PostgreSQL Source Code  git master
xlogreader.c File Reference
#include "postgres.h"
#include <unistd.h>
#include "access/transam.h"
#include "access/xlog_internal.h"
#include "access/xlogreader.h"
#include "access/xlogrecord.h"
#include "catalog/pg_control.h"
#include "common/pg_lzcompress.h"
#include "replication/origin.h"
#include "pgstat.h"
Include dependency graph for xlogreader.c:

Go to the source code of this file.

Macros

#define MAX_ERRORMSG_LEN   1000
 
#define DEFAULT_DECODE_BUFFER_SIZE   (64 * 1024)
 
#define COPY_HEADER_FIELD(_dst, _size)
 

Functions

static void report_invalid_record (XLogReaderState *state, const char *fmt,...) pg_attribute_printf(2
 
static void static void allocate_recordbuf (XLogReaderState *state, uint32 reclength)
 
static int ReadPageInternal (XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
 
static void XLogReaderInvalReadState (XLogReaderState *state)
 
static XLogPageReadResult XLogDecodeNextRecord (XLogReaderState *state, bool nonblocking)
 
static bool ValidXLogRecordHeader (XLogReaderState *state, XLogRecPtr RecPtr, XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess)
 
static bool ValidXLogRecord (XLogReaderState *state, XLogRecord *record, XLogRecPtr recptr)
 
static void ResetDecoder (XLogReaderState *state)
 
static void WALOpenSegmentInit (WALOpenSegment *seg, WALSegmentContext *segcxt, int segsize, const char *waldir)
 
void XLogReaderSetDecodeBuffer (XLogReaderState *state, void *buffer, size_t size)
 
XLogReaderStateXLogReaderAllocate (int wal_segment_size, const char *waldir, XLogReaderRoutine *routine, void *private_data)
 
void XLogReaderFree (XLogReaderState *state)
 
void XLogBeginRead (XLogReaderState *state, XLogRecPtr RecPtr)
 
XLogRecPtr XLogReleasePreviousRecord (XLogReaderState *state)
 
DecodedXLogRecordXLogNextRecord (XLogReaderState *state, char **errormsg)
 
XLogRecordXLogReadRecord (XLogReaderState *state, char **errormsg)
 
static DecodedXLogRecordXLogReadRecordAlloc (XLogReaderState *state, size_t xl_tot_len, bool allow_oversized)
 
DecodedXLogRecordXLogReadAhead (XLogReaderState *state, bool nonblocking)
 
bool XLogReaderValidatePageHeader (XLogReaderState *state, XLogRecPtr recptr, char *phdr)
 
void XLogReaderResetError (XLogReaderState *state)
 
XLogRecPtr XLogFindNextRecord (XLogReaderState *state, XLogRecPtr RecPtr)
 
bool WALRead (XLogReaderState *state, char *buf, XLogRecPtr startptr, Size count, TimeLineID tli, WALReadError *errinfo)
 
size_t DecodeXLogRecordRequiredSpace (size_t xl_tot_len)
 
bool DecodeXLogRecord (XLogReaderState *state, DecodedXLogRecord *decoded, XLogRecord *record, XLogRecPtr lsn, char **errormsg)
 
void XLogRecGetBlockTag (XLogReaderState *record, uint8 block_id, RelFileLocator *rlocator, ForkNumber *forknum, BlockNumber *blknum)
 
bool XLogRecGetBlockTagExtended (XLogReaderState *record, uint8 block_id, RelFileLocator *rlocator, ForkNumber *forknum, BlockNumber *blknum, Buffer *prefetch_buffer)
 
char * XLogRecGetBlockData (XLogReaderState *record, uint8 block_id, Size *len)
 
bool RestoreBlockImage (XLogReaderState *record, uint8 block_id, char *page)
 
FullTransactionId XLogRecGetFullXid (XLogReaderState *record)
 

Macro Definition Documentation

◆ COPY_HEADER_FIELD

#define COPY_HEADER_FIELD (   _dst,
  _size 
)
Value:
do { \
if (remaining < _size) \
goto shortdata_err; \
memcpy(_dst, ptr, _size); \
ptr += _size; \
remaining -= _size; \
} while(0)
int remaining
Definition: informix.c:673

◆ DEFAULT_DECODE_BUFFER_SIZE

#define DEFAULT_DECODE_BUFFER_SIZE   (64 * 1024)

Definition at line 64 of file xlogreader.c.

◆ MAX_ERRORMSG_LEN

#define MAX_ERRORMSG_LEN   1000

Definition at line 58 of file xlogreader.c.

Function Documentation

◆ allocate_recordbuf()

static void allocate_recordbuf ( XLogReaderState state,
uint32  reclength 
)
static

Definition at line 190 of file xlogreader.c.

191 {
192  uint32 newSize = reclength;
193 
194  newSize += XLOG_BLCKSZ - (newSize % XLOG_BLCKSZ);
195  newSize = Max(newSize, 5 * Max(BLCKSZ, XLOG_BLCKSZ));
196 
197  if (state->readRecordBuf)
198  pfree(state->readRecordBuf);
199  state->readRecordBuf = (char *) palloc(newSize);
200  state->readRecordBufSize = newSize;
201 }
unsigned int uint32
Definition: c.h:506
#define Max(x, y)
Definition: c.h:998
void pfree(void *pointer)
Definition: mcxt.c:1520
void * palloc(Size size)
Definition: mcxt.c:1316
Definition: regguts.h:323

References Max, palloc(), and pfree().

Referenced by XLogDecodeNextRecord(), and XLogReaderAllocate().

◆ DecodeXLogRecord()

bool DecodeXLogRecord ( XLogReaderState state,
DecodedXLogRecord decoded,
XLogRecord record,
XLogRecPtr  lsn,
char **  errormsg 
)

Definition at line 1662 of file xlogreader.c.

