text: /*-------------------------------------------------------------------------
   *
   * pg_waldump.c - decode and display WAL
   *
   * Copyright (c) 2013-2020, PostgreSQL Global Development Group
   *
   * IDENTIFICATION
   *		  src/bin/pg_waldump/pg_waldump.c
   *-------------------------------------------------------------------------
   */
  
  #define FRONTEND 1
  #include "postgres.h"
  
  #include <dirent.h>
  #include <sys/stat.h>
  #include <unistd.h>
  
  #include "access/transam.h"
  #include "access/xlog_internal.h"
  #include "access/xlogreader.h"
  #include "access/xlogrecord.h"
  #include "common/fe_memutils.h"
  #include "common/logging.h"
  #include "getopt_long.h"
  #include "rmgrdesc.h"
  
  static const char *progname;
  
  static int	WalSegSz;
  
  typedef struct XLogDumpPrivate
  {
  	TimeLineID	timeline;
  	XLogRecPtr	startptr;
  	XLogRecPtr	endptr;
  	bool		endptr_reached;
  } XLogDumpPrivate;
  
  typedef struct XLogDumpConfig
  {
  	/* display options */
  	bool		quiet;
  	bool		bkp_details;
  	int			stop_after_records;
  	int			already_displayed_records;
  	bool		follow;
  	bool		stats;
  	bool		stats_per_record;
  
  	/* filter options */
  	int			filter_by_rmgr;
  	TransactionId filter_by_xid;
  	bool		filter_by_xid_enabled;
  } XLogDumpConfig;
  
  typedef struct Stats
  {
  	uint64		count;
  	uint64		rec_len;
  	uint64		fpi_len;
  } Stats;
  
  #define MAX_XLINFO_TYPES 16
  
  typedef struct XLogDumpStats
  {
  	uint64		count;
  	Stats		rmgr_stats[RM_NEXT_ID];
  	Stats		record_stats[RM_NEXT_ID][MAX_XLINFO_TYPES];
  } XLogDumpStats;
  
  #define fatal_error(...) do { pg_log_fatal(__VA_ARGS__); exit(EXIT_FAILURE); } while(0)
  
  static void
  print_rmgr_list(void)
  {
  	int			i;
  
  	for (i = 0; i <= RM_MAX_ID; i++)
  	{
  		printf("%s\n", RmgrDescTable[i].rm_name);
  	}
  }
  
  /*
   * Check whether directory exists and whether we can open it. Keep errno set so
   * that the caller can report errors somewhat more accurately.
   */
  static bool
  verify_directory(const char *directory)
  {
  	DIR		   *dir = opendir(directory);
  
  	if (dir == NULL)
  		return false;
  	closedir(dir);
  	return true;
  }
  
  /*
   * Split a pathname as dirname(1) and basename(1) would.
   *
   * XXX this probably doesn't do very well on Windows.  We probably need to
   * apply canonicalize_path(), at the very least.
   */
  static void
  split_path(const char *path, char **dir, char **fname)
  {
  	char	   *sep;
  
  	/* split filepath into directory & filename */
  	sep = strrchr(path, '/');
  
  	/* directory path */
  	if (sep != NULL)
  	{
  		*dir = pnstrdup(path, sep - path);
  		*fname = pg_strdup(sep + 1);
  	}
  	/* local directory */
  	else
  	{
  		*dir = NULL;
  		*fname = pg_strdup(path);
  	}
  }
  
  /*
   * Open the file in the valid target directory.
   *
   * return a read only fd
   */
  static int
  open_file_in_directory(const char *directory, const char *fname)
  {
  	int			fd = -1;
  	char		fpath[MAXPGPATH];
  
  	Assert(directory != NULL);
  
  	snprintf(fpath, MAXPGPATH, "%s/%s", directory, fname);
  	fd = open(fpath, O_RDONLY | PG_BINARY, 0);
  
  	if (fd < 0 && errno != ENOENT)
  		fatal_error("could not open file \"%s\": %m", fname);
  	return fd;
  }
  
  /*
   * Try to find fname in the given directory. Returns true if it is found,
   * false otherwise. If fname is NULL, search the complete directory for any
   * file with a valid WAL file name. If file is successfully opened, set the
   * wal segment size.
   */
  static bool
  search_directory(const char *directory, const char *fname)
  {
  	int			fd = -1;
  	DIR		   *xldir;
  
  	/* open file if valid filename is provided */
  	if (fname != NULL)
  		fd = open_file_in_directory(directory, fname);
  
