elog.c

}

/*
 * FreeErrorData --- free the structure returned by CopyErrorData.
 *
 * Error handlers should use this in preference to assuming they know all
 * the separately-allocated fields.
 */
void
FreeErrorData(ErrorData *edata)
{
	if (edata->message)
		pfree(edata->message);
	if (edata->detail)
		pfree(edata->detail);
	if (edata->hint)
		pfree(edata->hint);
	if (edata->context)
		pfree(edata->context);
	if (edata->internalquery)
		pfree(edata->internalquery);
	pfree(edata);
}

/*
 * FlushErrorState --- flush the error state after error recovery
 *
 * This should be called by an error handler after it's done processing
 * the error; or as soon as it's done CopyErrorData, if it intends to
 * do stuff that is likely to provoke another error.  You are not "out" of
 * the error subsystem until you have done this.
 */
void
FlushErrorState(void)
{
	/*
	 * Reset stack to empty.  The only case where it would be more than one
	 * deep is if we serviced an error that interrupted construction of
	 * another message.  We assume control escaped out of that message
	 * construction and won't ever go back.
	 */
	errordata_stack_depth = -1;
	recursion_depth = 0;
	/* Delete all data in ErrorContext */
	MemoryContextResetAndDeleteChildren(ErrorContext);
}

/*
 * ReThrowError --- re-throw a previously copied error
 *
 * A handler can do CopyErrorData/FlushErrorState to get out of the error
 * subsystem, then do some processing, and finally ReThrowError to re-throw
 * the original error.	This is slower than just PG_RE_THROW() but should
 * be used if the "some processing" is likely to incur another error.
 */
void
ReThrowError(ErrorData *edata)
{
	ErrorData  *newedata;

	Assert(edata->elevel == ERROR);

	/* Push the data back into the error context */
	recursion_depth++;
	MemoryContextSwitchTo(ErrorContext);

	if (++errordata_stack_depth >= ERRORDATA_STACK_SIZE)
	{
		/*
		 * Wups, stack not big enough.	We treat this as a PANIC condition
		 * because it suggests an infinite loop of errors during error
		 * recovery.
		 */
		errordata_stack_depth = -1;		/* make room on stack */
		ereport(PANIC, (errmsg_internal("ERRORDATA_STACK_SIZE exceeded")));
	}

	newedata = &errordata[errordata_stack_depth];
	memcpy(newedata, edata, sizeof(ErrorData));

	/* Make copies of separately-allocated fields */
	if (newedata->message)
		newedata->message = pstrdup(newedata->message);
	if (newedata->detail)
		newedata->detail = pstrdup(newedata->detail);
	if (newedata->hint)
		newedata->hint = pstrdup(newedata->hint);
	if (newedata->context)
		newedata->context = pstrdup(newedata->context);
	if (newedata->internalquery)
		newedata->internalquery = pstrdup(newedata->internalquery);

	recursion_depth--;
	PG_RE_THROW();
}

/*
 * Initialization of error output file
 */
void
DebugFileOpen(void)
{
	int			fd,
				istty;

	if (OutputFileName[0])
	{
		/*
		 * A debug-output file name was given.
		 *
		 * Make sure we can write the file, and find out if it's a tty.
		 */
		if ((fd = open(OutputFileName, O_CREAT | O_APPEND | O_WRONLY,
					   0666)) < 0)
			ereport(FATAL,
					(errcode_for_file_access(),
				  errmsg("could not open file \"%s\": %m", OutputFileName)));
		istty = isatty(fd);
		close(fd);

		/*
		 * Redirect our stderr to the debug output file.
		 */
		if (!freopen(OutputFileName, "a", stderr))
			ereport(FATAL,
					(errcode_for_file_access(),
					 errmsg("could not reopen file \"%s\" as stderr: %m",
							OutputFileName)));