1667 {
1668  /*
1669  * read next _size bytes from record buffer, but check for overrun first.
1670  */
1671 #define COPY_HEADER_FIELD(_dst, _size) \
1672  do { \
1673  if (remaining < _size) \
1674  goto shortdata_err; \
1675  memcpy(_dst, ptr, _size); \
1676  ptr += _size; \
1677  remaining -= _size; \
1678  } while(0)
1679 
1680  char *ptr;
1681  char *out;
1682  uint32 remaining;
1683  uint32 datatotal;
1684  RelFileLocator *rlocator = NULL;
1685  uint8 block_id;
1686 
1687  decoded->header = *record;
1688  decoded->lsn = lsn;
1689  decoded->next = NULL;
1690  decoded->record_origin = InvalidRepOriginId;
1692  decoded->main_data = NULL;
1693  decoded->main_data_len = 0;
1694  decoded->max_block_id = -1;
1695  ptr = (char *) record;
1696  ptr += SizeOfXLogRecord;
1698 
1699  /* Decode the headers */
1700  datatotal = 0;
1701  while (remaining > datatotal)
1702  {
1703  COPY_HEADER_FIELD(&block_id, sizeof(uint8));
1704 
1705  if (block_id == XLR_BLOCK_ID_DATA_SHORT)
1706  {
1707  /* XLogRecordDataHeaderShort */
1708  uint8 main_data_len;
1709 
1710  COPY_HEADER_FIELD(&main_data_len, sizeof(uint8));
1711 
1712  decoded->main_data_len = main_data_len;
1713  datatotal += main_data_len;
1714  break; /* by convention, the main data fragment is
1715  * always last */
1716  }
1717  else if (block_id == XLR_BLOCK_ID_DATA_LONG)
1718  {
1719  /* XLogRecordDataHeaderLong */
1720  uint32 main_data_len;
1721 
1722  COPY_HEADER_FIELD(&main_data_len, sizeof(uint32));
1723  decoded->main_data_len = main_data_len;
1724  datatotal += main_data_len;
1725  break; /* by convention, the main data fragment is
1726  * always last */
1727  }
1728  else if (block_id == XLR_BLOCK_ID_ORIGIN)
1729  {
1730  COPY_HEADER_FIELD(&decoded->record_origin, sizeof(RepOriginId));
1731  }
1732  else if (block_id == XLR_BLOCK_ID_TOPLEVEL_XID)
1733  {
1734  COPY_HEADER_FIELD(&decoded->toplevel_xid, sizeof(TransactionId));
1735  }
1736  else if (block_id <= XLR_MAX_BLOCK_ID)
1737  {
1738  /* XLogRecordBlockHeader */
1739  DecodedBkpBlock *blk;
1740  uint8 fork_flags;
1741 
1742  /* mark any intervening block IDs as not in use */
1743  for (int i = decoded->max_block_id + 1; i < block_id; ++i)
1744  decoded->blocks[i].in_use = false;
1745 
1746  if (block_id <= decoded->max_block_id)
1747  {
1749  "out-of-order block_id %u at %X/%X",
1750  block_id,
1751  LSN_FORMAT_ARGS(state->ReadRecPtr));
1752  goto err;
1753  }
1754  decoded->max_block_id = block_id;
1755 
1756  blk = &decoded->blocks[block_id];
1757  blk->in_use = true;
1758  blk->apply_image = false;
1759 
1760  COPY_HEADER_FIELD(&fork_flags, sizeof(uint8));
1761  blk->forknum = fork_flags & BKPBLOCK_FORK_MASK;
1762  blk->flags = fork_flags;
1763  blk->has_image = ((fork_flags & BKPBLOCK_HAS_IMAGE) != 0);
1764  blk->has_data = ((fork_flags & BKPBLOCK_HAS_DATA) != 0);
1765 
1767 
1768  COPY_HEADER_FIELD(&blk->data_len, sizeof(uint16));
1769  /* cross-check that the HAS_DATA flag is set iff data_length > 0 */
1770  if (blk->has_data && blk->data_len == 0)
1771  {
1773  "BKPBLOCK_HAS_DATA set, but no data included at %X/%X",
1774  LSN_FORMAT_ARGS(state->ReadRecPtr));
1775  goto err;
1776  }
1777  if (!blk->has_data && blk->data_len != 0)
1778  {
1780  "BKPBLOCK_HAS_DATA not set, but data length is %u at %X/%X",
1781  (unsigned int) blk->data_len,
1782  LSN_FORMAT_ARGS(state->ReadRecPtr));
1783  goto err;
1784  }
1785  datatotal += blk->data_len;
1786 
1787  if (blk->has_image)
1788  {
1789  COPY_HEADER_FIELD(&blk->bimg_len, sizeof(uint16));
1790  COPY_HEADER_FIELD(&blk->hole_offset, sizeof(uint16));
1791  COPY_HEADER_FIELD(&blk->bimg_info, sizeof(uint8));
1792 
1793  blk->apply_image = ((blk->bimg_info & BKPIMAGE_APPLY) != 0);
1794 
1795  if (BKPIMAGE_COMPRESSED(blk->bimg_info))
1796  {
1797  if (blk->bimg_info & BKPIMAGE_HAS_HOLE)
1798  COPY_HEADER_FIELD(&blk->hole_length, sizeof(uint16));
1799  else
1800  blk->hole_length = 0;
1801  }
1802  else
1803  blk->hole_length = BLCKSZ - blk->bimg_len;
1804  datatotal += blk->bimg_len;
1805 
1806  /*
1807  * cross-check that hole_offset > 0, hole_length > 0 and
1808  * bimg_len < BLCKSZ if the HAS_HOLE flag is set.
1809  */
1810  if ((blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1811  (blk->hole_offset == 0 ||
1812  blk->hole_length == 0 ||
1813  blk->bimg_len == BLCKSZ))
1814  {
1816  "BKPIMAGE_HAS_HOLE set, but hole offset %u length %u block image length %u at %X/%X",
1817  (unsigned int) blk->hole_offset,
1818  (unsigned int) blk->hole_length,
1819  (unsigned int) blk->bimg_len,
1820  LSN_FORMAT_ARGS(state->ReadRecPtr));
1821  goto err;
1822  }
1823 
1824  /*
1825  * cross-check that hole_offset == 0 and hole_length == 0 if
1826  * the HAS_HOLE flag is not set.
1827  */
1828  if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1829  (blk->hole_offset != 0 || blk->hole_length != 0))
1830  {
1832  "BKPIMAGE_HAS_HOLE not set, but hole offset %u length %u at %X/%X",
1833  (unsigned int) blk->hole_offset,
1834  (unsigned int) blk->hole_length,
1835  LSN_FORMAT_ARGS(state->ReadRecPtr));
1836  goto err;
1837  }
1838 
1839  /*
1840  * Cross-check that bimg_len < BLCKSZ if it is compressed.
1841  */
1842  if (BKPIMAGE_COMPRESSED(blk->bimg_info) &&
1843  blk->bimg_len == BLCKSZ)
1844  {
1846  "BKPIMAGE_COMPRESSED set, but block image length %u at %X/%X",
1847  (unsigned int) blk->bimg_len,
1848  LSN_FORMAT_ARGS(state->ReadRecPtr));
1849  goto err;
1850  }
1851 
1852  /*
1853  * cross-check that bimg_len = BLCKSZ if neither HAS_HOLE is
1854  * set nor COMPRESSED().
1855  */
1856  if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1857  !BKPIMAGE_COMPRESSED(blk->bimg_info) &&
1858  blk->bimg_len != BLCKSZ)
1859  {
1861  "neither BKPIMAGE_HAS_HOLE nor BKPIMAGE_COMPRESSED set, but block image length is %u at %X/%X",
1862  (unsigned int) blk->data_len,
1863  LSN_FORMAT_ARGS(state->ReadRecPtr));
1864  goto err;
1865  }
1866  }
1867  if (!(fork_flags & BKPBLOCK_SAME_REL))
1868  {
1869  COPY_HEADER_FIELD(&blk->rlocator, sizeof(RelFileLocator));
1870  rlocator = &blk->rlocator;
1871  }
1872  else
1873  {
1874  if (rlocator == NULL)
1875  {
1877  "BKPBLOCK_SAME_REL set but no previous rel at %X/%X",
1878  LSN_FORMAT_ARGS(state->ReadRecPtr));
1879  goto err;
1880  }
1881 
1882  blk->rlocator = *rlocator;
1883  }
1884  COPY_HEADER_FIELD(&blk->blkno, sizeof(BlockNumber));
1885  }
1886  else
1887  {
1889  "invalid block_id %u at %X/%X",
1890  block_id, LSN_FORMAT_ARGS(state->ReadRecPtr));
1891  goto err;
1892  }
1893  }
1894 
1895  if (remaining != datatotal)
1896  goto shortdata_err;
1897 
1898  /*
1899  * Ok, we've parsed the fragment headers, and verified that the total
1900  * length of the payload in the fragments is equal to the amount of data
1901  * left. Copy the data of each fragment to contiguous space after the
1902  * blocks array, inserting alignment padding before the data fragments so
1903  * they can be cast to struct pointers by REDO routines.
1904  */
1905  out = ((char *) decoded) +
1906  offsetof(DecodedXLogRecord, blocks) +
1907  sizeof(decoded->blocks[0]) * (decoded->max_block_id + 1);
1908 
1909  /* block data first */
1910  for (block_id = 0; block_id <= decoded->max_block_id; block_id++)
1911  {
1912  DecodedBkpBlock *blk = &decoded->blocks[block_id];
1913 
1914  if (!blk->in_use)
1915  continue;
1916 
1917  Assert(blk->has_image || !blk->apply_image);
1918 
1919  if (blk->has_image)
1920  {
1921  /* no need to align image */
1922  blk->bkp_image = out;
1923  memcpy(out, ptr, blk->bimg_len);
1924  ptr += blk->bimg_len;
1925  out += blk->bimg_len;
1926  }
1927  if (blk->has_data)
1928  {
1929  out = (char *) MAXALIGN(out);
1930  blk->data = out;
1931  memcpy(blk->data, ptr, blk->data_len);
1932  ptr += blk->data_len;
1933  out += blk->data_len;
1934  }
1935  }
1936 
1937  /* and finally, the main data */
1938  if (decoded->main_data_len > 0)
1939  {
1940  out = (char *) MAXALIGN(out);
1941  decoded->main_data = out;
1942  memcpy(decoded->main_data, ptr, decoded->main_data_len);
1943  ptr += decoded->main_data_len;
1944  out += decoded->main_data_len;
1945  }
1946 
1947  /* Report the actual size we used. */
1948  decoded->size = MAXALIGN(out - (char *) decoded);
1950  decoded->size);
1951 
1952  return true;
1953 
1954 shortdata_err:
1956  "record with invalid length at %X/%X",
1957  LSN_FORMAT_ARGS(state->ReadRecPtr));
1958 err:
1959  *errormsg = state->errormsg_buf;
1960 
1961  return false;
1962 }
uint32 BlockNumber
Definition: block.h:31
#define InvalidBuffer
Definition: buf.h:25
unsigned short uint16
Definition: c.h:505
#define MAXALIGN(LEN)
Definition: c.h:811
#define Assert(condition)
Definition: c.h:858
unsigned char uint8
Definition: c.h:504
uint32 TransactionId
Definition: c.h:652
void err(int eval, const char *fmt,...)
Definition: err.c:43
int i
Definition: isn.c:73
#define InvalidRepOriginId
Definition: origin.h:33
uint16 hole_length
Definition: xlogreader.h:140
char * bkp_image
Definition: xlogreader.h:138
Buffer prefetch_buffer
Definition: xlogreader.h:130
RelFileLocator rlocator
Definition: xlogreader.h:125
BlockNumber blkno
Definition: xlogreader.h:127
ForkNumber forknum
Definition: xlogreader.h:126
uint16 hole_offset
Definition: xlogreader.h:139
XLogRecord header
Definition: xlogreader.h:166
struct DecodedXLogRecord * next
Definition: xlogreader.h:161
TransactionId toplevel_xid
Definition: xlogreader.h:168
uint32 main_data_len
Definition: xlogreader.h:170
RepOriginId record_origin
Definition: xlogreader.h:167
DecodedBkpBlock blocks[FLEXIBLE_ARRAY_MEMBER]
Definition: xlogreader.h:172
XLogRecPtr lsn
Definition: xlogreader.h:164
uint32 xl_tot_len
Definition: xlogrecord.h:43
#define InvalidTransactionId
Definition: transam.h:31
#define LSN_FORMAT_ARGS(lsn)
Definition: xlogdefs.h:43
uint16 RepOriginId
Definition: xlogdefs.h:65
static void report_invalid_record(XLogReaderState *state, const char *fmt,...) pg_attribute_printf(2
Definition: xlogreader.c:71
#define COPY_HEADER_FIELD(_dst, _size)
size_t DecodeXLogRecordRequiredSpace(size_t xl_tot_len)
Definition: xlogreader.c:1629
#define BKPBLOCK_FORK_MASK
Definition: xlogrecord.h:195
#define BKPBLOCK_HAS_DATA
Definition: xlogrecord.h:198
#define BKPIMAGE_APPLY
Definition: xlogrecord.h:158
#define BKPIMAGE_HAS_HOLE
Definition: xlogrecord.h:157
#define XLR_BLOCK_ID_DATA_LONG
Definition: xlogrecord.h:242
#define BKPIMAGE_COMPRESSED(info)
Definition: xlogrecord.h:164
#define XLR_BLOCK_ID_TOPLEVEL_XID
Definition: xlogrecord.h:244
#define XLR_BLOCK_ID_DATA_SHORT
Definition: xlogrecord.h:241
#define XLR_MAX_BLOCK_ID
Definition: xlogrecord.h:239
#define BKPBLOCK_SAME_REL
Definition: xlogrecord.h:200
#define XLR_BLOCK_ID_ORIGIN
Definition: xlogrecord.h:243
#define SizeOfXLogRecord
Definition: xlogrecord.h:55
#define BKPBLOCK_HAS_IMAGE
Definition: xlogrecord.h:197

References DecodedBkpBlock::apply_image, Assert, DecodedBkpBlock::bimg_info, DecodedBkpBlock::bimg_len, DecodedBkpBlock::bkp_image, BKPBLOCK_FORK_MASK, BKPBLOCK_HAS_DATA, BKPBLOCK_HAS_IMAGE, BKPBLOCK_SAME_REL, BKPIMAGE_APPLY, BKPIMAGE_COMPRESSED, BKPIMAGE_HAS_HOLE, DecodedBkpBlock::blkno, DecodedXLogRecord::blocks, COPY_HEADER_FIELD, DecodedBkpBlock::data, DecodedBkpBlock::data_len, DecodeXLogRecordRequiredSpace(), err(), DecodedBkpBlock::flags, DecodedBkpBlock::forknum, DecodedBkpBlock::has_data, DecodedBkpBlock::has_image, DecodedXLogRecord::header, DecodedBkpBlock::hole_length, DecodedBkpBlock::hole_offset, i, DecodedBkpBlock::in_use, InvalidBuffer, InvalidRepOriginId, InvalidTransactionId, DecodedXLogRecord::lsn, LSN_FORMAT_ARGS, DecodedXLogRecord::main_data, DecodedXLogRecord::main_data_len, DecodedXLogRecord::max_block_id, MAXALIGN, DecodedXLogRecord::next, DecodedBkpBlock::prefetch_buffer, DecodedXLogRecord::record_origin, remaining, report_invalid_record(), DecodedBkpBlock::rlocator, DecodedXLogRecord::size, SizeOfXLogRecord, DecodedXLogRecord::toplevel_xid, XLogRecord::xl_tot_len, XLR_BLOCK_ID_DATA_LONG, XLR_BLOCK_ID_DATA_SHORT, XLR_BLOCK_ID_ORIGIN, XLR_BLOCK_ID_TOPLEVEL_XID, and XLR_MAX_BLOCK_ID.

Referenced by XLogDecodeNextRecord(), and XLogInsertRecord().

◆ DecodeXLogRecordRequiredSpace()

size_t DecodeXLogRecordRequiredSpace ( size_t  xl_tot_len)

Definition at line 1629 of file xlogreader.c.

1630 {
1631  size_t size = 0;
1632 
1633  /* Account for the fixed size part of the decoded record struct. */
1634  size += offsetof(DecodedXLogRecord, blocks[0]);
1635  /* Account for the flexible blocks array of maximum possible size. */
1636  size += sizeof(DecodedBkpBlock) * (XLR_MAX_BLOCK_ID + 1);
1637  /* Account for all the raw main and block data. */
1638  size += xl_tot_len;
1639  /* We might insert padding before main_data. */
1640  size += (MAXIMUM_ALIGNOF - 1);
1641  /* We might insert padding before each block's data. */
1642  size += (MAXIMUM_ALIGNOF - 1) * (XLR_MAX_BLOCK_ID + 1);
1643  /* We might insert padding at the end. */
1644  size += (MAXIMUM_ALIGNOF - 1);
1645 
1646  return size;
1647 }
static pg_noinline void Size size
Definition: slab.c:607

References size, and XLR_MAX_BLOCK_ID.

Referenced by DecodeXLogRecord(), InitXLogInsert(), XLogInsertRecord(), and XLogReadRecordAlloc().

◆ ReadPageInternal()

static int ReadPageInternal ( XLogReaderState state,
XLogRecPtr  pageptr,
int  reqLen 
)
static

Definition at line 1000 of file xlogreader.c.

