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First cut at XLOG file reset utility.

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Could do with more testing, but it works in the simple cases.
REL7_1_STABLE
Tom Lane 25 years ago
parent f192da1ba3
commit eeaf3fc3a1
5 changed files with 1079 additions and 2 deletions
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  1. 4
      contrib/Makefile
  2. 10
      contrib/README
  3. 37
      contrib/pg_resetxlog/Makefile
  4. 39
      contrib/pg_resetxlog/README.pg_resetxlog
  5. 991
      contrib/pg_resetxlog/pg_resetxlog.c

4
contrib/Makefile
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@ -1,4 +1,4 @@
# $Header: /cvsroot/pgsql/contrib/Makefile,v 1.17 2001/03/13 19:28:02 petere Exp $
# $Header: /cvsroot/pgsql/contrib/Makefile,v 1.18 2001/03/14 00:57:43 tgl Exp $
subdir = contrib
top_builddir = ..
@ -18,8 +18,10 @@ WANTED_DIRS = \
miscutil \
noupdate \
oid2name \
pg_controldata \
pg_dumplo \
pg_logger \
pg_resetxlog \
pgbench \
pgcrypto \
rserv \

10
contrib/README
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@ -52,6 +52,10 @@ intarray -
by Teodor Sigaev <teodor@stack.net> and Oleg Bartunov
<oleg@sai.msu.su>.
ipc_check -
Simple test script to help in configuring IPC.
FreeBSD only, for now.
isbn_issn -
PostgreSQL type extensions for ISBN (books) and ISSN (serials)
by Garrett A. Wollman <wollman@khavrinen.lcs.mit.edu>
@ -86,7 +90,7 @@ oid2name -
by B Palmer <bpalmer@crimelabs.net>
pg_controldata -
Dump internal database site structures
Dump contents of pg_control (database master file)
by Oliver Elphick <olly@lfix.co.uk>
pg_dumplo -
@ -97,6 +101,10 @@ pg_logger -
Stdin-to-syslog gateway for PostgreSQL
by Nathan Myers <ncm@nospam.cantrip.org>
pg_resetxlog -
Reset the WAL log (pg_xlog) to recover from crash or format change
by Tom Lane <tgl@sss.pgh.pa.us>
pgbench -
TPC-B like benchmarking tool
by Tatsuo Ishii <t-ishii@sra.co.jp>

37
contrib/pg_resetxlog/Makefile
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#
# $Header: /cvsroot/pgsql/contrib/pg_resetxlog/Attic/Makefile,v 1.1 2001/03/14 00:57:43 tgl Exp $
#
subdir = contrib/pg_resetxlog
top_builddir = ../..
include $(top_builddir)/src/Makefile.global
OBJS = pg_resetxlog.o pg_crc.o
all: pg_resetxlog
pg_resetxlog: $(OBJS)
$(CC) $(CFLAGS) $(OBJS) $(LDFLAGS) $(LIBS) -o $@
pg_crc.c: $(top_builddir)/src/backend/utils/hash/pg_crc.c
rm -f $@ && $(LN_S) $< .
install: all installdirs
$(INSTALL_PROGRAM) pg_resetxlog$(X) $(bindir)
$(INSTALL_DATA) README.pg_resetxlog $(docdir)/contrib
installdirs:
$(mkinstalldirs) $(bindir) $(docdir)/contrib
uninstall:
rm -f $(bindir)/pg_resetxlog$(X) $(docdir)/contrib/README.pg_resetxlog
clean distclean maintainer-clean:
rm -f pg_resetxlog$(X) $(OBJS) pg_crc.c
depend dep:
$(CC) -MM -MG $(CFLAGS) *.c > depend
ifeq (depend,$(wildcard depend))
include depend
endif

39
contrib/pg_resetxlog/README.pg_resetxlog
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pg_resetxlog is a program to clear the WAL transaction log (stored in
$PGDATA/pg_xlog/), replacing whatever had been in it with just a dummy
shutdown-checkpoint record. It also regenerates the pg_control file
if necessary.
THIS PROGRAM WILL DESTROY VALUABLE LOG DATA!!! Don't run it unless you
really need it!!!
pg_resetxlog is primarily intended for disaster recovery --- that is,
if your pg_control and/or xlog are hosed badly enough that Postgres refuses
to start up, this program will get you past that problem and let you get to
your data files. But realize that without the xlog, your data files may be
corrupt due to partially-applied transactions, incomplete index-file
updates, etc. You should dump your data, check it for accuracy, then initdb
and reload.