  	/*
  	 * A valid file name is not passed, so search the complete directory.  If
  	 * we find any file whose name is a valid WAL file name then try to open
  	 * it.  If we cannot open it, bail out.
  	 */
  	else if ((xldir = opendir(directory)) != NULL)
  	{
  		struct dirent *xlde;
  
  		while ((xlde = readdir(xldir)) != NULL)
  		{
  			if (IsXLogFileName(xlde->d_name))
  			{
  				fd = open_file_in_directory(directory, xlde->d_name);
  				fname = xlde->d_name;
  				break;
  			}
  		}
  
  		closedir(xldir);
  	}
  
  	/* set WalSegSz if file is successfully opened */
  	if (fd >= 0)
  	{
  		PGAlignedXLogBlock buf;
  		int			r;
  
  		r = read(fd, buf.data, XLOG_BLCKSZ);
  		if (r == XLOG_BLCKSZ)
  		{
  			XLogLongPageHeader longhdr = (XLogLongPageHeader) buf.data;
  
  			WalSegSz = longhdr->xlp_seg_size;
  
  			if (!IsValidWalSegSize(WalSegSz))
  				fatal_error(ngettext("WAL segment size must be a power of two between 1 MB and 1 GB, but the WAL file \"%s\" header specifies %d byte",
  									 "WAL segment size must be a power of two between 1 MB and 1 GB, but the WAL file \"%s\" header specifies %d bytes",
  									 WalSegSz),
  							fname, WalSegSz);
  		}
  		else
  		{
  			if (errno != 0)
  				fatal_error("could not read file \"%s\": %m",
  							fname);
  			else
  				fatal_error("could not read file \"%s\": read %d of %zu",
  							fname, r, (Size) XLOG_BLCKSZ);
  		}
  		close(fd);
  		return true;
  	}
  
  	return false;
  }
  
  /*
   * Identify the target directory.
   *
   * Try to find the file in several places:
   * if directory != NULL:
   *	 directory /
   *	 directory / XLOGDIR /
   * else
   *	 .
   *	 XLOGDIR /
   *	 $PGDATA / XLOGDIR /
   *
   * The valid target directory is returned.
   */
  static char *
  identify_target_directory(char *directory, char *fname)
  {
  	char		fpath[MAXPGPATH];
  
  	if (directory != NULL)
  	{
  		if (search_directory(directory, fname))
  			return pg_strdup(directory);
  
  		/* directory / XLOGDIR */
  		snprintf(fpath, MAXPGPATH, "%s/%s", directory, XLOGDIR);
  		if (search_directory(fpath, fname))
  			return pg_strdup(fpath);
  	}
  	else
  	{
  		const char *datadir;
  
  		/* current directory */
  		if (search_directory(".", fname))
  			return pg_strdup(".");
  		/* XLOGDIR */
  		if (search_directory(XLOGDIR, fname))
  			return pg_strdup(XLOGDIR);
  
  		datadir = getenv("PGDATA");
  		/* $PGDATA / XLOGDIR */
  		if (datadir != NULL)
  		{
  			snprintf(fpath, MAXPGPATH, "%s/%s", datadir, XLOGDIR);
  			if (search_directory(fpath, fname))
  				return pg_strdup(fpath);
  		}
  	}
  
  	/* could not locate WAL file */
  	if (fname)
  		fatal_error("could not locate WAL file \"%s\"", fname);
  	else
  		fatal_error("could not find any WAL file");
  
  	return NULL;				/* not reached */
  }
  
  /* pg_waldump's XLogReaderRoutine->segment_open callback */
  static void
  WALDumpOpenSegment(XLogReaderState *state, XLogSegNo nextSegNo,
  				   TimeLineID *tli_p)
  {
  	TimeLineID	tli = *tli_p;
  	char		fname[MAXPGPATH];
  	int			tries;
  
  	XLogFileName(fname, tli, nextSegNo, state->segcxt.ws_segsize);
  
  	/*
  	 * In follow mode there is a short period of time after the server has
  	 * written the end of the previous file before the new file is available.
  	 * So we loop for 5 seconds looking for the file to appear before giving
  	 * up.
  	 */
  	for (tries = 0; tries < 10; tries++)
  	{
  		state->seg.ws_file = open_file_in_directory(state->segcxt.ws_dir, fname);
  		if (state->seg.ws_file >= 0)
  			return;
  		if (errno == ENOENT)
  		{
  			int			save_errno = errno;
  
  			/* File not there yet, try again */
  			pg_usleep(500 * 1000);
  
  			errno = save_errno;
  			continue;
  		}
  		/* Any other error, fall through and fail */
  		break;
  	}
  
  	fatal_error("could not find file \"%s\": %m", fname);
  }
  
  /*
   * pg_waldump's XLogReaderRoutine->segment_close callback.  Same as
   * wal_segment_close
   */
  static void
  WALDumpCloseSegment(XLogReaderState *state)
  {
  	close(state->seg.ws_file);
  	/* need to check errno? */
  	state->seg.ws_file = -1;
  }
  