1001 {
1002  int readLen;
1003  uint32 targetPageOff;
1004  XLogSegNo targetSegNo;
1005  XLogPageHeader hdr;
1006 
1007  Assert((pageptr % XLOG_BLCKSZ) == 0);
1008 
1009  XLByteToSeg(pageptr, targetSegNo, state->segcxt.ws_segsize);
1010  targetPageOff = XLogSegmentOffset(pageptr, state->segcxt.ws_segsize);
1011 
1012  /* check whether we have all the requested data already */
1013  if (targetSegNo == state->seg.ws_segno &&
1014  targetPageOff == state->segoff && reqLen <= state->readLen)
1015  return state->readLen;
1016 
1017  /*
1018  * Invalidate contents of internal buffer before read attempt. Just set
1019  * the length to 0, rather than a full XLogReaderInvalReadState(), so we
1020  * don't forget the segment we last successfully read.
1021  */
1022  state->readLen = 0;
1023 
1024  /*
1025  * Data is not in our buffer.
1026  *
1027  * Every time we actually read the segment, even if we looked at parts of
1028  * it before, we need to do verification as the page_read callback might
1029  * now be rereading data from a different source.
1030  *
1031  * Whenever switching to a new WAL segment, we read the first page of the
1032  * file and validate its header, even if that's not where the target
1033  * record is. This is so that we can check the additional identification
1034  * info that is present in the first page's "long" header.
1035  */
1036  if (targetSegNo != state->seg.ws_segno && targetPageOff != 0)
1037  {
1038  XLogRecPtr targetSegmentPtr = pageptr - targetPageOff;
1039 
1040  readLen = state->routine.page_read(state, targetSegmentPtr, XLOG_BLCKSZ,
1041  state->currRecPtr,
1042  state->readBuf);
1043  if (readLen == XLREAD_WOULDBLOCK)
1044  return XLREAD_WOULDBLOCK;
1045  else if (readLen < 0)
1046  goto err;
1047 
1048  /* we can be sure to have enough WAL available, we scrolled back */
1049  Assert(readLen == XLOG_BLCKSZ);
1050 
1051  if (!XLogReaderValidatePageHeader(state, targetSegmentPtr,
1052  state->readBuf))
1053  goto err;
1054  }
1055 
1056  /*
1057  * First, read the requested data length, but at least a short page header
1058  * so that we can validate it.
1059  */
1060  readLen = state->routine.page_read(state, pageptr, Max(reqLen, SizeOfXLogShortPHD),
1061  state->currRecPtr,
1062  state->readBuf);
1063  if (readLen == XLREAD_WOULDBLOCK)
1064  return XLREAD_WOULDBLOCK;
1065  else if (readLen < 0)
1066  goto err;
1067 
1068  Assert(readLen <= XLOG_BLCKSZ);
1069 
1070  /* Do we have enough data to check the header length? */
1071  if (readLen <= SizeOfXLogShortPHD)
1072  goto err;
1073 
1074  Assert(readLen >= reqLen);
1075 
1076  hdr = (XLogPageHeader) state->readBuf;
1077 
1078  /* still not enough */
1079  if (readLen < XLogPageHeaderSize(hdr))
1080  {
1081  readLen = state->routine.page_read(state, pageptr, XLogPageHeaderSize(hdr),
1082  state->currRecPtr,
1083  state->readBuf);
1084  if (readLen == XLREAD_WOULDBLOCK)
1085  return XLREAD_WOULDBLOCK;
1086  else if (readLen < 0)
1087  goto err;
1088  }
1089 
1090  /*
1091  * Now that we know we have the full header, validate it.
1092  */
1093  if (!XLogReaderValidatePageHeader(state, pageptr, (char *) hdr))
1094  goto err;
1095 
1096  /* update read state information */
1097  state->seg.ws_segno = targetSegNo;
1098  state->segoff = targetPageOff;
1099  state->readLen = readLen;
1100 
1101  return readLen;
1102 
1103 err:
1105 
1106  return XLREAD_FAIL;
1107 }
if(TABLE==NULL||TABLE_index==NULL)
Definition: isn.c:77
#define XLogSegmentOffset(xlogptr, wal_segsz_bytes)
XLogPageHeaderData * XLogPageHeader
Definition: xlog_internal.h:54
#define XLByteToSeg(xlrp, logSegNo, wal_segsz_bytes)
#define SizeOfXLogShortPHD
Definition: xlog_internal.h:52
#define XLogPageHeaderSize(hdr)
Definition: xlog_internal.h:84
uint64 XLogRecPtr
Definition: xlogdefs.h:21
uint64 XLogSegNo
Definition: xlogdefs.h:48
static void XLogReaderInvalReadState(XLogReaderState *state)
Definition: xlogreader.c:1113
bool XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr, char *phdr)
Definition: xlogreader.c:1224
@ XLREAD_WOULDBLOCK
Definition: xlogreader.h:353
@ XLREAD_FAIL
Definition: xlogreader.h:352
static uint32 readLen
Definition: xlogrecovery.c:233

References Assert, err(), if(), Max, readLen, SizeOfXLogShortPHD, XLByteToSeg, XLogPageHeaderSize, XLogReaderInvalReadState(), XLogReaderValidatePageHeader(), XLogSegmentOffset, XLREAD_FAIL, and XLREAD_WOULDBLOCK.

Referenced by XLogDecodeNextRecord(), and XLogFindNextRecord().

◆ report_invalid_record()

static void report_invalid_record ( XLogReaderState state,
const char *  fmt,
  ... 
)
static

Definition at line 71 of file xlogreader.c.

72 {
73  va_list args;
74 
75  fmt = _(fmt);
76 
77  va_start(args, fmt);
78  vsnprintf(state->errormsg_buf, MAX_ERRORMSG_LEN, fmt, args);
79  va_end(args);
80 
81  state->errormsg_deferred = true;
82 }
#define _(x)
Definition: elog.c:90
static void const char * fmt
va_end(args)
va_start(args, fmt)
#define vsnprintf
Definition: port.h:237
#define MAX_ERRORMSG_LEN
Definition: xlogreader.c:58

References _, generate_unaccent_rules::args, fmt, MAX_ERRORMSG_LEN, va_end(), va_start(), and vsnprintf.

Referenced by DecodeXLogRecord(), RestoreBlockImage(), ValidXLogRecord(), ValidXLogRecordHeader(), XLogDecodeNextRecord(), and XLogReaderValidatePageHeader().

◆ ResetDecoder()

static void ResetDecoder ( XLogReaderState state)
static

Definition at line 1595 of file xlogreader.c.

1596 {
1597  DecodedXLogRecord *r;
1598 
1599  /* Reset the decoded record queue, freeing any oversized records. */
1600  while ((r = state->decode_queue_head) != NULL)
1601  {
1602  state->decode_queue_head = r->next;
1603  if (r->oversized)
1604  pfree(r);
1605  }
1606  state->decode_queue_tail = NULL;
1607  state->decode_queue_head = NULL;
1608  state->record = NULL;
1609 
1610  /* Reset the decode buffer to empty. */
1611  state->decode_buffer_tail = state->decode_buffer;
1612  state->decode_buffer_head = state->decode_buffer;
1613 
1614  /* Clear error state. */
1615  state->errormsg_buf[0] = '\0';
1616  state->errormsg_deferred = false;
1617 }

References DecodedXLogRecord::next, DecodedXLogRecord::oversized, and pfree().

Referenced by XLogBeginRead().

◆ RestoreBlockImage()

bool RestoreBlockImage ( XLogReaderState record,
uint8  block_id,
char *  page 
)

Definition at line 2056 of file xlogreader.c.

2057 {
2058  DecodedBkpBlock *bkpb;
2059  char *ptr;
2060  PGAlignedBlock tmp;
2061 
2062  if (block_id > record->record->max_block_id ||
2063  !record->record->blocks[block_id].in_use)
2064  {
2065  report_invalid_record(record,
2066  "could not restore image at %X/%X with invalid block %d specified",
2067  LSN_FORMAT_ARGS(record->ReadRecPtr),
2068  block_id);
2069  return false;
2070  }
2071  if (!record->record->blocks[block_id].has_image)
2072  {
2073  report_invalid_record(record, "could not restore image at %X/%X with invalid state, block %d",
2074  LSN_FORMAT_ARGS(record->ReadRecPtr),
2075  block_id);
2076  return false;
2077  }
2078 
2079  bkpb = &record->record->blocks[block_id];
2080  ptr = bkpb->bkp_image;
2081 
2082  if (BKPIMAGE_COMPRESSED(bkpb->bimg_info))
2083  {
2084  /* If a backup block image is compressed, decompress it */
2085  bool decomp_success = true;
2086 
2087  if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_PGLZ) != 0)
2088  {
2089  if (pglz_decompress(ptr, bkpb->bimg_len, tmp.data,
2090  BLCKSZ - bkpb->hole_length, true) < 0)
2091  decomp_success = false;
2092  }
2093  else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_LZ4) != 0)
2094  {
2095 #ifdef USE_LZ4
2096  if (LZ4_decompress_safe(ptr, tmp.data,
2097  bkpb->bimg_len, BLCKSZ - bkpb->hole_length) <= 0)
2098  decomp_success = false;
2099 #else
2100  report_invalid_record(record, "could not restore image at %X/%X compressed with %s not supported by build, block %d",
2101  LSN_FORMAT_ARGS(record->ReadRecPtr),
2102  "LZ4",
2103  block_id);
2104  return false;
2105 #endif
2106  }
2107  else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_ZSTD) != 0)
2108  {
2109 #ifdef USE_ZSTD
2110  size_t decomp_result = ZSTD_decompress(tmp.data,
2111  BLCKSZ - bkpb->hole_length,
2112  ptr, bkpb->bimg_len);
2113 
2114  if (ZSTD_isError(decomp_result))
2115  decomp_success = false;
2116 #else
2117  report_invalid_record(record, "could not restore image at %X/%X compressed with %s not supported by build, block %d",
2118  LSN_FORMAT_ARGS(record->ReadRecPtr),
2119  "zstd",
2120  block_id);
2121  return false;
2122 #endif
2123  }
2124  else
2125  {
2126  report_invalid_record(record, "could not restore image at %X/%X compressed with unknown method, block %d",
2127  LSN_FORMAT_ARGS(record->ReadRecPtr),
2128  block_id);
2129  return false;
2130  }
2131 
2132  if (!decomp_success)
2133  {
2134  report_invalid_record(record, "could not decompress image at %X/%X, block %d",
2135  LSN_FORMAT_ARGS(record->ReadRecPtr),
2136  block_id);
2137  return false;
2138  }
2139 
2140  ptr = tmp.data;
2141  }
2142 
2143  /* generate page, taking into account hole if necessary */
2144  if (bkpb->hole_length == 0)
2145  {
2146  memcpy(page, ptr, BLCKSZ);
2147  }
2148  else
2149  {
2150  memcpy(page, ptr, bkpb->hole_offset);
2151  /* must zero-fill the hole */
2152  MemSet(page + bkpb->hole_offset, 0, bkpb->hole_length);
2153  memcpy(page + (bkpb->hole_offset + bkpb->hole_length),
2154  ptr + bkpb->hole_offset,
2155  BLCKSZ - (bkpb->hole_offset + bkpb->hole_length));
2156  }
2157 
2158  return true;
2159 }
#define MemSet(start, val, len)
Definition: c.h:1020
int32 pglz_decompress(const char *source, int32 slen, char *dest, int32 rawsize, bool check_complete)
DecodedXLogRecord * record
Definition: xlogreader.h:236
XLogRecPtr ReadRecPtr
Definition: xlogreader.h:206
char data[BLCKSZ]
Definition: c.h:1119
#define BKPIMAGE_COMPRESS_ZSTD
Definition: xlogrecord.h:162
#define BKPIMAGE_COMPRESS_LZ4
Definition: xlogrecord.h:161
#define BKPIMAGE_COMPRESS_PGLZ
Definition: xlogrecord.h:160

References DecodedBkpBlock::bimg_info, DecodedBkpBlock::bimg_len, DecodedBkpBlock::bkp_image, BKPIMAGE_COMPRESS_LZ4, BKPIMAGE_COMPRESS_PGLZ, BKPIMAGE_COMPRESS_ZSTD, BKPIMAGE_COMPRESSED, DecodedXLogRecord::blocks, PGAlignedBlock::data, DecodedBkpBlock::has_image, DecodedBkpBlock::hole_length, DecodedBkpBlock::hole_offset, DecodedBkpBlock::in_use, LSN_FORMAT_ARGS, DecodedXLogRecord::max_block_id, MemSet, pglz_decompress(), XLogReaderState::ReadRecPtr, XLogReaderState::record, and report_invalid_record().