A secondary purpose is to cope with xlog format changes without requiring
initdb. To use pg_resetxlog for this purpose, just be sure that you have
cleanly shut down your old postmaster (if you're not sure, see the contrib
module pg_controldata and run it to be sure the DB state is SHUTDOWN).
Then run pg_resetxlog, and finally install and start the new version of
the database software.
To run the program, make sure your postmaster is not running, then
(as the Postgres admin user) do
pg_resetxlog $PGDATA
As a safety measure, the target data directory must be specified on the
command line, it cannot be defaulted.
If pg_resetxlog complains that it can't reconstruct valid data for pg_control,
you can force it to invent plausible data values with
pg_resetxlog -f $PGDATA
If this turns out to be necessary then you *definitely* should plan on
immediate dump, initdb, reload --- any modifications you do to the database
after "pg_resetxlog -f" would be likely to corrupt things even worse.

991
contrib/pg_resetxlog/pg_resetxlog.c
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/*-------------------------------------------------------------------------
*
* 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 0 with
* just a checkpoint record in it.
* This is all pretty straightforward except for the intuition part of
* step 2 ...
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Header: /cvsroot/pgsql/contrib/pg_resetxlog/Attic/pg_resetxlog.c,v 1.1 2001/03/14 00:57:43 tgl 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)
/*
* Compute ID and segment from an XLogRecPtr.
*
* For XLByteToSeg, do the computation at face value. For XLByteToPrevSeg,
* a boundary byte is taken to be in the previous segment. This is suitable
* for deciding which segment to write given a pointer to a record end,
* for example.
*/
#define XLByteToSeg(xlrp, logId, logSeg) \
( logId = (xlrp).xlogid, \
logSeg = (xlrp).xrecoff / XLogSegSize \
)
#define XLByteToPrevSeg(xlrp, logId, logSeg) \
( logId = (xlrp).xlogid, \
logSeg = ((xlrp).xrecoff - 1) / XLogSegSize \
)
/*
* Is an XLogRecPtr within a particular XLOG segment?
*
* For XLByteInSeg, do the computation at face value. For XLByteInPrevSeg,
* a boundary byte is taken to be in the previous segment.
*/
#define XLByteInSeg(xlrp, logId, logSeg) \
((xlrp).xlogid == (logId) && \
(xlrp).xrecoff / XLogSegSize == (logSeg))
#define XLByteInPrevSeg(xlrp, logId, logSeg) \
((xlrp).xlogid == (logId) && \
((xlrp).xrecoff - 1) / XLogSegSize == (logSeg))
#define XLogFileName(path, log, seg) \
snprintf(path, MAXPGPATH, "%s%c%08X%08X", \
XLogDir, SEP_CHAR, log, seg)
/*
* _INTL_MAXLOGRECSZ: max space needed for a record including header and
* any backup-block data.
*/
#define _INTL_MAXLOGRECSZ (SizeOfXLogRecord + MAXLOGRECSZ + \
XLR_MAX_BKP_BLOCKS * (sizeof(BkpBlock) + BLCKSZ))
/******************** end of stuff copied from xlog.c ********************/
static char *DataDir; /* locations of important stuff */
static char XLogDir[MAXPGPATH];
static char ControlFilePath[MAXPGPATH];
static ControlFileData ControlFile; /* pg_control values */
static bool guessed = false; /* T if we had to guess at any values */
static bool CheckControlVersion0(char *buffer, int len);
static int
XLogFileOpen(uint32 log, uint32 seg)
{
char path[MAXPGPATH];
int fd;
XLogFileName(path, log, seg);
fd = open(path, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR);
return (fd);
}
/*
* 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)
{
/* Seems to be current 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;
}
/*
* Maybe it's a 7.1beta pg_control.
*/
if (CheckControlVersion0(buffer, len))
return true;
/* Looks like it's a mess. */
fprintf(stderr, "pg_control exists but is broken or unknown version; ignoring it.\n");
return false;
}
/******************* routines for old XLOG format *******************/
/*
* This format was in use in 7.1 beta releases through 7.1beta5. The
* pg_control layout was different, and so were the XLOG page headers.
* The XLOG record header format was physically the same as 7.1 release,
* but interpretation of the xl_len field was not.