		/*
		 * If the file is a tty and we're running under the postmaster, try to
		 * send stdout there as well (if it isn't a tty then stderr will block
		 * out stdout, so we may as well let stdout go wherever it was going
		 * before).
		 */
		if (istty && IsUnderPostmaster)
			if (!freopen(OutputFileName, "a", stdout))
				ereport(FATAL,
						(errcode_for_file_access(),
						 errmsg("could not reopen file \"%s\" as stdout: %m",
								OutputFileName)));
	}
}



#ifdef HAVE_SYSLOG

/*
 * Set or update the parameters for syslog logging
 */
void
set_syslog_parameters(const char *ident, int facility)
{
	/*
	 * guc.c is likely to call us repeatedly with same parameters, so don't
	 * thrash the syslog connection unnecessarily.	Also, we do not re-open
	 * the connection until needed, since this routine will get called whether
	 * or not Log_destination actually mentions syslog.
	 *
	 * Note that we make our own copy of the ident string rather than relying
	 * on guc.c's.  This may be overly paranoid, but it ensures that we cannot
	 * accidentally free a string that syslog is still using.
	 */
	if (syslog_ident == NULL || strcmp(syslog_ident, ident) != 0 ||
		syslog_facility != facility)
	{
		if (openlog_done)
		{
			closelog();
			openlog_done = false;
		}
		if (syslog_ident)
			free(syslog_ident);
		syslog_ident = strdup(ident);
		/* if the strdup fails, we will cope in write_syslog() */
		syslog_facility = facility;
	}
}


#ifndef PG_SYSLOG_LIMIT
#define PG_SYSLOG_LIMIT 128
#endif

/*
 * Write a message line to syslog
 */
static void
write_syslog(int level, const char *line)
{
	static unsigned long seq = 0;

	int			len;

	/* Open syslog connection if not done yet */
	if (!openlog_done)
	{
		openlog(syslog_ident ? syslog_ident : "postgres",
				LOG_PID | LOG_NDELAY | LOG_NOWAIT,
				syslog_facility);
		openlog_done = true;
	}

	/*
	 * We add a sequence number to each log message to suppress "same"
	 * messages.
	 */
	seq++;

	/*
	 * Our problem here is that many syslog implementations don't handle long
	 * messages in an acceptable manner. While this function doesn't help that
	 * fact, it does work around by splitting up messages into smaller pieces.
	 *
	 * We divide into multiple syslog() calls if message is too long or if the
	 * message contains embedded NewLine(s) '\n'.
	 */
	len = strlen(line);
	if (len > PG_SYSLOG_LIMIT || strchr(line, '\n') != NULL)
	{
		int			chunk_nr = 0;

		while (len > 0)
		{
			char		buf[PG_SYSLOG_LIMIT + 1];
			int			buflen;
			int			i;

			/* if we start at a newline, move ahead one char */
			if (line[0] == '\n')
			{
				line++;
				len--;
				continue;
			}

			strncpy(buf, line, PG_SYSLOG_LIMIT);
			buf[PG_SYSLOG_LIMIT] = '\0';
			if (strchr(buf, '\n') != NULL)
				*strchr(buf, '\n') = '\0';

			buflen = strlen(buf);

			/* trim to multibyte letter boundary */
			buflen = pg_mbcliplen(buf, buflen, buflen);
			if (buflen <= 0)
				return;
			buf[buflen] = '\0';

			/* already word boundary? */
			if (line[buflen] != '\0' &&
				!isspace((unsigned char) line[buflen]))
			{
				/* try to divide at word boundary */
				i = buflen - 1;
				while (i > 0 && !isspace((unsigned char) buf[i]))
					i--;

				if (i > 0)		/* else couldn't divide word boundary */
				{
					buflen = i;
					buf[i] = '\0';
				}
			}

			chunk_nr++;

			syslog(level, "[%lu-%d] %s", seq, chunk_nr, buf);
			line += buflen;
			len -= buflen;
		}
	}
	else
	{
		/* message short enough */
		syslog(level, "[%lu] %s", seq, line);
	}
}
#endif   /* HAVE_SYSLOG */