Referenced by GetWALBlockInfo(), verifyBackupPageConsistency(), XLogReadBufferForRedoExtended(), and XLogRecordSaveFPWs().

◆ ValidXLogRecord()

static bool ValidXLogRecord ( XLogReaderState state,
XLogRecord record,
XLogRecPtr  recptr 
)
static

Definition at line 1193 of file xlogreader.c.

1194 {
1195  pg_crc32c crc;
1196 
1197  Assert(record->xl_tot_len >= SizeOfXLogRecord);
1198 
1199  /* Calculate the CRC */
1200  INIT_CRC32C(crc);
1201  COMP_CRC32C(crc, ((char *) record) + SizeOfXLogRecord, record->xl_tot_len - SizeOfXLogRecord);
1202  /* include the record header last */
1203  COMP_CRC32C(crc, (char *) record, offsetof(XLogRecord, xl_crc));
1204  FIN_CRC32C(crc);
1205 
1206  if (!EQ_CRC32C(record->xl_crc, crc))
1207  {
1209  "incorrect resource manager data checksum in record at %X/%X",
1210  LSN_FORMAT_ARGS(recptr));
1211  return false;
1212  }
1213 
1214  return true;
1215 }
uint32 pg_crc32c
Definition: pg_crc32c.h:38
#define COMP_CRC32C(crc, data, len)
Definition: pg_crc32c.h:98
#define EQ_CRC32C(c1, c2)
Definition: pg_crc32c.h:42
#define INIT_CRC32C(crc)
Definition: pg_crc32c.h:41
#define FIN_CRC32C(crc)
Definition: pg_crc32c.h:103
return crc

References Assert, COMP_CRC32C, crc, EQ_CRC32C, FIN_CRC32C, INIT_CRC32C, LSN_FORMAT_ARGS, report_invalid_record(), SizeOfXLogRecord, XLogRecord::xl_crc, and XLogRecord::xl_tot_len.

Referenced by XLogDecodeNextRecord().

◆ ValidXLogRecordHeader()

static bool ValidXLogRecordHeader ( XLogReaderState state,
XLogRecPtr  RecPtr,
XLogRecPtr  PrevRecPtr,
XLogRecord record,
bool  randAccess 
)
static

Definition at line 1127 of file xlogreader.c.

1130 {
1131  if (record->xl_tot_len < SizeOfXLogRecord)
1132  {
1134  "invalid record length at %X/%X: expected at least %u, got %u",
1135  LSN_FORMAT_ARGS(RecPtr),
1136  (uint32) SizeOfXLogRecord, record->xl_tot_len);
1137  return false;
1138  }
1139  if (!RmgrIdIsValid(record->xl_rmid))
1140  {
1142  "invalid resource manager ID %u at %X/%X",
1143  record->xl_rmid, LSN_FORMAT_ARGS(RecPtr));
1144  return false;
1145  }
1146  if (randAccess)
1147  {
1148  /*
1149  * We can't exactly verify the prev-link, but surely it should be less
1150  * than the record's own address.
1151  */
1152  if (!(record->xl_prev < RecPtr))
1153  {
1155  "record with incorrect prev-link %X/%X at %X/%X",
1156  LSN_FORMAT_ARGS(record->xl_prev),
1157  LSN_FORMAT_ARGS(RecPtr));
1158  return false;
1159  }
1160  }
1161  else
1162  {
1163  /*
1164  * Record's prev-link should exactly match our previous location. This
1165  * check guards against torn WAL pages where a stale but valid-looking
1166  * WAL record starts on a sector boundary.
1167  */
1168  if (record->xl_prev != PrevRecPtr)
1169  {
1171  "record with incorrect prev-link %X/%X at %X/%X",
1172  LSN_FORMAT_ARGS(record->xl_prev),
1173  LSN_FORMAT_ARGS(RecPtr));
1174  return false;
1175  }
1176  }
1177 
1178  return true;
1179 }
#define RmgrIdIsValid(rmid)
Definition: rmgr.h:53
XLogRecPtr xl_prev
Definition: xlogrecord.h:45
RmgrId xl_rmid
Definition: xlogrecord.h:47

References LSN_FORMAT_ARGS, report_invalid_record(), RmgrIdIsValid, SizeOfXLogRecord, XLogRecord::xl_prev, XLogRecord::xl_rmid, and XLogRecord::xl_tot_len.

Referenced by XLogDecodeNextRecord().

◆ WALOpenSegmentInit()

static void WALOpenSegmentInit ( WALOpenSegment seg,
WALSegmentContext segcxt,
int  segsize,
const char *  waldir 
)
static

Definition at line 207 of file xlogreader.c.

209 {
210  seg->ws_file = -1;
211  seg->ws_segno = 0;
212  seg->ws_tli = 0;
213 
214  segcxt->ws_segsize = segsize;
215  if (waldir)
216  snprintf(segcxt->ws_dir, MAXPGPATH, "%s", waldir);
217 }
#define MAXPGPATH
#define snprintf
Definition: port.h:238
XLogSegNo ws_segno
Definition: xlogreader.h:48
TimeLineID ws_tli
Definition: xlogreader.h:49
char ws_dir[MAXPGPATH]
Definition: xlogreader.h:55

References MAXPGPATH, snprintf, WALSegmentContext::ws_dir, WALOpenSegment::ws_file, WALOpenSegment::ws_segno, WALSegmentContext::ws_segsize, and WALOpenSegment::ws_tli.

Referenced by XLogReaderAllocate().

◆ WALRead()

bool WALRead ( XLogReaderState state,
char *  buf,
XLogRecPtr  startptr,
Size  count,
TimeLineID  tli,
WALReadError errinfo 
)

Definition at line 1503 of file xlogreader.c.

1506 {
1507  char *p;
1508  XLogRecPtr recptr;
1509  Size nbytes;
1510 
1511  p = buf;
1512  recptr = startptr;
1513  nbytes = count;
1514 
1515  while (nbytes > 0)
1516  {
1517  uint32 startoff;
1518  int segbytes;
1519  int readbytes;
1520 
1521  startoff = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
1522 
1523  /*
1524  * If the data we want is not in a segment we have open, close what we
1525  * have (if anything) and open the next one, using the caller's
1526  * provided segment_open callback.
1527  */
1528  if (state->seg.ws_file < 0 ||
1529  !XLByteInSeg(recptr, state->seg.ws_segno, state->segcxt.ws_segsize) ||
1530  tli != state->seg.ws_tli)
1531  {
1532  XLogSegNo nextSegNo;
1533 
1534  if (state->seg.ws_file >= 0)
1535  state->routine.segment_close(state);
1536 
1537  XLByteToSeg(recptr, nextSegNo, state->segcxt.ws_segsize);
1538  state->routine.segment_open(state, nextSegNo, &tli);
1539 
1540  /* This shouldn't happen -- indicates a bug in segment_open */
1541  Assert(state->seg.ws_file >= 0);
1542 
1543  /* Update the current segment info. */
1544  state->seg.ws_tli = tli;
1545  state->seg.ws_segno = nextSegNo;
1546  }
1547 
1548  /* How many bytes are within this segment? */
1549  if (nbytes > (state->segcxt.ws_segsize - startoff))
1550  segbytes = state->segcxt.ws_segsize - startoff;
1551  else
1552  segbytes = nbytes;
1553 
1554 #ifndef FRONTEND
1555  pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
1556 #endif
1557 
1558  /* Reset errno first; eases reporting non-errno-affecting errors */
1559  errno = 0;
1560  readbytes = pg_pread(state->seg.ws_file, p, segbytes, (off_t) startoff);
1561 
1562 #ifndef FRONTEND
1564 #endif
1565 
1566  if (readbytes <= 0)
1567  {
1568  errinfo->wre_errno = errno;
1569  errinfo->wre_req = segbytes;
1570  errinfo->wre_read = readbytes;
1571  errinfo->wre_off = startoff;
1572  errinfo->wre_seg = state->seg;
1573  return false;
1574  }
1575 
1576  /* Update state for read */
1577  recptr += readbytes;
1578  nbytes -= readbytes;
1579  p += readbytes;
1580  }
1581 
1582  return true;
1583 }
size_t Size
Definition: c.h:605
static char * buf
Definition: pg_test_fsync.c:73
#define pg_pread
Definition: port.h:225
WALOpenSegment wre_seg
Definition: xlogreader.h:388
static void pgstat_report_wait_start(uint32 wait_event_info)
Definition: wait_event.h:82
static void pgstat_report_wait_end(void)
Definition: wait_event.h:98
#define XLByteInSeg(xlrp, logSegNo, wal_segsz_bytes)

References Assert, buf, pg_pread, pgstat_report_wait_end(), pgstat_report_wait_start(), WALReadError::wre_errno, WALReadError::wre_off, WALReadError::wre_read, WALReadError::wre_req, WALReadError::wre_seg, XLByteInSeg, XLByteToSeg, and XLogSegmentOffset.

Referenced by logical_read_xlog_page(), read_local_xlog_page_guts(), summarizer_read_local_xlog_page(), WALDumpReadPage(), and XLogSendPhysical().

◆ XLogBeginRead()

void XLogBeginRead ( XLogReaderState state,
XLogRecPtr  RecPtr 
)

Definition at line 231 of file xlogreader.c.

232 {
233  Assert(!XLogRecPtrIsInvalid(RecPtr));
234 
236 
237  /* Begin at the passed-in record pointer. */
238  state->EndRecPtr = RecPtr;
239  state->NextRecPtr = RecPtr;
240  state->ReadRecPtr = InvalidXLogRecPtr;
241  state->DecodeRecPtr = InvalidXLogRecPtr;
242 }
#define XLogRecPtrIsInvalid(r)
Definition: xlogdefs.h:29
#define InvalidXLogRecPtr
Definition: xlogdefs.h:28
static void ResetDecoder(XLogReaderState *state)
Definition: xlogreader.c:1595

References Assert, InvalidXLogRecPtr, ResetDecoder(), and XLogRecPtrIsInvalid.

Referenced by DecodingContextFindStartpoint(), extractPageMap(), findLastCheckpoint(), LogicalReplicationSlotHasPendingWal(), LogicalSlotAdvanceAndCheckSnapState(), pg_logical_slot_get_changes_guts(), readOneRecord(), StartLogicalReplication(), SummarizeWAL(), XLogFindNextRecord(), XLogPrefetcherBeginRead(), and XlogReadTwoPhaseData().

◆ XLogDecodeNextRecord()

static XLogPageReadResult XLogDecodeNextRecord ( XLogReaderState state,
bool  nonblocking 
)
static

Definition at line 528 of file xlogreader.c.

