Add a "SQLSTATE-only" error verbosity option to libpq and psql.

This is intended for use mostly in test scripts for external tools,
which could do without cross-PG-version variations in error message
wording.  Of course, the SQLSTATE isn't guaranteed stable either, but
it should be more so than the error message text.

Note: there's a bit of an ABI change for libpq here, but it seems
OK because if somebody compiles against a newer version of libpq-fe.h,
and then tries to pass PQERRORS_SQLSTATE to PQsetErrorVerbosity()
of an older libpq library, it will be accepted and then act like
PQERRORS_DEFAULT, thanks to the way the tests in pqBuildErrorMessage3
have historically been phrased.  That seems acceptable.

Didier Gautheron, reviewed by Dagfinn Ilmari Mannsåker

Discussion: https://postgr.es/m/CAJRYxuKyj4zA+JGVrtx8OWAuBfE-_wN4sUMK4H49EuPed=mOBw@mail.gmail.com

1 files changed, 18 insertions, 0 deletions

diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index ec51fee383d..d582cfd4e9c 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -1017,6 +1017,24 @@ pqBuildErrorMessage3(PQExpBuffer msg, const PGresult *res,
 	val = PQresultErrorField(res, PG_DIAG_SEVERITY);
 	if (val)
 		appendPQExpBuffer(msg, "%s:  ", val);
+
+	if (verbosity == PQERRORS_SQLSTATE)
+	{
+		/*
+		 * If we have a SQLSTATE, print that and nothing else.  If not (which
+		 * shouldn't happen for server-generated errors, but might possibly
+		 * happen for libpq-generated ones), fall back to TERSE format, as
+		 * that seems better than printing nothing at all.
+		 */
+		val = PQresultErrorField(res, PG_DIAG_SQLSTATE);
+		if (val)
+		{
+			appendPQExpBuffer(msg, "%s\n", val);
+			return;
+		}
+		verbosity = PQERRORS_TERSE;
+	}
+
 	if (verbosity == PQERRORS_VERBOSE)
 	{
 		val = PQresultErrorField(res, PG_DIAG_SQLSTATE);