patch for distinguishing PG instances in event log

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
new file mode 100644
index 5d37065..46260d0
*** a/doc/src/sgml/config.sgml
--- b/doc/src/sgml/config.sgml
*************** local0.*    /var/log/postgresql
*** 2949,2954 ****
--- 2949,2961 ----
           to the  <application>syslog</application> daemon's configuration file
           to make it work.
          </para>
+         <para>
+          On Windows, you need to register an event source
+          and its library with the operating system in order
+          to make use of the <systemitem>eventlog</systemitem> option for
+          <varname>log_destination</>.
+          See <xref linkend="event-log-registration"> for details.
+         </para>
         </note>
        </listitem>
       </varlistentry>
*************** local0.*    /var/log/postgresql
*** 3189,3194 ****
--- 3196,3219 ----
           <productname>PostgreSQL</productname> messages in
           <application>syslog</application> logs. The default is
           <literal>postgres</literal>.
+          This parameter can only be set in the <filename>postgresql.conf</>
+          file or on the server command line.
+         </para>
+        </listitem>
+       </varlistentry>
+ 
+      <varlistentry id="guc-event-source" xreflabel="event_source">
+       <term><varname>event_source</varname> (<type>string</type>)</term>
+       <indexterm>
+        <primary><varname>event_source</> configuration parameter</primary>
+       </indexterm>
+        <listitem>
+         <para>
+          When logging to <application>event log</> is enabled, this parameter
+          determines the program name used to identify
+          <productname>PostgreSQL</productname> messages in
+          <application>event log</application>. The default is
+          <literal>PostgreSQL</literal>.
           This parameter can only be set in the <filename>postgresql.conf</>
           file or on the server command line.
          </para>
diff --git a/doc/src/sgml/installation.sgml b/doc/src/sgml/installation.sgml
new file mode 100644
index 96387bd..262b91a
*** a/doc/src/sgml/installation.sgml
--- b/doc/src/sgml/installation.sgml
*************** PostgreSQL, contrib and HTML documentati
*** 1551,1569 ****
    </procedure>
  
    <formalpara>
-    <title>Registering <application>eventlog</> on <systemitem
-    class="osname">Windows</>:</title>
-    <para>
-     To register a <systemitem class="osname">Windows</> <application>eventlog</>
-     library with the operating system, issue this command after installation:
- <screen>
- <userinput>regsvr32 <replaceable>pgsql_library_directory</>/pgevent.dll</>
- </screen>
-     This creates registry entries used by the event viewer.
-    </para>
-   </formalpara>
- 
-   <formalpara>
     <title>Uninstallation:</title>
     <para>
      To undo the installation use the command <command>gmake
--- 1551,1556 ----
diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
new file mode 100644
index d18ba79..9a8a22d
*** a/doc/src/sgml/runtime.sgml
--- b/doc/src/sgml/runtime.sgml
*************** ssh -L 63333:db.foo.com:5432 joe@shell.f
*** 2294,2297 ****
--- 2294,2347 ----
  
   </sect1>
  
+  <sect1 id="event-log-registration">
+   <title>Registering <application>Event Log</> on <systemitem
+   class="osname">Windows</></title>
+ 
+   <indexterm zone="event-log-registration">
+    <primary>event log</primary>
+    <secondary>event log</secondary>
+   </indexterm>
+ 
+   <para>
+    To register a <systemitem class="osname">Windows</> <application>event log</>
+    library with the operating system, issue this command:
+ <screen>
+ <userinput>regsvr32 <replaceable>pgsql_library_directory</>/pgevent.dll</>
+ </screen>
+    This creates registry entries used by the event viewer, under the default event
+    source named "PostgreSQL".
+    </para>
+ 
+    <para>
+    You can specify the event source name with /i option. In this case, -n option
+    is necessary, too:
+ <screen>
+ <userinput>regsvr32 /n /i:<replaceable>event_source_name</>
+  <replaceable>pgsql_library_directory</>/pgevent.dll</>
+ </screen>
+    You also need to set <xref linkend="guc-event-source"> in
+    <filename>postgresql.conf</filename>. Note that the event source specification
+    only takes effect for the database server. Other applications like
+    <command>pg_ctl</command> always use "PostgreSQL" event source.
+    </para>
+ 
+    <para>
+    To unregister the <application>event log</> library from
+    the operating system, issue this command:
+ <screen>
+ <userinput>regsvr32 /u [/i:<replaceable>event_source_name</>]
+  <replaceable>pgsql_library_directory</>/pgevent.dll</>
+ </screen>
+    </para>
+ 
+   <note>
+    <para>
+     To enable event logging in the database server, modify
+     <xref linkend="guc-log-destination"> to include
+     <systemitem>eventlog</systemitem> in <filename>postgresql.conf</filename>.
+    </para>
+   </note>
+  </sect1>
+ 
  </chapter>
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
new file mode 100644
index 337b875..0744987
*** a/src/backend/utils/error/elog.c
--- b/src/backend/utils/error/elog.c
*************** static void write_syslog(int level, cons
*** 122,127 ****
--- 122,129 ----
  static void write_console(const char *line, int len);
  