529 {
530  XLogRecPtr RecPtr;
531  XLogRecord *record;
532  XLogRecPtr targetPagePtr;
533  bool randAccess;
534  uint32 len,
535  total_len;
536  uint32 targetRecOff;
537  uint32 pageHeaderSize;
538  bool assembled;
539  bool gotheader;
540  int readOff;
541  DecodedXLogRecord *decoded;
542  char *errormsg; /* not used */
543 
544  /*
545  * randAccess indicates whether to verify the previous-record pointer of
546  * the record we're reading. We only do this if we're reading
547  * sequentially, which is what we initially assume.
548  */
549  randAccess = false;
550 
551  /* reset error state */
552  state->errormsg_buf[0] = '\0';
553  decoded = NULL;
554 
555  state->abortedRecPtr = InvalidXLogRecPtr;
556  state->missingContrecPtr = InvalidXLogRecPtr;
557 
558  RecPtr = state->NextRecPtr;
559 
560  if (state->DecodeRecPtr != InvalidXLogRecPtr)
561  {
562  /* read the record after the one we just read */
563 
564  /*
565  * NextRecPtr is pointing to end+1 of the previous WAL record. If
566  * we're at a page boundary, no more records can fit on the current
567  * page. We must skip over the page header, but we can't do that until
568  * we've read in the page, since the header size is variable.
569  */
570  }
571  else
572  {
573  /*
574  * Caller supplied a position to start at.
575  *
576  * In this case, NextRecPtr should already be pointing either to a
577  * valid record starting position or alternatively to the beginning of
578  * a page. See the header comments for XLogBeginRead.
579  */
580  Assert(RecPtr % XLOG_BLCKSZ == 0 || XRecOffIsValid(RecPtr));
581  randAccess = true;
582  }
583 
584 restart:
585  state->nonblocking = nonblocking;
586  state->currRecPtr = RecPtr;
587  assembled = false;
588 
589  targetPagePtr = RecPtr - (RecPtr % XLOG_BLCKSZ);
590  targetRecOff = RecPtr % XLOG_BLCKSZ;
591 
592  /*
593  * Read the page containing the record into state->readBuf. Request enough
594  * byte to cover the whole record header, or at least the part of it that
595  * fits on the same page.
596  */
597  readOff = ReadPageInternal(state, targetPagePtr,
598  Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ));
599  if (readOff == XLREAD_WOULDBLOCK)
600  return XLREAD_WOULDBLOCK;
601  else if (readOff < 0)
602  goto err;
603 
604  /*
605  * ReadPageInternal always returns at least the page header, so we can
606  * examine it now.
607  */
608  pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
609  if (targetRecOff == 0)
610  {
611  /*
612  * At page start, so skip over page header.
613  */
614  RecPtr += pageHeaderSize;
615  targetRecOff = pageHeaderSize;
616  }
617  else if (targetRecOff < pageHeaderSize)
618  {
619  report_invalid_record(state, "invalid record offset at %X/%X: expected at least %u, got %u",
620  LSN_FORMAT_ARGS(RecPtr),
621  pageHeaderSize, targetRecOff);
622  goto err;
623  }
624 
625  if ((((XLogPageHeader) state->readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
626  targetRecOff == pageHeaderSize)
627  {
628  report_invalid_record(state, "contrecord is requested by %X/%X",
629  LSN_FORMAT_ARGS(RecPtr));
630  goto err;
631  }
632 
633  /* ReadPageInternal has verified the page header */
634  Assert(pageHeaderSize <= readOff);
635 
636  /*
637  * Read the record length.
638  *
639  * NB: Even though we use an XLogRecord pointer here, the whole record
640  * header might not fit on this page. xl_tot_len is the first field of the
641  * struct, so it must be on this page (the records are MAXALIGNed), but we
642  * cannot access any other fields until we've verified that we got the
643  * whole header.
644  */
645  record = (XLogRecord *) (state->readBuf + RecPtr % XLOG_BLCKSZ);
646  total_len = record->xl_tot_len;
647 
648  /*
649  * If the whole record header is on this page, validate it immediately.
650  * Otherwise do just a basic sanity check on xl_tot_len, and validate the
651  * rest of the header after reading it from the next page. The xl_tot_len
652  * check is necessary here to ensure that we enter the "Need to reassemble
653  * record" code path below; otherwise we might fail to apply
654  * ValidXLogRecordHeader at all.
655  */
656  if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord)
657  {
658  if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr, record,
659  randAccess))
660  goto err;
661  gotheader = true;
662  }
663  else
664  {
665  /* There may be no next page if it's too small. */
666  if (total_len < SizeOfXLogRecord)
667  {
669  "invalid record length at %X/%X: expected at least %u, got %u",
670  LSN_FORMAT_ARGS(RecPtr),
671  (uint32) SizeOfXLogRecord, total_len);
672  goto err;
673  }
674  /* We'll validate the header once we have the next page. */
675  gotheader = false;
676  }
677 
678  /*
679  * Try to find space to decode this record, if we can do so without
680  * calling palloc. If we can't, we'll try again below after we've
681  * validated that total_len isn't garbage bytes from a recycled WAL page.
682  */
683  decoded = XLogReadRecordAlloc(state,
684  total_len,
685  false /* allow_oversized */ );
686  if (decoded == NULL && nonblocking)
687  {
688  /*
689  * There is no space in the circular decode buffer, and the caller is
690  * only reading ahead. The caller should consume existing records to
691  * make space.
692  */
693  return XLREAD_WOULDBLOCK;
694  }
695 
696  len = XLOG_BLCKSZ - RecPtr % XLOG_BLCKSZ;
697  if (total_len > len)
698  {
699  /* Need to reassemble record */
700  char *contdata;
701  XLogPageHeader pageHeader;
702  char *buffer;
703  uint32 gotlen;
704 
705  assembled = true;
706 
707  /*
708  * We always have space for a couple of pages, enough to validate a
709  * boundary-spanning record header.
710  */
711  Assert(state->readRecordBufSize >= XLOG_BLCKSZ * 2);
712  Assert(state->readRecordBufSize >= len);
713 
714  /* Copy the first fragment of the record from the first page. */
715  memcpy(state->readRecordBuf,
716  state->readBuf + RecPtr % XLOG_BLCKSZ, len);
717  buffer = state->readRecordBuf + len;
718  gotlen = len;
719 
720  do
721  {
722  /* Calculate pointer to beginning of next page */
723  targetPagePtr += XLOG_BLCKSZ;
724 
725  /* Wait for the next page to become available */
726  readOff = ReadPageInternal(state, targetPagePtr,
727  Min(total_len - gotlen + SizeOfXLogShortPHD,
728  XLOG_BLCKSZ));
729 
730  if (readOff == XLREAD_WOULDBLOCK)
731  return XLREAD_WOULDBLOCK;
732  else if (readOff < 0)
733  goto err;
734 
736 
737  pageHeader = (XLogPageHeader) state->readBuf;
738 
739  /*
740  * If we were expecting a continuation record and got an
741  * "overwrite contrecord" flag, that means the continuation record
742  * was overwritten with a different record. Restart the read by
743  * assuming the address to read is the location where we found
744  * this flag; but keep track of the LSN of the record we were
745  * reading, for later verification.
746  */
748  {
749  state->overwrittenRecPtr = RecPtr;
750  RecPtr = targetPagePtr;
751  goto restart;
752  }
753 
754  /* Check that the continuation on next page looks valid */
755  if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD))
756  {
758  "there is no contrecord flag at %X/%X",
759  LSN_FORMAT_ARGS(RecPtr));
760  goto err;
761  }
762 
763  /*
764  * Cross-check that xlp_rem_len agrees with how much of the record
765  * we expect there to be left.
766  */
767  if (pageHeader->xlp_rem_len == 0 ||
768  total_len != (pageHeader->xlp_rem_len + gotlen))
769  {
771  "invalid contrecord length %u (expected %lld) at %X/%X",
772  pageHeader->xlp_rem_len,
773  ((long long) total_len) - gotlen,
774  LSN_FORMAT_ARGS(RecPtr));
775  goto err;
776  }
777 
778  /* Append the continuation from this page to the buffer */
779  pageHeaderSize = XLogPageHeaderSize(pageHeader);
780 
781  if (readOff < pageHeaderSize)
782  readOff = ReadPageInternal(state, targetPagePtr,
783  pageHeaderSize);
784 
785  Assert(pageHeaderSize <= readOff);
786 
787  contdata = (char *) state->readBuf + pageHeaderSize;
788  len = XLOG_BLCKSZ - pageHeaderSize;
789  if (pageHeader->xlp_rem_len < len)
790  len = pageHeader->xlp_rem_len;
791 
792  if (readOff < pageHeaderSize + len)
793  readOff = ReadPageInternal(state, targetPagePtr,
794  pageHeaderSize + len);
795 
796  memcpy(buffer, (char *) contdata, len);
797  buffer += len;
798  gotlen += len;
799 
800  /* If we just reassembled the record header, validate it. */
801  if (!gotheader)
802  {
803  record = (XLogRecord *) state->readRecordBuf;
804  if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr,
805  record, randAccess))
806  goto err;
807  gotheader = true;
808  }
809 
810  /*
811  * We might need a bigger buffer. We have validated the record
812  * header, in the case that it split over a page boundary. We've
813  * also cross-checked total_len against xlp_rem_len on the second
814  * page, and verified xlp_pageaddr on both.
815  */
816  if (total_len > state->readRecordBufSize)
817  {
818  char save_copy[XLOG_BLCKSZ * 2];
819 
820  /*
821  * Save and restore the data we already had. It can't be more
822  * than two pages.
823  */
824  Assert(gotlen <= lengthof(save_copy));
825  Assert(gotlen <= state->readRecordBufSize);
826  memcpy(save_copy, state->readRecordBuf, gotlen);
827  allocate_recordbuf(state, total_len);
828  memcpy(state->readRecordBuf, save_copy, gotlen);
829  buffer = state->readRecordBuf + gotlen;
830  }
831  } while (gotlen < total_len);
832  Assert(gotheader);
833 
834  record = (XLogRecord *) state->readRecordBuf;
835  if (!ValidXLogRecord(state, record, RecPtr))
836  goto err;
837 
838  pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
839  state->DecodeRecPtr = RecPtr;
840  state->NextRecPtr = targetPagePtr + pageHeaderSize
841  + MAXALIGN(pageHeader->xlp_rem_len);
842  }
843  else
844  {
845  /* Wait for the record data to become available */
846  readOff = ReadPageInternal(state, targetPagePtr,
847  Min(targetRecOff + total_len, XLOG_BLCKSZ));
848  if (readOff == XLREAD_WOULDBLOCK)
849  return XLREAD_WOULDBLOCK;
850  else if (readOff < 0)
851  goto err;
852 
853  /* Record does not cross a page boundary */
854  if (!ValidXLogRecord(state, record, RecPtr))
855  goto err;
856 
857  state->NextRecPtr = RecPtr + MAXALIGN(total_len);
858 
859  state->DecodeRecPtr = RecPtr;
860  }
861 
862  /*
863  * Special processing if it's an XLOG SWITCH record
864  */
865  if (record->xl_rmid == RM_XLOG_ID &&
866  (record->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH)
867  {
868  /* Pretend it extends to end of segment */
869  state->NextRecPtr += state->segcxt.ws_segsize - 1;
870  state->NextRecPtr -= XLogSegmentOffset(state->NextRecPtr, state->segcxt.ws_segsize);
871  }
872 
873  /*
874  * If we got here without a DecodedXLogRecord, it means we needed to
875  * validate total_len before trusting it, but by now we've done that.
876  */
877  if (decoded == NULL)
878  {
879  Assert(!nonblocking);
880  decoded = XLogReadRecordAlloc(state,
881  total_len,
882  true /* allow_oversized */ );
883  /* allocation should always happen under allow_oversized */
884  Assert(decoded != NULL);
885  }
886 
887  if (DecodeXLogRecord(state, decoded, record, RecPtr, &errormsg))
888  {
889  /* Record the location of the next record. */
890  decoded->next_lsn = state->NextRecPtr;
891 
892  /*
893  * If it's in the decode buffer, mark the decode buffer space as
894  * occupied.
895  */
896  if (!decoded->oversized)
897  {
898  /* The new decode buffer head must be MAXALIGNed. */
899  Assert(decoded->size == MAXALIGN(decoded->size));
900  if ((char *) decoded == state->decode_buffer)
901  state->decode_buffer_tail = state->decode_buffer + decoded->size;
902  else
903  state->decode_buffer_tail += decoded->size;
904  }
905 
906  /* Insert it into the queue of decoded records. */
907  Assert(state->decode_queue_tail != decoded);
908  if (state->decode_queue_tail)
909  state->decode_queue_tail->next = decoded;
910  state->decode_queue_tail = decoded;
911  if (!state->decode_queue_head)
912  state->decode_queue_head = decoded;
913  return XLREAD_SUCCESS;
914  }
915 
916 err:
917  if (assembled)
918  {
919  /*
920  * We get here when a record that spans multiple pages needs to be
921  * assembled, but something went wrong -- perhaps a contrecord piece
922  * was lost. If caller is WAL replay, it will know where the aborted
923  * record was and where to direct followup WAL to be written, marking
924  * the next piece with XLP_FIRST_IS_OVERWRITE_CONTRECORD, which will
925  * in turn signal downstream WAL consumers that the broken WAL record
926  * is to be ignored.
927  */
928  state->abortedRecPtr = RecPtr;
929  state->missingContrecPtr = targetPagePtr;
930 
931  /*
932  * If we got here without reporting an error, make sure an error is
933  * queued so that XLogPrefetcherReadRecord() doesn't bring us back a
934  * second time and clobber the above state.
935  */
936  state->errormsg_deferred = true;
937  }
938 
939  if (decoded && decoded->oversized)
940  pfree(decoded);
941 
942  /*
943  * Invalidate the read state. We might read from a different source after
944  * failure.
945  */
947 
948  /*
949  * If an error was written to errmsg_buf, it'll be returned to the caller
950  * of XLogReadRecord() after all successfully decoded records from the
951  * read queue.
952  */
953 
954  return XLREAD_FAIL;
955 }
#define Min(x, y)
Definition: c.h:1004
#define lengthof(array)
Definition: c.h:788
#define XLOG_SWITCH
Definition: pg_control.h:71
const void size_t len
XLogRecPtr next_lsn
Definition: xlogreader.h:165
uint8 xl_info
Definition: xlogrecord.h:46
struct state * next
Definition: regguts.h:332
#define XLP_FIRST_IS_CONTRECORD
Definition: xlog_internal.h:74
#define XLP_FIRST_IS_OVERWRITE_CONTRECORD
Definition: xlog_internal.h:80
#define XRecOffIsValid(xlrp)
static int ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
Definition: xlogreader.c:1000
static void static void allocate_recordbuf(XLogReaderState *state, uint32 reclength)
Definition: xlogreader.c:190
bool DecodeXLogRecord(XLogReaderState *state, DecodedXLogRecord *decoded, XLogRecord *record, XLogRecPtr lsn, char **errormsg)
Definition: xlogreader.c:1662
static bool ValidXLogRecord(XLogReaderState *state, XLogRecord *record, XLogRecPtr recptr)
Definition: xlogreader.c:1193
static DecodedXLogRecord * XLogReadRecordAlloc(XLogReaderState *state, size_t xl_tot_len, bool allow_oversized)
Definition: xlogreader.c:438
static bool ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr, XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess)
Definition: xlogreader.c:1127
@ XLREAD_SUCCESS
Definition: xlogreader.h:351
#define XLR_INFO_MASK
Definition: xlogrecord.h:62
static uint32 readOff
Definition: xlogrecovery.c:232