*/
typedef struct crc64V0
{
uint32 crc1;
uint32 crc2;
} crc64V0;
static uint32 crc_tableV0[] = {
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};
#define INIT_CRC64V0(crc) ((crc).crc1 = 0xffffffff, (crc).crc2 = 0xffffffff)
#define FIN_CRC64V0(crc) ((crc).crc1 ^= 0xffffffff, (crc).crc2 ^= 0xffffffff)
#define COMP_CRC64V0(crc, data, len) \
{\
uint32 __c1 = (crc).crc1;\
uint32 __c2 = (crc).crc2;\
char *__data = (char *) (data);\
uint32 __len = (len);\
\
while (__len >= 2)\
{\
__c1 = crc_tableV0[(__c1 ^ *__data++) & 0xff] ^ (__c1 >> 8);\
__c2 = crc_tableV0[(__c2 ^ *__data++) & 0xff] ^ (__c2 >> 8);\
__len -= 2;\
}\
if (__len > 0)\
__c1 = crc_tableV0[(__c1 ^ *__data++) & 0xff] ^ (__c1 >> 8);\
(crc).crc1 = __c1;\
(crc).crc2 = __c2;\
}
#define EQ_CRC64V0(c1,c2) ((c1).crc1 == (c2).crc1 && (c1).crc2 == (c2).crc2)
#define LOCALE_NAME_BUFLEN_V0 128
typedef struct ControlFileDataV0
{
crc64V0 crc;
uint32 logId; /* current log file id */
uint32 logSeg; /* current log file segment (1-based) */
XLogRecPtr checkPoint; /* last check point record ptr */
time_t time; /* time stamp of last modification */
DBState state; /* see enum above */
uint32 blcksz; /* block size for this DB */
uint32 relseg_size; /* blocks per segment of large relation */
uint32 catalog_version_no; /* internal version number */
char lc_collate[LOCALE_NAME_BUFLEN_V0];
char lc_ctype[LOCALE_NAME_BUFLEN_V0];
char archdir[MAXPGPATH]; /* where to move offline log files */
} ControlFileDataV0;
typedef struct CheckPointV0
{
XLogRecPtr redo; /* next RecPtr available when we */
/* began to create CheckPoint */
/* (i.e. REDO start point) */
XLogRecPtr undo; /* first record of oldest in-progress */
/* transaction when we started */
/* (i.e. UNDO end point) */
StartUpID ThisStartUpID;
TransactionId nextXid;
Oid nextOid;
bool Shutdown;
} CheckPointV0;
typedef struct XLogRecordV0
{
crc64V0 xl_crc;
XLogRecPtr xl_prev; /* ptr to previous record in log */
XLogRecPtr xl_xact_prev; /* ptr to previous record of this xact */
TransactionId xl_xid; /* xact id */
uint16 xl_len; /* total len of record *data* */
uint8 xl_info;
RmgrId xl_rmid; /* resource manager inserted this record */
} XLogRecordV0;
#define SizeOfXLogRecordV0 DOUBLEALIGN(sizeof(XLogRecordV0))
typedef struct XLogContRecordV0
{
uint16 xl_len; /* len of data left */
} XLogContRecordV0;
#define SizeOfXLogContRecordV0 DOUBLEALIGN(sizeof(XLogContRecordV0))
#define XLOG_PAGE_MAGIC_V0 0x17345168
typedef struct XLogPageHeaderDataV0
{
uint32 xlp_magic;
uint16 xlp_info;
} XLogPageHeaderDataV0;
#define SizeOfXLogPHDV0 DOUBLEALIGN(sizeof(XLogPageHeaderDataV0))
typedef XLogPageHeaderDataV0 *XLogPageHeaderV0;
static bool RecordIsValidV0(XLogRecordV0 *record);
static XLogRecordV0 *ReadRecordV0(XLogRecPtr *RecPtr, char *buffer);
static bool ValidXLOGHeaderV0(XLogPageHeaderV0 hdr);
/*
* Try to interpret pg_control contents as "version 0" format.
