Get rid of not-very-portable fcntl(F_SETLK) mechanism for locking the Unix

socket file, in favor of having an ordinary lockfile beside the socket file.
Clean up a few robustness problems in the lockfile code.  If postmaster is
going to reject a connection request based on database state, it will now
tell you so before authentication exchange not after.  (Of course, a failure
after is still possible if conditions change meanwhile, but this makes life
easier for a yet-to-be-written pg_ping utility.)

configure.in

@@ -758,23 +758,6 @@ PGAC_VAR_INT_TIMEZONE
 AC_FUNC_ACCEPT_ARGTYPES
 PGAC_FUNC_GETTIMEOFDAY_1ARG
 
-AC_MSG_CHECKING([for fcntl(F_SETLK)])
-case $host_os in
-  linux*)       AC_MSG_RESULT([broken on Linux]) ;;
-  *)
-AC_TRY_LINK(
-[#include <stdio.h>
-#include <fcntl.h>
-],
-[struct flock lck;
-lck.l_whence = SEEK_SET; lck.l_start = lck.l_len = 0;
-lck.l_type = F_WRLCK;
-fcntl(0, F_SETLK, &lck);],
-[AC_DEFINE(HAVE_FCNTL_SETLK) AC_MSG_RESULT(yes)],
-[AC_MSG_RESULT(no)])
-        ;;
-esac
-
 AC_CHECK_FUNCS([fcvt getopt_long memmove pstat setproctitle setsid sigprocmask sysconf waitpid dlopen])
 
 AC_CACHE_CHECK([for PS_STRINGS], [pgac_cv_var_PS_STRINGS],

src/backend/libpq/pqcomm.c

@@ -29,7 +29,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	$Id: pqcomm.c,v 1.113 2000/11/21 23:03:53 petere Exp $
+ *	$Id: pqcomm.c,v 1.114 2000/11/29 20:59:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -169,7 +169,7 @@ StreamDoUnlink(void)
 /*
  * StreamServerPort -- open a sock stream "listening" port.
  *
- * This initializes the Postmaster's connection-accepting port fdP.
+ * This initializes the Postmaster's connection-accepting port *fdP.
  *
  * RETURNS: STATUS_OK or STATUS_ERROR
  */
@@ -183,9 +183,6 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 				err;
 	size_t		len = 0;
 	int			one = 1;
-#ifdef HAVE_FCNTL_SETLK
-	int			lock_fd;
-#endif
 
 	Assert(family == AF_INET || family == AF_UNIX);
 
@@ -223,22 +220,15 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 		len = UNIXSOCK_LEN(saddr.un);
 		strcpy(sock_path, saddr.un.sun_path);
 		/*
-		 * If the socket exists but nobody has an advisory lock on it we
-		 * can safely delete the file.
+		 * Grab an interlock file associated with the socket file.
+		 */
+		if (! CreateSocketLockFile(sock_path, true))
+			return STATUS_ERROR;
+		/*
+		 * Once we have the interlock, we can safely delete any pre-existing
+		 * socket file to avoid failure at bind() time.
 		 */
-#ifdef HAVE_FCNTL_SETLK
-		if ((lock_fd = open(sock_path, O_WRONLY | O_NONBLOCK | PG_BINARY, 0666)) >= 0)
-		{
-			struct flock lck;
-
-			lck.l_whence = SEEK_SET;
-			lck.l_start = lck.l_len = 0;
-			lck.l_type = F_WRLCK;
-			if (fcntl(lock_fd, F_SETLK, &lck) != -1)
 		unlink(sock_path);
-			close(lock_fd);
-		}
-#endif	 /* HAVE_FCNTL_SETLK */
 	}
 #endif /* HAVE_UNIX_SOCKETS */
 
@@ -274,8 +264,8 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 	{
 		snprintf(PQerrormsg, PQERRORMSG_LENGTH,
 				 "FATAL: StreamServerPort: bind() failed: %s\n"
-			   "\tIs another postmaster already running on that port?\n",
-				 strerror(errno));
+				 "\tIs another postmaster already running on port %d?\n",
+				 strerror(errno), (int) portNumber);
 		if (family == AF_UNIX)
 			snprintf(PQerrormsg + strlen(PQerrormsg),
 					 PQERRORMSG_LENGTH - strlen(PQerrormsg),
@@ -293,41 +283,14 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 #ifdef HAVE_UNIX_SOCKETS
 	if (family == AF_UNIX)
 	{
+		/* Arrange to unlink the socket file at exit */
 		on_proc_exit(StreamDoUnlink, 0);
 