References allocate_recordbuf(), Assert, DecodeXLogRecord(), err(), if(), InvalidXLogRecPtr, len, lengthof, LSN_FORMAT_ARGS, MAXALIGN, Min, state::next, DecodedXLogRecord::next_lsn, DecodedXLogRecord::oversized, pfree(), readOff, ReadPageInternal(), report_invalid_record(), DecodedXLogRecord::size, SizeOfXLogRecord, SizeOfXLogShortPHD, ValidXLogRecord(), ValidXLogRecordHeader(), XLogRecord::xl_info, XLogRecord::xl_rmid, XLogRecord::xl_tot_len, XLOG_SWITCH, XLogPageHeaderSize, XLogReaderInvalReadState(), XLogReadRecordAlloc(), XLogSegmentOffset, XLP_FIRST_IS_CONTRECORD, XLP_FIRST_IS_OVERWRITE_CONTRECORD, XLogPageHeaderData::xlp_info, XLogPageHeaderData::xlp_rem_len, XLR_INFO_MASK, XLREAD_FAIL, XLREAD_SUCCESS, XLREAD_WOULDBLOCK, and XRecOffIsValid.

Referenced by XLogReadAhead().

◆ XLogFindNextRecord()

XLogRecPtr XLogFindNextRecord ( XLogReaderState state,
XLogRecPtr  RecPtr 
)

Definition at line 1383 of file xlogreader.c.

1384 {
1385  XLogRecPtr tmpRecPtr;
1386  XLogRecPtr found = InvalidXLogRecPtr;
1387  XLogPageHeader header;
1388  char *errormsg;
1389 
1390  Assert(!XLogRecPtrIsInvalid(RecPtr));
1391 
1392  /* Make sure ReadPageInternal() can't return XLREAD_WOULDBLOCK. */
1393  state->nonblocking = false;
1394 
1395  /*
1396  * skip over potential continuation data, keeping in mind that it may span
1397  * multiple pages
1398  */
1399  tmpRecPtr = RecPtr;
1400  while (true)
1401  {
1402  XLogRecPtr targetPagePtr;
1403  int targetRecOff;
1404  uint32 pageHeaderSize;
1405  int readLen;
1406 
1407  /*
1408  * Compute targetRecOff. It should typically be equal or greater than
1409  * short page-header since a valid record can't start anywhere before
1410  * that, except when caller has explicitly specified the offset that
1411  * falls somewhere there or when we are skipping multi-page
1412  * continuation record. It doesn't matter though because
1413  * ReadPageInternal() is prepared to handle that and will read at
1414  * least short page-header worth of data
1415  */
1416  targetRecOff = tmpRecPtr % XLOG_BLCKSZ;
1417 
1418  /* scroll back to page boundary */
1419  targetPagePtr = tmpRecPtr - targetRecOff;
1420 
1421  /* Read the page containing the record */
1422  readLen = ReadPageInternal(state, targetPagePtr, targetRecOff);
1423  if (readLen < 0)
1424  goto err;
1425 
1426  header = (XLogPageHeader) state->readBuf;
1427 
1428  pageHeaderSize = XLogPageHeaderSize(header);
1429 
1430  /* make sure we have enough data for the page header */
1431  readLen = ReadPageInternal(state, targetPagePtr, pageHeaderSize);
1432  if (readLen < 0)
1433  goto err;
1434 
1435  /* skip over potential continuation data */
1436  if (header->xlp_info & XLP_FIRST_IS_CONTRECORD)
1437  {
1438  /*
1439  * If the length of the remaining continuation data is more than
1440  * what can fit in this page, the continuation record crosses over
1441  * this page. Read the next page and try again. xlp_rem_len in the
1442  * next page header will contain the remaining length of the
1443  * continuation data
1444  *
1445  * Note that record headers are MAXALIGN'ed
1446  */
1447  if (MAXALIGN(header->xlp_rem_len) >= (XLOG_BLCKSZ - pageHeaderSize))
1448  tmpRecPtr = targetPagePtr + XLOG_BLCKSZ;
1449  else
1450  {
1451  /*
1452  * The previous continuation record ends in this page. Set
1453  * tmpRecPtr to point to the first valid record
1454  */
1455  tmpRecPtr = targetPagePtr + pageHeaderSize
1456  + MAXALIGN(header->xlp_rem_len);
1457  break;
1458  }
1459  }
1460  else
1461  {
1462  tmpRecPtr = targetPagePtr + pageHeaderSize;
1463  break;
1464  }
1465  }
1466 
1467  /*
1468  * we know now that tmpRecPtr is an address pointing to a valid XLogRecord
1469  * because either we're at the first record after the beginning of a page
1470  * or we just jumped over the remaining data of a continuation.
1471  */
1472  XLogBeginRead(state, tmpRecPtr);
1473  while (XLogReadRecord(state, &errormsg) != NULL)
1474  {
1475  /* past the record we've found, break out */
1476  if (RecPtr <= state->ReadRecPtr)
1477  {
1478  /* Rewind the reader to the beginning of the last record. */
1479  found = state->ReadRecPtr;
1480  XLogBeginRead(state, found);
1481  return found;
1482  }
1483  }
1484 
1485 err:
1487 
1488  return InvalidXLogRecPtr;
1489 }
XLogRecord * XLogReadRecord(XLogReaderState *state, char **errormsg)
Definition: xlogreader.c:389
void XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr)
Definition: xlogreader.c:231

References Assert, err(), InvalidXLogRecPtr, MAXALIGN, readLen, ReadPageInternal(), XLogBeginRead(), XLogPageHeaderSize, XLogReaderInvalReadState(), XLogReadRecord(), XLogRecPtrIsInvalid, XLP_FIRST_IS_CONTRECORD, XLogPageHeaderData::xlp_info, and XLogPageHeaderData::xlp_rem_len.

Referenced by InitXLogReaderState(), main(), and SummarizeWAL().

◆ XLogNextRecord()

DecodedXLogRecord* XLogNextRecord ( XLogReaderState state,
char **  errormsg 
)

Definition at line 325 of file xlogreader.c.

326 {
327  /* Release the last record returned by XLogNextRecord(). */
329 
330  if (state->decode_queue_head == NULL)
331  {
332  *errormsg = NULL;
333  if (state->errormsg_deferred)
334  {
335  if (state->errormsg_buf[0] != '\0')
336  *errormsg = state->errormsg_buf;
337  state->errormsg_deferred = false;
338  }
339 
340  /*
341  * state->EndRecPtr is expected to have been set by the last call to
342  * XLogBeginRead() or XLogNextRecord(), and is the location of the
343  * error.
344  */
345  Assert(!XLogRecPtrIsInvalid(state->EndRecPtr));
346 
347  return NULL;
348  }
349 
350  /*
351  * Record this as the most recent record returned, so that we'll release
352  * it next time. This also exposes it to the traditional
353  * XLogRecXXX(xlogreader) macros, which work with the decoder rather than
354  * the record for historical reasons.
355  */
356  state->record = state->decode_queue_head;
357 
358  /*
359  * Update the pointers to the beginning and one-past-the-end of this
360  * record, again for the benefit of historical code that expected the
361  * decoder to track this rather than accessing these fields of the record
362  * itself.
363  */
364  state->ReadRecPtr = state->record->lsn;
365  state->EndRecPtr = state->record->next_lsn;
366 
367  *errormsg = NULL;
368 
369  return state->record;
370 }
XLogRecPtr XLogReleasePreviousRecord(XLogReaderState *state)
Definition: xlogreader.c:249

References Assert, XLogRecPtrIsInvalid, and XLogReleasePreviousRecord().

Referenced by XLogPrefetcherReadRecord(), and XLogReadRecord().

◆ XLogReadAhead()

DecodedXLogRecord* XLogReadAhead ( XLogReaderState state,
bool  nonblocking 
)

Definition at line 966 of file xlogreader.c.

