Add -D option to specify data directory to pg_controldata and pg_resetxlog.

It was confusing that to other commands, like initdb and postgres, you would
pass the data directory with "-D datadir", but pg_controldata and
pg_resetxlog would take just plain path, without the "-D". With this patch,
pg_controldata and pg_resetxlog also accept "-D datadir".

Abhijit Menon-Sen, with minor kibitzing by me

doc/src/sgml/ref/pg_controldata.sgml

@@ -23,7 +23,7 @@ PostgreSQL documentation
   <cmdsynopsis>
    <command>pg_controldata</command>
    <arg choice="opt"><replaceable class="parameter">option</replaceable></arg>
-   <arg choice="opt"><replaceable class="parameter">datadir</replaceable></arg>
+   <arg choice="opt"><arg choice="opt"><option>-D</option></arg> <replaceable class="parameter">datadir</replaceable></arg>
   </cmdsynopsis>
  </refsynopsisdiv>
 

doc/src/sgml/ref/pg_resetxlog.sgml

@@ -30,7 +30,7 @@ PostgreSQL documentation
    <arg choice="opt"><option>-m</option> <replaceable class="parameter">mxid</replaceable>,<replaceable class="parameter">mxid</replaceable></arg>
    <arg choice="opt"><option>-O</option> <replaceable class="parameter">mxoff</replaceable></arg>
    <arg choice="opt"><option>-l</option> <replaceable class="parameter">xlogfile</replaceable></arg>
-   <arg choice="plain"><replaceable>datadir</replaceable></arg>
+   <arg choice="req"><arg choice="opt"><option>-D</option></arg> <replaceable class="parameter">datadir</replaceable></arg>
   </cmdsynopsis>
  </refsynopsisdiv>
 

src/bin/pg_controldata/pg_controldata.c

@@ -33,7 +33,7 @@ usage(const char *progname)
 {
 	printf(_("%s displays control information of a PostgreSQL database cluster.\n\n"), progname);
 	printf(_("Usage:\n"));
-	printf(_("  %s [OPTION] [DATADIR]\n"), progname);
+	printf(_("  %s [OPTION] [[-D] DATADIR]\n"), progname);
 	printf(_("\nOptions:\n"));
 	printf(_("  -V, --version  output version information, then exit\n"));
 	printf(_("  -?, --help     show this help, then exit\n"));

src/bin/pg_resetxlog/pg_resetxlog.c

@@ -89,7 +89,7 @@ main(int argc, char *argv[])
 	MultiXactId set_oldestmxid = 0;
 	char	   *endptr;
 	char	   *endptr2;
-	char	   *DataDir;
+	char	   *DataDir = NULL;
 	int			fd;
 
 	set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_resetxlog"));
@@ -111,10 +111,14 @@ main(int argc, char *argv[])
 	}
 
 
-	while ((c = getopt(argc, argv, "fl:m:no:O:x:e:")) != -1)
+	while ((c = getopt(argc, argv, "D:fl:m:no:O:x:e:")) != -1)
 	{
 		switch (c)
 		{
+			case 'D':
+				DataDir = optarg;
+				break;
+
 			case 'f':
 				force = true;
 				break;
@@ -233,12 +237,14 @@ main(int argc, char *argv[])
 		}
 	}
 
-	if (optind == argc)
+	if (DataDir == NULL && optind == argc)
 	{
 		fprintf(stderr, _("%s: no data directory specified\n"), progname);
 		fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 		exit(1);
 	}
+	if (DataDir == NULL)
+		DataDir = argv[optind];
 
 	/*
 	 * Don't allow pg_resetxlog to be run as root, to avoid overwriting the
@@ -257,8 +263,6 @@ main(int argc, char *argv[])
 	}
 #endif
 
-	DataDir = argv[optind];
-
 	if (chdir(DataDir) < 0)
 	{
 		fprintf(stderr, _("%s: could not change directory to \"%s\": %s\n"),
@@ -1077,7 +1081,7 @@ static void
 usage(void)
 {
 	printf(_("%s resets the PostgreSQL transaction log.\n\n"), progname);
-	printf(_("Usage:\n  %s [OPTION]... DATADIR\n\n"), progname);
+	printf(_("Usage:\n  %s [OPTION]... {[-D] DATADIR}\n\n"), progname);
 	printf(_("Options:\n"));
 	printf(_("  -e XIDEPOCH      set next transaction ID epoch\n"));
 	printf(_("  -f               force update to be done\n"));