/**
* Set up a raw page so that it looks like a database page holding no entries.
*
* @param sqlJetBtree
* @param flags
* @throws SqlJetException
*/
void zeroPage(int flags) throws SqlJetException {
ISqlJetMemoryPointer data = aData;
byte hdr = hdrOffset;
int first;
assert (pDbPage.getPageNumber() == pgno);
assert (pDbPage.getExtra() == this);
assert (pDbPage.getData().getBuffer() == data.getBuffer());
assert (pBt.mutex.held());
SqlJetUtility.putUnsignedByte(data, hdr, (short) flags);
first = hdr + 8 + 4 * ((flags & SqlJetMemPage.PTF_LEAF) == 0 ? 1 : 0);
// SqlJetUtility.memset(data, hdr + 1, (byte) 0, 4);
SqlJetUtility.put4byte(data, hdr + 1, 0);
//
SqlJetUtility.putUnsignedByte(data, hdr + 7, (short) 0);
SqlJetUtility.put2byte(data, hdr + 5, pBt.usableSize);
nFree = pBt.usableSize - first;
decodeFlags(flags);
hdrOffset = hdr;
cellOffset = first;
nOverflow = 0;
assert (pBt.pageSize >= 512 && pBt.pageSize <= 32768);
maskPage = pBt.pageSize - 1;
nCell = 0;
isInit = true;
}
/**
* Somewhere on pPage, which is guarenteed to be a btree page, not an overflow page, is a pointer
* to page iFrom. Modify this pointer so that it points to iTo. Parameter eType describes the type
* of pointer to be modified, as follows:
*
* <p>PTRMAP_BTREE: pPage is a btree-page. The pointer points at a child page of pPage.
*
* <p>PTRMAP_OVERFLOW1: pPage is a btree-page. The pointer points at an overflow page pointed to
* by one of the cells on pPage.
*
* <p>PTRMAP_OVERFLOW2: pPage is an overflow-page. The pointer points at the next overflow page in
* the list.
*
* @throws SqlJetExceptionRemove
*/
public void modifyPagePointer(int iFrom, int iTo, short s) throws SqlJetException {
assert (pBt.mutex.held());
if (s == SqlJetBtreeShared.PTRMAP_OVERFLOW2) {
/* The pointer is always the first 4 bytes of the page in this case. */
if (get4byte(aData) != iFrom) {
throw new SqlJetException(SqlJetErrorCode.CORRUPT);
}
put4byte(aData, iTo);
} else {
boolean isInitOrig = this.isInit;
int i;
int nCell;
initPage();
nCell = this.nCell;
for (i = 0; i < nCell; i++) {
ISqlJetMemoryPointer pCell = findCell(i);
if (s == SqlJetBtreeShared.PTRMAP_OVERFLOW1) {
SqlJetBtreeCellInfo info;
info = parseCellPtr(pCell);
if (info.iOverflow > 0) {
if (iFrom == get4byte(pCell, info.iOverflow)) {
put4byte(pCell, info.iOverflow, iTo);
break;
}
}
} else {
if (get4byte(pCell) == iFrom) {
put4byte(pCell, iTo);
break;
}
}
}
if (i == nCell) {
if (s != SqlJetBtreeShared.PTRMAP_BTREE || get4byte(aData, hdrOffset + 8) != iFrom) {
throw new SqlJetException(SqlJetErrorCode.CORRUPT);
}
put4byte(aData, hdrOffset + 8, iTo);
}
this.isInit = isInitOrig;
}
}
/**
* Insert a new cell on pPage at cell index "i". pCell points to the content of the cell.
*
* <p>If the cell content will fit on the page, then put it there. If it will not fit, then make a
* copy of the cell content into pTemp if pTemp is not null. Regardless of pTemp, allocate a new
* entry in pPage->aOvfl[] and make it point to the cell content (either in pTemp or the original
* pCell) and also record its index. Allocating a new entry in pPage->aCell[] implies that
* pPage->nOverflow is incremented.
*
* <p>If nSkip is non-zero, then do not copy the first nSkip bytes of the cell. The caller will
* overwrite them after this function returns. If nSkip is non-zero, then pCell may not point to
* an invalid memory location (but pCell+nSkip is always valid).