  /* pg_waldump's XLogReaderRoutine->page_read callback */
  static int
  WALDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
  				XLogRecPtr targetPtr, char *readBuff)
  {
  	XLogDumpPrivate *private = state->private_data;
  	int			count = XLOG_BLCKSZ;
  	WALReadError errinfo;
  
  	if (private->endptr != InvalidXLogRecPtr)
  	{
  		if (targetPagePtr + XLOG_BLCKSZ <= private->endptr)
  			count = XLOG_BLCKSZ;
  		else if (targetPagePtr + reqLen <= private->endptr)
  			count = private->endptr - targetPagePtr;
  		else
  		{
  			private->endptr_reached = true;
  			return -1;
  		}
  	}
  
  	if (!WALRead(state, readBuff, targetPagePtr, count, private->timeline,
  				 &errinfo))
  	{
  		WALOpenSegment *seg = &errinfo.wre_seg;
  		char		fname[MAXPGPATH];
  
  		XLogFileName(fname, seg->ws_tli, seg->ws_segno,
  					 state->segcxt.ws_segsize);
  
  		if (errinfo.wre_errno != 0)
  		{
  			errno = errinfo.wre_errno;
  			fatal_error("could not read from file %s, offset %u: %m",
  						fname, errinfo.wre_off);
  		}
  		else
  			fatal_error("could not read from file %s, offset %u: read %d of %zu",
  						fname, errinfo.wre_off, errinfo.wre_read,
  						(Size) errinfo.wre_req);
  	}
  
  	return count;
  }
  
  /*
   * Calculate the size of a record, split into !FPI and FPI parts.
   */
  static void
  XLogDumpRecordLen(XLogReaderState *record, uint32 *rec_len, uint32 *fpi_len)
  {
  	int			block_id;
  
  	/*
  	 * Calculate the amount of FPI data in the record.
  	 *
  	 * XXX: We peek into xlogreader's private decoded backup blocks for the
  	 * bimg_len indicating the length of FPI data. It doesn't seem worth it to
  	 * add an accessor macro for this.
  	 */
  	*fpi_len = 0;
  	for (block_id = 0; block_id <= record->max_block_id; block_id++)
  	{
  		if (XLogRecHasBlockImage(record, block_id))
  			*fpi_len += record->blocks[block_id].bimg_len;
  	}
  
  	/*
  	 * Calculate the length of the record as the total length - the length of
  	 * all the block images.
  	 */
  	*rec_len = XLogRecGetTotalLen(record) - *fpi_len;
  }
  
  /*
   * Store per-rmgr and per-record statistics for a given record.
   */
  static void
  XLogDumpCountRecord(XLogDumpConfig *config, XLogDumpStats *stats,
  					XLogReaderState *record)
  {
  	RmgrId		rmid;
  	uint8		recid;
  	uint32		rec_len;
  	uint32		fpi_len;
  
  	stats->count++;
  
  	rmid = XLogRecGetRmid(record);
  
  	XLogDumpRecordLen(record, &rec_len, &fpi_len);
  
  	/* Update per-rmgr statistics */
  
  	stats->rmgr_stats[rmid].count++;
  	stats->rmgr_stats[rmid].rec_len += rec_len;
  	stats->rmgr_stats[rmid].fpi_len += fpi_len;
  
  	/*
  	 * Update per-record statistics, where the record is identified by a
  	 * combination of the RmgrId and the four bits of the xl_info field that
  	 * are the rmgr's domain (resulting in sixteen possible entries per
  	 * RmgrId).
  	 */
  
  	recid = XLogRecGetInfo(record) >> 4;
  
  	stats->record_stats[rmid][recid].count++;
  	stats->record_stats[rmid][recid].rec_len += rec_len;
  	stats->record_stats[rmid][recid].fpi_len += fpi_len;
  }
  
  /*
   * Print a record to stdout
   */
  static void
  XLogDumpDisplayRecord(XLogDumpConfig *config, XLogReaderState *record)
  {
  	const char *id;
  	const RmgrDescData *desc = &RmgrDescTable[XLogRecGetRmid(record)];
  	uint32		rec_len;
  	uint32		fpi_len;
  	RelFileNode rnode;
  	ForkNumber	forknum;
  	BlockNumber blk;
  	int			block_id;
  	uint8		info = XLogRecGetInfo(record);
  	XLogRecPtr	xl_prev = XLogRecGetPrev(record);
  	StringInfoData s;
  
