Arrange for the postmaster (and standalone backends, initdb, etc) to

chdir into PGDATA and subsequently use relative paths instead of absolute
paths to access all files under PGDATA.  This seems to give a small
performance improvement, and it should make the system more robust
against naive DBAs doing things like moving a database directory that
has a live postmaster in it.  Per recent discussion.

4 files changed, 41 insertions, 91 deletions

diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index e5eecb2dbc..2f52053a2c 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -19,7 +19,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/pgarch.c,v 1.16 2005/06/19 21:34:01 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/pgarch.c,v 1.17 2005/07/04 04:51:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -248,9 +248,6 @@ PgArchiverMain(int argc, char *argv[])
 	init_ps_display("archiver process", "", "");
 	set_ps_display("");
 
-	/* Init XLOG file paths --- needed in EXEC_BACKEND case */
-	XLOGPathInit();
-
 	pgarch_MainLoop();
 
 	exit(0);
@@ -400,7 +397,7 @@ pgarch_archiveXlog(char *xlog)
 	const char *sp;
 	int			rc;
 
-	snprintf(pathname, MAXPGPATH, "%s/%s", XLogDir, xlog);
+	snprintf(pathname, MAXPGPATH, XLOGDIR "/%s", xlog);
 
 	/*
 	 * construct the command to be executed
@@ -502,7 +499,7 @@ pgarch_readyXlog(char *xlog)
 	struct dirent *rlde;
 	bool		found = false;
 
-	snprintf(XLogArchiveStatusDir, MAXPGPATH, "%s/archive_status", XLogDir);
+	snprintf(XLogArchiveStatusDir, MAXPGPATH, XLOGDIR "/archive_status");
 	rldir = AllocateDir(XLogArchiveStatusDir);
 	if (rldir == NULL)
 		ereport(ERROR,
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 86b873ab36..325bb8b451 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -13,7 +13,7 @@
  *
  *	Copyright (c) 2001-2005, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.98 2005/06/29 22:51:55 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.99 2005/07/04 04:51:47 tgl Exp $
  * ----------
  */
 #include "postgres.h"
@@ -54,12 +54,11 @@
 
 
 /* ----------
- * Paths for the statistics files. The %s is replaced with the
- * installation's $PGDATA.
+ * Paths for the statistics files (relative to installation's $PGDATA).
  * ----------
  */
-#define PGSTAT_STAT_FILENAME	"%s/global/pgstat.stat"
-#define PGSTAT_STAT_TMPFILE		"%s/global/pgstat.tmp.%d"
+#define PGSTAT_STAT_FILENAME	"global/pgstat.stat"
+#define PGSTAT_STAT_TMPFILE		"global/pgstat.tmp"
 
 /* ----------
  * Timer definitions.
@@ -134,9 +133,6 @@ static HTAB *pgStatBeDead = NULL;
 static PgStat_StatBeEntry *pgStatBeTable = NULL;
 static int	pgStatNumBackends = 0;
 
-static char pgStat_fname[MAXPGPATH];
-static char pgStat_tmpfname[MAXPGPATH];
-
 
 /* ----------
  * Local function forward declarations
@@ -221,20 +217,11 @@ pgstat_init(void)
 		pgstat_collect_startcollector = true;
 
 	/*
-	 * Initialize the filename for the status reports.	(In the
-	 * EXEC_BACKEND case, this only sets the value in the postmaster.  The
-	 * collector subprocess will recompute the value for itself, and
-	 * individual backends must do so also if they want to access the
-	 * file.)
-	 */
-	snprintf(pgStat_fname, MAXPGPATH, PGSTAT_STAT_FILENAME, DataDir);
-
-	/*
 	 * If we don't have to start a collector or should reset the collected
-	 * statistics on postmaster start, simply remove the file.
+	 * statistics on postmaster start, simply remove the stats file.
 	 */
 	if (!pgstat_collect_startcollector || pgstat_collect_resetonpmstart)
-		unlink(pgStat_fname);
+		unlink(PGSTAT_STAT_FILENAME);
 
 	/*
 	 * Nothing else required if collector will not get started
@@ -1471,14 +1458,6 @@ PgstatCollectorMain(int argc, char *argv[])
 	set_ps_display("");
 
