postgres/src/backend/utils/error/elog.c

/*-------------------------------------------------------------------------
 *
 * elog.c
 *	  error logging and reporting
 *
 * Some notes about recursion and errors during error processing:
 *
 * We need to be robust about recursive-error scenarios --- for example,
 * if we run out of memory, it's important to be able to report that fact.
 * There are a number of considerations that go into this.
 *
 * First, distinguish between re-entrant use and actual recursion.	It
 * is possible for an error or warning message to be emitted while the
 * parameters for an error message are being computed.	In this case
 * errstart has been called for the outer message, and some field values
 * may have already been saved, but we are not actually recursing.	We handle
 * this by providing a (small) stack of ErrorData records.	The inner message
 * can be computed and sent without disturbing the state of the outer message.
 * (If the inner message is actually an error, this isn't very interesting
 * because control won't come back to the outer message generator ... but
 * if the inner message is only debug or log data, this is critical.)
 *
 * Second, actual recursion will occur if an error is reported by one of
 * the elog.c routines or something they call.	By far the most probable
 * scenario of this sort is "out of memory"; and it's also the nastiest
 * to handle because we'd likely also run out of memory while trying to
 * report this error!  Our escape hatch for this case is to reset the
 * ErrorContext to empty before trying to process the inner error.  Since
 * ErrorContext is guaranteed to have at least 8K of space in it (see mcxt.c),
 * we should be able to process an "out of memory" message successfully.
 * Since we lose the prior error state due to the reset, we won't be able
 * to return to processing the original error, but we wouldn't have anyway.
 * (NOTE: the escape hatch is not used for recursive situations where the
 * inner message is of less than ERROR severity; in that case we just
 * try to process it and return normally.  Usually this will work, but if
 * it ends up in infinite recursion, we will PANIC due to error stack
 * overflow.)
 *
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.157 2005/02/27 01:02:57 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <fcntl.h>
#include <time.h>
#include <unistd.h>
#include <signal.h>
#include <ctype.h>
#ifdef HAVE_SYSLOG
#include <syslog.h>
#endif

#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "postmaster/postmaster.h"
#include "postmaster/syslogger.h"
#include "storage/ipc.h"
#include "tcop/tcopprot.h"
#include "utils/memutils.h"
#include "utils/guc.h"


/* Global variables */
ErrorContextCallback *error_context_stack = NULL;

sigjmp_buf *PG_exception_stack = NULL;

/* GUC parameters */
PGErrorVerbosity Log_error_verbosity = PGERROR_VERBOSE;
char	   *Log_line_prefix = NULL;		/* format for extra log line info */
int			Log_destination = LOG_DESTINATION_STDERR;

#ifdef HAVE_SYSLOG
char	   *Syslog_facility;	/* openlog() parameters */
char	   *Syslog_ident;

static void write_syslog(int level, const char *line);
#endif
#ifdef WIN32
static void write_eventlog(int level, const char *line);
#endif

/* We provide a small stack of ErrorData records for re-entrant cases */
#define ERRORDATA_STACK_SIZE  5

static ErrorData errordata[ERRORDATA_STACK_SIZE];

static int	errordata_stack_depth = -1; /* index of topmost active frame */

static int	recursion_depth = 0;	/* to detect actual recursion */


/* Macro for checking errordata_stack_depth is reasonable */
#define CHECK_STACK_DEPTH() \
	do { \
		if (errordata_stack_depth < 0) \
		{ \
			errordata_stack_depth = -1; \
			ereport(ERROR, (errmsg_internal("errstart was not called"))); \
		} \
	} while (0)


static void log_line_prefix(StringInfo buf);
static void send_message_to_server_log(ErrorData *edata);
static void send_message_to_frontend(ErrorData *edata);
static char *expand_fmt_string(const char *fmt, ErrorData *edata);
static const char *useful_strerror(int errnum);
static const char *error_severity(int elevel);
static void append_with_tabs(StringInfo buf, const char *str);


