Code review for postmaster.pid contents changes.

Fix broken test for pre-existing postmaster, caused by wrong code for
appending lines to the lockfile; don't write a failed listen_address
setting into the lockfile; don't arbitrarily change the location of the
data directory in the lockfile compared to previous releases; provide more
consistent and useful definitions of the socket path and listen_address
entries; avoid assuming that pg_ctl has the same DEFAULT_PGSOCKET_DIR as
the postmaster; assorted code style improvements.

doc/src/sgml/storage.sgml

@@ -117,9 +117,14 @@ last started with</entry>
 <row>
  <entry><filename>postmaster.pid</></entry>
  <entry>A lock file recording the current postmaster process id (PID),
- postmaster start time, cluster data directory, port number, user-specified
+  cluster data directory path,
- Unix domain socket directory, first valid listen_address host, and
+  postmaster start timestamp,
- shared memory segment ID</entry>
+  port number,
+  Unix-domain socket directory path (empty on Windows),
+  first valid listen_address (IP address or <literal>*</>, or empty if
+  not listening on TCP),
+  and shared memory segment ID
+  (this file is not present after server shutdown)</entry>
 </row>
 
 </tbody>

src/backend/port/ipc_test.c

@@ -104,7 +104,7 @@ on_exit_reset(void)
 }
 
 void
-AddToLockFile(int target_line, const char *str)
+AddToDataDirLockFile(int target_line, const char *str)
 {
 }
 
@@ -135,7 +135,7 @@ errcode_for_file_access(void)
 
 bool
 errstart(int elevel, const char *filename, int lineno,
-		 const char *funcname)
+		 const char *funcname, const char *domain)
 {
 	return (elevel >= ERROR);
 }

src/backend/port/sysv_shmem.c

@@ -199,15 +199,16 @@ InternalIpcMemoryCreate(IpcMemoryKey memKey, Size size)
 	on_shmem_exit(IpcMemoryDetach, PointerGetDatum(memAddress));
 
 	/*
-	 * Append record key and ID in lockfile for data directory. Format
+	 * Store shmem key and ID in data directory lockfile.  Format to try to
-	 * to try to keep it the same length.
+	 * keep it the same length always (trailing junk in the lockfile won't
+	 * hurt, but might confuse humans).
 	 */
 	{
-		char line[32];
+		char line[64];
 
-		sprintf(line, "%9lu %9lu\n", (unsigned long) memKey,
+		sprintf(line, "%9lu %9lu",
-									 (unsigned long) shmid);
+				(unsigned long) memKey, (unsigned long) shmid);
-		AddToLockFile(LOCK_FILE_LINES, line);
+		AddToDataDirLockFile(LOCK_FILE_LINE_SHMEM_KEY, line);
 	}
 
 	return memAddress;

src/backend/postmaster/postmaster.c

@@ -482,8 +482,8 @@ PostmasterMain(int argc, char *argv[])
 	int			opt;
 	int			status;
 	char	   *userDoption = NULL;
+	bool		listen_addr_saved = false;
 	int			i;
-	bool		connection_line_output = false;
 
 	MyProcPid = PostmasterPid = getpid();
 
@@ -861,24 +861,21 @@ PostmasterMain(int argc, char *argv[])
 										  UnixSocketDir,
 										  ListenSocket, MAXLISTEN);
 			else
-			{
 				status = StreamServerPort(AF_UNSPEC, curhost,
 										  (unsigned short) PostPortNumber,
 										  UnixSocketDir,
 										  ListenSocket, MAXLISTEN);
-				/* must supply a valid listen_address for PQping() */
-				if (!connection_line_output)
-				{
-					char line[MAXPGPATH + 2];
-
-					sprintf(line, "%s\n", curhost);
-					AddToLockFile(LOCK_FILE_LINES - 1, line);
-					connection_line_output = true;
-				}
-			}
 
 			if (status == STATUS_OK)
+			{
 				success++;
+				/* record the first successful host addr in lockfile */
+				if (!listen_addr_saved)
+				{
+					AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, curhost);
+					listen_addr_saved = true;
+				}
+			}
 			else
 				ereport(WARNING,
 						(errmsg("could not create listen socket for \"%s\"",
@@ -893,10 +890,6 @@ PostmasterMain(int argc, char *argv[])
 		pfree(rawstring);
 	}
 
-	/* Supply an empty listen_address line for PQping() */
-	if (!connection_line_output)
-		AddToLockFile(LOCK_FILE_LINES - 1, "\n");
-
 #ifdef USE_BONJOUR
 	/* Register for Bonjour only if we opened TCP socket(s) */
 	if (enable_bonjour && ListenSocket[0] != PGINVALID_SOCKET)
@@ -952,6 +945,14 @@ PostmasterMain(int argc, char *argv[])
 		ereport(FATAL,
 				(errmsg("no socket created for listening")));
 