 		/*
-		 * Open the socket file and get an advisory lock on it. The
-		 * lock_fd is left open to keep the lock.
-		 */
-#ifdef HAVE_FCNTL_SETLK
-		if ((lock_fd = open(sock_path, O_WRONLY | O_NONBLOCK | PG_BINARY, 0666)) >= 0)
-		{
-			struct flock lck;
-
-			lck.l_whence = SEEK_SET;
-			lck.l_start = lck.l_len = 0;
-			lck.l_type = F_WRLCK;
-			if (fcntl(lock_fd, F_SETLK, &lck) != 0)
-				elog(DEBUG, "flock error on %s: %s", sock_path, strerror(errno));
-		}
-#endif	 /* HAVE_FCNTL_SETLK */
-	}
-#endif /* HAVE_UNIX_SOCKETS */
-
-	listen(fd, SOMAXCONN);
-
-	/*
-	 * MS: I took this code from Dillon's version.  It makes the listening
-	 * port non-blocking.  That is not necessary (and may tickle kernel
-	 * bugs).
-	 *
-	 * fcntl(fd, F_SETFD, 1); fcntl(fd, F_SETFL, FNDELAY);
+		 * Fix socket ownership/permission if requested.  Note we must
+		 * do this before we listen() to avoid a window where unwanted
+		 * connections could get accepted.
 		 */
-
-	*fdP = fd;
-
-	if (family == AF_UNIX)
-	{
 		Assert(Unix_socket_group);
 		if (Unix_socket_group[0] != '\0')
 		{
@@ -379,6 +342,12 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 			return STATUS_ERROR;
 		}
 	}
+#endif /* HAVE_UNIX_SOCKETS */
+
+	listen(fd, SOMAXCONN);
+
+	*fdP = fd;
+
 	return STATUS_OK;
 }
 

src/backend/tcop/postgres.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.191 2000/11/25 20:33:52 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.192 2000/11/29 20:59:52 tgl Exp $
  *
  * NOTES
  *	  this is the "main" module of the postgres backend and
@@ -1514,16 +1514,10 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
 		}
 
 		/*
-		 * Try to create pid file.
+		 * Create lockfile for data directory.
 		 */
-		SetPidFname(DataDir);
-		if (SetPidFile(-getpid()))
-			proc_exit(0);
-
-		/*
-		 * Register clean up proc.
-		 */
-		on_proc_exit(UnlinkPidFile, 0);
+		if (! CreateDataDirLockFile(DataDir, false))
+			proc_exit(1);
 
 		XLOGPathInit();
 		BaseInit();
@@ -1635,7 +1629,7 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
 	if (!IsUnderPostmaster)
 	{
 		puts("\nPOSTGRES backend interactive interface ");
-		puts("$Revision: 1.191 $ $Date: 2000/11/25 20:33:52 $\n");
+		puts("$Revision: 1.192 $ $Date: 2000/11/29 20:59:52 $\n");
 	}
 
 	/*

src/backend/utils/misc/guc.c

@@ -4,7 +4,7 @@
  * Support for grand unified configuration scheme, including SET
  * command, configuration file, and command line options.
  *
- * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.23 2000/11/25 04:13:17 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.24 2000/11/29 20:59:53 tgl Exp $
  *
  * Copyright 2000 by PostgreSQL Global Development Group
  * Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -319,7 +319,7 @@ ConfigureNamesString[] =
 	{"unix_socket_directory",	  PGC_POSTMASTER,       &UnixSocketDir,
 	 "", NULL},
 
-	{"virtual_host",         		  PGC_POSTMASTER,       &Virtual_host,
+	{"virtual_host",			  PGC_POSTMASTER,		&VirtualHost,
 	 "", NULL},
 