/*
 * errstart --- begin an error-reporting cycle
 *
 * Create a stack entry and store the given parameters in it.  Subsequently,
 * errmsg() and perhaps other routines will be called to further populate
 * the stack entry.  Finally, errfinish() will be called to actually process
 * the error report.
 *
 * Returns TRUE in normal case.  Returns FALSE to short-circuit the error
 * report (if it's a warning or lower and not to be reported anywhere).
 */
bool
errstart(int elevel, const char *filename, int lineno,
		 const char *funcname)
{
	ErrorData  *edata;
	bool		output_to_server = false;
	bool		output_to_client = false;
	int			i;

	/*
	 * Check some cases in which we want to promote an error into a more
	 * severe error.  None of this logic applies for non-error messages.
	 */
	if (elevel >= ERROR)
	{
		/*
		 * If we are inside a critical section, all errors become PANIC
		 * errors.	See miscadmin.h.
		 */
		if (CritSectionCount > 0)
			elevel = PANIC;

		/*
		 * Check reasons for treating ERROR as FATAL:
		 *
		 * 1. we have no handler to pass the error to (implies we are in the
		 * postmaster or in backend startup).
		 *
		 * 2. ExitOnAnyError mode switch is set (initdb uses this).
		 *
		 * 3. the error occurred after proc_exit has begun to run.	(It's
		 * proc_exit's responsibility to see that this doesn't turn into
		 * infinite recursion!)
		 */
		if (elevel == ERROR)
		{
			if (PG_exception_stack == NULL ||
				ExitOnAnyError ||
				proc_exit_inprogress)
				elevel = FATAL;
		}

		/*
		 * If the error level is ERROR or more, errfinish is not going to
		 * return to caller; therefore, if there is any stacked error already
		 * in progress it will be lost.  This is more or less okay, except we
		 * do not want to have a FATAL or PANIC error downgraded because the
		 * reporting process was interrupted by a lower-grade error.  So check
		 * the stack and make sure we panic if panic is warranted.
		 */
		for (i = 0; i <= errordata_stack_depth; i++)
			elevel = Max(elevel, errordata[i].elevel);
	}

	/*
	 * Now decide whether we need to process this report at all; if it's
	 * warning or less and not enabled for logging, just return FALSE
	 * without starting up any error logging machinery.
	 */

	/* Determine whether message is enabled for server log output */
	if (IsPostmasterEnvironment)
	{
		/* Complicated because LOG is sorted out-of-order for this purpose */
		if (elevel == LOG || elevel == COMMERROR)
		{
			if (log_min_messages == LOG)
				output_to_server = true;
			else if (log_min_messages < FATAL)
				output_to_server = true;
		}
		else
		{
			/* elevel != LOG */
			if (log_min_messages == LOG)
			{
				if (elevel >= FATAL)
					output_to_server = true;
			}
			/* Neither is LOG */
			else if (elevel >= log_min_messages)
				output_to_server = true;
		}
	}
	else
	{
		/* In bootstrap/standalone case, do not sort LOG out-of-order */
		output_to_server = (elevel >= log_min_messages);
	}

	/* Determine whether message is enabled for client output */
	if (whereToSendOutput == Remote && elevel != COMMERROR)
	{
		/*
		 * client_min_messages is honored only after we complete the
		 * authentication handshake.  This is required both for security
		 * reasons and because many clients can't handle NOTICE messages
		 * during authentication.
		 */
		if (ClientAuthInProgress)
			output_to_client = (elevel >= ERROR);
		else
			output_to_client = (elevel >= client_min_messages ||
								elevel == INFO);
	}

	/* Skip processing effort if non-error message will not be output */
	if (elevel < ERROR && !output_to_server && !output_to_client)
		return false;

	/*
	 * Okay, crank up a stack entry to store the info in.
	 */

	if (recursion_depth++ > 0 && elevel >= ERROR)
	{
		/*
		 * Ooops, error during error processing.  Clear ErrorContext as
		 * discussed at top of file.  We will not return to the original
		 * error's reporter or handler, so we don't need it.
		 */
		MemoryContextReset(ErrorContext);

		/*
		 * If we recurse more than once, the problem might be something
		 * broken in a context traceback routine.  Abandon them too.
		 */
		if (recursion_depth > 2)
			error_context_stack = NULL;
	}
	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")));
	}

