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_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/4027fb60b9691f3fada876822396c8a00e697beb

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