  	XLogDumpRecordLen(record, &rec_len, &fpi_len);
  
  	printf("rmgr: %-11s len (rec/tot): %6u/%6u, tx: %10u, lsn: %X/%08X, prev %X/%08X, ",
  		   desc->rm_name,
  		   rec_len, XLogRecGetTotalLen(record),
  		   XLogRecGetXid(record),
  		   (uint32) (record->ReadRecPtr >> 32), (uint32) record->ReadRecPtr,
  		   (uint32) (xl_prev >> 32), (uint32) xl_prev);
  
  	id = desc->rm_identify(info);
  	if (id == NULL)
  		printf("desc: UNKNOWN (%x) ", info & ~XLR_INFO_MASK);
  	else
  		printf("desc: %s ", id);
  
  	initStringInfo(&s);
  	desc->rm_desc(&s, record);
  	printf("%s", s.data);
  	pfree(s.data);
  
  	if (!config->bkp_details)
  	{
  		/* print block references (short format) */
  		for (block_id = 0; block_id <= record->max_block_id; block_id++)
  		{
  			if (!XLogRecHasBlockRef(record, block_id))
  				continue;
  
  			XLogRecGetBlockTag(record, block_id, &rnode, &forknum, &blk);
  			if (forknum != MAIN_FORKNUM)
  				printf(", blkref #%u: rel %u/%u/%u fork %s blk %u",
  					   block_id,
  					   rnode.spcNode, rnode.dbNode, rnode.relNode,
  					   forkNames[forknum],
  					   blk);
  			else
  				printf(", blkref #%u: rel %u/%u/%u blk %u",
  					   block_id,
  					   rnode.spcNode, rnode.dbNode, rnode.relNode,
  					   blk);
  			if (XLogRecHasBlockImage(record, block_id))
  			{
  				if (XLogRecBlockImageApply(record, block_id))
  					printf(" FPW");
  				else
  					printf(" FPW for WAL verification");
  			}
  		}
  		putchar('\n');
  	}
  	else
  	{
  		/* print block references (detailed format) */
  		putchar('\n');
  		for (block_id = 0; block_id <= record->max_block_id; block_id++)
  		{
  			if (!XLogRecHasBlockRef(record, block_id))
  				continue;
  
  			XLogRecGetBlockTag(record, block_id, &rnode, &forknum, &blk);
  			printf("\tblkref #%u: rel %u/%u/%u fork %s blk %u",
  				   block_id,
  				   rnode.spcNode, rnode.dbNode, rnode.relNode,
  				   forkNames[forknum],
  				   blk);
  			if (XLogRecHasBlockImage(record, block_id))
  			{
  				if (record->blocks[block_id].bimg_info &
  					BKPIMAGE_IS_COMPRESSED)
  				{
  					printf(" (FPW%s); hole: offset: %u, length: %u, "
  						   "compression saved: %u",
  						   XLogRecBlockImageApply(record, block_id) ?
  						   "" : " for WAL verification",
  						   record->blocks[block_id].hole_offset,
  						   record->blocks[block_id].hole_length,
  						   BLCKSZ -
  						   record->blocks[block_id].hole_length -
  						   record->blocks[block_id].bimg_len);
  				}
  				else
  				{
  					printf(" (FPW%s); hole: offset: %u, length: %u",
  						   XLogRecBlockImageApply(record, block_id) ?
  						   "" : " for WAL verification",
  						   record->blocks[block_id].hole_offset,
  						   record->blocks[block_id].hole_length);
  				}
  			}
  			putchar('\n');
  		}
  	}
  }
  
  /*
   * Display a single row of record counts and sizes for an rmgr or record.
   */
  static void
  XLogDumpStatsRow(const char *name,
  				 uint64 n, uint64 total_count,
  				 uint64 rec_len, uint64 total_rec_len,
  				 uint64 fpi_len, uint64 total_fpi_len,
  				 uint64 tot_len, uint64 total_len)
  {
  	double		n_pct,
  				rec_len_pct,
  				fpi_len_pct,
  				tot_len_pct;
  
  	n_pct = 0;
  	if (total_count != 0)
  		n_pct = 100 * (double) n / total_count;
  
  	rec_len_pct = 0;
  	if (total_rec_len != 0)
  		rec_len_pct = 100 * (double) rec_len / total_rec_len;
  
  	fpi_len_pct = 0;
  	if (total_fpi_len != 0)
  		fpi_len_pct = 100 * (double) fpi_len / total_fpi_len;
  
  	tot_len_pct = 0;
  	if (total_len != 0)
  		tot_len_pct = 100 * (double) tot_len / total_len;
  
  	printf("%-27s "
  		   "%20" INT64_MODIFIER "u (%6.02f) "
  		   "%20" INT64_MODIFIER "u (%6.02f) "
  		   "%20" INT64_MODIFIER "u (%6.02f) "
  		   "%20" INT64_MODIFIER "u (%6.02f)\n",
  		   name, n, n_pct, rec_len, rec_len_pct, fpi_len, fpi_len_pct,
  		   tot_len, tot_len_pct);
  }
  