	/* Initialize data for this error frame */
	edata = &errordata[errordata_stack_depth];
	MemSet(edata, 0, sizeof(ErrorData));
	edata->elevel = elevel;
	edata->output_to_server = output_to_server;
	edata->output_to_client = output_to_client;
	edata->filename = filename;
	edata->lineno = lineno;
	edata->funcname = funcname;
	/* Select default errcode based on elevel */
	if (elevel >= ERROR)
		edata->sqlerrcode = ERRCODE_INTERNAL_ERROR;
	else if (elevel == WARNING)
		edata->sqlerrcode = ERRCODE_WARNING;
	else
		edata->sqlerrcode = ERRCODE_SUCCESSFUL_COMPLETION;
	/* errno is saved here so that error parameter eval can't change it */
	edata->saved_errno = errno;

	recursion_depth--;
	return true;
}

/*
 * errfinish --- end an error-reporting cycle
 *
 * Produce the appropriate error report(s) and pop the error stack.
 *
 * If elevel is ERROR or worse, control does not return to the caller.
 * See elog.h for the error level definitions.
 */
void
errfinish(int dummy,...)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];
	int			elevel = edata->elevel;
	MemoryContext oldcontext;
	ErrorContextCallback *econtext;

	recursion_depth++;
	CHECK_STACK_DEPTH();

	/*
	 * Do processing in ErrorContext, which we hope has enough reserved
	 * space to report an error.
	 */
	oldcontext = MemoryContextSwitchTo(ErrorContext);

	/*
	 * Call any context callback functions.  Errors occurring in callback
	 * functions will be treated as recursive errors --- this ensures we
	 * will avoid infinite recursion (see errstart).
	 */
	for (econtext = error_context_stack;
		 econtext != NULL;
		 econtext = econtext->previous)
		(*econtext->callback) (econtext->arg);

	/*
	 * If ERROR (not more nor less) we pass it off to the current handler.
	 * Printing it and popping the stack is the responsibility of
	 * the handler.
	 */
	if (elevel == ERROR)
	{
		/*
		 * We do some minimal cleanup before longjmp'ing so that handlers
		 * can execute in a reasonably sane state.
		 */

		/* This is just in case the error came while waiting for input */
		ImmediateInterruptOK = false;

		/*
		 * Reset InterruptHoldoffCount in case we ereport'd from
		 * inside an interrupt holdoff section.  (We assume here that
		 * no handler will itself be inside a holdoff section.	If
		 * necessary, such a handler could save and restore
		 * InterruptHoldoffCount for itself, but this should make life
		 * easier for most.)
		 */
		InterruptHoldoffCount = 0;

		CritSectionCount = 0;		/* should be unnecessary, but... */

		/*
		 * Note that we leave CurrentMemoryContext set to ErrorContext.
		 * The handler should reset it to something else soon.
		 */

		recursion_depth--;
		PG_RE_THROW();
	}

	/*
	 * If we are doing FATAL or PANIC, abort any old-style COPY OUT in
	 * progress, so that we can report the message before dying.  (Without
	 * this, pq_putmessage will refuse to send the message at all, which
	 * is what we want for NOTICE messages, but not for fatal exits.) This
	 * hack is necessary because of poor design of old-style copy
	 * protocol.  Note we must do this even if client is fool enough to
	 * have set client_min_messages above FATAL, so don't look at
	 * output_to_client.
	 */
	if (elevel >= FATAL && whereToSendOutput == Remote)
		pq_endcopyout(true);

	/* Emit the message to the right places */
	EmitErrorReport();

	/* Now free up subsidiary data attached to stack entry, and release it */
	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);

	errordata_stack_depth--;

	/* Exit error-handling context */
	MemoryContextSwitchTo(oldcontext);
	recursion_depth--;

	/*
	 * Perform error recovery action as specified by elevel.
	 */
	if (elevel == FATAL)
	{
		/*
		 * For a FATAL error, we let proc_exit clean up and exit.
		 */
		ImmediateInterruptOK = false;

		/*
		 * If we just reported a startup failure, the client will
		 * disconnect on receiving it, so don't send any more to the
		 * client.
		 */
		if (PG_exception_stack == NULL && whereToSendOutput == Remote)
			whereToSendOutput = None;

