UCP/CORE: Return an error if there is no modifiable configuration.

Author: rakhmets

src/ucp/core/ucp_context.c

@@ -23,6 +23,7 @@
 #include <ucs/debug/debug_int.h>
 #include <ucs/sys/compiler.h>
 #include <ucs/sys/string.h>
+#include <ucs/type/init_once.h>
 #include <ucs/vfs/base/vfs_cb.h>
 #include <ucs/vfs/base/vfs_obj.h>
 #include <string.h>
@@ -863,6 +864,47 @@ ucs_status_t ucp_config_modify_internal(ucp_config_t *config, const char *name,
                                        value);
 }
 
+static void ucp_config_query_uct_components(void)
+{
+    static ucs_init_once_t init_once = UCS_INIT_ONCE_INITIALIZER;
+    uct_component_h *components;
+    unsigned num_components;
+    ucs_status_t status;
+
+    UCS_INIT_ONCE(&init_once) {
+        status = uct_query_components(&components, &num_components);
+        if (status == UCS_OK) {
+            uct_release_component_list(components);
+        } else {
+            ucs_warn("failed to query UCT components: %s",
+                     ucs_status_string(status));
+        }
+    }
+}
+
+static int ucp_config_global_list_has_field(const char *name)
+{
+    const ucs_config_global_list_entry_t *entry;
+    const char *field_name;
+    size_t prefix_len;
+
+    ucs_list_for_each(entry, &ucs_config_global_list, list) {
+        field_name = name;
+        if (entry->prefix != NULL) {
+            prefix_len = strlen(entry->prefix);
+            if (!strncmp(entry->prefix, field_name, prefix_len)) {
+                field_name += prefix_len;
+            }
+        }
+
+        if (ucs_config_parser_has_field(entry->table, field_name)) {
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
 ucs_status_t ucp_config_modify(ucp_config_t *config, const char *name,
                                const char *value)
 {
@@ -878,6 +920,17 @@ ucs_status_t ucp_config_modify(ucp_config_t *config, const char *name,
         return status;
     }
 
+    if (ucs_global_opts_is_unmodifiable(name)) {
+        ucs_debug("%s configuration cannot be changed, the change is only "
+                  "available through the environment variable", name);
+        return UCS_ERR_UNSUPPORTED;
+    }
+
+    ucp_config_query_uct_components();
+    if (!ucp_config_global_list_has_field(name)) {
+        return UCS_ERR_NO_ELEM;
+    }
+
     return ucp_config_cached_key_add(&config->cached_key_list, name, value);
 }
 

src/ucs/config/global_opts.c

@@ -368,6 +368,11 @@ ucs_status_t ucs_global_opts_set_value_modifiable(const char *name,
                                        NULL, name, value);
 }
 
+int ucs_global_opts_is_unmodifiable(const char *name)
+{
+    return ucs_config_parser_has_field(ucs_global_opts_read_only_table, name);
+}
+
 ucs_status_t ucs_global_opts_get_value(const char *name, char *value,
                                        size_t max)
 {

src/ucs/config/global_opts.h

@@ -180,6 +180,14 @@ ucs_status_t ucs_global_opts_clone(void *dst);
 void ucs_global_opts_release(void);
 void ucs_global_opts_print(FILE *stream, ucs_config_print_flags_t print_flags);
 
+/**
+ * Check if a field is unmodifiable.
+ *
+ * @param name Field name to check.
+ * @return     1 if the field is unmodifiable, 0 otherwise.
+ */
+int ucs_global_opts_is_unmodifiable(const char *name);
+
 END_C_DECLS
 
 #endif

src/ucs/config/parser.c

@@ -2461,3 +2461,31 @@ void ucs_config_parser_cleanup()
     })
     kh_destroy_inplace(ucs_config_map, &ucs_config_file_vars);
 }
+
+int
+ucs_config_parser_has_field(const ucs_config_field_t *fields, const char *name)
+{
+    const ucs_config_field_t *field;
+    size_t table_name_len;
+
+    if (!fields || !name) {
+        return 0;
+    }
+
+    for (field = fields; !ucs_config_field_is_last(field); ++field) {
+        if (!strncmp(field->name, name, strlen(name))) {
+            return 1;
+        }
+
+        if (ucs_config_is_table_field(field)) {
+            table_name_len = strlen(field->name);
+            if (!strncmp(field->name, name, table_name_len) &&
+                ucs_config_parser_has_field(field->parser.arg,
+                                            name + table_name_len)) {
+                return 1;
+            }
+        }
+    }
+
+    return 0;
+}

src/ucs/config/parser.h

@@ -640,6 +640,16 @@ void ucs_config_parser_get_env_vars(ucs_string_buffer_t *env_strb,
 void ucs_config_parser_cleanup(void);
 
 
+/**
+ * Check if a field exists in the configuration table.
+ *
+ * @param fields Array of fields which define the configuration table.
+ * @param name   Field name to check.
+ * @return       1 if the field exists, 0 otherwise.
+ */
+int
+ucs_config_parser_has_field(const ucs_config_field_t *fields, const char *name);
+
 END_C_DECLS
 
 #endif