+	/*
+	 * If no valid TCP ports, write an empty line for listen address,
+	 * indicating the Unix socket must be used.  Note that this line is not
+	 * added to the lock file until there is a socket backing it.
+	 */
+	if (!listen_addr_saved)
+		AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, "");
+
 	/*
 	 * Set up shared memory and semaphores.
 	 */

src/backend/utils/init/miscinit.c

@@ -46,19 +46,6 @@
 
 
 #define DIRECTORY_LOCK_FILE		"postmaster.pid"
-/*
- *	The lock file contents are:
- *
- * line #
- *		1	pid
- *		2	postmaster start time
- *		3	data directory
- *		4	port #
- *		5	user-specified socket directory
- *			(the lines below are added later)
- *		6	first valid listen_address
- *		7	shared memory key
- */
 
 ProcessingMode Mode = InitProcessing;
 
@@ -244,7 +231,6 @@ static int	SecurityRestrictionContext = 0;
 static bool SetRoleIsActive = false;
 
 
-
 /*
  * GetUserId - get the current effective user ID.
  *
@@ -691,7 +677,7 @@ CreateLockFile(const char *filename, bool amPostmaster,
 			   bool isDDLock, const char *refName)
 {
 	int			fd;
-	char		buffer[MAXPGPATH * 3 + 256];
+	char		buffer[MAXPGPATH * 2 + 256];
 	int			ntries;
 	int			len;
 	int			encoded_pid;
@@ -852,26 +838,26 @@ CreateLockFile(const char *filename, bool amPostmaster,
 		 * looking to see if there is an associated shmem segment that is
 		 * still in use.
 		 *
-		 * Note: because postmaster.pid is written in two steps, we might not
+		 * Note: because postmaster.pid is written in multiple steps, we might
-		 * find the shmem ID values in it; we can't treat that as an error.
+		 * not find the shmem ID values in it; we can't treat that as an
+		 * error.
 		 */
 		if (isDDLock)
 		{
 			char	   *ptr = buffer;
-			unsigned long id1, id2;
+			unsigned long id1,
+						id2;
 			int			lineno;
 
-			for (lineno = 1; lineno <= LOCK_FILE_LINES - 1; lineno++)
+			for (lineno = 1; lineno < LOCK_FILE_LINE_SHMEM_KEY; lineno++)
 			{
 				if ((ptr = strchr(ptr, '\n')) == NULL)
-				{
-					elog(LOG, "bogus data in \"%s\"", DIRECTORY_LOCK_FILE);
 					break;
-				}
 				ptr++;
 			}
 
-			if (ptr && sscanf(ptr, "%lu %lu", &id1, &id2) == 2)
+			if (ptr != NULL &&
+				sscanf(ptr, "%lu %lu", &id1, &id2) == 2)
 			{
 				if (PGSharedMemoryIsInUse(id1, id2))
 					ereport(FATAL,
@@ -903,12 +889,23 @@ CreateLockFile(const char *filename, bool amPostmaster,
 	}
 
 	/*
-	 * Successfully created the file, now fill it.
+	 * Successfully created the file, now fill it.  See comment in miscadmin.h
+	 * about the contents.  Note that we write the same info into both datadir
+	 * and socket lockfiles; although more stuff may get added to the datadir
+	 * lockfile later.
 	 */
-	snprintf(buffer, sizeof(buffer), "%d\n%ld\n%s\n%d\n%s\n",
+	snprintf(buffer, sizeof(buffer), "%d\n%s\n%ld\n%d\n%s\n",
 			 amPostmaster ? (int) my_pid : -((int) my_pid),
-			 (long) MyStartTime, DataDir, PostPortNumber,
+			 DataDir,
-			 UnixSocketDir);
+			 (long) MyStartTime,
+			 PostPortNumber,
+#ifdef HAVE_UNIX_SOCKETS
+			 (*UnixSocketDir != '\0') ? UnixSocketDir : DEFAULT_PGSOCKET_DIR
+#else
+			 ""
+#endif
+			 );
+
 	errno = 0;
 	if (write(fd, buffer, strlen(buffer)) != strlen(buffer))
 	{
@@ -1019,17 +1016,20 @@ TouchSocketLockFile(void)
 