		/*
		 * fflush here is just to improve the odds that we get to see the
		 * error message, in case things are so hosed that proc_exit
		 * crashes.  Any other code you might be tempted to add here
		 * should probably be in an on_proc_exit callback instead.
		 */
		fflush(stdout);
		fflush(stderr);

		/*
		 * If proc_exit is already running, we exit with nonzero exit code
		 * to indicate that something's pretty wrong.  We also want to
		 * exit with nonzero exit code if not running under the postmaster
		 * (for example, if we are being run from the initdb script, we'd
		 * better return an error status).
		 */
		proc_exit(proc_exit_inprogress || !IsUnderPostmaster);
	}

	if (elevel >= PANIC)
	{
		/*
		 * Serious crash time. Postmaster will observe nonzero process
		 * exit status and kill the other backends too.
		 *
		 * XXX: what if we are *in* the postmaster?  abort() won't kill our
		 * children...
		 */
		ImmediateInterruptOK = false;
		fflush(stdout);
		fflush(stderr);
		abort();
	}

	/* We reach here if elevel <= WARNING. OK to return to caller. */
}


/*
 * errcode --- add SQLSTATE error code to the current error
 *
 * The code is expected to be represented as per MAKE_SQLSTATE().
 */
int
errcode(int sqlerrcode)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];

	/* we don't bother incrementing recursion_depth */
	CHECK_STACK_DEPTH();

	edata->sqlerrcode = sqlerrcode;

	return 0;					/* return value does not matter */
}


/*
 * errcode_for_file_access --- add SQLSTATE error code to the current error
 *
 * The SQLSTATE code is chosen based on the saved errno value.	We assume
 * that the failing operation was some type of disk file access.
 *
 * NOTE: the primary error message string should generally include %m
 * when this is used.
 */
int
errcode_for_file_access(void)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];

	/* we don't bother incrementing recursion_depth */
	CHECK_STACK_DEPTH();

	switch (edata->saved_errno)
	{
			/* Permission-denied failures */
		case EPERM:				/* Not super-user */
		case EACCES:			/* Permission denied */
#ifdef EROFS
		case EROFS:				/* Read only file system */
#endif
			edata->sqlerrcode = ERRCODE_INSUFFICIENT_PRIVILEGE;
			break;

			/* File not found */
		case ENOENT:			/* No such file or directory */
			edata->sqlerrcode = ERRCODE_UNDEFINED_FILE;
			break;

			/* Duplicate file */
		case EEXIST:			/* File exists */
			edata->sqlerrcode = ERRCODE_DUPLICATE_FILE;
			break;

			/* Wrong object type or state */
		case ENOTDIR:			/* Not a directory */
		case EISDIR:			/* Is a directory */
#if defined(ENOTEMPTY) && (ENOTEMPTY != EEXIST) /* same code on AIX */
		case ENOTEMPTY: /* Directory not empty */
#endif
			edata->sqlerrcode = ERRCODE_WRONG_OBJECT_TYPE;
			break;

			/* Insufficient resources */
		case ENOSPC:			/* No space left on device */
			edata->sqlerrcode = ERRCODE_DISK_FULL;
			break;

		case ENFILE:			/* File table overflow */
		case EMFILE:			/* Too many open files */
			edata->sqlerrcode = ERRCODE_INSUFFICIENT_RESOURCES;
			break;

			/* Hardware failure */
		case EIO:				/* I/O error */
			edata->sqlerrcode = ERRCODE_IO_ERROR;
			break;

			/* All else is classified as internal errors */
		default:
			edata->sqlerrcode = ERRCODE_INTERNAL_ERROR;
			break;
	}

	return 0;					/* return value does not matter */
}

/*
 * errcode_for_socket_access --- add SQLSTATE error code to the current error
 *
 * The SQLSTATE code is chosen based on the saved errno value.	We assume
 * that the failing operation was some type of socket access.
 *
 * NOTE: the primary error message string should generally include %m
 * when this is used.
 */
int
errcode_for_socket_access(void)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];

