From ebe21663797de5376a569cc7b00ec31a89400638 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Thu, 12 Dec 2013 23:54:52 +0900
Subject: [PATCH] Refactor code in pgsql_src for server monitoring

Most of those things are taken from pg_ctl.c, but were somewhat not
really in a place corresponding to their role.
---
 Makefile                       |  2 +-
 pgsql_src/COPYRIGHT.pgsql_src  | 24 ---------------
 pgsql_src/pg_ctl.c => status.c | 55 +++++++++++++++++++++-------------
 3 files changed, 35 insertions(+), 46 deletions(-)
 delete mode 100644 pgsql_src/COPYRIGHT.pgsql_src
 rename pgsql_src/pg_ctl.c => status.c (70%)

diff --git a/Makefile b/Makefile
index 0f53c969..908ba0e3 100644
--- a/Makefile
+++ b/Makefile
@@ -10,10 +10,10 @@ SRCS = \
 	pg_rman.c \
 	restore.c \
 	show.c \
+	status.c \
 	util.c \
 	validate.c \
 	xlog.c \
-	pgsql_src/pg_ctl.c \
 	pgut/pgut.c \
 	pgut/pgut-port.c
 OBJS = $(SRCS:.c=.o)
diff --git a/pgsql_src/COPYRIGHT.pgsql_src b/pgsql_src/COPYRIGHT.pgsql_src
deleted file mode 100644
index eee220e0..00000000
--- a/pgsql_src/COPYRIGHT.pgsql_src
+++ /dev/null
@@ -1,24 +0,0 @@
-Files in this directory are parts of PostgreSQL Database Management System.
-Copyright holders of those files are following organizations:
-
-
-Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
-
-Portions Copyright (c) 1994, The Regents of the University of California
-
-Permission to use, copy, modify, and distribute this software and its
-documentation for any purpose, without fee, and without a written agreement
-is hereby granted, provided that the above copyright notice and this
-paragraph and the following two paragraphs appear in all copies.
-
-IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
-DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
-LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
-DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE
-POSSIBILITY OF SUCH DAMAGE.
-
-THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
-INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
-AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
-ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO
-PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
diff --git a/pgsql_src/pg_ctl.c b/status.c
similarity index 70%
rename from pgsql_src/pg_ctl.c
rename to status.c
index 90ed71f8..fa5f7f69 100644
--- a/pgsql_src/pg_ctl.c
+++ b/status.c
@@ -1,10 +1,10 @@
 /*-------------------------------------------------------------------------
  *
- * pg_ctl --- start/stops/restarts the PostgreSQL server
+ * status.c
  *
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/bin/pg_ctl/pg_ctl.c,v 1.111 2009/06/11 14:49:07 momjian Exp $
+ * Monitor status of a PostgreSQL server.
  *
  *-------------------------------------------------------------------------
  */
@@ -24,16 +24,20 @@ typedef long pgpid_t;
 static pgpid_t get_pgpid(void);
 static bool postmaster_is_alive(pid_t pid);
 
-static char pid_file[MAXPGPATH];
-
-
+/*
+ * get_pgpid
+ *
+ * Get PID of postmaster, by scanning postmaster.pid.
+ */
 static pgpid_t
 get_pgpid(void)
 {
 	FILE	   *pidf;
 	long		pid;
+	char		pid_file[MAXPGPATH];
 
 	snprintf(pid_file, lengthof(pid_file), "%s/postmaster.pid", pgdata);
+
 	pidf = fopen(pid_file, "r");
 	if (pidf == NULL)
 	{
@@ -41,19 +45,30 @@ get_pgpid(void)
 		if (errno == ENOENT)
 			return 0;
 		else
+		{
 			elog(ERROR_SYSTEM, _("could not open PID file \"%s\": %s\n"),
-						 pid_file, strerror(errno));
+				 pid_file, strerror(errno));
+		}
+		if (fscanf(pidf, "%ld", &pid) != 1)
+		{
+			/* Is the file empty? */
+			if (ftell(pidf) == 0 && feof(pidf))
+				elog(ERROR_SYSTEM, _("the PID file \"%s\" is empty\n"),
+					 pid_file);
+			else
+				elog(ERROR_SYSTEM, _("invalid data in PID file \"%s\"\n"),
+					 pid_file);
+		}
 	}
-	if (fscanf(pidf, "%ld", &pid) != 1)
-		elog(ERROR_PID_BROKEN, _("invalid data in PID file \"%s\"\n"), pid_file);
 	fclose(pidf);
 	return (pgpid_t) pid;
 }
 
 /*
- *	utility routines
+ * postmaster_is_alive
+ *
+ * Check whether postmaster is alive or not.
  */
-
 static bool
 postmaster_is_alive(pid_t pid)
 {
@@ -79,13 +94,9 @@ postmaster_is_alive(pid_t pid)
 }
 
 /*
- * original is do_status() in src/bin/pg_ctl/pg_ctl.c
- * changes are:
- *   renamed from do_status() from do_status().
- *   return true if PG server is running.
- *   don't print any message.
- *   don't print postopts file.
- *   log with elog() in pgut library.
+ * is_pg_running
+ *
+ *
  */
 bool
 is_pg_running(void)
@@ -93,13 +104,15 @@ is_pg_running(void)
 	pgpid_t		pid;
 
 	pid = get_pgpid();
-	if (pid == 0)				/* 0 means no pid file */
+
+	/* 0 means no pid file */
+	if (pid == 0)
 		return false;
 
-	if (pid < 0)			/* standalone backend */
+	/* Case of a standalone backend */
+	if (pid < 0)
 		pid = -pid;
 
-
+	/* Check if postmaster is alive */
 	return postmaster_is_alive((pid_t) pid);
 }
-