Add 'noError' argument to encoding conversion functions.

With the 'noError' argument, you can try to convert a buffer without
knowing the character boundaries beforehand. The functions now need to
return the number of input bytes successfully converted.

This is is a backwards-incompatible change, if you have created a custom
encoding conversion with CREATE CONVERSION. This adds a check to
pg_upgrade for that, refusing the upgrade if there are any user-defined
encoding conversions. Custom conversions are very rare, there are no
commonly used extensions that I know of that uses that feature. No other
objects can depend on conversions, so if you do have one, you can fairly
easily drop it before upgrading, and recreate it after the upgrade with
an updated version.

Add regression tests for built-in encoding conversions. This doesn't cover
every conversion, but it covers all the internal functions in conv.c that
are used to implement the conversions.

Reviewed-by: John Naylor
Discussion: https://www.postgresql.org/message-id/e7861509-3960-538a-9025-b75a61188e01%40iki.fi

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..6ba37fe63b6 100644
--- a/src/test/regress/input/create_function_1.source
+++ b/src/test/regress/input/create_function_1.source
@@ -78,6 +78,10 @@ CREATE FUNCTION test_opclass_options_func(internal)
     AS '@libdir@/regress@DLSUFFIX@', 'test_opclass_options_func'
     LANGUAGE C;
 
+CREATE FUNCTION test_enc_conversion(bytea, name, name, bool, validlen OUT int, result OUT bytea)
+    AS '@libdir@/regress@DLSUFFIX@', 'test_enc_conversion'
+    LANGUAGE C;
+
 -- Things that shouldn't work:
 
 CREATE FUNCTION test1 (int) RETURNS int LANGUAGE SQL