 
 /*
- * Add lines to the data directory lock file.  This erases all following
+ * Add (or replace) a line in the data directory lock file.
- * lines, but that is OK because lines are added in order.
+ * The given string should not include a trailing newline.
+ *
+ * Caution: this erases all following lines.  In current usage that is OK
+ * because lines are added in order.  We could improve it if needed.
  */
 void
-AddToLockFile(int target_line, const char *str)
+AddToDataDirLockFile(int target_line, const char *str)
 {
 	int			fd;
 	int			len;
 	int			lineno;
 	char	   *ptr;
-	char		buffer[MAXPGPATH * 3 + 256];
+	char		buffer[BLCKSZ];
 
 	fd = open(DIRECTORY_LOCK_FILE, O_RDWR | PG_BINARY, 0);
 	if (fd < 0)
@@ -1040,7 +1040,7 @@ AddToLockFile(int target_line, const char *str)
 						DIRECTORY_LOCK_FILE)));
 		return;
 	}
-	len = read(fd, buffer, sizeof(buffer) - 100);
+	len = read(fd, buffer, sizeof(buffer) - 1);
 	if (len < 0)
 	{
 		ereport(LOG,
@@ -1053,7 +1053,7 @@ AddToLockFile(int target_line, const char *str)
 	buffer[len] = '\0';
 
 	/*
-	 * Skip over first four lines (PID, pgdata, portnum, socketdir).
+	 * Skip over lines we are not supposed to rewrite.
 	 */
 	ptr = buffer;
 	for (lineno = 1; lineno < target_line; lineno++)
@@ -1067,7 +1067,10 @@ AddToLockFile(int target_line, const char *str)
 		ptr++;
 	}
 
-	strlcat(buffer, str, sizeof(buffer));
+	/*
+	 * Write or rewrite the target line.
+	 */
+	snprintf(ptr, buffer + sizeof(buffer) - ptr, "%s\n", str);
 
 	/*
 	 * And rewrite the data.  Since we write in a single kernel call, this

src/bin/pg_ctl/pg_ctl.c

@@ -22,7 +22,6 @@
 
 #include <locale.h>
 #include <signal.h>
-#include <stdlib.h>
 #include <time.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -91,6 +90,24 @@ static char *register_username = NULL;
 static char *register_password = NULL;
 static char *argv0 = NULL;
 static bool allow_core_files = false;
+static time_t start_time;
+
+static char postopts_file[MAXPGPATH];
+static char pid_file[MAXPGPATH];
+static char backup_file[MAXPGPATH];
+static char recovery_file[MAXPGPATH];
+
+#if defined(WIN32) || defined(__CYGWIN__)
+static DWORD pgctl_start_type = SERVICE_AUTO_START;
+static SERVICE_STATUS status;
+static SERVICE_STATUS_HANDLE hStatus = (SERVICE_STATUS_HANDLE) 0;
+static HANDLE shutdownHandles[2];
+static pid_t postmasterPID = -1;
+
+#define shutdownEvent	  shutdownHandles[0]
+#define postmasterProcess shutdownHandles[1]
+#endif
+
 
 static void
 write_stderr(const char *fmt,...)
@@ -122,15 +139,6 @@ static void WINAPI pgwin32_ServiceHandler(DWORD);
 static void WINAPI pgwin32_ServiceMain(DWORD, LPTSTR *);
 static void pgwin32_doRunAsService(void);
 static int	CreateRestrictedProcess(char *cmd, PROCESS_INFORMATION *processInfo, bool as_service);
-
-static DWORD pgctl_start_type = SERVICE_AUTO_START;
-static SERVICE_STATUS status;
-static SERVICE_STATUS_HANDLE hStatus = (SERVICE_STATUS_HANDLE) 0;
-static HANDLE shutdownHandles[2];
-static pid_t postmasterPID = -1;
-
-#define shutdownEvent	  shutdownHandles[0]
-#define postmasterProcess shutdownHandles[1]
 #endif
 
 static pgpid_t get_pgpid(void);
@@ -140,12 +148,6 @@ static void read_post_opts(void);
 
 static PGPing test_postmaster_connection(bool);
 static bool postmaster_is_alive(pid_t pid);
-static time_t start_time;
-
-static char postopts_file[MAXPGPATH];
-static char pid_file[MAXPGPATH];
-static char backup_file[MAXPGPATH];
-static char recovery_file[MAXPGPATH];
 
 #if defined(HAVE_GETRLIMIT) && defined(RLIMIT_CORE)
 static void unlimit_core_size(void);
@@ -406,14 +408,10 @@ start_postmaster(void)
 static PGPing
 test_postmaster_connection(bool do_checkpoint)
 {
-	int			portnum = 0;
-	char		host_str[MAXPGPATH];
-	char		connstr[MAXPGPATH + 256];
 	PGPing		ret = PQPING_OK;	/* assume success for wait == zero */
-	char	  **optlines;
+	char		connstr[MAXPGPATH * 2 + 256];
 	int			i;
 
