Add pg_encoding_set_invalid()

There are cases where we cannot / do not want to error out for invalidly
encoded input. In such cases it can be useful to replace e.g. an incomplete
multi-byte characters with bytes that will trigger an error when getting
validated as part of a larger string.

Unfortunately, until now, for some encoding no such sequence existed. For
those encodings this commit removes one previously accepted input combination
- we consider that to be ok, as the chosen bytes are outside of the valid
ranges for the encodings, we just previously failed to detect that.

As we cannot add a new field to pg_wchar_table without breaking ABI, this is
implemented "in-line" in the newly added function.

Author: Noah Misch <noah@leadboat.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Backpatch-through: 13
Security: CVE-2025-1094

1 files changed, 4 insertions, 0 deletions

diff --git a/src/test/regress/input/create_function_1.source b/src/test/regress/input/create_function_1.source
index 412e339fcf2..b230a8a6a81 100644
--- a/src/test/regress/input/create_function_1.source
+++ b/src/test/regress/input/create_function_1.source
@@ -62,6 +62,10 @@ CREATE FUNCTION test_atomic_ops()
     AS '@libdir@/regress@DLSUFFIX@'
     LANGUAGE C;
 
+CREATE FUNCTION test_enc_setup() RETURNS void
+    AS '@libdir@/regress@DLSUFFIX@', 'test_enc_setup'
+    LANGUAGE C STRICT;
+
 -- Tests creating a FDW handler
 CREATE FUNCTION test_fdw_handler()
     RETURNS fdw_handler