	/* we don't bother incrementing recursion_depth */
	CHECK_STACK_DEPTH();

	switch (edata->saved_errno)
	{
			/* Loss of connection */
		case EPIPE:
#ifdef ECONNRESET
		case ECONNRESET:
#endif
			edata->sqlerrcode = ERRCODE_CONNECTION_FAILURE;
			break;

			/* All else is classified as internal errors */
		default:
			edata->sqlerrcode = ERRCODE_INTERNAL_ERROR;
			break;
	}

	return 0;					/* return value does not matter */
}


/*
 * This macro handles expansion of a format string and associated parameters;
 * it's common code for errmsg(), errdetail(), etc.  Must be called inside
 * a routine that is declared like "const char *fmt, ..." and has an edata
 * pointer set up.	The message is assigned to edata->targetfield, or
 * appended to it if appendval is true.
 *
 * Note: we pstrdup the buffer rather than just transferring its storage
 * to the edata field because the buffer might be considerably larger than
 * really necessary.
 */
#define EVALUATE_MESSAGE(targetfield, appendval)  \
	{ \
		char		   *fmtbuf; \
		StringInfoData	buf; \
		/* Internationalize the error format string */ \
		fmt = _(fmt); \
		/* Expand %m in format string */ \
		fmtbuf = expand_fmt_string(fmt, edata); \
		initStringInfo(&buf); \
		if ((appendval) && edata->targetfield) \
			appendStringInfo(&buf, "%s\n", edata->targetfield); \
		/* Generate actual output --- have to use appendStringInfoVA */ \
		for (;;) \
		{ \
			va_list		args; \
			bool		success; \
			va_start(args, fmt); \
			success = appendStringInfoVA(&buf, fmtbuf, args); \
			va_end(args); \
			if (success) \
				break; \
			enlargeStringInfo(&buf, buf.maxlen); \
		} \
		/* Done with expanded fmt */ \
		pfree(fmtbuf); \
		/* Save the completed message into the stack item */ \
		if (edata->targetfield) \
			pfree(edata->targetfield); \
		edata->targetfield = pstrdup(buf.data); \
		pfree(buf.data); \
	}


/*
 * errmsg --- add a primary error message text to the current error
 *
 * In addition to the usual %-escapes recognized by printf, "%m" in
 * fmt is replaced by the error message for the caller's value of errno.
 *
 * Note: no newline is needed at the end of the fmt string, since
 * ereport will provide one for the output methods that need it.
 */
int
errmsg(const char *fmt,...)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];
	MemoryContext oldcontext;

	recursion_depth++;
	CHECK_STACK_DEPTH();
	oldcontext = MemoryContextSwitchTo(ErrorContext);

	EVALUATE_MESSAGE(message, false);

	MemoryContextSwitchTo(oldcontext);
	recursion_depth--;
	return 0;					/* return value does not matter */
}


/*
 * errmsg_internal --- add a primary error message text to the current error
 *
 * This is exactly like errmsg() except that strings passed to errmsg_internal
 * are customarily left out of the internationalization message dictionary.
 * This should be used for "can't happen" cases that are probably not worth
 * spending translation effort on.
 */
int
errmsg_internal(const char *fmt,...)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];
	MemoryContext oldcontext;

	recursion_depth++;
	CHECK_STACK_DEPTH();
	oldcontext = MemoryContextSwitchTo(ErrorContext);

	EVALUATE_MESSAGE(message, false);

	MemoryContextSwitchTo(oldcontext);
	recursion_depth--;
	return 0;					/* return value does not matter */
}


/*
 * errdetail --- add a detail error message text to the current error
 */
int
errdetail(const char *fmt,...)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];
	MemoryContext oldcontext;

	recursion_depth++;
	CHECK_STACK_DEPTH();
	oldcontext = MemoryContextSwitchTo(ErrorContext);

	EVALUATE_MESSAGE(detail, false);

	MemoryContextSwitchTo(oldcontext);
	recursion_depth--;
	return 0;					/* return value does not matter */
}


/*
 * errhint --- add a hint error message text to the current error
 */
int
errhint(const char *fmt,...)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];
	MemoryContext oldcontext;

	recursion_depth++;
	CHECK_STACK_DEPTH();
	oldcontext = MemoryContextSwitchTo(ErrorContext);