*/
static bool
CheckControlVersion0(char *buffer, int len)
{
crc64V0 crc;
ControlFileDataV0 *oldfile;
XLogRecordV0 *record;
CheckPointV0 *oldchkpt;
if (len < sizeof(ControlFileDataV0))
return false;
/* Check CRC the version-0 way. */
INIT_CRC64V0(crc);
COMP_CRC64V0(crc,
buffer + sizeof(crc64V0),
sizeof(ControlFileDataV0) - sizeof(crc64V0));
FIN_CRC64V0(crc);
if (!EQ_CRC64V0(crc, ((ControlFileDataV0 *) buffer)->crc))
return false;
/* Valid data, convert useful fields to new-style pg_control format */
oldfile = (ControlFileDataV0 *) buffer;
memset(&ControlFile, 0, sizeof(ControlFile));
ControlFile.pg_control_version = PG_CONTROL_VERSION;
ControlFile.catalog_version_no = oldfile->catalog_version_no;
ControlFile.state = oldfile->state;
ControlFile.blcksz = oldfile->blcksz;
ControlFile.relseg_size = oldfile->relseg_size;
strcpy(ControlFile.lc_collate, oldfile->lc_collate);
strcpy(ControlFile.lc_ctype, oldfile->lc_ctype);
/*
* Since this format did not include a copy of the latest checkpoint
* record, we have to go rooting in the old XLOG to get that.
*/
record = ReadRecordV0(&oldfile->checkPoint,
(char *) malloc(_INTL_MAXLOGRECSZ));
if (record == NULL)
{
/*
* We have to guess at the checkpoint contents.
*/
guessed = true;
ControlFile.checkPointCopy.ThisStartUpID = 0;
ControlFile.checkPointCopy.nextXid = (TransactionId) 514; /* XXX */
ControlFile.checkPointCopy.nextOid = BootstrapObjectIdData;
return true;
}
oldchkpt = (CheckPointV0 *) XLogRecGetData(record);
ControlFile.checkPointCopy.ThisStartUpID = oldchkpt->ThisStartUpID;
ControlFile.checkPointCopy.nextXid = oldchkpt->nextXid;
ControlFile.checkPointCopy.nextOid = oldchkpt->nextOid;
return true;
}
/*
* CRC-check an XLOG V0 record. We do not believe the contents of an XLOG
* record (other than to the minimal extent of computing the amount of
* data to read in) until we've checked the CRCs.
*
* We assume all of the record has been read into memory at *record.
*/
static bool
RecordIsValidV0(XLogRecordV0 *record)
{
crc64V0 crc;
uint32 len = record->xl_len;
/*
* NB: this code is not right for V0 records containing backup blocks,
* but for now it's only going to be applied to checkpoint records,
* so I'm not going to worry about it...
*/
INIT_CRC64V0(crc);
COMP_CRC64V0(crc, XLogRecGetData(record), len);
COMP_CRC64V0(crc, (char*) record + sizeof(crc64V0),
SizeOfXLogRecordV0 - sizeof(crc64V0));
FIN_CRC64V0(crc);
if (!EQ_CRC64V0(record->xl_crc, crc))
return false;
return(true);
}
/*
* Attempt to read an XLOG V0 record at recptr.
*
* If no valid record is available, returns NULL.
*
* buffer is a workspace at least _INTL_MAXLOGRECSZ bytes long. It is needed
* to reassemble a record that crosses block boundaries. Note that on
* successful return, the returned record pointer always points at buffer.
*/
static XLogRecordV0 *
ReadRecordV0(XLogRecPtr *RecPtr, char *buffer)
{
static int readFile = -1;
static uint32 readId = 0;
static uint32 readSeg = 0;
static uint32 readOff = 0;
static char *readBuf = NULL;
XLogRecordV0 *record;
uint32 len,
total_len;
uint32 targetPageOff;
if (readBuf == NULL)
readBuf = (char *) malloc(BLCKSZ);
XLByteToSeg(*RecPtr, readId, readSeg);
if (readFile < 0)
{
readFile = XLogFileOpen(readId, readSeg);
if (readFile < 0)
goto next_record_is_invalid;
readOff = (uint32) (-1); /* force read to occur below */
}
targetPageOff = ((RecPtr->xrecoff % XLogSegSize) / BLCKSZ) * BLCKSZ;
if (readOff != targetPageOff)
{
readOff = targetPageOff;
if (lseek(readFile, (off_t) readOff, SEEK_SET) < 0)
goto next_record_is_invalid;
if (read(readFile, readBuf, BLCKSZ) != BLCKSZ)
goto next_record_is_invalid;
if (!ValidXLOGHeaderV0((XLogPageHeaderV0) readBuf))
goto next_record_is_invalid;
}
if ((((XLogPageHeaderV0) readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
RecPtr->xrecoff % BLCKSZ == SizeOfXLogPHDV0)
goto next_record_is_invalid;
record = (XLogRecordV0 *) ((char *) readBuf + RecPtr->xrecoff % BLCKSZ);
if (record->xl_len == 0)
goto next_record_is_invalid;
/*
* Compute total length of record including any appended backup blocks.