 	/*
-	 * Initialize filenames needed for status reports.
-	 */
-	snprintf(pgStat_fname, MAXPGPATH, PGSTAT_STAT_FILENAME, DataDir);
-	/* tmpfname need only be set correctly in this process */
-	snprintf(pgStat_tmpfname, MAXPGPATH, PGSTAT_STAT_TMPFILE,
-			 DataDir, (int)getpid());
-
-	/*
 	 * Arrange to write the initial status file right away
 	 */
 	gettimeofday(&next_statwrite, NULL);
@@ -2161,13 +2140,13 @@ pgstat_write_statsfile(void)
 	/*
 	 * Open the statistics temp file to write out the current values.
 	 */
-	fpout = fopen(pgStat_tmpfname, PG_BINARY_W);
+	fpout = fopen(PGSTAT_STAT_TMPFILE, PG_BINARY_W);
 	if (fpout == NULL)
 	{
 		ereport(LOG,
 				(errcode_for_file_access(),
 			errmsg("could not open temporary statistics file \"%s\": %m",
-				   pgStat_tmpfname)));
+				   PGSTAT_STAT_TMPFILE)));
 		return;
 	}
 
@@ -2276,16 +2255,16 @@ pgstat_write_statsfile(void)
 		ereport(LOG,
 				(errcode_for_file_access(),
 		   errmsg("could not close temporary statistics file \"%s\": %m",
-				  pgStat_tmpfname)));
+				  PGSTAT_STAT_TMPFILE)));
 	}
 	else
 	{
-		if (rename(pgStat_tmpfname, pgStat_fname) < 0)
+		if (rename(PGSTAT_STAT_TMPFILE, PGSTAT_STAT_FILENAME) < 0)
 		{
 			ereport(LOG,
 					(errcode_for_file_access(),
 					 errmsg("could not rename temporary statistics file \"%s\" to \"%s\": %m",
-							pgStat_tmpfname, pgStat_fname)));
+							PGSTAT_STAT_TMPFILE, PGSTAT_STAT_FILENAME)));
 		}
 	}
 
@@ -2377,23 +2356,11 @@ pgstat_read_statsfile(HTAB **dbhash, Oid onlydb,
 		*betab = NULL;
 
 	/*
-	 * In EXEC_BACKEND case, we won't have inherited pgStat_fname from
-	 * postmaster, so compute it first time through.
-	 */
-#ifdef EXEC_BACKEND
-	if (pgStat_fname[0] == '\0')
-	{
-		Assert(DataDir != NULL);
-		snprintf(pgStat_fname, MAXPGPATH, PGSTAT_STAT_FILENAME, DataDir);
-	}
-#endif
-
-	/*
 	 * Try to open the status file. If it doesn't exist, the backends
 	 * simply return zero for anything and the collector simply starts
 	 * from scratch with empty counters.
 	 */
-	if ((fpin = AllocateFile(pgStat_fname, PG_BINARY_R)) == NULL)
+	if ((fpin = AllocateFile(PGSTAT_STAT_FILENAME, PG_BINARY_R)) == NULL)
 		return;
 
 	/*
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index d14f6db163..2de5527648 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.457 2005/06/30 10:02:22 petere Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.458 2005/07/04 04:51:47 tgl Exp $
  *
  * NOTES
  *
@@ -585,6 +585,15 @@ PostmasterMain(int argc, char *argv[])
 		ExitPostmaster(1);
 	}
 
+#ifdef EXEC_BACKEND
+	/* Locate executable backend before we change working directory */
+	if (find_other_exec(argv[0], "postgres", PG_VERSIONSTR,
+						postgres_exec_path) < 0)
+		ereport(FATAL,
+			 (errmsg("%s: could not locate matching postgres executable",
+					 progname)));
+#endif
+
 	/*
 	 * Locate the proper configuration files and data directory, and
 	 * read postgresql.conf for the first time.
@@ -595,6 +604,9 @@ PostmasterMain(int argc, char *argv[])
 	/* Verify that DataDir looks reasonable */
 	checkDataDir();
 
+	/* And switch working directory into it */
+	ChangeToDataDir();
+
 	/*
 	 * Check for invalid combinations of GUC settings.
 	 */
@@ -650,14 +662,6 @@ PostmasterMain(int argc, char *argv[])
 		 (errmsg_internal("-----------------------------------------")));
 	}
 
-#ifdef EXEC_BACKEND
-	if (find_other_exec(argv[0], "postgres", PG_VERSIONSTR,
-						postgres_exec_path) < 0)
-		ereport(FATAL,
-			 (errmsg("%s: could not locate matching postgres executable",
-					 progname)));
-#endif
-
 	/*
 	 * Initialize SSL library, if specified.
 	 */
@@ -691,7 +695,7 @@ PostmasterMain(int argc, char *argv[])
 	 * :-(). For the same reason, it's best to grab the TCP socket(s)
 	 * before the Unix socket.
 	 */
-	CreateDataDirLockFile(DataDir, true);
+	CreateDataDirLockFile(true);
 