#ifdef WIN32
/*
 * Write a message line to the windows event log
 */
static void
write_eventlog(int level, const char *line)
{
	int			eventlevel = EVENTLOG_ERROR_TYPE;
	static HANDLE evtHandle = INVALID_HANDLE_VALUE;

	if (evtHandle == INVALID_HANDLE_VALUE)
	{
		evtHandle = RegisterEventSource(NULL, "PostgreSQL");
		if (evtHandle == NULL)
		{
			evtHandle = INVALID_HANDLE_VALUE;
			return;
		}
	}

	switch (level)
	{
		case DEBUG5:
		case DEBUG4:
		case DEBUG3:
		case DEBUG2:
		case DEBUG1:
		case LOG:
		case COMMERROR:
		case INFO:
		case NOTICE:
			eventlevel = EVENTLOG_INFORMATION_TYPE;
			break;
		case WARNING:
			eventlevel = EVENTLOG_WARNING_TYPE;
			break;
		case ERROR:
		case FATAL:
		case PANIC:
		default:
			eventlevel = EVENTLOG_ERROR_TYPE;
			break;
	}


	ReportEvent(evtHandle,
				eventlevel,
				0,
				0,				/* All events are Id 0 */
				NULL,
				1,
				0,
				&line,
				NULL);
}
#endif   /* WIN32 */

/*
 * Format tag info for log lines; append to the provided buffer.
 */
static void
log_line_prefix(StringInfo buf)
{
	/* static counter for line numbers */
	static long log_line_number = 0;

	/* has counter been reset in current process? */
	static int	log_my_pid = 0;

	int			format_len;
	int			i;

	/*
	 * This is one of the few places where we'd rather not inherit a static
	 * variable's value from the postmaster.  But since we will, reset it when
	 * MyProcPid changes.
	 */
	if (log_my_pid != MyProcPid)
	{
		log_line_number = 0;
		log_my_pid = MyProcPid;
	}
	log_line_number++;

	if (Log_line_prefix == NULL)
		return;					/* in case guc hasn't run yet */

	format_len = strlen(Log_line_prefix);

	for (i = 0; i < format_len; i++)
	{
		if (Log_line_prefix[i] != '%')
		{
			/* literal char, just copy */
			appendStringInfoChar(buf, Log_line_prefix[i]);
			continue;
		}
		/* go to char after '%' */
		i++;
		if (i >= format_len)
			break;				/* format error - ignore it */

		/* process the option */
		switch (Log_line_prefix[i])
		{
			case 'u':
				if (MyProcPort)
				{
					const char *username = MyProcPort->user_name;

					if (username == NULL || *username == '\0')
						username = _("[unknown]");
					appendStringInfo(buf, "%s", username);
				}
				break;
			case 'd':
				if (MyProcPort)
				{
					const char *dbname = MyProcPort->database_name;

					if (dbname == NULL || *dbname == '\0')
						dbname = _("[unknown]");
					appendStringInfo(buf, "%s", dbname);
				}
				break;
			case 'c':
				if (MyProcPort)
				{
					appendStringInfo(buf, "%lx.%x",
									 (long) (MyProcPort->session_start),
									 MyProcPid);
				}
				break;
			case 'p':
				appendStringInfo(buf, "%d", MyProcPid);
				break;
			case 'l':
				appendStringInfo(buf, "%ld", log_line_number);
				break;
			case 'm':
				{
					/*
					 * Note: for %m, %t, and %s we deliberately use the C
					 * library's strftime/localtime, and not the equivalent
					 * functions from src/timezone.  This ensures that all
					 * backends will report log entries in the same timezone,
					 * namely whatever C-library setting they inherit from the
					 * postmaster.	If we used src/timezone then local
					 * settings of the TimeZone GUC variable would confuse the
					 * log.
					 */
					time_t		stamp_time;
					char		strfbuf[128],
								msbuf[8];
					struct timeval tv;

					gettimeofday(&tv, NULL);
					stamp_time = tv.tv_sec;

					strftime(strfbuf, sizeof(strfbuf),
					/* leave room for milliseconds... */
					/* Win32 timezone names are too long so don't print them */
#ifndef WIN32
							 "%Y-%m-%d %H:%M:%S     %Z",
#else
							 "%Y-%m-%d %H:%M:%S     ",
#endif
							 localtime(&stamp_time));

