From 4eda0a64705763854225a29703b606692af50e77 Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Fri, 7 Aug 2015 15:10:56 +0200
Subject: [PATCH] Don't include low level locking code from frontend code.

Some frontend code like e.g. pg_xlogdump or pg_resetxlog, has to use
backend headers. Unfortunately until now that code includes most of the
locking code. It's generally not nice to expose such low level details,
but de6fd1c898 made that a hard problem. We fall back to defining
'inline' away if the compiler doesn't support it - that can cause linker
errors like on buildfarm animal pademelon if a inline function
references backend only code.

To fix that problem separate definitions from lock.h that are required
from frontend code into lockdefs.h and use it in the relevant
places. I've only removed the minimal amount of necessary definitions
for now - it might turn out that we want more for other reasons.

To avoid such details being exposed again put some checks against being
included from frontend code into atomics.h, lock.h, lwlock.h and
s_lock.h. It's otherwise fairly easy to indirectly include these
headers.

Discussion: 20150806070902.GE12214@awork2.anarazel.de
---
 src/backend/utils/hash/hashfn.c     |  1 +
 src/include/access/genam.h          |  2 +-
 src/include/access/hash.h           |  2 +-
 src/include/access/tuptoaster.h     |  2 +-
 src/include/catalog/objectaddress.h |  2 +-
 src/include/port/atomics.h          |  4 +++
 src/include/storage/lock.h          | 43 +++-------------------
 src/include/storage/lockdefs.h      | 56 +++++++++++++++++++++++++++++
 src/include/storage/lwlock.h        |  4 +++
 src/include/storage/procarray.h     |  1 +
 src/include/storage/s_lock.h        |  4 +++
 src/include/storage/standby.h       |  2 +-
 12 files changed, 80 insertions(+), 43 deletions(-)
 create mode 100644 src/include/storage/lockdefs.h

diff --git a/src/backend/utils/hash/hashfn.c b/src/backend/utils/hash/hashfn.c
index 260d8806db..bdd438d4ca 100644
--- a/src/backend/utils/hash/hashfn.c
+++ b/src/backend/utils/hash/hashfn.c
@@ -22,6 +22,7 @@
 #include "postgres.h"
 
 #include "access/hash.h"
+#include "utils/hsearch.h"
 
 
 /*
diff --git a/src/include/access/genam.h b/src/include/access/genam.h
index d86590ac11..d9d05a08ff 100644
--- a/src/include/access/genam.h
+++ b/src/include/access/genam.h
@@ -17,7 +17,7 @@
 #include "access/sdir.h"
 #include "access/skey.h"
 #include "nodes/tidbitmap.h"
-#include "storage/lock.h"
+#include "storage/lockdefs.h"
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
diff --git a/src/include/access/hash.h b/src/include/access/hash.h
index 93cc8afceb..97cb859fa5 100644
--- a/src/include/access/hash.h
+++ b/src/include/access/hash.h
@@ -24,7 +24,7 @@
 #include "fmgr.h"
 #include "lib/stringinfo.h"
 #include "storage/bufmgr.h"
-#include "storage/lock.h"
+#include "storage/lockdefs.h"
 #include "utils/relcache.h"
 
 /*
diff --git a/src/include/access/tuptoaster.h b/src/include/access/tuptoaster.h
index 7d18535771..77f637e90d 100644
--- a/src/include/access/tuptoaster.h
+++ b/src/include/access/tuptoaster.h
@@ -14,8 +14,8 @@
 #define TUPTOASTER_H
 
 #include "access/htup_details.h"
+#include "storage/lockdefs.h"
 #include "utils/relcache.h"
-#include "storage/lock.h"
 
 /*
  * This enables de-toasting of index entries.  Needed until VACUUM is
diff --git a/src/include/catalog/objectaddress.h b/src/include/catalog/objectaddress.h
index 37808c03c6..0fc16ed717 100644
--- a/src/include/catalog/objectaddress.h
+++ b/src/include/catalog/objectaddress.h
@@ -14,7 +14,7 @@
 #define OBJECTADDRESS_H
 
