From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 24 Feb 2019 17:51:51 +0000 (-0500)
Subject: Fix ecpg bugs caused by missing semicolons in the backend grammar.
X-Git-Tag: REL9_5_17~52
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=3a682a21b7f9fcd996e282cd7c6d778e9a7febc2;p=postgresql

Fix ecpg bugs caused by missing semicolons in the backend grammar.

The Bison documentation clearly states that a semicolon is required
after every grammar rule, and our scripts that generate ecpg's
grammar from the backend's implicitly assumed this is true.  But it
turns out that only ancient versions of Bison actually enforce that.
There have been a couple of rules without trailing semicolons in
gram.y for some time, and as a consequence, ecpg's grammar was faulty
and produced wrong output for the affected statements.

To fix, add the missing semis, and add some cross-checks to ecpg's
scripts so that they'll bleat if we mess this up again.

The cases that were broken were:
* "SET variable = DEFAULT" (but not "SET variable TO DEFAULT"),
  as well as allied syntaxes such as ALTER SYSTEM SET ... DEFAULT.
  These produced syntactically invalid output that the server
  would reject.
* Multiple type names in DROP TYPE/DOMAIN commands.  Only the
  first type name would be listed in the emitted command.

Per report from Daisuke Higuchi.  Back-patch to all supported versions.

Discussion: https://postgr.es/m/1803D792815FC24D871C00D17AE95905DB51CE@g01jpexmbkw24
---

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9f08926e77..96910cf6ed 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -1424,6 +1424,7 @@ generic_set:
 					n->name = $1;
 					$$ = n;
 				}
+		;
 
 set_rest_more:	/* Generic SET syntaxes: */
 			generic_set 						{$$ = $1;}
@@ -5630,6 +5631,7 @@ attrs:		'.' attr_name
 type_name_list:
 			Typename								{ $$ = list_make1(list_make1($1)); }
 			| type_name_list ',' Typename			{ $$ = lappend($1, list_make1($3)); }
+		;
 
 /*****************************************************************************
  *
diff --git a/src/interfaces/ecpg/preproc/check_rules.pl b/src/interfaces/ecpg/preproc/check_rules.pl
index d5377733f2..147d2e877a 100644
--- a/src/interfaces/ecpg/preproc/check_rules.pl
+++ b/src/interfaces/ecpg/preproc/check_rules.pl
@@ -1,7 +1,7 @@
 #!/usr/bin/perl
 # src/interfaces/ecpg/preproc/check_rules.pl
-# test parser generater for ecpg
-# call with backend parser as stdin
+# test parser generator for ecpg
+# call with backend grammar as stdin
 #
 # Copyright (c) 2009-2015, PostgreSQL Global Development Group
 #
@@ -47,6 +47,7 @@ my %replace_line = (
 
 my $block        = '';
 my $yaccmode     = 0;
+my $in_rule      = 0;
 my $brace_indent = 0;
 my (@arr, %found);
 my $comment     = 0;
@@ -131,10 +132,14 @@ while (<GRAM>)
 			$found{$block} = 1;
 			$cc++;
 			$block = '';
+			$in_rule = 0 if $arr[$fieldIndexer] eq ';';
 		}
 		elsif (($arr[$fieldIndexer] =~ '[A-Za-z0-9]+:')
 			|| $arr[ $fieldIndexer + 1 ] eq ':')
 		{
+			die "unterminated rule at grammar line $.\n"
+			  if $in_rule;
+			$in_rule     = 1;
 			$non_term_id = $arr[$fieldIndexer];
 			$non_term_id =~ tr/://d;
 		}
@@ -145,6 +150,9 @@ while (<GRAM>)
 	}
 }
 
+die "unterminated rule at end of grammar\n"
+  if $in_rule;
+
 close GRAM;
 if ($verbose)
 {
diff --git a/src/interfaces/ecpg/preproc/parse.pl b/src/interfaces/ecpg/preproc/parse.pl
index cfce4b1928..ac1c1e3d5b 100644
--- a/src/interfaces/ecpg/preproc/parse.pl
+++ b/src/interfaces/ecpg/preproc/parse.pl
@@ -22,6 +22,7 @@ $path = "." unless $path;
 my $copymode              = 0;
 my $brace_indent          = 0;
 my $yaccmode              = 0;
+my $in_rule               = 0;
 my $header_included       = 0;
 my $feature_not_supported = 0;
 my $tokenmode             = 0;
@@ -288,6 +289,7 @@ sub main
 				@fields  = ();
 				$infield = 0;
 				$line    = '';
+				$in_rule = 0;
 				next;
 			}
 
@@ -365,6 +367,9 @@ sub main
 				$line    = '';
 				@fields  = ();
 				$infield = 1;
+				die "unterminated rule at grammar line $.\n"
+				  if $in_rule;
+				$in_rule = 1;
 				next;
 			}
 			elsif ($copymode)
@@ -415,6 +420,9 @@ sub main
 			}
 		}
 	}
+	die "unterminated rule at end of grammar\n"
+	  if $in_rule;
+	return;
 }