					/* 'paste' milliseconds into place... */
					sprintf(msbuf, ".%03d", (int) (tv.tv_usec / 1000));
					strncpy(strfbuf + 19, msbuf, 4);

					appendStringInfoString(buf, strfbuf);
				}
				break;
			case 't':
				{
					time_t		stamp_time = time(NULL);
					char		strfbuf[128];

					strftime(strfbuf, sizeof(strfbuf),
					/* Win32 timezone names are too long so don't print them. */
#ifndef WIN32
							 "%Y-%m-%d %H:%M:%S %Z",
#else
							 "%Y-%m-%d %H:%M:%S",
#endif
							 localtime(&stamp_time));
					appendStringInfoString(buf, strfbuf);
				}
				break;
			case 's':
				if (MyProcPort)
				{
					char		strfbuf[128];

					strftime(strfbuf, sizeof(strfbuf),
							 "%Y-%m-%d %H:%M:%S %Z",
							 localtime(&MyProcPort->session_start));
					appendStringInfoString(buf, strfbuf);
				}
				break;
			case 'i':
				if (MyProcPort)
				{
					const char *psdisp;
					int			displen;

					psdisp = get_ps_display(&displen);
					appendStringInfo(buf, "%.*s", displen, psdisp);
				}
				break;
			case 'r':
				if (MyProcPort && MyProcPort->remote_host)
				{
					appendStringInfo(buf, "%s", MyProcPort->remote_host);
					if (MyProcPort->remote_port &&
						MyProcPort->remote_port[0] != '\0')
						appendStringInfo(buf, "(%s)",
										 MyProcPort->remote_port);
				}
				break;
			case 'h':
				if (MyProcPort && MyProcPort->remote_host)
					appendStringInfo(buf, "%s", MyProcPort->remote_host);
				break;
			case 'q':
				/* in postmaster and friends, stop if %q is seen */
				/* in a backend, just ignore */
				if (MyProcPort == NULL)
					i = format_len;
				break;
			case 'x':
				if (MyProcPort)
				{
					if (IsTransactionState())
						appendStringInfo(buf, "%u", GetTopTransactionId());
					else
						appendStringInfo(buf, "%u", InvalidTransactionId);
				}
				break;
			case '%':
				appendStringInfoChar(buf, '%');
				break;
			default:
				/* format error - ignore it */
				break;
		}
	}
}

/*
 * Unpack MAKE_SQLSTATE code. Note that this returns a pointer to a
 * static buffer.
 */
char *
unpack_sql_state(int sql_state)
{
	static char buf[12];
	int			i;

	for (i = 0; i < 5; i++)
	{
		buf[i] = PGUNSIXBIT(sql_state);
		sql_state >>= 6;
	}

	buf[i] = '\0';
	return buf;
}


/*
 * Write error report to server's log
 */
static void
send_message_to_server_log(ErrorData *edata)
{
	StringInfoData buf;

	initStringInfo(&buf);

	log_line_prefix(&buf);
	appendStringInfo(&buf, "%s:  ", error_severity(edata->elevel));

	if (Log_error_verbosity >= PGERROR_VERBOSE)
		appendStringInfo(&buf, "%s: ", unpack_sql_state(edata->sqlerrcode));

	if (edata->message)
		append_with_tabs(&buf, edata->message);
	else
		append_with_tabs(&buf, _("missing error text"));

	if (edata->cursorpos > 0)
		appendStringInfo(&buf, _(" at character %d"),
						 edata->cursorpos);
	else if (edata->internalpos > 0)
		appendStringInfo(&buf, _(" at character %d"),
						 edata->internalpos);