-	host_str[0] = '\0';
 	connstr[0] = '\0';
 	
 	for (i = 0; i < wait_seconds; i++)
@@ -421,108 +419,111 @@ test_postmaster_connection(bool do_checkpoint)
 		/* Do we need a connection string? */
 		if (connstr[0] == '\0')
 		{
-			/*
+			/*----------
 			 * The number of lines in postmaster.pid tells us several things:
 			 *
 			 * # of lines
 			 *		0	lock file created but status not written
 			 *		2	pre-9.1 server, shared memory not created
 			 *		3	pre-9.1 server, shared memory created
-			 *		5	9.1+ server, listen host not created
+			 *		5	9.1+ server, ports not opened
 			 *		6	9.1+ server, shared memory not created
 			 *		7	9.1+ server, shared memory created
 			 *
-			 *	For pre-9.1 Unix servers, we grab the port number from the
+			 * This code does not support pre-9.1 servers.  On Unix machines
-			 *	shmem key (first value on line 3).  Pre-9.1 Win32 has no
+			 * we could consider extracting the port number from the shmem
-			 *	written shmem key, so we fail.  9.1+ writes connection
+			 * key, but that (a) is not robust, and (b) doesn't help with
-			 *	information in the file for us to use.
+			 * finding out the socket directory.  And it wouldn't work anyway
-			 *	(PG_VERSION could also have told us the major version.)
+			 * on Windows.
+			 *
+			 * If we see less than 6 lines in postmaster.pid, just keep
+			 * waiting.
+			 *----------
 			 */
+			char	  **optlines;
 
-			/* Try to read a completed postmaster.pid file */
+			/* Try to read the postmaster.pid file */
 			if ((optlines = readfile(pid_file)) != NULL &&
 				optlines[0] != NULL &&
 				optlines[1] != NULL &&
-				optlines[2] != NULL &&
+				optlines[2] != NULL)
-				/* pre-9.1 server or listen_address line is present? */
-				(optlines[3] == NULL ||
-				 optlines[5] != NULL))
 			{
-				/* A 3-line file? */
 				if (optlines[3] == NULL)
 				{
-					/*
+					/* File is exactly three lines, must be pre-9.1 */
-					 *	Pre-9.1:  on Unix, we get the port number by
+					write_stderr(_("%s: -w option is not supported when starting a pre-9.1 server\n"),
-					 *	deriving it from the shmem key (the first number on
-					 *	on the line);  see
-					 *	miscinit.c::RecordSharedMemoryInLockFile().
-					 */
-					portnum = atoi(optlines[2]) / 1000;
-					/* Win32 does not give us a shmem key, so we fail. */
-					if (portnum == 0)
-					{
-						write_stderr(_("%s: -w option is not supported on this platform\nwhen connecting to a pre-9.1 server\n"),
 								 progname);
 					return PQPING_NO_ATTEMPT;
 				}
-				}
+				else if (optlines[4] != NULL &&
-				else
+						 optlines[5] != NULL)
 				{
+					/* File is complete enough for us, parse it */
+					time_t	pmstart;
+					int		portnum;
+					char   *sockdir;
+					char   *hostaddr;
+					char	host_str[MAXPGPATH];
+
 					/*
-					 *	Easy check to see if we are looking at the right
+					 * Easy cross-check that we are looking at the right data
-					 *	data directory:  Is the postmaster older than this
+					 * directory: is the postmaster older than this execution
-					 *	execution of pg_ctl?  Subtract 2 seconds to account
+					 * of pg_ctl?  Subtract 2 seconds to allow for possible
-					 *	for possible clock skew between pg_ctl and the
+					 * clock skew between pg_ctl and the postmaster.
-					 *	postmaster.
 					 */
-					if (atol(optlines[1]) < start_time - 2)
+					pmstart = atol(optlines[LOCK_FILE_LINE_START_TIME - 1]);
+					if (pmstart < start_time - 2)
 					{
-						write_stderr(_("%s: this data directory is running an older postmaster\n"),
+						write_stderr(_("%s: this data directory is running a pre-existing postmaster\n"),
 									 progname);
 						return PQPING_NO_ATTEMPT;
 					}
 