967 {
968  XLogPageReadResult result;
969 
970  if (state->errormsg_deferred)
971  return NULL;
972 
973  result = XLogDecodeNextRecord(state, nonblocking);
974  if (result == XLREAD_SUCCESS)
975  {
976  Assert(state->decode_queue_tail != NULL);
977  return state->decode_queue_tail;
978  }
979 
980  return NULL;
981 }
static XLogPageReadResult XLogDecodeNextRecord(XLogReaderState *state, bool nonblocking)
Definition: xlogreader.c:528
XLogPageReadResult
Definition: xlogreader.h:350

References Assert, XLogDecodeNextRecord(), and XLREAD_SUCCESS.

Referenced by XLogPrefetcherNextBlock(), and XLogReadRecord().

◆ XLogReaderAllocate()

XLogReaderState* XLogReaderAllocate ( int  wal_segment_size,
const char *  waldir,
XLogReaderRoutine routine,
void *  private_data 
)

Definition at line 106 of file xlogreader.c.

108 {
110 
111  state = (XLogReaderState *)
114  if (!state)
115  return NULL;
116 
117  /* initialize caller-provided support functions */
118  state->routine = *routine;
119 
120  /*
121  * Permanently allocate readBuf. We do it this way, rather than just
122  * making a static array, for two reasons: (1) no need to waste the
123  * storage in most instantiations of the backend; (2) a static char array
124  * isn't guaranteed to have any particular alignment, whereas
125  * palloc_extended() will provide MAXALIGN'd storage.
126  */
127  state->readBuf = (char *) palloc_extended(XLOG_BLCKSZ,
129  if (!state->readBuf)
130  {
131  pfree(state);
132  return NULL;
133  }
134 
135  /* Initialize segment info. */
137  waldir);
138 
139  /* system_identifier initialized to zeroes above */
140  state->private_data = private_data;
141  /* ReadRecPtr, EndRecPtr and readLen initialized to zeroes above */
142  state->errormsg_buf = palloc_extended(MAX_ERRORMSG_LEN + 1,
144  if (!state->errormsg_buf)
145  {
146  pfree(state->readBuf);
147  pfree(state);
148  return NULL;
149  }
150  state->errormsg_buf[0] = '\0';
151 
152  /*
153  * Allocate an initial readRecordBuf of minimal size, which can later be
154  * enlarged if necessary.
155  */
157  return state;
158 }
#define MCXT_ALLOC_ZERO
Definition: fe_memutils.h:18
#define MCXT_ALLOC_NO_OOM
Definition: fe_memutils.h:17
void * palloc_extended(Size size, int flags)
Definition: mcxt.c:1367
int wal_segment_size
Definition: xlog.c:143
static void WALOpenSegmentInit(WALOpenSegment *seg, WALSegmentContext *segcxt, int segsize, const char *waldir)
Definition: xlogreader.c:207

References allocate_recordbuf(), MAX_ERRORMSG_LEN, MCXT_ALLOC_NO_OOM, MCXT_ALLOC_ZERO, palloc_extended(), pfree(), wal_segment_size, and WALOpenSegmentInit().

Referenced by extractPageMap(), findLastCheckpoint(), InitWalRecovery(), InitXLogReaderState(), main(), readOneRecord(), StartReplication(), StartupDecodingContext(), SummarizeWAL(), XLogInsertRecord(), and XlogReadTwoPhaseData().

◆ XLogReaderFree()

void XLogReaderFree ( XLogReaderState state)

Definition at line 161 of file xlogreader.c.

162 {
163  if (state->seg.ws_file != -1)
164  state->routine.segment_close(state);
165 
166  if (state->decode_buffer && state->free_decode_buffer)
167  pfree(state->decode_buffer);
168 
169  pfree(state->errormsg_buf);
170  if (state->readRecordBuf)
171  pfree(state->readRecordBuf);
172  pfree(state->readBuf);
173  pfree(state);
174 }

References pfree().

Referenced by extractPageMap(), findLastCheckpoint(), FreeDecodingContext(), GetWALRecordsInfo(), main(), pg_get_wal_block_info(), pg_get_wal_record_info(), readOneRecord(), ShutdownWalRecovery(), SummarizeWAL(), and XlogReadTwoPhaseData().

◆ XLogReaderInvalReadState()

static void XLogReaderInvalReadState ( XLogReaderState state)
static

Definition at line 1113 of file xlogreader.c.

1114 {
1115  state->seg.ws_segno = 0;
1116  state->segoff = 0;
1117  state->readLen = 0;
1118 }

Referenced by ReadPageInternal(), XLogDecodeNextRecord(), and XLogFindNextRecord().

◆ XLogReaderResetError()

void XLogReaderResetError ( XLogReaderState state)

Definition at line 1365 of file xlogreader.c.

1366 {
1367  state->errormsg_buf[0] = '\0';
1368  state->errormsg_deferred = false;
1369 }

Referenced by XLogPageRead().

◆ XLogReaderSetDecodeBuffer()

void XLogReaderSetDecodeBuffer ( XLogReaderState state,
void *  buffer,
size_t  size 
)

Definition at line 90 of file xlogreader.c.

91 {
92  Assert(state->decode_buffer == NULL);
93 
94  state->decode_buffer = buffer;
95  state->decode_buffer_size = size;
96  state->decode_buffer_tail = buffer;
97  state->decode_buffer_head = buffer;
98 }

References Assert, and size.

Referenced by InitWalRecovery().

◆ XLogReaderValidatePageHeader()

bool XLogReaderValidatePageHeader ( XLogReaderState state,
XLogRecPtr  recptr,
char *  phdr 
)

Definition at line 1224 of file xlogreader.c.

1226 {
1227  XLogSegNo segno;
1228  int32 offset;
1229  XLogPageHeader hdr = (XLogPageHeader) phdr;
1230 
1231  Assert((recptr % XLOG_BLCKSZ) == 0);
1232 
1233  XLByteToSeg(recptr, segno, state->segcxt.ws_segsize);
1234  offset = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
1235 
1236  if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
1237  {
1238  char fname[MAXFNAMELEN];
1239 
1240  XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1241 
1243  "invalid magic number %04X in WAL segment %s, LSN %X/%X, offset %u",
1244  hdr->xlp_magic,
1245  fname,
1246  LSN_FORMAT_ARGS(recptr),
1247  offset);
1248  return false;
1249  }
1250 
1251  if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0)
1252  {
1253  char fname[MAXFNAMELEN];
1254 
1255  XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1256 
1258  "invalid info bits %04X in WAL segment %s, LSN %X/%X, offset %u",
1259  hdr->xlp_info,
1260  fname,
1261  LSN_FORMAT_ARGS(recptr),
1262  offset);
1263  return false;
1264  }
1265 
1266  if (hdr->xlp_info & XLP_LONG_HEADER)
1267  {
1268  XLogLongPageHeader longhdr = (XLogLongPageHeader) hdr;
1269 
1270  if (state->system_identifier &&
1271  longhdr->xlp_sysid != state->system_identifier)
1272  {
1274  "WAL file is from different database system: WAL file database system identifier is %llu, pg_control database system identifier is %llu",
1275  (unsigned long long) longhdr->xlp_sysid,
1276  (unsigned long long) state->system_identifier);
1277  return false;
1278  }
1279  else if (longhdr->xlp_seg_size != state->segcxt.ws_segsize)
1280  {
1282  "WAL file is from different database system: incorrect segment size in page header");
1283  return false;
1284  }
1285  else if (longhdr->xlp_xlog_blcksz != XLOG_BLCKSZ)
1286  {
1288  "WAL file is from different database system: incorrect XLOG_BLCKSZ in page header");
1289  return false;
1290  }
1291  }
1292  else if (offset == 0)
1293  {
1294  char fname[MAXFNAMELEN];
1295 
1296  XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1297 
1298  /* hmm, first page of file doesn't have a long header? */
1300  "invalid info bits %04X in WAL segment %s, LSN %X/%X, offset %u",
1301  hdr->xlp_info,
1302  fname,
1303  LSN_FORMAT_ARGS(recptr),
1304  offset);
1305  return false;
1306  }
1307 
1308  /*
1309  * Check that the address on the page agrees with what we expected. This
1310  * check typically fails when an old WAL segment is recycled, and hasn't
1311  * yet been overwritten with new data yet.
1312  */
1313  if (hdr->xlp_pageaddr != recptr)
1314  {
1315  char fname[MAXFNAMELEN];
1316 
1317  XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1318 
1320  "unexpected pageaddr %X/%X in WAL segment %s, LSN %X/%X, offset %u",
1322  fname,
1323  LSN_FORMAT_ARGS(recptr),
1324  offset);
1325  return false;
1326  }
1327 
1328  /*
1329  * Since child timelines are always assigned a TLI greater than their
1330  * immediate parent's TLI, we should never see TLI go backwards across
1331  * successive pages of a consistent WAL sequence.
1332  *
1333  * Sometimes we re-read a segment that's already been (partially) read. So
1334  * we only verify TLIs for pages that are later than the last remembered
1335  * LSN.
1336  */
1337  if (recptr > state->latestPagePtr)
1338  {
1339  if (hdr->xlp_tli < state->latestPageTLI)
1340  {
1341  char fname[MAXFNAMELEN];
1342 
1343  XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1344 
1346  "out-of-sequence timeline ID %u (after %u) in WAL segment %s, LSN %X/%X, offset %u",
1347  hdr->xlp_tli,
1348  state->latestPageTLI,
1349  fname,
1350  LSN_FORMAT_ARGS(recptr),
1351  offset);
1352  return false;
1353  }
1354  }
1355  state->latestPagePtr = recptr;
1356  state->latestPageTLI = hdr->xlp_tli;
1357 
1358  return true;
1359 }
signed int int32
Definition: c.h:494
TimeLineID xlp_tli
Definition: xlog_internal.h:40
XLogRecPtr xlp_pageaddr
Definition: xlog_internal.h:41
XLogLongPageHeaderData * XLogLongPageHeader
Definition: xlog_internal.h:71
#define MAXFNAMELEN
#define XLP_LONG_HEADER
Definition: xlog_internal.h:76
#define XLP_ALL_FLAGS
Definition: xlog_internal.h:82
#define XLOG_PAGE_MAGIC
Definition: xlog_internal.h:34
static void XLogFileName(char *fname, TimeLineID tli, XLogSegNo logSegNo, int wal_segsz_bytes)

References Assert, LSN_FORMAT_ARGS, MAXFNAMELEN, report_invalid_record(), XLByteToSeg, XLOG_PAGE_MAGIC, XLogFileName(), XLogSegmentOffset, XLP_ALL_FLAGS, XLogPageHeaderData::xlp_info, XLP_LONG_HEADER, XLogPageHeaderData::xlp_magic, XLogPageHeaderData::xlp_pageaddr, XLogLongPageHeaderData::xlp_seg_size, XLogLongPageHeaderData::xlp_sysid, XLogPageHeaderData::xlp_tli, and XLogLongPageHeaderData::xlp_xlog_blcksz.

Referenced by ReadPageInternal(), and XLogPageRead().

◆ XLogReadRecord()

XLogRecord* XLogReadRecord ( XLogReaderState state,
char **  errormsg 
)

Definition at line 389 of file xlogreader.c.

390 {
391  DecodedXLogRecord *decoded;
392 
393  /*
394  * Release last returned record, if there is one. We need to do this so
395  * that we can check for empty decode queue accurately.
396  */
398 
399  /*
400  * Call XLogReadAhead() in blocking mode to make sure there is something
401  * in the queue, though we don't use the result.
402  */
404  XLogReadAhead(state, false /* nonblocking */ );
405 
406  /* Consume the head record or error. */
407  decoded = XLogNextRecord(state, errormsg);
408  if (decoded)
409  {
410  /*
411  * This function returns a pointer to the record's header, not the
412  * actual decoded record. The caller will access the decoded record
413  * through the XLogRecGetXXX() macros, which reach the decoded
414  * recorded as xlogreader->record.
415  */
416  Assert(state->record == decoded);
417  return &decoded->header;
418  }
419 
420  return NULL;
421 }
DecodedXLogRecord * XLogNextRecord(XLogReaderState *state, char **errormsg)
Definition: xlogreader.c:325
DecodedXLogRecord * XLogReadAhead(XLogReaderState *state, bool nonblocking)
Definition: xlogreader.c:966
static bool XLogReaderHasQueuedRecordOrError(XLogReaderState *state)
Definition: xlogreader.h:325

References Assert, DecodedXLogRecord::header, XLogNextRecord(), XLogReadAhead(), XLogReaderHasQueuedRecordOrError(), and XLogReleasePreviousRecord().

