Add files for pg_resetxlog.

23 years ago · 33e3c9b085
parent 6945ea3445
commit 33e3c9b085
2 changed files with 647 additions and 0 deletions
--- a/src/bin/pg_resetxlog/Makefile
+++ b/src/bin/pg_resetxlog/Makefile
@ -0,0 +1,35 @@
+#-------------------------------------------------------------------------
+#
+# Makefile for src/bin/pg_resetxlog
+#
+# Copyright (c) 1998, PostgreSQL Global Development Group
+#
+# $Header: /cvsroot/pgsql/src/bin/pg_resetxlog/Makefile,v 1.1 2002/08/17 02:44:24 momjian Exp $
+#
+#-------------------------------------------------------------------------
+
+subdir = src/bin/pg_resetxlog
+top_builddir = ../../..
+include $(top_builddir)/src/Makefile.global
+
+OBJS= pg_resetxlog.o pg_crc.o
+
+pg_crc.c: $(top_builddir)/src/backend/utils/hash/pg_crc.c
+	rm -f $@ && $(LN_S) $< .
+
+all: submake-libpgport pg_resetxlog
+
+pg_resetxlog: $(OBJS)
+	$(CC) $(CFLAGS) $^ $(libpq) $(LDFLAGS) $(LIBS) -o $@
+
+install: all installdirs
+	$(INSTALL_PROGRAM) pg_resetxlog$(X) $(DESTDIR)$(bindir)/pg_resetxlog$(X)
+
+installdirs:
+	$(mkinstalldirs) $(DESTDIR)$(bindir)
+
+uninstall:
+	rm -f $(DESTDIR)$(bindir)/pg_resetxlog$(X)
+
+clean distclean maintainer-clean:
+	rm -f pg_resetxlog$(X) pg_resetxlog.o pg_crc.o pg_crc.c
--- a/src/bin/pg_resetxlog/pg_resetxlog.c
+++ b/src/bin/pg_resetxlog/pg_resetxlog.c
@ -0,0 +1,612 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_resetxlog.c
+ *	  A utility to "zero out" the xlog when it's corrupt beyond recovery.
+ *	  Can also rebuild pg_control if needed.
+ *
+ * The theory of operation is fairly simple:
+ *	  1. Read the existing pg_control (which will include the last
+ *		 checkpoint record).  If it is an old format then update to
+ *		 current format.
+ *	  2. If pg_control is corrupt, attempt to intuit reasonable values,
+ *		 by scanning the old xlog if necessary.
+ *	  3. Modify pg_control to reflect a "shutdown" state with a checkpoint
+ *		 record at the start of xlog.
+ *	  4. Flush the existing xlog files and write a new segment with
+ *		 just a checkpoint record in it.  The new segment is positioned
+ *		 just past the end of the old xlog, so that existing LSNs in
+ *		 data pages will appear to be "in the past".
+ * This is all pretty straightforward except for the intuition part of
+ * step 2 ...
+ *
+ *
+ * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * $Header: /cvsroot/pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v 1.1 2002/08/17 02:44:24 momjian Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <errno.h>
+#include <unistd.h>
+#include <time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <dirent.h>
+#ifdef USE_LOCALE
+#include <locale.h>
+#endif
+
+#include "access/xlog.h"
+#include "catalog/catversion.h"
+#include "catalog/pg_control.h"
+
+
+/******************** stuff copied from xlog.c ********************/
+
+/* Increment an xlogid/segment pair */
+#define NextLogSeg(logId, logSeg)	\
+	do { \
+		if ((logSeg) >= XLogSegsPerFile-1) \
+		{ \
+			(logId)++; \
+			(logSeg) = 0; \
+		} \
+		else \
+			(logSeg)++; \
+	} while (0)
+
+#define XLogFileName(path, log, seg)	\
+			snprintf(path, MAXPGPATH, "%s/%08X%08X",	\
+					 XLogDir, log, seg)
+
+/******************** end of stuff copied from xlog.c ********************/
+
+
+static char *DataDir;			/* locations of important stuff */
+static char *XLogDir;
+static char ControlFilePath[MAXPGPATH];
+
+static ControlFileData ControlFile;		/* pg_control values */
+static uint32 newXlogId,
+			newXlogSeg;			/* ID/Segment of new XLOG segment */
+static bool guessed = false;	/* T if we had to guess at any values */
+
+
+/*
+ * Try to read the existing pg_control file.
+ *
+ * This routine is also responsible for updating old pg_control versions
+ * to the current format.