  #ifdef WIN32
+ static char *event_source = NULL;
+ 
  static void write_eventlog(int level, const char *line, int len);
  #endif
  
*************** write_syslog(int level, const char *line
*** 1633,1638 ****
--- 1635,1655 ----
  #endif   /* HAVE_SYSLOG */
  
  #ifdef WIN32
+ 
+ /*
+  * Set or update the parameters for event log logging
+  */
+ void
+ set_eventlog_parameters(const char *source)
+ {
+ 	if (event_source == NULL || strcmp(event_source, source) != 0)
+ 	{
+ 		if (event_source)
+ 			free(event_source);
+ 		event_source = strdup(source);
+ 	}
+ }
+ 
  /*
   * Write a message line to the windows event log
   */
*************** write_eventlog(int level, const char *li
*** 1645,1651 ****
  
  	if (evtHandle == INVALID_HANDLE_VALUE)
  	{
! 		evtHandle = RegisterEventSource(NULL, "PostgreSQL");
  		if (evtHandle == NULL)
  		{
  			evtHandle = INVALID_HANDLE_VALUE;
--- 1662,1668 ----
  
  	if (evtHandle == INVALID_HANDLE_VALUE)
  	{
! 		evtHandle = RegisterEventSource(NULL, event_source ? event_source : "PostgreSQL");
  		if (evtHandle == NULL)
  		{
  			evtHandle = INVALID_HANDLE_VALUE;
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
new file mode 100644
index 92391ed..07ce52d
*** a/src/backend/utils/misc/guc.c
--- b/src/backend/utils/misc/guc.c
*************** static int	syslog_facility = 0;
*** 175,180 ****
--- 175,183 ----
  
  static void assign_syslog_facility(int newval, void *extra);
  static void assign_syslog_ident(const char *newval, void *extra);
+ #ifdef WIN32
+ static void assign_event_source(const char *newval, void *extra);
+ #endif
  static void assign_session_replication_role(int newval, void *extra);
  static bool check_temp_buffers(int *newval, void **extra, GucSource source);
  static bool check_phony_autocommit(bool *newval, void **extra, GucSource source);
*************** int			tcp_keepalives_count;
*** 449,454 ****
--- 452,460 ----
  static char *log_destination_string;
  
  static char *syslog_ident_str;
+ #ifdef WIN32
+ static char *event_source_str;
+ #endif
  static bool phony_autocommit;
  static bool session_auth_is_superuser;
  static double phony_random_seed;
*************** static struct config_string ConfigureNam
*** 2822,2827 ****
--- 2828,2846 ----
  		NULL, assign_syslog_ident, NULL
  	},
  
+ #ifdef WIN32
+ 	{
+ 		{"event_source", PGC_POSTMASTER, LOGGING_WHERE,
+ 			gettext_noop("Sets the program name used to identify PostgreSQL "
+ 						 "messages in event log."),
+ 			NULL
+ 		},
+ 		&event_source_str,
+ 		"PostgreSQL",
+ 		NULL, assign_event_source, NULL
+ 	},
+ #endif
+ 
  	{
  		{"TimeZone", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the time zone for displaying and interpreting time stamps."),
*************** assign_syslog_ident(const char *newval, 
*** 8213,8218 ****
--- 8232,8245 ----
  #endif
  	/* Without syslog support, it will always be set to "none", so ignore */
  }
+ 
+ #ifdef WIN32
+ static void
+ assign_event_source(const char *newval, void *extra)
+ {
+ 	set_eventlog_parameters(newval);
+ }
+ #endif
  
  
  static void
diff --git a/src/bin/pgevent/pgevent.c b/src/bin/pgevent/pgevent.c
new file mode 100644
index 1fcde86..402d00a
*** a/src/bin/pgevent/pgevent.c
--- b/src/bin/pgevent/pgevent.c
***************
*** 15,31 ****
--- 15,75 ----
  #include <windows.h>
  #include <olectl.h>
  #include <string.h>
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <Tchar.h>
  
  /* Global variables */
  HANDLE		g_module = NULL;	/* hModule of DLL */
+ /*
+  * The event source is stored as a registry key.
+  * The maximum length of a registry key is 255 characters.
+  * http://msdn.microsoft.com/en-us/library/ms724872(v=vs.85).aspx
+  */
+ _TCHAR		event_source[256] = _T("PostgreSQL");
  
  /* Prototypes */
+ HRESULT DllInstall(BOOL bInstall, __in_opt LPCWSTR pszCmdLine);
  STDAPI
  DllRegisterServer(void);
  STDAPI		DllUnregisterServer(void);
  BOOL WINAPI DllMain(HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved);
  