	EVALUATE_MESSAGE(hint, false);

	MemoryContextSwitchTo(oldcontext);
	recursion_depth--;
	return 0;					/* return value does not matter */
}


/*
 * errcontext --- add a context error message text to the current error
 *
 * Unlike other cases, multiple calls are allowed to build up a stack of
 * context information.  We assume earlier calls represent more-closely-nested
 * states.
 */
int
errcontext(const char *fmt,...)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];
	MemoryContext oldcontext;

	recursion_depth++;
	CHECK_STACK_DEPTH();
	oldcontext = MemoryContextSwitchTo(ErrorContext);

	EVALUATE_MESSAGE(context, true);

	MemoryContextSwitchTo(oldcontext);
	recursion_depth--;
	return 0;					/* return value does not matter */
}


/*
 * errfunction --- add reporting function name to the current error
 *
 * This is used when backwards compatibility demands that the function
 * name appear in messages sent to old-protocol clients.  Note that the
 * passed string is expected to be a non-freeable constant string.
 */
int
errfunction(const char *funcname)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];

	/* we don't bother incrementing recursion_depth */
	CHECK_STACK_DEPTH();

	edata->funcname = funcname;
	edata->show_funcname = true;

	return 0;					/* return value does not matter */
}

/*
 * errposition --- add cursor position to the current error
 */
int
errposition(int cursorpos)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];

	/* we don't bother incrementing recursion_depth */
	CHECK_STACK_DEPTH();

	edata->cursorpos = cursorpos;

	return 0;					/* return value does not matter */
}

/*
 * internalerrposition --- add internal cursor position to the current error
 */
int
internalerrposition(int cursorpos)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];

	/* we don't bother incrementing recursion_depth */
	CHECK_STACK_DEPTH();

	edata->internalpos = cursorpos;

	return 0;					/* return value does not matter */
}

/*
 * internalerrquery --- add internal query text to the current error
 *
 * Can also pass NULL to drop the internal query text entry.  This case
 * is intended for use in error callback subroutines that are editorializing
 * on the layout of the error report.
 */
int
internalerrquery(const char *query)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];

	/* we don't bother incrementing recursion_depth */
	CHECK_STACK_DEPTH();

	if (edata->internalquery)
	{
		pfree(edata->internalquery);
		edata->internalquery = NULL;
	}

	if (query)
		edata->internalquery = MemoryContextStrdup(ErrorContext, query);

	return 0;					/* return value does not matter */
}

/*
 * geterrposition --- return the currently set error position (0 if none)
 *
 * This is only intended for use in error callback subroutines, since there
 * is no other place outside elog.c where the concept is meaningful.
 */
int
geterrposition(void)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];

	/* we don't bother incrementing recursion_depth */
	CHECK_STACK_DEPTH();

	return edata->cursorpos;
}

/*
 * getinternalerrposition --- same for internal error position
 *
 * This is only intended for use in error callback subroutines, since there
 * is no other place outside elog.c where the concept is meaningful.
 */
int
getinternalerrposition(void)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];

	/* we don't bother incrementing recursion_depth */
	CHECK_STACK_DEPTH();

	return edata->internalpos;
}


/*
 * elog_start --- startup for old-style API
 *
 * All that we do here is stash the hidden filename/lineno/funcname
 * arguments into a stack entry.
 *
 * We need this to be separate from elog_finish because there's no other
 * portable way to deal with inserting extra arguments into the elog call.
 * (If macros with variable numbers of arguments were portable, it'd be
 * easy, but they aren't.)
 */
void
elog_start(const char *filename, int lineno, const char *funcname)
{
	ErrorData  *edata;

	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")));
	}

	edata = &errordata[errordata_stack_depth];
	edata->filename = filename;
	edata->lineno = lineno;
	edata->funcname = funcname;
	/* errno is saved now so that error parameter eval can't change it */
	edata->saved_errno = errno;
}

/*
 * elog_finish --- finish up for old-style API
 */
void
elog_finish(int elevel, const char *fmt,...)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];
	MemoryContext oldcontext;

	CHECK_STACK_DEPTH();

