Fix a number of places that produced XX000 errors in the regression tests.

It's against project policy to use elog() for user-facing errors, or to
omit an errcode() selection for errors that aren't supposed to be "can't
happen" cases.  Fix all the violations of this policy that result in
ERRCODE_INTERNAL_ERROR log entries during the standard regression tests,
as errors that can reliably be triggered from SQL surely should be
considered user-facing.

I also looked through all the files touched by this commit and fixed
other nearby problems of the same ilk.  I do not claim to have fixed
all violations of the policy, just the ones in these files.

In a few places I also changed existing ERRCODE choices that didn't
seem particularly appropriate; mainly replacing ERRCODE_SYNTAX_ERROR
by something more specific.

Back-patch to 9.5, but no further; changing ERRCODE assignments in
stable branches doesn't seem like a good idea.

1 files changed, 9 insertions, 4 deletions

diff --git a/src/backend/utils/adt/txid.c b/src/backend/utils/adt/txid.c
index ce1d9abddea..ba4b48298fd 100644
--- a/src/backend/utils/adt/txid.c
+++ b/src/backend/utils/adt/txid.c
@@ -334,8 +334,11 @@ parse_snapshot(const char *str)
 	return buf_finalize(buf);
 
 bad_format:
-	elog(ERROR, "invalid input for txid_snapshot: \"%s\"", str_start);
-	return NULL;
+	ereport(ERROR,
+			(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
+			 errmsg("invalid input syntax for type txid_snapshot: \"%s\"",
+					str_start)));
+	return NULL;				/* keep compiler quiet */
 }
 
 /*
@@ -526,8 +529,10 @@ txid_snapshot_recv(PG_FUNCTION_ARGS)
 	PG_RETURN_POINTER(snap);
 
 bad_format:
-	elog(ERROR, "invalid snapshot data");
-	return (Datum) NULL;
+	ereport(ERROR,
+			(errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
+			 errmsg("invalid external txid_snapshot data")));
+	PG_RETURN_POINTER(NULL);	/* keep compiler quiet */
 }
 
 /*