 #include "nodes/pg_list.h"
-#include "storage/lock.h"
+#include "storage/lockdefs.h"
 #include "utils/acl.h"
 #include "utils/relcache.h"
 
diff --git a/src/include/port/atomics.h b/src/include/port/atomics.h
index bb87945088..65cfa3f824 100644
--- a/src/include/port/atomics.h
+++ b/src/include/port/atomics.h
@@ -37,6 +37,10 @@
 #ifndef ATOMICS_H
 #define ATOMICS_H
 
+#ifdef FRONTEND
+#error "atomics.h may not be included from frontend code"
+#endif
+
 #define INSIDE_ATOMICS_H
 
 #include <limits.h>
diff --git a/src/include/storage/lock.h b/src/include/storage/lock.h
index 96fe3a66ab..a9cd08c527 100644
--- a/src/include/storage/lock.h
+++ b/src/include/storage/lock.h
@@ -14,6 +14,11 @@
 #ifndef LOCK_H_
 #define LOCK_H_
 
+#ifdef FRONTEND
+#error "lock.h may not be included from frontend code"
+#endif
+
+#include "storage/lockdefs.h"
 #include "storage/backendid.h"
 #include "storage/lwlock.h"
 #include "storage/shmem.h"
@@ -77,15 +82,6 @@ typedef struct
 	((vxid).backendId = (proc).backendId, \
 	 (vxid).localTransactionId = (proc).lxid)
 
-
-/*
- * LOCKMODE is an integer (1..N) indicating a lock type.  LOCKMASK is a bit
- * mask indicating a set of held or requested lock types (the bit 1<<mode
- * corresponds to a particular lock mode).
- */
-typedef int LOCKMASK;
-typedef int LOCKMODE;
-
 /* MAX_LOCKMODES cannot be larger than the # of bits in LOCKMASK */
 #define MAX_LOCKMODES		10
 
@@ -133,28 +129,6 @@ typedef uint16 LOCKMETHODID;
 #define DEFAULT_LOCKMETHOD	1
 #define USER_LOCKMETHOD		2
 
-/*
- * These are the valid values of type LOCKMODE for all the standard lock
- * methods (both DEFAULT and USER).
- */
-
-/* NoLock is not a lock mode, but a flag value meaning "don't get a lock" */
-#define NoLock					0
-
-#define AccessShareLock			1		/* SELECT */
-#define RowShareLock			2		/* SELECT FOR UPDATE/FOR SHARE */
-#define RowExclusiveLock		3		/* INSERT, UPDATE, DELETE */
-#define ShareUpdateExclusiveLock 4		/* VACUUM (non-FULL),ANALYZE, CREATE
-										 * INDEX CONCURRENTLY */
-#define ShareLock				5		/* CREATE INDEX (WITHOUT CONCURRENTLY) */
-#define ShareRowExclusiveLock	6		/* like EXCLUSIVE MODE, but allows ROW
-										 * SHARE */
-#define ExclusiveLock			7		/* blocks ROW SHARE/SELECT...FOR
-										 * UPDATE */
-#define AccessExclusiveLock		8		/* ALTER TABLE, DROP TABLE, VACUUM
-										 * FULL, and unqualified LOCK TABLE */
-
-
 /*
  * LOCKTAG is the key information needed to look up a LOCK item in the
  * lock hashtable.  A LOCKTAG value uniquely identifies a lockable object.
@@ -536,13 +510,6 @@ extern void RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode);
 extern Size LockShmemSize(void);
 extern LockData *GetLockStatusData(void);
 
-typedef struct xl_standby_lock
-{
-	TransactionId xid;			/* xid of holder of AccessExclusiveLock */
-	Oid			dbOid;
-	Oid			relOid;
-} xl_standby_lock;
-
 extern xl_standby_lock *GetRunningTransactionLocks(int *nlocks);
 extern const char *GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode);
 