  
  /*
   * Display summary statistics about the records seen so far.
   */
  static void
  XLogDumpDisplayStats(XLogDumpConfig *config, XLogDumpStats *stats)
  {
  	int			ri,
  				rj;
  	uint64		total_count = 0;
  	uint64		total_rec_len = 0;
  	uint64		total_fpi_len = 0;
  	uint64		total_len = 0;
  	double		rec_len_pct,
  				fpi_len_pct;
  
  	/* ---
  	 * Make a first pass to calculate column totals:
  	 * count(*),
  	 * sum(xl_len+SizeOfXLogRecord),
  	 * sum(xl_tot_len-xl_len-SizeOfXLogRecord), and
  	 * sum(xl_tot_len).
  	 * These are used to calculate percentages for each record type.
  	 * ---
  	 */
  
  	for (ri = 0; ri < RM_NEXT_ID; ri++)
  	{
  		total_count += stats->rmgr_stats[ri].count;
  		total_rec_len += stats->rmgr_stats[ri].rec_len;
  		total_fpi_len += stats->rmgr_stats[ri].fpi_len;
  	}
  	total_len = total_rec_len + total_fpi_len;
  
  	/*
  	 * 27 is strlen("Transaction/COMMIT_PREPARED"), 20 is strlen(2^64), 8 is
  	 * strlen("(100.00%)")
  	 */
  
  	printf("%-27s %20s %8s %20s %8s %20s %8s %20s %8s\n"
  		   "%-27s %20s %8s %20s %8s %20s %8s %20s %8s\n",
  		   "Type", "N", "(%)", "Record size", "(%)", "FPI size", "(%)", "Combined size", "(%)",
  		   "----", "-", "---", "-----------", "---", "--------", "---", "-------------", "---");
  
  	for (ri = 0; ri < RM_NEXT_ID; ri++)
  	{
  		uint64		count,
  					rec_len,
  					fpi_len,
  					tot_len;
  		const RmgrDescData *desc = &RmgrDescTable[ri];
  
  		if (!config->stats_per_record)
  		{
  			count = stats->rmgr_stats[ri].count;
  			rec_len = stats->rmgr_stats[ri].rec_len;
  			fpi_len = stats->rmgr_stats[ri].fpi_len;
  			tot_len = rec_len + fpi_len;
  
  			XLogDumpStatsRow(desc->rm_name,
  							 count, total_count, rec_len, total_rec_len,
  							 fpi_len, total_fpi_len, tot_len, total_len);
  		}
  		else
  		{
  			for (rj = 0; rj < MAX_XLINFO_TYPES; rj++)
  			{
  				const char *id;
  
  				count = stats->record_stats[ri][rj].count;
  				rec_len = stats->record_stats[ri][rj].rec_len;
  				fpi_len = stats->record_stats[ri][rj].fpi_len;
  				tot_len = rec_len + fpi_len;
  
  				/* Skip undefined combinations and ones that didn't occur */
  				if (count == 0)
  					continue;
  
  				/* the upper four bits in xl_info are the rmgr's */
  				id = desc->rm_identify(rj << 4);
  				if (id == NULL)
  					id = psprintf("UNKNOWN (%x)", rj << 4);
  
  				XLogDumpStatsRow(psprintf("%s/%s", desc->rm_name, id),
  								 count, total_count, rec_len, total_rec_len,
  								 fpi_len, total_fpi_len, tot_len, total_len);
  			}
  		}
  	}
  
  	printf("%-27s %20s %8s %20s %8s %20s %8s %20s\n",
  		   "", "--------", "", "--------", "", "--------", "", "--------");
  
  	/*
  	 * The percentages in earlier rows were calculated against the column
  	 * total, but the ones that follow are against the row total. Note that
  	 * these are displayed with a % symbol to differentiate them from the
  	 * earlier ones, and are thus up to 9 characters long.
  	 */
  
  	rec_len_pct = 0;
  	if (total_len != 0)
  		rec_len_pct = 100 * (double) total_rec_len / total_len;
  
  	fpi_len_pct = 0;
  	if (total_len != 0)
  		fpi_len_pct = 100 * (double) total_fpi_len / total_len;
  
  	printf("%-27s "
  		   "%20" INT64_MODIFIER "u %-9s"
  		   "%20" INT64_MODIFIER "u %-9s"
  		   "%20" INT64_MODIFIER "u %-9s"
  		   "%20" INT64_MODIFIER "u %-6s\n",
  		   "Total", stats->count, "",
  		   total_rec_len, psprintf("[%.02f%%]", rec_len_pct),
  		   total_fpi_len, psprintf("[%.02f%%]", fpi_len_pct),
  		   total_len, "[100%]");
  }
  
