--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * 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;
+}
projects / postgresql / commitdiff