pgsql: Reject too many arguments in CREATE TRIGGER

Reject too many arguments in CREATE TRIGGER

The number of trigger arguments is stored as a smallint, but there was
no check that the number of arguments fits with the catalog data type.
This could result in an invalid negative value being stored once one
defined more than INT16_MAX arguments, with an overflowed value stored
in the catalogs.

Looking at other catalogs that store a number of arguments, we have
similar protections already in place (aggregates, functions, etc.).

Reported-by: Xingwang Xiang <v3rdant(dot)xiang(at)gmail(dot)com>
Author: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>
Discussion: https://postgr.es/m/19627-5b72a57e332e2b3f@postgresql.org
Backpatch-through: 14

Branch
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REL_17_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/259ca794c983772e5f8a321ad49c64f7d85d2c9f

Modified Files
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src/backend/commands/trigger.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)