Make object address handling more robust

pg_identify_object_as_address crashes when passed certain tuples from
inconsistent system catalogs.  Make it more defensive.

Author: Álvaro Herrera
Reviewed-by: Michaël Paquier
Discussion: https://postgr.es/m/20190218202743.GA12392@alvherre.pgsql

diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c
index bd55dfd08e33d3b1cfffb3ba7f7e65e6092085f8..b5e28c8ba6ac43c549da561baebb2f8d64a2e5dd 100644 (file)
--- a/src/backend/catalog/objectaddress.c
+++ b/src/backend/catalog/objectaddress.c
@@ -3576,7 +3576,10 @@ pg_identify_object_as_address(PG_FUNCTION_ARGS)
        pfree(identity);
 
        /* object_names */
-       values[1] = PointerGetDatum(strlist_to_textarray(names));
+       if (names != NIL)
+               values[1] = PointerGetDatum(strlist_to_textarray(names));
+       else
+               values[1] = PointerGetDatum(construct_empty_array(TEXTOID));
        nulls[1] = false;
 
        /* object_args */
@@ -4803,10 +4806,12 @@ strlist_to_textarray(List *list)
 {
        ArrayType  *arr;
        Datum      *datums;
+       bool       *nulls;
        int                     j = 0;
        ListCell   *cell;
        MemoryContext memcxt;
        MemoryContext oldcxt;
+       int                     lb[1];
 
        memcxt = AllocSetContextCreate(CurrentMemoryContext,
                                                                   "strlist to array",
@@ -4814,17 +4819,25 @@ strlist_to_textarray(List *list)
        oldcxt = MemoryContextSwitchTo(memcxt);
 
        datums = palloc(sizeof(text *) * list_length(list));
+       nulls = palloc(sizeof(bool) * list_length(list));
        foreach(cell, list)
        {
                char       *name = lfirst(cell);
 
-               datums[j++] = CStringGetTextDatum(name);
+               if (name)
+               {
+                       nulls[j] = false;
+                       datums[j++] = CStringGetTextDatum(name);
+               }
+               else
+                       nulls[j++] = true;
        }
 
        MemoryContextSwitchTo(oldcxt);
 
-       arr = construct_array(datums, list_length(list),
-                                                 TEXTOID, -1, false, 'i');
+       lb[0] = 1;
+       arr = construct_md_array(datums, nulls, 1, &j,
+                                                        lb, TEXTOID, -1, false, 'i');
        MemoryContextDelete(memcxt);
 
        return arr;