*/
total_len = SizeOfXLogRecordV0 + record->xl_len;
/*
* Make sure it will fit in buffer (currently, it is mechanically
* impossible for this test to fail, but it seems like a good idea
* anyway).
*/
if (total_len > _INTL_MAXLOGRECSZ)
goto next_record_is_invalid;
len = BLCKSZ - RecPtr->xrecoff % BLCKSZ;
if (total_len > len)
{
/* Need to reassemble record */
XLogContRecordV0 *contrecord;
uint32 gotlen = len;
memcpy(buffer, record, len);
record = (XLogRecordV0 *) buffer;
buffer += len;
for (;;)
{
readOff += BLCKSZ;
if (readOff >= XLogSegSize)
{
close(readFile);
readFile = -1;
NextLogSeg(readId, readSeg);
readFile = XLogFileOpen(readId, readSeg);
if (readFile < 0)
goto next_record_is_invalid;
readOff = 0;
}
if (read(readFile, readBuf, BLCKSZ) != BLCKSZ)
goto next_record_is_invalid;
if (!ValidXLOGHeaderV0((XLogPageHeaderV0) readBuf))
goto next_record_is_invalid;
if (!(((XLogPageHeaderV0) readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD))
goto next_record_is_invalid;
contrecord = (XLogContRecordV0 *) ((char *) readBuf + SizeOfXLogPHDV0);
if (contrecord->xl_len == 0 ||
total_len != (contrecord->xl_len + gotlen))
goto next_record_is_invalid;
len = BLCKSZ - SizeOfXLogPHDV0 - SizeOfXLogContRecordV0;
if (contrecord->xl_len > len)
{
memcpy(buffer, (char *)contrecord + SizeOfXLogContRecordV0, len);
gotlen += len;
buffer += len;
continue;
}
memcpy(buffer, (char *) contrecord + SizeOfXLogContRecordV0,
contrecord->xl_len);
break;
}
if (!RecordIsValidV0(record))
goto next_record_is_invalid;
return record;
}
/* Record does not cross a page boundary */
if (!RecordIsValidV0(record))
goto next_record_is_invalid;
memcpy(buffer, record, total_len);
return (XLogRecordV0 *) buffer;
next_record_is_invalid:;
close(readFile);
readFile = -1;
return NULL;
}
/*
* Check whether the xlog header of a page just read in looks valid.
*
* This is just a convenience subroutine to avoid duplicated code in
* ReadRecord. It's not intended for use from anywhere else.
*/
static bool
ValidXLOGHeaderV0(XLogPageHeaderV0 hdr)
{
if (hdr->xlp_magic != XLOG_PAGE_MAGIC_V0)
return false;
if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0)
return false;
return true;
}
/******************* end of routines for old XLOG format *******************/
/*
* 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(void)
{
printf("Guessed-at pg_control values:\n\n"
"pg_control version number: %u\n"
"Catalog version number: %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",
ControlFile.pg_control_version,
ControlFile.catalog_version_no,
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.
*/
ControlFile.checkPointCopy.redo.xlogid = 0;
ControlFile.checkPointCopy.redo.xrecoff = SizeOfXLogPHD;
ControlFile.checkPointCopy.undo = ControlFile.checkPointCopy.redo;
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.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);
}
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
{
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)
{
sprintf(path, "%s%c%s", XLogDir, SEP_CHAR, 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;
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, 0, 0);
unlink(path);
fd = open(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
{
perror(path);
exit(1);
}
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
{
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)
{
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
{
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] PGDataDirectory\n\n"
" -f\tforce update to be done\n"
" -n\tno update, just show extracted pg_control values (for testing)\n");
exit(1);
}
int
main(int argc, char ** argv)
{
int argn;
bool force = false;
bool noupdate = false;
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
usage();
}
if (argn != argc-1) /* one required non-switch argument */
usage();
DataDir = argv[argn++];
snprintf(XLogDir, MAXPGPATH, "%s%cpg_xlog", DataDir, SEP_CHAR);
snprintf(ControlFilePath, MAXPGPATH, "%s%cglobal%cpg_control",
DataDir, SEP_CHAR, SEP_CHAR);
/*
* 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%cpostmaster.pid", DataDir, SEP_CHAR);
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();
if (!noupdate)
printf("\nIf these values seem acceptable, use -f to force reset.\n");
exit(1);
}
/*
* 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.
*/
RewriteControlFile();
KillExistingXLOG();
WriteEmptyXLOG();
printf("XLOG reset.\n");
return 0;
}
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