 	{NULL, 0, NULL, NULL, NULL}

src/bin/pg_ctl/pg_ctl.sh

@@ -8,7 +8,7 @@
 #
 #
 # IDENTIFICATION
-#    $Header: /cvsroot/pgsql/src/bin/pg_ctl/Attic/pg_ctl.sh,v 1.15 2000/11/27 02:50:17 tgl Exp $
+#    $Header: /cvsroot/pgsql/src/bin/pg_ctl/Attic/pg_ctl.sh,v 1.16 2000/11/29 20:59:53 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -187,7 +187,7 @@ PIDFILE=$PGDATA/postmaster.pid
 
 if [ $op = "status" ];then
     if [ -f $PIDFILE ];then
-	PID=`cat $PIDFILE`
+	PID=`head -1 $PIDFILE`
 	if [ $PID -lt 0 ];then
 	    PID=`expr 0 - $PID`
 	    echo "$CMDNAME: postgres is running (pid: $PID)"
@@ -205,7 +205,7 @@ fi
 
 if [ $op = "stop" -o $op = "restart" ];then
     if [ -f $PIDFILE ];then
-	PID=`cat $PIDFILE`
+	PID=`head -1 $PIDFILE`
 	if [ $PID -lt 0 ];then
 	    PID=`expr 0 - $PID`
 	    echo "$CMDNAME: Cannot restart postmaster. postgres is running (pid: $PID)"
@@ -213,7 +213,7 @@ if [ $op = "stop" -o $op = "restart" ];then
 	    exit 1
 	fi
 
-	kill $sig `cat $PIDFILE`
+	kill $sig $PID
 
 	# wait for postmaster shutting down
 	if [ "$wait" = 1 -o $op = "restart" ];then
@@ -253,7 +253,7 @@ fi
 if [ $op = "start" -o $op = "restart" ];then
     if [ -f $PIDFILE ];then
 	echo "$CMDNAME: It seems another postmaster is running. Trying to start postmaster anyway."
-	pid=`cat $PIDFILE`
+	pid=`head -1 $PIDFILE`
     fi
 
     # no -o given
@@ -275,7 +275,7 @@ if [ $op = "start" -o $op = "restart" ];then
     fi
 
     if [ -f $PIDFILE ];then
-	if [ "`cat $PIDFILE`" = "$pid" ];then
+	if [ "`head -1 $PIDFILE`" = "$pid" ];then
 	    echo "$CMDNAME: Cannot start postmaster. Is another postmaster is running?"
 	    exit 1
         fi

src/include/config.h.in

@@ -8,7 +8,7 @@
  * or in config.h afterwards.  Of course, if you edit config.h, then your
  * changes will be overwritten the next time you run configure.
  *
- * $Id: config.h.in,v 1.149 2000/11/20 16:52:54 petere Exp $
+ * $Id: config.h.in,v 1.150 2000/11/29 20:59:54 tgl Exp $
  */
 
 #ifndef CONFIG_H
@@ -567,9 +567,6 @@ extern void srandom(unsigned int seed);
 /* Set to 1 if you have struct sockaddr_un */
 #undef HAVE_STRUCT_SOCKADDR_UN
 
-/* Set to 1 if you have F_SETLK option for fcntl() */
-#undef HAVE_FCNTL_SETLK
-
 /* Set to 1 if type "long int" works and is 64 bits */
 #undef HAVE_LONG_INT_64
 

src/include/miscadmin.h

@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: miscadmin.h,v 1.74 2000/11/25 22:34:13 momjian Exp $
+ * $Id: miscadmin.h,v 1.75 2000/11/29 20:59:54 tgl Exp $
  *
  * NOTES
  *	  some of the information in this file will be moved to
@@ -114,7 +114,7 @@ extern int PostPortNumber;
 extern int Unix_socket_permissions;
 extern char *Unix_socket_group;
 extern char *UnixSocketDir;
-extern char *Virtual_host;
+extern char *VirtualHost;
 
 
 /*****************************************************************************
@@ -227,17 +227,8 @@ extern bool IsIgnoringSystemIndexes(void);
 extern bool IsCacheInitialized(void);
 extern void SetWaitingForLock(bool);
 
-/*
- * "postmaster.pid" is a file containing postmaster's pid, being
- * created uder $PGDATA upon postmaster's starting up. When postmaster
- * shuts down, it will be unlinked.
-*/
-#define PIDFNAME	"postmaster.pid"
-
-extern void SetPidFname(char *datadir);
-extern void UnlinkPidFile(void);
-extern int	SetPidFile(pid_t pid);
-
+extern bool CreateDataDirLockFile(const char *datadir, bool amPostmaster);
+extern bool CreateSocketLockFile(const char *socketfile, bool amPostmaster);
 
 extern void ValidatePgVersion(const char *path);