	appendStringInfoChar(&buf, '\n');

	if (Log_error_verbosity >= PGERROR_DEFAULT)
	{
		if (edata->detail)
		{
			log_line_prefix(&buf);
			appendStringInfoString(&buf, _("DETAIL:  "));
			append_with_tabs(&buf, edata->detail);
			appendStringInfoChar(&buf, '\n');
		}
		if (edata->hint)
		{
			log_line_prefix(&buf);
			appendStringInfoString(&buf, _("HINT:  "));
			append_with_tabs(&buf, edata->hint);
			appendStringInfoChar(&buf, '\n');
		}
		if (edata->internalquery)
		{
			log_line_prefix(&buf);
			appendStringInfoString(&buf, _("QUERY:  "));
			append_with_tabs(&buf, edata->internalquery);
			appendStringInfoChar(&buf, '\n');
		}
		if (edata->context)
		{
			log_line_prefix(&buf);
			appendStringInfoString(&buf, _("CONTEXT:  "));
			append_with_tabs(&buf, edata->context);
			appendStringInfoChar(&buf, '\n');
		}
		if (Log_error_verbosity >= PGERROR_VERBOSE)
		{
			/* assume no newlines in funcname or filename... */
			if (edata->funcname && edata->filename)
			{
				log_line_prefix(&buf);
				appendStringInfo(&buf, _("LOCATION:  %s, %s:%d\n"),
								 edata->funcname, edata->filename,
								 edata->lineno);
			}
			else if (edata->filename)
			{
				log_line_prefix(&buf);
				appendStringInfo(&buf, _("LOCATION:  %s:%d\n"),
								 edata->filename, edata->lineno);
			}
		}
	}

	/*
	 * If the user wants the query that generated this error logged, do it.
	 */
	if (edata->elevel >= log_min_error_statement && debug_query_string != NULL)
	{
		log_line_prefix(&buf);
		appendStringInfoString(&buf, _("STATEMENT:  "));
		append_with_tabs(&buf, debug_query_string);
		appendStringInfoChar(&buf, '\n');
	}

#ifdef HAVE_SYSLOG
	/* Write to syslog, if enabled */
	if (Log_destination & LOG_DESTINATION_SYSLOG)
	{
		int			syslog_level;

		switch (edata->elevel)
		{
			case DEBUG5:
			case DEBUG4:
			case DEBUG3:
			case DEBUG2:
			case DEBUG1:
				syslog_level = LOG_DEBUG;
				break;
			case LOG:
			case COMMERROR:
			case INFO:
				syslog_level = LOG_INFO;
				break;
			case NOTICE:
			case WARNING:
				syslog_level = LOG_NOTICE;
				break;
			case ERROR:
				syslog_level = LOG_WARNING;
				break;
			case FATAL:
				syslog_level = LOG_ERR;
				break;
			case PANIC:
			default:
				syslog_level = LOG_CRIT;
				break;
		}

		write_syslog(syslog_level, buf.data);
	}
#endif   /* HAVE_SYSLOG */

#ifdef WIN32
	/* Write to eventlog, if enabled */
	if (Log_destination & LOG_DESTINATION_EVENTLOG)
	{
		write_eventlog(edata->elevel, buf.data);
	}
#endif   /* WIN32 */

	/* Write to stderr, if enabled */
	if ((Log_destination & LOG_DESTINATION_STDERR) || whereToSendOutput == DestDebug)
	{
#ifdef WIN32

		/*
		 * In a win32 service environment, there is no usable stderr. Capture
		 * anything going there and write it to the eventlog instead.
		 *
		 * If stderr redirection is active, it's ok to write to stderr because
		 * that's really a pipe to the syslogger process.
		 */
		if ((!Redirect_stderr || am_syslogger) && pgwin32_is_service())
			write_eventlog(edata->elevel, buf.data);
		else
#endif
			fprintf(stderr, "%s", buf.data);
	}