  static void
  usage(void)
  {
  	printf(_("%s decodes and displays PostgreSQL write-ahead logs for debugging.\n\n"),
  		   progname);
  	printf(_("Usage:\n"));
  	printf(_("  %s [OPTION]... [STARTSEG [ENDSEG]]\n"), progname);
  	printf(_("\nOptions:\n"));
  	printf(_("  -b, --bkp-details      output detailed information about backup blocks\n"));
  	printf(_("  -e, --end=RECPTR       stop reading at WAL location RECPTR\n"));
  	printf(_("  -f, --follow           keep retrying after reaching end of WAL\n"));
  	printf(_("  -n, --limit=N          number of records to display\n"));
  	printf(_("  -p, --path=PATH        directory in which to find log segment files or a\n"
  			 "                         directory with a ./pg_wal that contains such files\n"
  			 "                         (default: current directory, ./pg_wal, $PGDATA/pg_wal)\n"));
  	printf(_("  -q, --quiet            do not print any output, except for errors\n"));
  	printf(_("  -r, --rmgr=RMGR        only show records generated by resource manager RMGR;\n"
  			 "                         use --rmgr=list to list valid resource manager names\n"));
  	printf(_("  -s, --start=RECPTR     start reading at WAL location RECPTR\n"));
  	printf(_("  -t, --timeline=TLI     timeline from which to read log records\n"
  			 "                         (default: 1 or the value used in STARTSEG)\n"));
  	printf(_("  -V, --version          output version information, then exit\n"));
  	printf(_("  -x, --xid=XID          only show records with transaction ID XID\n"));
  	printf(_("  -z, --stats[=record]   show statistics instead of records\n"
  			 "                         (optionally, show per-record statistics)\n"));
  	printf(_("  -?, --help             show this help, then exit\n"));
  	printf(_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
  	printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
  }
  
  int
  main(int argc, char **argv)
  {
  	uint32		xlogid;
  	uint32		xrecoff;
  	XLogReaderState *xlogreader_state;
  	XLogDumpPrivate private;
  	XLogDumpConfig config;
  	XLogDumpStats stats;
  	XLogRecord *record;
  	XLogRecPtr	first_record;
  	char	   *waldir = NULL;
  	char	   *errormsg;
  
  	static struct option long_options[] = {
  		{"bkp-details", no_argument, NULL, 'b'},
  		{"end", required_argument, NULL, 'e'},
  		{"follow", no_argument, NULL, 'f'},
  		{"help", no_argument, NULL, '?'},
  		{"limit", required_argument, NULL, 'n'},
  		{"path", required_argument, NULL, 'p'},
  		{"quiet", no_argument, NULL, 'q'},
  		{"rmgr", required_argument, NULL, 'r'},
  		{"start", required_argument, NULL, 's'},
  		{"timeline", required_argument, NULL, 't'},
  		{"xid", required_argument, NULL, 'x'},
  		{"version", no_argument, NULL, 'V'},
  		{"stats", optional_argument, NULL, 'z'},
  		{NULL, 0, NULL, 0}
  	};
  
  	int			option;
  	int			optindex = 0;
  
  	pg_logging_init(argv[0]);
  	set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_waldump"));
  	progname = get_progname(argv[0]);
  
  	if (argc > 1)
  	{
  		if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
  		{
  			usage();
  			exit(0);
  		}
  		if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
  		{
  			puts("pg_waldump (PostgreSQL) " PG_VERSION);
  			exit(0);
  		}
  	}
  
  	memset(&private, 0, sizeof(XLogDumpPrivate));
  	memset(&config, 0, sizeof(XLogDumpConfig));
  	memset(&stats, 0, sizeof(XLogDumpStats));
  
  	private.timeline = 1;
  	private.startptr = InvalidXLogRecPtr;
  	private.endptr = InvalidXLogRecPtr;
  	private.endptr_reached = false;
  
  	config.quiet = false;
  	config.bkp_details = false;
  	config.stop_after_records = -1;
  	config.already_displayed_records = 0;
  	config.follow = false;
  	config.filter_by_rmgr = -1;
  	config.filter_by_xid = InvalidTransactionId;
  	config.filter_by_xid_enabled = false;
  	config.stats = false;
  	config.stats_per_record = false;
  
  	if (argc <= 1)
  	{
  		pg_log_error("no arguments specified");
  		goto bad_argument;
  	}
  