 	/*
 	 * Remove old temporary files.	At this point there can be no other
@@ -786,8 +790,6 @@ PostmasterMain(int argc, char *argv[])
 		ereport(FATAL,
 				(errmsg("no socket created for listening")));
 
-	XLOGPathInit();
-
 	/*
 	 * Set up shared memory and semaphores.
 	 */
@@ -2866,20 +2868,16 @@ internal_forkexec(int argc, char *argv[], Port *port)
 		return -1;				/* log made by save_backend_variables */
 
 	/* Calculate name for temp file */
-	Assert(DataDir);
-	snprintf(tmpfilename, MAXPGPATH, "%s/%s/%s.backend_var.%d.%lu",
-			 DataDir, PG_TEMP_FILES_DIR, PG_TEMP_FILE_PREFIX,
+	snprintf(tmpfilename, MAXPGPATH, "%s/%s.backend_var.%d.%lu",
+			 PG_TEMP_FILES_DIR, PG_TEMP_FILE_PREFIX,
 			 MyProcPid, ++tmpBackendFileNum);
 
 	/* Open file */
 	fp = AllocateFile(tmpfilename, PG_BINARY_W);
 	if (!fp)
 	{
-		/* As per OpenTemporaryFile... */
-		char		dirname[MAXPGPATH];
-
-		snprintf(dirname, MAXPGPATH, "%s/%s", DataDir, PG_TEMP_FILES_DIR);
-		mkdir(dirname, S_IRWXU);
+		/* As in OpenTemporaryFile, try to make the temp-file directory */
+		mkdir(PG_TEMP_FILES_DIR, S_IRWXU);
 
 		fp = AllocateFile(tmpfilename, PG_BINARY_W);
 		if (!fp)
@@ -3527,15 +3525,14 @@ StartChildProcess(int xlop)
 static bool
 CreateOptsFile(int argc, char *argv[], char *fullprogname)
 {
-	char		filename[MAXPGPATH];
 	FILE	   *fp;
 	int			i;
 
-	snprintf(filename, sizeof(filename), "%s/postmaster.opts", DataDir);
+#define OPTS_FILE	"postmaster.opts"
 
-	if ((fp = fopen(filename, "w")) == NULL)
+	if ((fp = fopen(OPTS_FILE, "w")) == NULL)
 	{
-		elog(LOG, "could not create file \"%s\": %m", filename);
+		elog(LOG, "could not create file \"%s\": %m", OPTS_FILE);
 		return false;
 	}
 
@@ -3546,7 +3543,7 @@ CreateOptsFile(int argc, char *argv[], char *fullprogname)
 
 	if (fclose(fp))
 	{
-		elog(LOG, "could not write file \"%s\": %m", filename);
+		elog(LOG, "could not write file \"%s\": %m", OPTS_FILE);
 		return false;
 	}
 
diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index 1899d8f21a..c6f02520bf 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -18,7 +18,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/syslogger.c,v 1.15 2005/04/19 03:13:59 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/syslogger.c,v 1.16 2005/07/04 04:51:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -422,17 +422,9 @@ SysLogger_Start(void)
 #endif
 
 	/*
-	 * create log directory if not present; ignore errors
+	 * Create log directory if not present; ignore errors
 	 */
-	if (is_absolute_path(Log_directory))
-		mkdir(Log_directory, 0700);
-	else
-	{
-		filename = palloc(MAXPGPATH);
-		snprintf(filename, MAXPGPATH, "%s/%s", DataDir, Log_directory);
-		mkdir(filename, 0700);
-		pfree(filename);
-	}
+	mkdir(Log_directory, 0700);
 
 	/*
 	 * The initial logfile is created right in the postmaster, to verify
@@ -823,10 +815,7 @@ logfile_getname(pg_time_t timestamp)
 
 	filename = palloc(MAXPGPATH);
 
-	if (is_absolute_path(Log_directory))
-		snprintf(filename, MAXPGPATH, "%s/", Log_directory);
-	else
-		snprintf(filename, MAXPGPATH, "%s/%s/", DataDir, Log_directory);
+	snprintf(filename, MAXPGPATH, "%s/", Log_directory);
 
 	len = strlen(filename);