	/*
	 * Do errstart() to see if we actually want to report the message.
	 */
	errordata_stack_depth--;
	errno = edata->saved_errno;
	if (!errstart(elevel, edata->filename, edata->lineno, edata->funcname))
		return;					/* nothing to do */

	/*
	 * Format error message just like errmsg().
	 */
	recursion_depth++;
	oldcontext = MemoryContextSwitchTo(ErrorContext);

	EVALUATE_MESSAGE(message, false);

	MemoryContextSwitchTo(oldcontext);
	recursion_depth--;

	/*
	 * And let errfinish() finish up.
	 */
	errfinish(0);
}

/*
 * Actual output of the top-of-stack error message
 *
 * In the ereport(ERROR) case this is called from PostgresMain (or not at all,
 * if the error is caught by somebody).  For all other severity levels this
 * is called by errfinish.
 */
void
EmitErrorReport(void)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];
	MemoryContext oldcontext;

	recursion_depth++;
	CHECK_STACK_DEPTH();
	oldcontext = MemoryContextSwitchTo(ErrorContext);

	/* Send to server log, if enabled */
	if (edata->output_to_server)
		send_message_to_server_log(edata);

	/* Send to client, if enabled */
	if (edata->output_to_client)
		send_message_to_frontend(edata);

	MemoryContextSwitchTo(oldcontext);
	recursion_depth--;
}

/*
 * CopyErrorData --- obtain a copy of the topmost error stack entry
 *
 * This is only for use in error handler code.	The data is copied into the
 * current memory context, so callers should always switch away from
 * ErrorContext first; otherwise it will be lost when FlushErrorState is done.
 */
ErrorData *
CopyErrorData(void)
{
	ErrorData  *edata = &errordata[errordata_stack_depth];
	ErrorData  *newedata;

	/*
	 * we don't increment recursion_depth because out-of-memory here does
	 * not indicate a problem within the error subsystem.
	 */
	CHECK_STACK_DEPTH();

	Assert(CurrentMemoryContext != ErrorContext);

	/* Copy the struct itself */
	newedata = (ErrorData *) palloc(sizeof(ErrorData));
	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);

	return newedata;
}

/*
 * 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

#ifndef PG_SYSLOG_LIMIT
#define PG_SYSLOG_LIMIT 128
#endif

/*
 * Write a message line to syslog if the syslog option is set.
 *
 * 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.
 */
static void
write_syslog(int level, const char *line)
{
	static bool openlog_done = false;
	static unsigned long seq = 0;
	static int	syslog_fac = LOG_LOCAL0;

	int			len = strlen(line);

	if (!openlog_done)
	{
		if (pg_strcasecmp(Syslog_facility, "LOCAL0") == 0)
			syslog_fac = LOG_LOCAL0;
		if (pg_strcasecmp(Syslog_facility, "LOCAL1") == 0)
			syslog_fac = LOG_LOCAL1;
		if (pg_strcasecmp(Syslog_facility, "LOCAL2") == 0)
			syslog_fac = LOG_LOCAL2;
		if (pg_strcasecmp(Syslog_facility, "LOCAL3") == 0)
			syslog_fac = LOG_LOCAL3;
		if (pg_strcasecmp(Syslog_facility, "LOCAL4") == 0)
			syslog_fac = LOG_LOCAL4;
		if (pg_strcasecmp(Syslog_facility, "LOCAL5") == 0)
			syslog_fac = LOG_LOCAL5;
		if (pg_strcasecmp(Syslog_facility, "LOCAL6") == 0)
			syslog_fac = LOG_LOCAL6;
		if (pg_strcasecmp(Syslog_facility, "LOCAL7") == 0)
			syslog_fac = LOG_LOCAL7;
		openlog(Syslog_ident, LOG_PID | LOG_NDELAY | LOG_NOWAIT, syslog_fac);
		openlog_done = true;
	}

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

	/* divide into multiple syslog() calls if message is too long */
	/* or if the message contains embedded NewLine(s) '\n' */
	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 (!isspace((unsigned char) line[buflen]) &&
				line[buflen] != '\0')
			{
				/* 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)
{
	static HANDLE evtHandle = INVALID_HANDLE_VALUE;

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

	ReportEvent(evtHandle,
				level,
				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)
		{
			/* format error - ignore it */
			break;
		}

