From 5bbee34d9f2e6097247ace3ebe1dde1f6aa80287 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 20 Dec 2018 15:58:58 -0500 Subject: Avoid producing over-length specific_name outputs in information_schema. information_schema output columns that are declared as being type sql_identifier are supposed to conform to the implementation's rules for valid identifiers, in particular the identifier length limit. Several places potentially violated this limit by concatenating a function's name and OID. (The OID is added to ensure name uniqueness within a schema, since the spec doesn't expect function name overloading.) Simply truncating the concatenation result to fit in "name" won't do, since losing part of the OID might wind up giving non-unique results. Instead, let's truncate the function name as necessary. The most practical way to do that is to do it in a C function; the information_schema.sql script doesn't have easy access to the value of NAMEDATALEN, nor does it have an easy way to truncate on the basis of resulting byte-length rather than number of characters. (There are still a couple of places that cast concatenation results to sql_identifier, but as far as I can see they are guaranteed not to produce over-length strings, at least with the normal value of NAMEDATALEN.) Discussion: https://postgr.es/m/23817.1545283477@sss.pgh.pa.us --- src/backend/utils/adt/name.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'src/backend/utils/adt/name.c') diff --git a/src/backend/utils/adt/name.c b/src/backend/utils/adt/name.c index 0cf8b9d46b..eb35188e06 100644 --- a/src/backend/utils/adt/name.c +++ b/src/backend/utils/adt/name.c @@ -364,3 +364,38 @@ current_schemas(PG_FUNCTION_ARGS) PG_RETURN_POINTER(array); } + +/* + * SQL-function nameconcatoid(name, oid) returns name + * + * This is used in the information_schema to produce specific_name columns, + * which are supposed to be unique per schema. We achieve that (in an ugly + * way) by appending the object's OID. The result is the same as + * ($1::text || '_' || $2::text)::name + * except that, if it would not fit in NAMEDATALEN, we make it do so by + * truncating the name input (not the oid). + */ +Datum +nameconcatoid(PG_FUNCTION_ARGS) +{ + Name nam = PG_GETARG_NAME(0); + Oid oid = PG_GETARG_OID(1); + Name result; + char suffix[20]; + int suflen; + int namlen; + + suflen = snprintf(suffix, sizeof(suffix), "_%u", oid); + namlen = strlen(NameStr(*nam)); + + /* Truncate oversize input by truncating name part, not suffix */ + if (namlen + suflen >= NAMEDATALEN) + namlen = pg_mbcliplen(NameStr(*nam), namlen, NAMEDATALEN - 1 - suflen); + + /* We use palloc0 here to ensure result is zero-padded */ + result = (Name) palloc0(NAMEDATALEN); + memcpy(NameStr(*result), NameStr(*nam), namlen); + memcpy(NameStr(*result) + namlen, suffix, suflen); + + PG_RETURN_NAME(result); +} -- cgit v1.2.1