Up until version 3.42.0, there was a bug in json_valid() such that it would

return False (0) for a NULL input.  That bug is fixed in 3.42.0.  This
check-in adds a compile-time option -DSQLITE_LEGACY_JSON_VALID that restores
the old buggy behavior for applications that depend on it.

FossilOrigin-Name: 15c2eadbff8e732cca45d6c3771d1fcea5aab2127e87f2a611b41ccfef4d1a0d

src/ctime.c

@@ -60,9 +60,6 @@ static const char * const sqlite3azCompileOpt[] = {
 #ifdef SQLITE_4_BYTE_ALIGNED_MALLOC
   "4_BYTE_ALIGNED_MALLOC",
 #endif
-#ifdef SQLITE_64BIT_STATS
-  "64BIT_STATS",
-#endif
 #ifdef SQLITE_ALLOW_COVERING_INDEX_SCAN
 # if SQLITE_ALLOW_COVERING_INDEX_SCAN != 1
   "ALLOW_COVERING_INDEX_SCAN=" CTIMEOPT_VAL(SQLITE_ALLOW_COVERING_INDEX_SCAN),
@@ -399,6 +396,9 @@ static const char * const sqlite3azCompileOpt[] = {
 #ifdef SQLITE_INTEGRITY_CHECK_ERROR_MAX
   "INTEGRITY_CHECK_ERROR_MAX=" CTIMEOPT_VAL(SQLITE_INTEGRITY_CHECK_ERROR_MAX),
 #endif
+#ifdef SQLITE_LEGACY_JSON_VALID
+  "LEGACY_JSON_VALID",
+#endif
 #ifdef SQLITE_LIKE_DOESNT_MATCH_BLOBS
   "LIKE_DOESNT_MATCH_BLOBS",
 #endif

src/json.c

@@ -3009,7 +3009,13 @@ static void jsonValidFunc(
 ){
   JsonParse *p;          /* The parse */
   UNUSED_PARAMETER(argc);
-  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
+  if( sqlite3_value_type(argv[0])==SQLITE_NULL ){
+#ifdef SQLITE_LEGACY_JSON_VALID
+    /* Incorrect legacy behavior was to return FALSE for a NULL input */
+    sqlite3_result_int(ctx, 0);
+#endif
+    return;
+  }
   p = jsonParseCached(ctx, argv[0], 0, 0);
   if( p==0 || p->oom ){
     sqlite3_result_error_nomem(ctx);