plugin_load(info, name, "*" DSL_EXT, errcode);
 
   if (pattern) free(pattern);
   return api;

src/utils/plugin.h

@@ -43,6 +43,11 @@
 #include "globmatch.h"
 #include "map.h"
 
+/* SWIG-compatible error codes */
+typedef enum {
+  pluginMemoryError=-12        /*!< Out of memory */
+} PluginErrCodes;
+
 
 /** Initial fields in all plugin APIs. */
 #define PluginAPI_HEAD                                                  \
@@ -138,9 +143,11 @@ int plugin_has_api(PluginInfo *info, const char *name);
   any shared library.  If a plugin with the provided name is found, it
   is loaded, registered and returned.
 
+  If the plugin is not found, err() is called with `eval` set to `errcode`.
+
   Otherwise NULL is returned.
  */
-const PluginAPI *plugin_get_api(PluginInfo *info, const char *name);
+const PluginAPI *plugin_get_api(PluginInfo *info, const char *name, int errcode);
 
 /**
   Load all plugins that can be found in the plugin search path.

src/utils/tests/test_plugin.c

@@ -26,7 +26,7 @@ MU_TEST(test_info_create)
 MU_TEST(test_get_api)
 {
   const TestAPI *api;
-  mu_check((api = (const TestAPI *)plugin_get_api(info, "testapi")));
+  mu_check((api = (const TestAPI *)plugin_get_api(info, "testapi", -2)));
   mu_assert_string_eq("testapi", api->name);
   mu_assert_int_eq(4, api->fun1(1, 3));
   mu_assert_double_eq(6.28, api->fun2(3.14));