  	while ((option = getopt_long(argc, argv, "be:fn:p:qr:s:t:x:z",
  								 long_options, &optindex)) != -1)
  	{
  		switch (option)
  		{
  			case 'b':
  				config.bkp_details = true;
  				break;
  			case 'e':
  				if (sscanf(optarg, "%X/%X", &xlogid, &xrecoff) != 2)
  				{
  					pg_log_error("could not parse end WAL location \"%s\"",
  								 optarg);
  					goto bad_argument;
  				}
  				private.endptr = (uint64) xlogid << 32 | xrecoff;
  				break;
  			case 'f':
  				config.follow = true;
  				break;
  			case 'n':
  				if (sscanf(optarg, "%d", &config.stop_after_records) != 1)
  				{
  					pg_log_error("could not parse limit \"%s\"", optarg);
  					goto bad_argument;
  				}
  				break;
  			case 'p':
  				waldir = pg_strdup(optarg);
  				break;
  			case 'q':
  				config.quiet = true;
  				break;
  			case 'r':
  				{
  					int			i;
  
  					if (pg_strcasecmp(optarg, "list") == 0)
  					{
  						print_rmgr_list();
  						exit(EXIT_SUCCESS);
  					}
  
  					for (i = 0; i <= RM_MAX_ID; i++)
  					{
  						if (pg_strcasecmp(optarg, RmgrDescTable[i].rm_name) == 0)
  						{
  							config.filter_by_rmgr = i;
  							break;
  						}
  					}
  
  					if (config.filter_by_rmgr == -1)
  					{
  						pg_log_error("resource manager \"%s\" does not exist",
  									 optarg);
  						goto bad_argument;
  					}
  				}
  				break;
  			case 's':
  				if (sscanf(optarg, "%X/%X", &xlogid, &xrecoff) != 2)
  				{
  					pg_log_error("could not parse start WAL location \"%s\"",
  								 optarg);
  					goto bad_argument;
  				}
  				else
  					private.startptr = (uint64) xlogid << 32 | xrecoff;
  				break;
  			case 't':
  				if (sscanf(optarg, "%d", &private.timeline) != 1)
  				{
  					pg_log_error("could not parse timeline \"%s\"", optarg);
  					goto bad_argument;
  				}
  				break;
  			case 'x':
  				if (sscanf(optarg, "%u", &config.filter_by_xid) != 1)
  				{
  					pg_log_error("could not parse \"%s\" as a transaction ID",
  								 optarg);
  					goto bad_argument;
  				}
  				config.filter_by_xid_enabled = true;
  				break;
  			case 'z':
  				config.stats = true;
  				config.stats_per_record = false;
  				if (optarg)
  				{
  					if (strcmp(optarg, "record") == 0)
  						config.stats_per_record = true;
  					else if (strcmp(optarg, "rmgr") != 0)
  					{
  						pg_log_error("unrecognized argument to --stats: %s",
  									 optarg);
  						goto bad_argument;
  					}
  				}
  				break;
  			default:
  				goto bad_argument;
  		}
  	}
  
  	if ((optind + 2) < argc)
  	{
  		pg_log_error("too many command-line arguments (first is \"%s\")",
  					 argv[optind + 2]);
  		goto bad_argument;
  	}
  
  	if (waldir != NULL)
  	{
  		/* validate path points to directory */
  		if (!verify_directory(waldir))
  		{
  			pg_log_error("could not open directory \"%s\": %m", waldir);
  			goto bad_argument;
  		}
  	}
  
  	/* parse files as start/end boundaries, extract path if not specified */
  	if (optind < argc)
  	{
  		char	   *directory = NULL;
  		char	   *fname = NULL;
  		int			fd;
  		XLogSegNo	segno;
  
  		split_path(argv[optind], &directory, &fname);
  
  		if (waldir == NULL && directory != NULL)
  		{
  			waldir = directory;
  
  			if (!verify_directory(waldir))
  				fatal_error("could not open directory \"%s\": %m", waldir);
  		}
  
  		waldir = identify_target_directory(waldir, fname);
  		fd = open_file_in_directory(waldir, fname);
  		if (fd < 0)
  			fatal_error("could not open file \"%s\"", fname);
  		close(fd);
  
  		/* parse position from file */
  		XLogFromFileName(fname, &private.timeline, &segno, WalSegSz);
  
  		if (XLogRecPtrIsInvalid(private.startptr))
  			XLogSegNoOffsetToRecPtr(segno, 0, WalSegSz, private.startptr);
  		else if (!XLByteInSeg(private.startptr, segno, WalSegSz))
  		{
  			pg_log_error("start WAL location %X/%X is not inside file \"%s\"",
  						 (uint32) (private.startptr >> 32),
  						 (uint32) private.startptr,
  						 fname);
  			goto bad_argument;
  		}
  
  		/* no second file specified, set end position */
  		if (!(optind + 1 < argc) && XLogRecPtrIsInvalid(private.endptr))
  			XLogSegNoOffsetToRecPtr(segno + 1, 0, WalSegSz, private.endptr);
  
  		/* parse ENDSEG if passed */
  		if (optind + 1 < argc)
  		{
  			XLogSegNo	endsegno;
  