Referenced by DecodingContextFindStartpoint(), extractPageMap(), findLastCheckpoint(), LogicalReplicationSlotHasPendingWal(), LogicalSlotAdvanceAndCheckSnapState(), main(), pg_logical_slot_get_changes_guts(), ReadNextXLogRecord(), readOneRecord(), SummarizeWAL(), XLogFindNextRecord(), XlogReadTwoPhaseData(), and XLogSendLogical().

◆ XLogReadRecordAlloc()

static DecodedXLogRecord* XLogReadRecordAlloc ( XLogReaderState state,
size_t  xl_tot_len,
bool  allow_oversized 
)
static

Definition at line 438 of file xlogreader.c.

439 {
440  size_t required_space = DecodeXLogRecordRequiredSpace(xl_tot_len);
441  DecodedXLogRecord *decoded = NULL;
442 
443  /* Allocate a circular decode buffer if we don't have one already. */
444  if (unlikely(state->decode_buffer == NULL))
445  {
446  if (state->decode_buffer_size == 0)
447  state->decode_buffer_size = DEFAULT_DECODE_BUFFER_SIZE;
448  state->decode_buffer = palloc(state->decode_buffer_size);
449  state->decode_buffer_head = state->decode_buffer;
450  state->decode_buffer_tail = state->decode_buffer;
451  state->free_decode_buffer = true;
452  }
453 
454  /* Try to allocate space in the circular decode buffer. */
455  if (state->decode_buffer_tail >= state->decode_buffer_head)
456  {
457  /* Empty, or tail is to the right of head. */
458  if (required_space <=
459  state->decode_buffer_size -
460  (state->decode_buffer_tail - state->decode_buffer))
461  {
462  /*-
463  * There is space between tail and end.
464  *
465  * +-----+--------------------+-----+
466  * | |////////////////////|here!|
467  * +-----+--------------------+-----+
468  * ^ ^
469  * | |
470  * h t
471  */
472  decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
473  decoded->oversized = false;
474  return decoded;
475  }
476  else if (required_space <
477  state->decode_buffer_head - state->decode_buffer)
478  {
479  /*-
480  * There is space between start and head.
481  *
482  * +-----+--------------------+-----+
483  * |here!|////////////////////| |
484  * +-----+--------------------+-----+
485  * ^ ^
486  * | |
487  * h t
488  */
489  decoded = (DecodedXLogRecord *) state->decode_buffer;
490  decoded->oversized = false;
491  return decoded;
492  }
493  }
494  else
495  {
496  /* Tail is to the left of head. */
497  if (required_space <
498  state->decode_buffer_head - state->decode_buffer_tail)
499  {
500  /*-
501  * There is space between tail and head.
502  *
503  * +-----+--------------------+-----+
504  * |/////|here! |/////|
505  * +-----+--------------------+-----+
506  * ^ ^
507  * | |
508  * t h
509  */
510  decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
511  decoded->oversized = false;
512  return decoded;
513  }
514  }
515 
516  /* Not enough space in the decode buffer. Are we allowed to allocate? */
517  if (allow_oversized)
518  {
519  decoded = palloc(required_space);
520  decoded->oversized = true;
521  return decoded;
522  }
523 
524  return NULL;
525 }
#define unlikely(x)
Definition: c.h:311
#define DEFAULT_DECODE_BUFFER_SIZE
Definition: xlogreader.c:64

References DecodeXLogRecordRequiredSpace(), DEFAULT_DECODE_BUFFER_SIZE, DecodedXLogRecord::oversized, palloc(), and unlikely.

Referenced by XLogDecodeNextRecord().

◆ XLogRecGetBlockData()

char* XLogRecGetBlockData ( XLogReaderState record,
uint8  block_id,
Size len 
)

◆ XLogRecGetBlockTag()

void XLogRecGetBlockTag ( XLogReaderState record,
uint8  block_id,
RelFileLocator rlocator,
ForkNumber forknum,
BlockNumber blknum 
)

Definition at line 1971 of file xlogreader.c.

1974 {
1975  if (!XLogRecGetBlockTagExtended(record, block_id, rlocator, forknum,
1976  blknum, NULL))
1977  {
1978 #ifndef FRONTEND
1979  elog(ERROR, "could not locate backup block with ID %d in WAL record",
1980  block_id);
1981 #else
1982  pg_fatal("could not locate backup block with ID %d in WAL record",
1983  block_id);
1984 #endif
1985  }
1986 }
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:224
#define pg_fatal(...)
bool XLogRecGetBlockTagExtended(XLogReaderState *record, uint8 block_id, RelFileLocator *rlocator, ForkNumber *forknum, BlockNumber *blknum, Buffer *prefetch_buffer)
Definition: xlogreader.c:1997

References elog, ERROR, pg_fatal, and XLogRecGetBlockTagExtended().

Referenced by brin_xlog_revmap_extend(), btree_xlog_delete(), btree_xlog_split(), DecodeDelete(), DecodeInsert(), DecodeMultiInsert(), DecodeSpecConfirm(), DecodeUpdate(), gistRedoDeleteRecord(), gistRedoPageSplitRecord(), hash_xlog_add_ovfl_page(), hash_xlog_init_bitmap_page(), hash_xlog_init_meta_page(), hash_xlog_vacuum_one_page(), heap_xlog_delete(), heap_xlog_insert(), heap_xlog_lock(), heap_xlog_lock_updated(), heap_xlog_multi_insert(), heap_xlog_prune_freeze(), heap_xlog_update(), heap_xlog_visible(), spgRedoAddLeaf(), spgRedoAddNode(), spgRedoMoveLeafs(), spgRedoPickSplit(), and spgRedoVacuumRedirect().

◆ XLogRecGetBlockTagExtended()

bool XLogRecGetBlockTagExtended ( XLogReaderState record,
uint8  block_id,
RelFileLocator rlocator,
ForkNumber forknum,
BlockNumber blknum,
Buffer prefetch_buffer 
)

Definition at line 1997 of file xlogreader.c.

2001 {
2002  DecodedBkpBlock *bkpb;
2003 
2004  if (!XLogRecHasBlockRef(record, block_id))
2005  return false;
2006 
2007  bkpb = &record->record->blocks[block_id];
2008  if (rlocator)
2009  *rlocator = bkpb->rlocator;
2010  if (forknum)
2011  *forknum = bkpb->forknum;
2012  if (blknum)
2013  *blknum = bkpb->blkno;
2014  if (prefetch_buffer)
2015  *prefetch_buffer = bkpb->prefetch_buffer;
2016  return true;
2017 }
#define XLogRecHasBlockRef(decoder, block_id)
Definition: xlogreader.h:420

References DecodedBkpBlock::blkno, DecodedXLogRecord::blocks, DecodedBkpBlock::forknum, DecodedBkpBlock::prefetch_buffer, XLogReaderState::record, DecodedBkpBlock::rlocator, and XLogRecHasBlockRef.

Referenced by btree_xlog_split(), extractPageInfo(), GetWALBlockInfo(), heap_xlog_update(), SummarizeWAL(), verifyBackupPageConsistency(), xlog_block_info(), XLogReadBufferForRedoExtended(), XLogRecGetBlockRefInfo(), XLogRecGetBlockTag(), XLogRecordMatchesRelationBlock(), and XLogRecordSaveFPWs().

◆ XLogRecGetFullXid()

FullTransactionId XLogRecGetFullXid ( XLogReaderState record)

Definition at line 2167 of file xlogreader.c.

2168 {
2169  TransactionId xid,
2170  next_xid;
2171  uint32 epoch;
2172 
2173  /*
2174  * This function is only safe during replay, because it depends on the
2175  * replay state. See AdvanceNextFullTransactionIdPastXid() for more.
2176  */
2178 
2179  xid = XLogRecGetXid(record);
2182 
2183  /*
2184  * If xid is numerically greater than next_xid, it has to be from the last
2185  * epoch.
2186  */
2187  if (unlikely(xid > next_xid))
2188  --epoch;
2189 
2191 }
bool IsUnderPostmaster
Definition: globals.c:117
#define AmStartupProcess()
Definition: miscadmin.h:382
FullTransactionId nextXid
Definition: transam.h:220
#define EpochFromFullTransactionId(x)
Definition: transam.h:47
#define XidFromFullTransactionId(x)
Definition: transam.h:48
static FullTransactionId FullTransactionIdFromEpochAndXid(uint32 epoch, TransactionId xid)
Definition: transam.h:71
TransamVariablesData * TransamVariables
Definition: varsup.c:34
static const unsigned __int64 epoch
#define XLogRecGetXid(decoder)
Definition: xlogreader.h:412

References AmStartupProcess, Assert, epoch, EpochFromFullTransactionId, FullTransactionIdFromEpochAndXid(), IsUnderPostmaster, TransamVariablesData::nextXid, TransamVariables, unlikely, XidFromFullTransactionId, and XLogRecGetXid.

◆ XLogReleasePreviousRecord()

XLogRecPtr XLogReleasePreviousRecord ( XLogReaderState state)

Definition at line 249 of file xlogreader.c.

250 {
251  DecodedXLogRecord *record;
252  XLogRecPtr next_lsn;
253 
254  if (!state->record)
255  return InvalidXLogRecPtr;
256 
257  /*
258  * Remove it from the decoded record queue. It must be the oldest item
259  * decoded, decode_queue_head.
260  */
261  record = state->record;
262  next_lsn = record->next_lsn;
263  Assert(record == state->decode_queue_head);
264  state->record = NULL;
265  state->decode_queue_head = record->next;
266 
267  /* It might also be the newest item decoded, decode_queue_tail. */
268  if (state->decode_queue_tail == record)
269  state->decode_queue_tail = NULL;
270 
271  /* Release the space. */
272  if (unlikely(record->oversized))
273  {
274  /* It's not in the decode buffer, so free it to release space. */
275  pfree(record);
276  }
277  else
278  {
279  /* It must be the head (oldest) record in the decode buffer. */
280  Assert(state->decode_buffer_head == (char *) record);
281 
282  /*
283  * We need to update head to point to the next record that is in the
284  * decode buffer, if any, being careful to skip oversized ones
285  * (they're not in the decode buffer).
286  */
287  record = record->next;
288  while (unlikely(record && record->oversized))
289  record = record->next;
290 
291  if (record)
292  {
293  /* Adjust head to release space up to the next record. */
294  state->decode_buffer_head = (char *) record;
295  }
296  else
297  {
298  /*
299  * Otherwise we might as well just reset head and tail to the
300  * start of the buffer space, because we're empty. This means
301  * we'll keep overwriting the same piece of memory if we're not
302  * doing any prefetching.
303  */
304  state->decode_buffer_head = state->decode_buffer;
305  state->decode_buffer_tail = state->decode_buffer;
306  }
307  }
308 
309  return next_lsn;
310 }

References Assert, InvalidXLogRecPtr, DecodedXLogRecord::next, DecodedXLogRecord::next_lsn, DecodedXLogRecord::oversized, pfree(), and unlikely.

Referenced by XLogNextRecord(), XLogPrefetcherReadRecord(), and XLogReadRecord().