Suppress complaints about leaks in TS dictionary loading.

Like the situation with function cache loading, text search
dictionary loading functions tend to leak some cruft into the
dictionary's long-lived cache context.  To judge by the examples in
the core regression tests, not very many bytes are at stake.
Moreover, I don't see a way to prevent such leaks without changing the
API for TS template initialization functions: right now they do not
have to worry about making sure that their results are long-lived.

Hence, I think we should install a suppression rule rather than trying
to fix this completely.  However, I did grab some low-hanging fruit:
several places were leaking the result of get_tsearch_config_filename.
This seems worth doing mostly because they are inconsistent with other
dictionaries that were freeing it already.

Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/285483.1746756246@sss.pgh.pa.us

src/backend/tsearch/dict_ispell.c

@@ -47,24 +47,30 @@ dispell_init(PG_FUNCTION_ARGS)
 
 		if (strcmp(defel->defname, "dictfile") == 0)
 		{
+			char	   *filename;
+
 			if (dictloaded)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 						 errmsg("multiple DictFile parameters")));
-			NIImportDictionary(&(d->obj),
-							   get_tsearch_config_filename(defGetString(defel),
-														   "dict"));
+			filename = get_tsearch_config_filename(defGetString(defel),
+												   "dict");
+			NIImportDictionary(&(d->obj), filename);
+			pfree(filename);
 			dictloaded = true;
 		}
 		else if (strcmp(defel->defname, "afffile") == 0)
 		{
+			char	   *filename;
+
 			if (affloaded)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 						 errmsg("multiple AffFile parameters")));
-			NIImportAffixes(&(d->obj),
-							get_tsearch_config_filename(defGetString(defel),
-														"affix"));
+			filename = get_tsearch_config_filename(defGetString(defel),
+												   "affix");
+			NIImportAffixes(&(d->obj), filename);
+			pfree(filename);
 			affloaded = true;
 		}
 		else if (strcmp(defel->defname, "stopwords") == 0)

src/backend/tsearch/dict_synonym.c

@@ -199,6 +199,7 @@ skipline:
 	}
 
 	tsearch_readline_end(&trst);
+	pfree(filename);
 
 	d->len = cur;
 	qsort(d->syn, d->len, sizeof(Syn), compareSyn);

src/backend/tsearch/dict_thesaurus.c

@@ -167,17 +167,17 @@ addWrd(DictThesaurus *d, char *b, char *e, uint32 idsubst, uint16 nwrd, uint16 p
 static void
 thesaurusRead(const char *filename, DictThesaurus *d)
 {
+	char	   *real_filename = get_tsearch_config_filename(filename, "ths");
 	tsearch_readline_state trst;
 	uint32		idsubst = 0;
 	bool		useasis = false;
 	char	   *line;
 
-	filename = get_tsearch_config_filename(filename, "ths");
-	if (!tsearch_readline_begin(&trst, filename))
+	if (!tsearch_readline_begin(&trst, real_filename))
 		ereport(ERROR,
 				(errcode(ERRCODE_CONFIG_FILE_ERROR),
 				 errmsg("could not open thesaurus file \"%s\": %m",
-						filename)));
+						real_filename)));
 
 	while ((line = tsearch_readline(&trst)) != NULL)
 	{
@@ -297,6 +297,7 @@ thesaurusRead(const char *filename, DictThesaurus *d)
 	d->nsubst = idsubst;
 
 	tsearch_readline_end(&trst);
+	pfree(real_filename);
 }
 
 static TheLexeme *

src/backend/utils/cache/ts_cache.c

@@ -321,7 +321,9 @@ lookup_ts_dictionary_cache(Oid dictId)
 
 			/*
 			 * Init method runs in dictionary's private memory context, and we
-			 * make sure the options are stored there too
+			 * make sure the options are stored there too.  This typically
+			 * results in a small amount of memory leakage, but it's not worth
+			 * complicating the API for tmplinit functions to avoid it.
 			 */
 			oldcontext = MemoryContextSwitchTo(entry->dictCtx);
 

src/tools/valgrind.supp

@@ -215,3 +215,15 @@
    ...
    fun:cached_function_compile
 }
+
+# Suppress complaints about stuff leaked during TS dictionary loading.
+# Not very much is typically lost there, and preventing it would
+# require a risky API change for TS tmplinit functions.
+{
+   hide_ts_dictionary_leaks
+   Memcheck:Leak
+   match-leak-kinds: definite,possible,indirect
+
+   ...
+   fun:lookup_ts_dictionary_cache
+}