		/* 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.tv_sec),
							   MyProcPid);
				}
				break;
			case 'p':
				appendStringInfo(buf, "%d", MyProcPid);
				break;
			case 'l':
				appendStringInfo(buf, "%ld", log_line_number);
				break;
			case 't':
				{
					/*
					 * Note: for %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 = 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)
				{
					time_t		stamp_time = MyProcPort->session_start.tv_sec;
					char		strfbuf[128];

					strftime(strfbuf, sizeof(strfbuf),
							 "%Y-%m-%d %H:%M:%S %Z",
							 localtime(&stamp_time));
					appendStringInfoString(buf, strfbuf);
				}
				break;
			case 'i':
				if (MyProcPort)
					appendStringInfo(buf, "%s", MyProcPort->commandTag);
				break;
			case 'r':
				if (MyProcPort)
				{
					appendStringInfo(buf, "%s", MyProcPort->remote_host);
					if (strlen(MyProcPort->remote_port) > 0)
						appendStringInfo(buf, "(%s)",
										 MyProcPort->remote_port);
				}
				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;
		}
	}
}


/*
 * 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)
	{
		/* unpack MAKE_SQLSTATE code */
		char		tbuf[12];
		int			ssval;
		int			i;

		ssval = edata->sqlerrcode;
		for (i = 0; i < 5; i++)
		{
			tbuf[i] = PGUNSIXBIT(ssval);
			ssval >>= 6;
		}
		tbuf[i] = '\0';
		appendStringInfo(&buf, "%s: ", tbuf);
	}

	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
	if (Log_destination & LOG_DESTINATION_EVENTLOG)
	{
		int			eventlog_level;

		switch (edata->elevel)
		{
			case DEBUG5:
			case DEBUG4:
			case DEBUG3:
			case DEBUG2:
			case DEBUG1:
			case LOG:
			case COMMERROR:
			case INFO:
			case NOTICE:
				eventlog_level = EVENTLOG_INFORMATION_TYPE;
				break;
			case WARNING:
				eventlog_level = EVENTLOG_WARNING_TYPE;
				break;
			case ERROR:
			case FATAL:
			case PANIC:
			default:
				eventlog_level = EVENTLOG_ERROR_TYPE;
				break;
		}
		write_eventlog(eventlog_level, buf.data);
	}
#endif   /* WIN32 */
	/* Write to stderr, if enabled */
	if ((Log_destination & LOG_DESTINATION_STDERR) || whereToSendOutput == Debug)
	{
#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, leave it to stderr because the
		   logger will capture it to a file. */
		if ((!Redirect_stderr || am_syslogger) && pgwin32_is_service())
			write_eventlog(EVENTLOG_ERROR_TYPE, 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;
	}

	return prefix;
}


/*
 *	append_with_tabs
 *
 *	Append the string to the StringInfo buffer, inserting a tab after any
 *	newline.
 */
static void
append_with_tabs(StringInfo buf, const char *str)
{
	char		ch;

	while ((ch = *str++) != '\0')
	{
		appendStringInfoCharMacro(buf, ch);
		if (ch == '\n')
			appendStringInfoCharMacro(buf, '\t');
	}
}


/*
 * Write errors to stderr (or by equal means when stderr is
 * not available). Used before ereport/elog can be used
 * safely (memory context, GUC load etc)
 */
void
write_stderr(const char *fmt,...)
{
	va_list		ap;

	fmt = _(fmt);

	va_start(ap, fmt);
#ifndef WIN32
	/* On Unix, we just fprintf to stderr */
	vfprintf(stderr, fmt, ap);
#else

	/*
	 * On Win32, we print to stderr if running on a console, or write to
	 * eventlog if running as a service
	 */
	if (pgwin32_is_service())	/* Running as a service */
	{
		char		errbuf[2048];		/* Arbitrary size? */

		vsnprintf(errbuf, sizeof(errbuf), fmt, ap);

		write_eventlog(EVENTLOG_ERROR_TYPE, errbuf);
	}
	else
		/* Not running as service, write to stderr */
		vfprintf(stderr, fmt, ap);
#endif
	va_end(ap);
}