From baebab3ace480477f210dadc4633d8d119dfa978 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 12 Jul 2016 18:06:50 -0400
Subject: [PATCH] Allow IMPORT FOREIGN SCHEMA within pl/pgsql.
Since IMPORT FOREIGN SCHEMA has an INTO clause, pl/pgsql needs to be
aware of that and avoid capturing the INTO as an INTO-variables clause.
This isn't hard, though it's annoying to have to make IMPORT a plpgsql
keyword just for this. (Fortunately, we have the infrastructure now
to make it an unreserved keyword, so at least this shouldn't break any
existing pl/pgsql code.)
Per report from Merlin Moncure. Back-patch to 9.5 where IMPORT FOREIGN
SCHEMA was introduced.
Report: <CAHyXU0wpHf2bbtKGL1gtUEFATCY86r=VKxfcACVcTMQ70mCyig@mail.gmail.com>
---
src/pl/plpgsql/src/pl_gram.y | 47 ++++++++++++++++++++++++++-------
src/pl/plpgsql/src/pl_scanner.c | 1 +
2 files changed, 39 insertions(+), 9 deletions(-)
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index df09575e123..0b41e3acb6c 100644
--- a/src/pl/plpgsql/src/pl_gram.y
+++ b/src/pl/plpgsql/src/pl_gram.y
@@ -287,6 +287,7 @@ static void check_raise_parameters(PLpgSQL_stmt_raise *stmt);
%token <keyword> K_GET
%token <keyword> K_HINT
%token <keyword> K_IF
+%token <keyword> K_IMPORT
%token <keyword> K_IN
%token <keyword> K_INFO
%token <keyword> K_INSERT
@@ -1929,7 +1930,11 @@ loop_body : proc_sect K_END K_LOOP opt_label ';'
* assignment. Give an appropriate complaint for that, instead of letting
* the core parser throw an unhelpful "syntax error".
*/
-stmt_execsql : K_INSERT
+stmt_execsql : K_IMPORT
+ {
+ $$ = make_execsql_stmt(K_IMPORT, @1);
+ }
+ | K_INSERT
{
$$ = make_execsql_stmt(K_INSERT, @1);
}
@@ -2418,6 +2423,7 @@ unreserved_keyword :
| K_FORWARD
| K_GET
| K_HINT
+ | K_IMPORT
| K_INFO
| K_INSERT
| K_IS
@@ -2843,12 +2849,32 @@ make_execsql_stmt(int firsttoken, int location)
plpgsql_IdentifierLookup = IDENTIFIER_LOOKUP_EXPR;
/*
- * We have to special-case the sequence INSERT INTO, because we don't want
- * that to be taken as an INTO-variables clause. Fortunately, this is the
- * only valid use of INTO in a pl/pgsql SQL command, and INTO is already a
- * fully reserved word in the main grammar. We have to treat it that way
- * anywhere in the string, not only at the start; consider CREATE RULE
- * containing an INSERT statement.
+ * Scan to the end of the SQL command. Identify any INTO-variables
+ * clause lurking within it, and parse that via read_into_target().
+ *
+ * Because INTO is sometimes used in the main SQL grammar, we have to be
+ * careful not to take any such usage of INTO as a pl/pgsql INTO clause.
+ * There are currently three such cases:
+ *
+ * 1. SELECT ... INTO. We don't care, we just override that with the
+ * pl/pgsql definition.
+ *
+ * 2. INSERT INTO. This is relatively easy to recognize since the words
+ * must appear adjacently; but we can't assume INSERT starts the command,
+ * because it can appear in CREATE RULE or WITH. Unfortunately, INSERT is
+ * *not* fully reserved, so that means there is a chance of a false match;
+ * but it's not very likely.
+ *
+ * 3. IMPORT FOREIGN SCHEMA ... INTO. This is not allowed in CREATE RULE
+ * or WITH, so we just check for IMPORT as the command's first token.
+ * (If IMPORT FOREIGN SCHEMA returned data someone might wish to capture
+ * with an INTO-variables clause, we'd have to work much harder here.)
+ *
+ * Fortunately, INTO is a fully reserved word in the main grammar, so
+ * at least we need not worry about it appearing as an identifier.
+ *
+ * Any future additional uses of INTO in the main grammar will doubtless
+ * break this logic again ... beware!
*/
tok = firsttoken;
for (;;)
@@ -2861,9 +2887,12 @@ make_execsql_stmt(int firsttoken, int location)
break;
if (tok == 0)
yyerror("unexpected end of function definition");
-
- if (tok == K_INTO && prev_tok != K_INSERT)
+ if (tok == K_INTO)
{
+ if (prev_tok == K_INSERT)
+ continue; /* INSERT INTO is not an INTO-target */
+ if (firsttoken == K_IMPORT)
+ continue; /* IMPORT ... INTO is not an INTO-target */
if (have_into)
yyerror("INTO specified more than once");
have_into = true;
diff --git a/src/pl/plpgsql/src/pl_scanner.c b/src/pl/plpgsql/src/pl_scanner.c
index bb0f25b18ce..2737fff3fbf 100644
--- a/src/pl/plpgsql/src/pl_scanner.c
+++ b/src/pl/plpgsql/src/pl_scanner.c
@@ -127,6 +127,7 @@ static const ScanKeyword unreserved_keywords[] = {
PG_KEYWORD("forward", K_FORWARD, UNRESERVED_KEYWORD)
PG_KEYWORD("get", K_GET, UNRESERVED_KEYWORD)
PG_KEYWORD("hint", K_HINT, UNRESERVED_KEYWORD)
+ PG_KEYWORD("import", K_IMPORT, UNRESERVED_KEYWORD)
PG_KEYWORD("info", K_INFO, UNRESERVED_KEYWORD)
PG_KEYWORD("insert", K_INSERT, UNRESERVED_KEYWORD)
PG_KEYWORD("is", K_IS, UNRESERVED_KEYWORD)
--
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