	/* If in the syslogger process, try to write messages direct to file */
	if (am_syslogger)
		write_syslogger_file(buf.data, buf.len);

	pfree(buf.data);
}


/*
 * Write error report to client
 */
static void
send_message_to_frontend(ErrorData *edata)
{
	StringInfoData msgbuf;

	/* 'N' (Notice) is for nonfatal conditions, 'E' is for errors */
	pq_beginmessage(&msgbuf, (edata->elevel < ERROR) ? 'N' : 'E');

	if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
	{
		/* New style with separate fields */
		char		tbuf[12];
		int			ssval;
		int			i;

		pq_sendbyte(&msgbuf, PG_DIAG_SEVERITY);
		pq_sendstring(&msgbuf, error_severity(edata->elevel));

		/* unpack MAKE_SQLSTATE code */
		ssval = edata->sqlerrcode;
		for (i = 0; i < 5; i++)
		{
			tbuf[i] = PGUNSIXBIT(ssval);
			ssval >>= 6;
		}
		tbuf[i] = '\0';

		pq_sendbyte(&msgbuf, PG_DIAG_SQLSTATE);
		pq_sendstring(&msgbuf, tbuf);

		/* M field is required per protocol, so always send something */
		pq_sendbyte(&msgbuf, PG_DIAG_MESSAGE_PRIMARY);
		if (edata->message)
			pq_sendstring(&msgbuf, edata->message);
		else
			pq_sendstring(&msgbuf, _("missing error text"));

		if (edata->detail)
		{
			pq_sendbyte(&msgbuf, PG_DIAG_MESSAGE_DETAIL);
			pq_sendstring(&msgbuf, edata->detail);
		}

		if (edata->hint)
		{
			pq_sendbyte(&msgbuf, PG_DIAG_MESSAGE_HINT);
			pq_sendstring(&msgbuf, edata->hint);
		}

		if (edata->context)
		{
			pq_sendbyte(&msgbuf, PG_DIAG_CONTEXT);
			pq_sendstring(&msgbuf, edata->context);
		}

		if (edata->cursorpos > 0)
		{
			snprintf(tbuf, sizeof(tbuf), "%d", edata->cursorpos);
			pq_sendbyte(&msgbuf, PG_DIAG_STATEMENT_POSITION);
			pq_sendstring(&msgbuf, tbuf);
		}

		if (edata->internalpos > 0)
		{
			snprintf(tbuf, sizeof(tbuf), "%d", edata->internalpos);
			pq_sendbyte(&msgbuf, PG_DIAG_INTERNAL_POSITION);
			pq_sendstring(&msgbuf, tbuf);
		}

		if (edata->internalquery)
		{
			pq_sendbyte(&msgbuf, PG_DIAG_INTERNAL_QUERY);
			pq_sendstring(&msgbuf, edata->internalquery);
		}

		if (edata->filename)
		{
			pq_sendbyte(&msgbuf, PG_DIAG_SOURCE_FILE);
			pq_sendstring(&msgbuf, edata->filename);
		}

		if (edata->lineno > 0)
		{
			snprintf(tbuf, sizeof(tbuf), "%d", edata->lineno);
			pq_sendbyte(&msgbuf, PG_DIAG_SOURCE_LINE);
			pq_sendstring(&msgbuf, tbuf);
		}

		if (edata->funcname)
		{
			pq_sendbyte(&msgbuf, PG_DIAG_SOURCE_FUNCTION);
			pq_sendstring(&msgbuf, edata->funcname);
		}

		pq_sendbyte(&msgbuf, '\0');		/* terminator */
	}
	else
	{
		/* Old style --- gin up a backwards-compatible message */
		StringInfoData buf;

		initStringInfo(&buf);

		appendStringInfo(&buf, "%s:  ", error_severity(edata->elevel));

		if (edata->show_funcname && edata->funcname)
			appendStringInfo(&buf, "%s: ", edata->funcname);

		if (edata->message)
			appendStringInfoString(&buf, edata->message);
		else
			appendStringInfoString(&buf, _("missing error text"));

		if (edata->cursorpos > 0)
			appendStringInfo(&buf, _(" at character %d"),
							 edata->cursorpos);
		else if (edata->internalpos > 0)
			appendStringInfo(&buf, _(" at character %d"),
							 edata->internalpos);

		appendStringInfoChar(&buf, '\n');

		pq_sendstring(&msgbuf, buf.data);

		pfree(buf.data);
	}

	pq_endmessage(&msgbuf);