  /*
+  * DllInstall --- Passes the command line argument to DLL
+  */
+ 
+ HRESULT
+ DllInstall(BOOL bInstall,
+ 		__in_opt LPCWSTR pszCmdLine)
+ {
+ #ifndef _UNICODE
+ 	size_t ret;
+ #endif
+ 
+ 	if (pszCmdLine && *pszCmdLine != '\0')
+ #ifdef _UNICODE
+ 		_tcsncpy(event_source, pszCmdLine, sizeof(event_source));
+ #else
+ 		wcstombs_s(&ret, event_source, sizeof(event_source), 
+ 			pszCmdLine, sizeof(event_source));
+ #endif
+ 
+ 	/*
+ 	 * This is an ugry part due to the strange behavior of "regsvr32 /i".
+ 	 * When installing, regsvr32 calls DllRegisterServer before DllInstall.
+ 	 * When uninstalling (i.e. "regsvr32 /u /i"), on the other hand, 
+ 	 * regsvr32 calls DllInstall and then DllUnregisterServer as expected.
+ 	 * This strange behavior forces us to specify -n (i.e. "regsvr32 /n /i").
+ 	 * Without -n, DllRegisterServer called before DllInstall would
+ 	 * mistakenly overwrite the default "PostgreSQL" event source registration.
+ 	 */
+ 	if (bInstall)
+ 		DllRegisterServer();
+ 	return S_OK;
+ }
+ 
+ /*
   * DllRegisterServer --- Instructs DLL to create its registry entries
   */
  
*************** DllRegisterServer(void)
*** 35,40 ****
--- 79,85 ----
  	HKEY		key;
  	DWORD		data;
  	char		buffer[_MAX_PATH];
+ 	_TCHAR		key_name[400];
  
  	/* Set the name of DLL full path name. */
  	if (!GetModuleFileName((HMODULE) g_module, buffer, sizeof(buffer)))
*************** DllRegisterServer(void)
*** 47,53 ****
  	 * Add PostgreSQL source name as a subkey under the Application key in the
  	 * EventLog registry key.
  	 */
! 	if (RegCreateKey(HKEY_LOCAL_MACHINE, "SYSTEM\\CurrentControlSet\\Services\\EventLog\\Application\\PostgreSQL", &key))
  	{
  		MessageBox(NULL, "Could not create the registry key.", "PostgreSQL error", MB_OK | MB_ICONSTOP);
  		return SELFREG_E_TYPELIB;
--- 92,101 ----
  	 * Add PostgreSQL source name as a subkey under the Application key in the
  	 * EventLog registry key.
  	 */
! 	_sntprintf(key_name, sizeof(key_name), 
! 		_T("SYSTEM\\CurrentControlSet\\Services\\EventLog\\Application\\%s"),
! 		event_source);
! 	if (RegCreateKey(HKEY_LOCAL_MACHINE, key_name, &key))
  	{
  		MessageBox(NULL, "Could not create the registry key.", "PostgreSQL error", MB_OK | MB_ICONSTOP);
  		return SELFREG_E_TYPELIB;
*************** DllRegisterServer(void)
*** 90,101 ****
  STDAPI
  DllUnregisterServer(void)
  {
  	/*
  	 * Remove PostgreSQL source name as a subkey under the Application key in
  	 * the EventLog registry key.
  	 */
  
! 	if (RegDeleteKey(HKEY_LOCAL_MACHINE, "SYSTEM\\CurrentControlSet\\Services\\EventLog\\Application\\PostgreSQL"))
  	{
  		MessageBox(NULL, "Could not delete the registry key.", "PostgreSQL error", MB_OK | MB_ICONSTOP);
  		return SELFREG_E_TYPELIB;
--- 138,154 ----
  STDAPI
  DllUnregisterServer(void)
  {
+ 	_TCHAR		key_name[400];
+ 
  	/*
  	 * Remove PostgreSQL source name as a subkey under the Application key in
  	 * the EventLog registry key.
  	 */
  
! 	_sntprintf(key_name, sizeof(key_name), 
! 		_T("SYSTEM\\CurrentControlSet\\Services\\EventLog\\Application\\%s"),
! 		event_source);
! 	if (RegDeleteKey(HKEY_LOCAL_MACHINE, key_name))
  	{
  		MessageBox(NULL, "Could not delete the registry key.", "PostgreSQL error", MB_OK | MB_ICONSTOP);
  		return SELFREG_E_TYPELIB;
diff --git a/src/bin/pgevent/pgevent.def b/src/bin/pgevent/pgevent.def
new file mode 100644
index 21bab7a..6b4d44a
*** a/src/bin/pgevent/pgevent.def
--- b/src/bin/pgevent/pgevent.def
***************
*** 2,4 ****
--- 2,5 ----
  EXPORTS
  	DllUnregisterServer ;
  	DllRegisterServer ;
+ 	DllInstall ;
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
new file mode 100644
index 4a3bd02..48bc784
*** a/src/include/utils/elog.h
--- b/src/include/utils/elog.h
*************** extern void DebugFileOpen(void);
*** 353,358 ****
--- 353,362 ----
  extern char *unpack_sql_state(int sql_state);
  extern bool in_error_recursion_trouble(void);
  
+ #ifdef WIN32
+ extern void set_eventlog_parameters(const char *source);
+ #endif
+ 
  #ifdef HAVE_SYSLOG
  extern void set_syslog_parameters(const char *ident, int facility);
  #endif