diff --git a/src/include/storage/lockdefs.h b/src/include/storage/lockdefs.h
new file mode 100644
index 0000000000..bfbcdbaf11
--- /dev/null
+++ b/src/include/storage/lockdefs.h
@@ -0,0 +1,56 @@
+/*-------------------------------------------------------------------------
+ *
+ * lockdefs.h
+ *	   Frontend exposed parts of postgres' low level lock mechanism
+ *
+ * The split between lockdefs.h and lock.h is not very principled. This file
+ * contains definition that have to (indirectly) be available when included by
+ * FRONTEND code.
+ *
+ * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/lockdefs.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef LOCKDEFS_H_
+#define LOCKDEFS_H_
+
+/*
+ * LOCKMODE is an integer (1..N) indicating a lock type.  LOCKMASK is a bit
+ * mask indicating a set of held or requested lock types (the bit 1<<mode
+ * corresponds to a particular lock mode).
+ */
+typedef int LOCKMASK;
+typedef int LOCKMODE;
+
+/*
+ * These are the valid values of type LOCKMODE for all the standard lock
+ * methods (both DEFAULT and USER).
+ */
+
+/* NoLock is not a lock mode, but a flag value meaning "don't get a lock" */
+#define NoLock					0
+
+#define AccessShareLock			1		/* SELECT */
+#define RowShareLock			2		/* SELECT FOR UPDATE/FOR SHARE */
+#define RowExclusiveLock		3		/* INSERT, UPDATE, DELETE */
+#define ShareUpdateExclusiveLock 4		/* VACUUM (non-FULL),ANALYZE, CREATE
+										 * INDEX CONCURRENTLY */
+#define ShareLock				5		/* CREATE INDEX (WITHOUT CONCURRENTLY) */
+#define ShareRowExclusiveLock	6		/* like EXCLUSIVE MODE, but allows ROW
+										 * SHARE */
+#define ExclusiveLock			7		/* blocks ROW SHARE/SELECT...FOR
+										 * UPDATE */
+#define AccessExclusiveLock		8		/* ALTER TABLE, DROP TABLE, VACUUM
+										 * FULL, and unqualified LOCK TABLE */
+
+typedef struct xl_standby_lock
+{
+	TransactionId xid;			/* xid of holder of AccessExclusiveLock */
+	Oid			dbOid;
+	Oid			relOid;
+} xl_standby_lock;
+
+#endif /* LOCKDEF_H_ */
diff --git a/src/include/storage/lwlock.h b/src/include/storage/lwlock.h
index cbd63184b9..f2ff6a06f0 100644
--- a/src/include/storage/lwlock.h
+++ b/src/include/storage/lwlock.h
@@ -14,6 +14,10 @@
 #ifndef LWLOCK_H
 #define LWLOCK_H
 
+#ifdef FRONTEND
+#error "lwlock.h may not be included from frontend code"
+#endif
+
 #include "lib/ilist.h"
 #include "storage/s_lock.h"
 #include "port/atomics.h"
diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h
index a9b40ed944..834f99b991 100644
--- a/src/include/storage/procarray.h
+++ b/src/include/storage/procarray.h
@@ -14,6 +14,7 @@
 #ifndef PROCARRAY_H
 #define PROCARRAY_H
 
+#include "storage/lock.h"
 #include "storage/standby.h"
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
diff --git a/src/include/storage/s_lock.h b/src/include/storage/s_lock.h
index 30f28b088a..c461fda251 100644
--- a/src/include/storage/s_lock.h
+++ b/src/include/storage/s_lock.h
@@ -96,6 +96,10 @@
 #ifndef S_LOCK_H
 #define S_LOCK_H
 
+#ifdef FRONTEND
+#error "s_lock.h may not be included from frontend code"
+#endif
+
 #ifdef HAVE_SPINLOCKS	/* skip spinlocks if requested */
 
 #if defined(__GNUC__) || defined(__INTEL_COMPILER)
diff --git a/src/include/storage/standby.h b/src/include/storage/standby.h
index 7626c4c4f4..40b329b2a3 100644
--- a/src/include/storage/standby.h
+++ b/src/include/storage/standby.h
@@ -16,7 +16,7 @@
 
 #include "access/xlogreader.h"
 #include "lib/stringinfo.h"
-#include "storage/lock.h"
+#include "storage/lockdefs.h"
 #include "storage/procsignal.h"
 #include "storage/relfilenode.h"
 
-- 
2.40.0