-					portnum = atoi(optlines[3]);
+					/*
+					 * OK, extract port number and host string to use.
+					 * Prefer using Unix socket if available.
+					 */
+					portnum = atoi(optlines[LOCK_FILE_LINE_PORT - 1]);
+
+					sockdir = optlines[LOCK_FILE_LINE_SOCKET_DIR - 1];
+					hostaddr = optlines[LOCK_FILE_LINE_LISTEN_ADDR - 1];
 
-					/*
-					 *	Determine the proper host string to use.
-					 */
-#ifdef HAVE_UNIX_SOCKETS
-					/*
-					 *	Use socket directory, if specified.  We assume if we
-					 *	have unix sockets, the server does too because we
-					 *	just started the postmaster.
-					 */
 					/*
 					 * While unix_socket_directory can accept relative
-					 *	directories, libpq's host must have a leading slash
+					 * directories, libpq's host parameter must have a leading
-					 *	to indicate a socket directory.
+					 * slash to indicate a socket directory.  So, ignore
+					 * sockdir if it's relative, and try to use TCP instead.
 					 */
-					if (optlines[4][0] != '\n' && optlines[4][0] != '/')
+					if (sockdir[0] == '/')
+						strlcpy(host_str, sockdir, sizeof(host_str));
+					else
+						strlcpy(host_str, hostaddr, sizeof(host_str));
+
+					/* remove trailing newline */
+					if (strchr(host_str, '\n') != NULL)
+						*strchr(host_str, '\n') = '\0';
+
+					/* Fail if we couldn't get either sockdir or host addr */
+					if (host_str[0] == '\0')
 					{
 						write_stderr(_("%s: -w option cannot use a relative socket directory specification\n"),
 									 progname);
 						return PQPING_NO_ATTEMPT;
 					}
-					strlcpy(host_str, optlines[4], sizeof(host_str));
+
-#else
+					/* If postmaster is listening on "*", use "localhost" */
-					strlcpy(host_str, optlines[5], sizeof(host_str));
+					if (strcmp(host_str, "*") == 0)
-#endif
+						strcpy(host_str, "localhost");
-					/* remove newline */
-					if (strchr(host_str, '\n') != NULL)
-						*strchr(host_str, '\n') = '\0';
-				}
 
 					/*
 					 * We need to set connect_timeout otherwise on Windows the
-				 * Service Control Manager (SCM) will probably timeout first.
+					 * Service Control Manager (SCM) will probably timeout
+					 * first.
 					 */
 					snprintf(connstr, sizeof(connstr),
-						 "dbname=postgres port=%d connect_timeout=5", portnum);
+							 "dbname=postgres port=%d host='%s' connect_timeout=5",
-
+							 portnum, host_str);
-				if (host_str[0] != '\0')
+				}
-					snprintf(connstr + strlen(connstr), sizeof(connstr) - strlen(connstr),
-						" host='%s'", host_str);
 			}
 		}
 

src/include/miscadmin.h

@@ -348,11 +348,35 @@ extern PGDLLIMPORT bool process_shared_preload_libraries_in_progress;
 extern char *shared_preload_libraries_string;
 extern char *local_preload_libraries_string;
 
-#define LOCK_FILE_LINES		7
+/*
+ * As of 9.1, the contents of the data-directory lock file are:
+ *
+ * line #
+ *		1	postmaster PID (or negative of a standalone backend's PID)
+ *		2	data directory path
+ *		3	postmaster start timestamp (time_t representation)
+ *		4	port number
+ *		5	socket directory path (empty on Windows)
+ *		6	first listen_address (IP address or "*"; empty if no TCP port)
+ *		7	shared memory key (not present on Windows)
+ *
+ * Lines 6 and up are added via AddToDataDirLockFile() after initial file
+ * creation; they have to be ordered according to time of addition.
+ *
+ * The socket lock file, if used, has the same contents as lines 1-5.
+ */
+#define LOCK_FILE_LINE_PID			1
+#define LOCK_FILE_LINE_DATA_DIR		2
+#define LOCK_FILE_LINE_START_TIME	3
+#define LOCK_FILE_LINE_PORT			4
+#define LOCK_FILE_LINE_SOCKET_DIR	5
+#define LOCK_FILE_LINE_LISTEN_ADDR	6
+#define LOCK_FILE_LINE_SHMEM_KEY	7
+
 extern void CreateDataDirLockFile(bool amPostmaster);
 extern void CreateSocketLockFile(const char *socketfile, bool amPostmaster);
 extern void TouchSocketLockFile(void);
-extern void AddToLockFile(int target_line, const char *str);
+extern void AddToDataDirLockFile(int target_line, const char *str);
 extern void ValidatePgVersion(const char *path);
 extern void process_shared_preload_libraries(void);
 extern void process_local_preload_libraries(void);