	/*
	 * This flush is normally not necessary, since postgres.c will flush out
	 * waiting data when control returns to the main loop. But it seems best
	 * to leave it here, so that the client has some clue what happened if the
	 * backend dies before getting back to the main loop ... error/notice
	 * messages should not be a performance-critical path anyway, so an extra
	 * flush won't hurt much ...
	 */
	pq_flush();
}


/*
 * Support routines for formatting error messages.
 */


/*
 * expand_fmt_string --- process special format codes in a format string
 *
 * We must replace %m with the appropriate strerror string, since vsnprintf
 * won't know what to do with it.
 *
 * The result is a palloc'd string.
 */
static char *
expand_fmt_string(const char *fmt, ErrorData *edata)
{
	StringInfoData buf;
	const char *cp;

	initStringInfo(&buf);

	for (cp = fmt; *cp; cp++)
	{
		if (cp[0] == '%' && cp[1] != '\0')
		{
			cp++;
			if (*cp == 'm')
			{
				/*
				 * Replace %m by system error string.  If there are any %'s in
				 * the string, we'd better double them so that vsnprintf won't
				 * misinterpret.
				 */
				const char *cp2;

				cp2 = useful_strerror(edata->saved_errno);
				for (; *cp2; cp2++)
				{
					if (*cp2 == '%')
						appendStringInfoCharMacro(&buf, '%');
					appendStringInfoCharMacro(&buf, *cp2);
				}
			}
			else
			{
				/* copy % and next char --- this avoids trouble with %%m */
				appendStringInfoCharMacro(&buf, '%');
				appendStringInfoCharMacro(&buf, *cp);
			}
		}
		else
			appendStringInfoCharMacro(&buf, *cp);
	}

	return buf.data;
}


/*
 * A slightly cleaned-up version of strerror()
 */
static const char *
useful_strerror(int errnum)
{
	/* this buffer is only used if errno has a bogus value */
	static char errorstr_buf[48];
	const char *str;

#ifdef WIN32
	/* Winsock error code range, per WinError.h */
	if (errnum >= 10000 && errnum <= 11999)
		return pgwin32_socket_strerror(errnum);
#endif
	str = strerror(errnum);

	/*
	 * Some strerror()s return an empty string for out-of-range errno. This is
	 * ANSI C spec compliant, but not exactly useful.
	 */
	if (str == NULL || *str == '\0')
	{
		/*
		 * translator: This string will be truncated at 47 characters
		 * expanded.
		 */
		snprintf(errorstr_buf, sizeof(errorstr_buf),
				 _("operating system error %d"), errnum);
		str = errorstr_buf;
	}

	return str;
}


/*
 * error_severity --- get localized string representing elevel
 */
static const char *
error_severity(int elevel)
{
	const char *prefix;

	switch (elevel)
	{
		case DEBUG1:
		case DEBUG2:
		case DEBUG3:
		case DEBUG4:
		case DEBUG5:
			prefix = _("DEBUG");
			break;
		case LOG:
		case COMMERROR:
			prefix = _("LOG");
			break;
		case INFO:
			prefix = _("INFO");
			break;
		case NOTICE:
			prefix = _("NOTICE");
			break;
		case WARNING:
			prefix = _("WARNING");
			break;
		case ERROR:
			prefix = _("ERROR");
			break;
		case FATAL:
			prefix = _("FATAL");
			break;
		case PANIC:
			prefix = _("PANIC");
			break;
		default:
			prefix = "???";
			break;
	}