+ */
+static bool
+ReadControlFile(void)
+{
+	int			fd;
+	int			len;
+	char	   *buffer;
+	crc64		crc;
+
+	if ((fd = open(ControlFilePath, O_RDONLY)) < 0)
+	{
+		/*
+		 * If pg_control is not there at all, or we can't read it, the
+		 * odds are we've been handed a bad DataDir path, so give up. User
+		 * can do "touch pg_control" to force us to proceed.
+		 */
+		perror("Failed to open $PGDATA/global/pg_control for reading");
+		if (errno == ENOENT)
+			fprintf(stderr, "If you're sure the PGDATA path is correct, do\n"
+					"  touch %s\n"
+					"and try again.\n", ControlFilePath);
+		exit(1);
+	}
+
+	/* Use malloc to ensure we have a maxaligned buffer */
+	buffer = (char *) malloc(BLCKSZ);
+
+	len = read(fd, buffer, BLCKSZ);
+	if (len < 0)
+	{
+		perror("Failed to read $PGDATA/global/pg_control");
+		exit(1);
+	}
+	close(fd);
+
+	if (len >= sizeof(ControlFileData) &&
+		((ControlFileData *) buffer)->pg_control_version == PG_CONTROL_VERSION)
+	{
+		/* Check the CRC. */
+		INIT_CRC64(crc);
+		COMP_CRC64(crc,
+				   buffer + sizeof(crc64),
+				   sizeof(ControlFileData) - sizeof(crc64));
+		FIN_CRC64(crc);
+
+		if (EQ_CRC64(crc, ((ControlFileData *) buffer)->crc))
+		{
+			/* Valid data... */
+			memcpy(&ControlFile, buffer, sizeof(ControlFile));
+			return true;
+		}
+
+		fprintf(stderr, "pg_control exists but has invalid CRC; proceed with caution.\n");
+		/* We will use the data anyway, but treat it as guessed. */
+		memcpy(&ControlFile, buffer, sizeof(ControlFile));
+		guessed = true;
+		return true;
+	}
+
+	/* Looks like it's a mess. */
+	fprintf(stderr, "pg_control exists but is broken or unknown version; ignoring it.\n");
+	return false;
+}
+
+
+/*
+ * Guess at pg_control values when we can't read the old ones.
+ */
+static void
+GuessControlValues(void)
+{
+#ifdef USE_LOCALE
+	char	   *localeptr;
+#endif
+
+	/*
+	 * Set up a completely default set of pg_control values.
+	 */
+	guessed = true;
+	memset(&ControlFile, 0, sizeof(ControlFile));
+
+	ControlFile.pg_control_version = PG_CONTROL_VERSION;
+	ControlFile.catalog_version_no = CATALOG_VERSION_NO;
+
+	ControlFile.checkPointCopy.redo.xlogid = 0;
+	ControlFile.checkPointCopy.redo.xrecoff = SizeOfXLogPHD;
+	ControlFile.checkPointCopy.undo = ControlFile.checkPointCopy.redo;
+	ControlFile.checkPointCopy.ThisStartUpID = 0;
+	ControlFile.checkPointCopy.nextXid = (TransactionId) 514;	/* XXX */
+	ControlFile.checkPointCopy.nextOid = BootstrapObjectIdData;
+	ControlFile.checkPointCopy.time = time(NULL);
+
+	ControlFile.state = DB_SHUTDOWNED;
+	ControlFile.time = time(NULL);
+	ControlFile.logId = 0;
+	ControlFile.logSeg = 1;
+	ControlFile.checkPoint = ControlFile.checkPointCopy.redo;
+
+	ControlFile.blcksz = BLCKSZ;
+	ControlFile.relseg_size = RELSEG_SIZE;
+#ifdef USE_LOCALE
+	localeptr = setlocale(LC_COLLATE, "");
+	if (!localeptr)
+	{
+		fprintf(stderr, "Invalid LC_COLLATE setting\n");
+		exit(1);
+	}
+	StrNCpy(ControlFile.lc_collate, localeptr, LOCALE_NAME_BUFLEN);
+	localeptr = setlocale(LC_CTYPE, "");
+	if (!localeptr)
+	{
+		fprintf(stderr, "Invalid LC_CTYPE setting\n");
+		exit(1);
+	}
+	StrNCpy(ControlFile.lc_ctype, localeptr, LOCALE_NAME_BUFLEN);
+#else
+	strcpy(ControlFile.lc_collate, "C");
+	strcpy(ControlFile.lc_ctype, "C");
+#endif
+
+	/*
+	 * XXX eventually, should try to grovel through old XLOG to develop
+	 * more accurate values for startupid, nextXID, and nextOID.