  			/* ignore directory, already have that */
  			split_path(argv[optind + 1], &directory, &fname);
  
  			fd = open_file_in_directory(waldir, fname);
  			if (fd < 0)
  				fatal_error("could not open file \"%s\"", fname);
  			close(fd);
  
  			/* parse position from file */
  			XLogFromFileName(fname, &private.timeline, &endsegno, WalSegSz);
  
  			if (endsegno < segno)
  				fatal_error("ENDSEG %s is before STARTSEG %s",
  							argv[optind + 1], argv[optind]);
  
  			if (XLogRecPtrIsInvalid(private.endptr))
  				XLogSegNoOffsetToRecPtr(endsegno + 1, 0, WalSegSz,
  										private.endptr);
  
  			/* set segno to endsegno for check of --end */
  			segno = endsegno;
  		}
  
  
  		if (!XLByteInSeg(private.endptr, segno, WalSegSz) &&
  			private.endptr != (segno + 1) * WalSegSz)
  		{
  			pg_log_error("end WAL location %X/%X is not inside file \"%s\"",
  						 (uint32) (private.endptr >> 32),
  						 (uint32) private.endptr,
  						 argv[argc - 1]);
  			goto bad_argument;
  		}
  	}
  	else
  		waldir = identify_target_directory(waldir, NULL);
  
  	/* we don't know what to print */
  	if (XLogRecPtrIsInvalid(private.startptr))
  	{
  		pg_log_error("no start WAL location given");
  		goto bad_argument;
  	}
  
  	/* done with argument parsing, do the actual work */
  
  	/* we have everything we need, start reading */
  	xlogreader_state =
  		XLogReaderAllocate(WalSegSz, waldir,
  						   XL_ROUTINE(.page_read = WALDumpReadPage,
  									  .segment_open = WALDumpOpenSegment,
  									  .segment_close = WALDumpCloseSegment),
  						   &private);
  	if (!xlogreader_state)
  		fatal_error("out of memory");
  
  	/* first find a valid recptr to start from */
  	first_record = XLogFindNextRecord(xlogreader_state, private.startptr);
  
  	if (first_record == InvalidXLogRecPtr)
  		fatal_error("could not find a valid record after %X/%X",
  					(uint32) (private.startptr >> 32),
  					(uint32) private.startptr);
  
  	/*
  	 * Display a message that we're skipping data if `from` wasn't a pointer
  	 * to the start of a record and also wasn't a pointer to the beginning of
  	 * a segment (e.g. we were used in file mode).
  	 */
  	if (first_record != private.startptr &&
  		XLogSegmentOffset(private.startptr, WalSegSz) != 0)
  		printf(ngettext("first record is after %X/%X, at %X/%X, skipping over %u byte\n",
  						"first record is after %X/%X, at %X/%X, skipping over %u bytes\n",
  						(first_record - private.startptr)),
  			   (uint32) (private.startptr >> 32), (uint32) private.startptr,
  			   (uint32) (first_record >> 32), (uint32) first_record,
  			   (uint32) (first_record - private.startptr));
  
  	for (;;)
  	{
  		/* try to read the next record */
  		record = XLogReadRecord(xlogreader_state, &errormsg);
  		if (!record)
  		{
  			if (!config.follow || private.endptr_reached)
  				break;
  			else
  			{
  				pg_usleep(1000000L);	/* 1 second */
  				continue;
  			}
  		}
  
  		/* apply all specified filters */
  		if (config.filter_by_rmgr != -1 &&
  			config.filter_by_rmgr != record->xl_rmid)
  			continue;
  
  		if (config.filter_by_xid_enabled &&
  			config.filter_by_xid != record->xl_xid)
  			continue;
  
  		/* perform any per-record work */
  		if (!config.quiet)
  		{
  			if (config.stats == true)
  				XLogDumpCountRecord(&config, &stats, xlogreader_state);
  			else
  				XLogDumpDisplayRecord(&config, xlogreader_state);
  		}
  
  		/* check whether we printed enough */
  		config.already_displayed_records++;
  		if (config.stop_after_records > 0 &&
  			config.already_displayed_records >= config.stop_after_records)
  			break;
  	}
  
  	if (config.stats == true && !config.quiet)
  		XLogDumpDisplayStats(&config, &stats);
  
  	if (errormsg)
  		fatal_error("error in WAL record at %X/%X: %s",
  					(uint32) (xlogreader_state->ReadRecPtr >> 32),
  					(uint32) xlogreader_state->ReadRecPtr,
  					errormsg);
  
  	XLogReaderFree(xlogreader_state);
  
  	return EXIT_SUCCESS;
  
  bad_argument:
  	fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
  	return EXIT_FAILURE;
  }
  