In typed_var_kvassign, include config names in error messages.

This should improve the usability of our configuration error messages.

2 files changed, 12 insertions, 2 deletions

diff --git a/src/lib/confmgt/typedvar.c b/src/lib/confmgt/typedvar.c
index 3a188db953..1955302cdc 100644
--- a/src/lib/confmgt/typedvar.c
+++ b/src/lib/confmgt/typedvar.c
@@ -24,6 +24,7 @@
 #include "lib/log/log.h"
 #include "lib/log/util_bug.h"
 #include "lib/malloc/malloc.h"
+#include "lib/string/printf.h"
 #include "lib/string/util_string.h"
 
 #include "lib/confmgt/var_type_def_st.h"
@@ -75,7 +76,15 @@ typed_var_kvassign(void *target, const config_line_t *line,
     return def->fns->kv_parse(target, line, errmsg, def->params);
   }
 
-  return typed_var_assign(target, line->value, errmsg, def);
+  int rv = typed_var_assign(target, line->value, errmsg, def);
+  if (rv < 0 && *errmsg != NULL) {
+    /* typed_var_assign() didn't know the line's keyword, but we do.
+     * Let's add it to the error message. */
+    char *oldmsg = *errmsg;
+    tor_asprintf(errmsg, "Could not parse %s: %s", line->key, oldmsg);
+    tor_free(oldmsg);
+  }
+  return rv;
 }
 
 /**
diff --git a/src/test/test_options.c b/src/test/test_options.c
index 129a8299e3..636d3c0e54 100644
--- a/src/test/test_options.c
+++ b/src/test/test_options.c
@@ -4269,7 +4269,8 @@ test_options_trial_assign(void *arg)
   v = options_trial_assign(lines, 0, &msg);
   tt_int_op(v, OP_EQ, SETOPT_ERR_PARSE);
   tt_str_op(msg, OP_EQ,
-            "Unrecognized value ambidextrous. Allowed values are 0 and 1.");
+            "Could not parse UseBridges: Unrecognized value ambidextrous. "
+            "Allowed values are 0 and 1.");
   tor_free(msg);
   config_free_lines(lines);