+	 */
+}
+
+
+/*
+ * Print the guessed pg_control values when we had to guess.
+ *
+ * NB: this display should be just those fields that will not be
+ * reset by RewriteControlFile().
+ */
+static void
+PrintControlValues(bool guessed)
+{
+	printf("%spg_control values:\n\n"
+		   "pg_control version number:            %u\n"
+		   "Catalog version number:               %u\n"
+		   "Current log file id:                  %u\n"
+		   "Next log file segment:                %u\n"
+		   "Latest checkpoint's StartUpID:        %u\n"
+		   "Latest checkpoint's NextXID:          %u\n"
+		   "Latest checkpoint's NextOID:          %u\n"
+		   "Database block size:                  %u\n"
+		   "Blocks per segment of large relation: %u\n"
+		   "LC_COLLATE:                           %s\n"
+		   "LC_CTYPE:                             %s\n",
+
+		   (guessed ? "Guessed-at " : ""),
+		   ControlFile.pg_control_version,
+		   ControlFile.catalog_version_no,
+		   ControlFile.logId,
+		   ControlFile.logSeg,
+		   ControlFile.checkPointCopy.ThisStartUpID,
+		   ControlFile.checkPointCopy.nextXid,
+		   ControlFile.checkPointCopy.nextOid,
+		   ControlFile.blcksz,
+		   ControlFile.relseg_size,
+		   ControlFile.lc_collate,
+		   ControlFile.lc_ctype);
+}
+
+
+/*
+ * Write out the new pg_control file.
+ */
+static void
+RewriteControlFile(void)
+{
+	int			fd;
+	char		buffer[BLCKSZ]; /* need not be aligned */
+
+	/*
+	 * Adjust fields as needed to force an empty XLOG starting at the next
+	 * available segment.
+	 */
+	newXlogId = ControlFile.logId;
+	newXlogSeg = ControlFile.logSeg;
+	/* be sure we wrap around correctly at end of a logfile */
+	NextLogSeg(newXlogId, newXlogSeg);
+
+	ControlFile.checkPointCopy.redo.xlogid = newXlogId;
+	ControlFile.checkPointCopy.redo.xrecoff =
+		newXlogSeg * XLogSegSize + SizeOfXLogPHD;
+	ControlFile.checkPointCopy.undo = ControlFile.checkPointCopy.redo;
+	ControlFile.checkPointCopy.time = time(NULL);
+
+	ControlFile.state = DB_SHUTDOWNED;
+	ControlFile.time = time(NULL);
+	ControlFile.logId = newXlogId;
+	ControlFile.logSeg = newXlogSeg + 1;
+	ControlFile.checkPoint = ControlFile.checkPointCopy.redo;
+	ControlFile.prevCheckPoint.xlogid = 0;
+	ControlFile.prevCheckPoint.xrecoff = 0;
+
+	/* Contents are protected with a CRC */
+	INIT_CRC64(ControlFile.crc);
+	COMP_CRC64(ControlFile.crc,
+			   (char *) &ControlFile + sizeof(crc64),
+			   sizeof(ControlFileData) - sizeof(crc64));
+	FIN_CRC64(ControlFile.crc);
+
+	/*
+	 * We write out BLCKSZ bytes into pg_control, zero-padding the excess
+	 * over sizeof(ControlFileData).  This reduces the odds of
+	 * premature-EOF errors when reading pg_control.  We'll still fail
+	 * when we check the contents of the file, but hopefully with a more
+	 * specific error than "couldn't read pg_control".
+	 */
+	if (sizeof(ControlFileData) > BLCKSZ)
+	{
+		fprintf(stderr, "sizeof(ControlFileData) is too large ... fix xlog.c\n");
+		exit(1);
+	}
+
+	memset(buffer, 0, BLCKSZ);
+	memcpy(buffer, &ControlFile, sizeof(ControlFileData));
+
+	unlink(ControlFilePath);
+
+	fd = open(ControlFilePath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY, S_IRUSR | S_IWUSR);
+	if (fd < 0)
+	{
+		perror("RewriteControlFile failed to create pg_control file");
+		exit(1);
+	}
+
+	errno = 0;
+	if (write(fd, buffer, BLCKSZ) != BLCKSZ)
+	{
+		/* if write didn't set errno, assume problem is no disk space */
+		if (errno == 0)
+			errno = ENOSPC;
+		perror("RewriteControlFile failed to write pg_control file");
+		exit(1);
+	}
+
+	if (fsync(fd) != 0)
+	{
+		perror("fsync");
+		exit(1);
+	}
+
+	close(fd);
+}
+
+
+/*
+ * Remove existing XLOG files
+ */
+static void
+KillExistingXLOG(void)
+{
+	DIR		   *xldir;
+	struct dirent *xlde;
+	char		path[MAXPGPATH];
+
+	xldir = opendir(XLogDir);
+	if (xldir == NULL)
+	{
+		perror("KillExistingXLOG: cannot open $PGDATA/pg_xlog directory");
+		exit(1);
+	}
+
+	errno = 0;
+	while ((xlde = readdir(xldir)) != NULL)
+	{
+		if (strlen(xlde->d_name) == 16 &&
+			strspn(xlde->d_name, "0123456789ABCDEF") == 16)
+		{
+			snprintf(path, MAXPGPATH, "%s/%s", XLogDir, xlde->d_name);
+			if (unlink(path) < 0)
+			{
+				perror(path);
+				exit(1);
+			}
+		}
+		errno = 0;
+	}
+	if (errno)
+	{
+		perror("KillExistingXLOG: cannot read $PGDATA/pg_xlog directory");
+		exit(1);
+	}
+	closedir(xldir);
+}
+
+
+/*
+ * Write an empty XLOG file, containing only the checkpoint record
+ * already set up in ControlFile.
+ */
+static void
+WriteEmptyXLOG(void)
+{
+	char	   *buffer;
+	XLogPageHeader page;
+	XLogRecord *record;
+	crc64		crc;
+	char		path[MAXPGPATH];
+	int			fd;
+	int			nbytes;
+
+	/* Use malloc() to ensure buffer is MAXALIGNED */
+	buffer = (char *) malloc(BLCKSZ);
+	page = (XLogPageHeader) buffer;
+
+	/* Set up the first page with initial record */
+	memset(buffer, 0, BLCKSZ);
+	page->xlp_magic = XLOG_PAGE_MAGIC;
+	page->xlp_info = 0;
+	page->xlp_sui = ControlFile.checkPointCopy.ThisStartUpID;
+	page->xlp_pageaddr.xlogid =
+		ControlFile.checkPointCopy.redo.xlogid;
+	page->xlp_pageaddr.xrecoff =
+		ControlFile.checkPointCopy.redo.xrecoff - SizeOfXLogPHD;
+	record = (XLogRecord *) ((char *) page + SizeOfXLogPHD);
+	record->xl_prev.xlogid = 0;
+	record->xl_prev.xrecoff = 0;
+	record->xl_xact_prev = record->xl_prev;
+	record->xl_xid = InvalidTransactionId;
+	record->xl_len = sizeof(CheckPoint);
+	record->xl_info = XLOG_CHECKPOINT_SHUTDOWN;
+	record->xl_rmid = RM_XLOG_ID;
+	memcpy(XLogRecGetData(record), &ControlFile.checkPointCopy,
+		   sizeof(CheckPoint));
+
+	INIT_CRC64(crc);
+	COMP_CRC64(crc, &ControlFile.checkPointCopy, sizeof(CheckPoint));
+	COMP_CRC64(crc, (char *) record + sizeof(crc64),
+			   SizeOfXLogRecord - sizeof(crc64));
+	FIN_CRC64(crc);
+	record->xl_crc = crc;
+
+	/* Write the first page */
+	XLogFileName(path, newXlogId, newXlogSeg);
+
+	unlink(path);
+
+	fd = open(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
+			  S_IRUSR | S_IWUSR);
+	if (fd < 0)
+	{
+		perror(path);
+		exit(1);
+	}
+
+	errno = 0;
+	if (write(fd, buffer, BLCKSZ) != BLCKSZ)
+	{
+		/* if write didn't set errno, assume problem is no disk space */
+		if (errno == 0)
+			errno = ENOSPC;
+		perror("WriteEmptyXLOG: failed to write xlog file");
+		exit(1);
+	}
+
+	/* Fill the rest of the file with zeroes */
+	memset(buffer, 0, BLCKSZ);
+	for (nbytes = BLCKSZ; nbytes < XLogSegSize; nbytes += BLCKSZ)
+	{
+		errno = 0;
+		if (write(fd, buffer, BLCKSZ) != BLCKSZ)
+		{
+			if (errno == 0)
+				errno = ENOSPC;
+			perror("WriteEmptyXLOG: failed to write xlog file");
+			exit(1);
+		}
+	}
+
+	if (fsync(fd) != 0)
+	{
+		perror("fsync");
+		exit(1);
+	}
+
+	close(fd);
+}
+
+
+static void
+usage(void)
+{
+	fprintf(stderr, "Usage: pg_resetxlog [-f] [-n] [-x xid] [ -l fileid seg ] PGDataDirectory\n"
+			"  -f\t\tforce update to be done\n"
+			"  -n\t\tno update, just show extracted pg_control values (for testing)\n"
+			"  -x xid\tset next transaction ID\n"
+			"  -l fileid seg\tforce minimum WAL starting location for new xlog\n");
+	exit(1);
+}
+
+
+int
+main(int argc, char **argv)
+{
+	int			argn;
+	bool		force = false;
+	bool		noupdate = false;
+	TransactionId set_xid = 0;
+	uint32		minXlogId = 0,
+				minXlogSeg = 0;
+	int			fd;
+	char		path[MAXPGPATH];
+
+	for (argn = 1; argn < argc; argn++)
+	{
+		if (argv[argn][0] != '-')
+			break;				/* end of switches */
+		if (strcmp(argv[argn], "-f") == 0)
+			force = true;
+		else if (strcmp(argv[argn], "-n") == 0)
+			noupdate = true;
+		else if (strcmp(argv[argn], "-x") == 0)
+		{
+			argn++;
+			if (argn == argc)
+				usage();
+			set_xid = strtoul(argv[argn], NULL, 0);
+			if (set_xid == 0)
+			{
+				fprintf(stderr, "XID can not be 0.\n");
+				exit(1);
+			}
+		}
+		else if (strcmp(argv[argn], "-l") == 0)
+		{
+			argn++;
+			if (argn == argc)
+				usage();
+			minXlogId = strtoul(argv[argn], NULL, 0);
+			argn++;
+			if (argn == argc)
+				usage();
+			minXlogSeg = strtoul(argv[argn], NULL, 0);
+		}
+		else
+			usage();
+	}
+
+	if (argn != argc - 1)		/* one required non-switch argument */
+		usage();
+
+	DataDir = argv[argn++];
+
+	XLogDir=malloc(MAXPGPATH);
+	snprintf(XLogDir, MAXPGPATH, "%s/pg_xlog", DataDir);
+
+	snprintf(ControlFilePath, MAXPGPATH, "%s/global/pg_control", DataDir);
+
+	/*
+	 * Check for a postmaster lock file --- if there is one, refuse to
+	 * proceed, on grounds we might be interfering with a live
+	 * installation.
+	 */
+	snprintf(path, MAXPGPATH, "%s/postmaster.pid", DataDir);
+
+	if ((fd = open(path, O_RDONLY)) < 0)
+	{
+		if (errno != ENOENT)
+		{
+			perror("Failed to open $PGDATA/postmaster.pid for reading");
+			exit(1);
+		}
+	}
+	else
+	{
+		fprintf(stderr, "Lock file '%s' exists --- is a postmaster running?\n"
+				"If not, delete the lock file and try again.\n",
+				path);
+		exit(1);
+	}
+
+	/*
+	 * Attempt to read the existing pg_control file
+	 */
+	if (!ReadControlFile())
+		GuessControlValues();
+
+	/*
+	 * If we had to guess anything, and -f was not given, just print the
+	 * guessed values and exit.  Also print if -n is given.
+	 */
+	if ((guessed && !force) || noupdate)
+	{
+		PrintControlValues(guessed);
+		if (!noupdate)
+		{
+			printf("\nIf these values seem acceptable, use -f to force reset.\n");
+			exit(1);
+		}
+		else
+			exit(0);
+	}
+
+	/*
+	 * Don't reset from a dirty pg_control without -f, either.
+	 */
+	if (ControlFile.state != DB_SHUTDOWNED && !force)
+	{
+		printf("The database was not shut down cleanly.\n"
+			   "Resetting the xlog may cause data to be lost!\n"
+			   "If you want to proceed anyway, use -f to force reset.\n");
+		exit(1);
+	}
+
+	/*
+	 * Else, do the dirty deed.
+	 *
+	 * First adjust fields if required by switches.
+	 */
+	if (set_xid != 0)
+		ControlFile.checkPointCopy.nextXid = set_xid;
+
+	if (minXlogId > ControlFile.logId ||
+		(minXlogId == ControlFile.logId && minXlogSeg > ControlFile.logSeg))
+	{
+		ControlFile.logId = minXlogId;
+		ControlFile.logSeg = minXlogSeg;
+	}
+
+	RewriteControlFile();
+	KillExistingXLOG();
+	WriteEmptyXLOG();
+
+	printf("XLOG reset.\n");
+	return 0;
+}