*
* @param i New cell becomes the i-th cell of the page
* @param pCell Content of the new cell
* @param sz Bytes of content in pCell
* @param pTemp Temp storage space for pCell, if needed
* @param nSkip Do not write the first nSkip bytes of the cell
* @throws SqlJetException
*/
public void insertCell(
int i, ISqlJetMemoryPointer pCell, int sz, ISqlJetMemoryPointer pTemp, int iChild)
throws SqlJetException {
int nSkip = (iChild > 0 ? 4 : 0);
final SqlJetMemPage pPage = this;
int idx; /* Where to write new cell content in data[] */
int j; /* Loop counter */
int top; /* First byte of content for any cell in data[] */
int end; /* First byte past the last cell pointer in data[] */
int ins; /* Index in data[] where new cell pointer is inserted */
int hdr; /* Offset into data[] of the page header */
int cellOffset; /* Address of first cell pointer in data[] */
ISqlJetMemoryPointer data; /* The content of the whole page */
assert (i >= 0 && i <= pPage.nCell + pPage.nOverflow);
assert (pPage.nCell <= pPage.pBt.MX_CELL() && pPage.pBt.MX_CELL() <= 5460);
assert (pPage.nOverflow <= pPage.aOvfl.length);
assert (sz == pPage.cellSizePtr(pCell) || (sz == 8 && iChild > 0));
assert (pPage.pBt.mutex.held());
if (pPage.nOverflow != 0 || sz + 2 > pPage.nFree) {
if (pTemp != null) {
memcpy(pTemp, nSkip, pCell, nSkip, sz - nSkip);
pCell = pTemp;
}
if (iChild > 0) {
put4byte(pCell, iChild);
}
j = pPage.nOverflow++;
// assert( j<(int)(sizeof(pPage.aOvfl)/sizeof(pPage.aOvfl[0])) );
pPage.aOvfl[j].pCell = pCell;
pPage.aOvfl[j].idx = i;
} else {
pPage.pDbPage.write();
assert (pPage.pDbPage.isWriteable());
data = pPage.aData;
hdr = pPage.hdrOffset;
top = get2byte(data, hdr + 5);
cellOffset = pPage.cellOffset;
end = cellOffset + 2 * pPage.nCell + 2;
ins = cellOffset + 2 * i;
if (end > top - sz) {
pPage.defragmentPage();
top = get2byte(data, hdr + 5);
assert (end + sz <= top);
}
idx = pPage.allocateSpace(sz);
assert (idx > 0);
assert (end <= get2byte(data, hdr + 5));
if (idx + sz > pPage.pBt.usableSize) {
throw new SqlJetException(SqlJetErrorCode.CORRUPT);
}
pPage.nCell++;
pPage.nFree -= (2 + sz);
memcpy(data, idx + nSkip, pCell, nSkip, sz - nSkip);
if (iChild > 0) {
put4byte(data, idx, iChild);
}
for (j = end - 2; j > ins; j -= 2) {
SqlJetUtility.putUnsignedByte(data, j, SqlJetUtility.getUnsignedByte(data, j - 2));
SqlJetUtility.putUnsignedByte(data, j + 1, SqlJetUtility.getUnsignedByte(data, j - 1));
}
put2byte(data, ins, idx);
put2byte(data, hdr + 3, pPage.nCell);
if (pPage.pBt.autoVacuum) {
/*
* The cell may contain a pointer to an overflow page. If so,
* write* the entry for the overflow page into the pointer map.
*/
SqlJetBtreeCellInfo info = pPage.parseCellPtr(pCell);
assert ((info.nData + (pPage.intKey ? 0 : info.nKey)) == info.nPayload);
if ((info.nData + (pPage.intKey ? 0 : info.nKey)) > info.nLocal) {
int pgnoOvfl = get4byte(pCell, info.iOverflow);
pPage.pBt.ptrmapPut(pgnoOvfl, SqlJetBtreeShared.PTRMAP_OVERFLOW1, pPage.pgno);
}
}
}
}
/** Add a page of the database file to the freelist. unref() is NOT called for pPage. */
public void freePage() throws SqlJetException {
SqlJetMemPage pPage1 = pBt.pPage1;
int n, k;
/* Prepare the page for freeing */
assert (pBt.mutex.held());
assert (this.pgno > 1);
this.isInit = false;
/* Increment the free page count on pPage1 */
pPage1.pDbPage.write();
n = get4byte(pPage1.aData, 36);
put4byte(pPage1.aData, 36, n + 1);
if (ISqlJetConfig.SECURE_DELETE) {
/*
* If the SQLITE_SECURE_DELETE compile-time option is enabled, then
* always fully overwrite deleted information with zeros.
*/
pDbPage.write();
memset(aData, (byte) 0, pBt.pageSize);
}
/*
* If the database supports auto-vacuum, write an entry in the
* pointer-map to indicate that the page is free.
*/
if (ISAUTOVACUUM()) {
pBt.ptrmapPut(pgno, SqlJetBtreeShared.PTRMAP_FREEPAGE, 0);
}
if (n == 0) {
/* This is the first free page */
pDbPage.write();
memset(aData, (byte) 0, 8);
put4byte(pPage1.aData, 32, pgno);
TRACE("FREE-PAGE: %d first\n", this.pgno);
} else {
/*
* Other free pages already exist. Retrive the first trunk page* of
* the freelist and find out how many leaves it has.
*/
SqlJetMemPage pTrunk;
pTrunk = pBt.getPage(get4byte(pPage1.aData, 32), false);
k = get4byte(pTrunk.aData, 4);
if (k >= pBt.usableSize / 4 - 8) {
/*
* The trunk is full. Turn the page being freed into a new*
* trunk page with no leaves.** Note that the trunk page is not
* really full until it contains* usableSize/4 - 2 entries, not
* usableSize/4 - 8 entries as we have* coded. But due to a
* coding error in versions of SQLite prior to* 3.6.0, databases
* with freelist trunk pages holding more than* usableSize/4 - 8
* entries will be reported as corrupt. In order* to maintain
* backwards compatibility with older versions of SQLite,* we
* will contain to restrict the number of entries to
* usableSize/4 - 8* for now. At some point in the future (once
* everyone has upgraded* to 3.6.0 or later) we should consider
* fixing the conditional above* to read "usableSize/4-2"
* instead of "usableSize/4-8".
*/
pDbPage.write();
put4byte(aData, pTrunk.pgno);
put4byte(aData, 4, 0);
put4byte(pPage1.aData, 32, pgno);
TRACE("FREE-PAGE: %d new trunk page replacing %d\n", this.pgno, pTrunk.pgno);
} else if (k < 0) {
throw new SqlJetException(SqlJetErrorCode.CORRUPT);
} else {
/* Add the newly freed page as a leaf on the current trunk */
pTrunk.pDbPage.write();
put4byte(pTrunk.aData, 4, k + 1);
put4byte(pTrunk.aData, 8 + k * 4, pgno);
if (ISqlJetConfig.SECURE_DELETE) {
pDbPage.dontWrite();
}
TRACE("FREE-PAGE: %d leaf on trunk page %d\n", this.pgno, pTrunk.pgno);
}
releasePage(pTrunk);
}
}
/**
* Create the byte sequence used to represent a cell on page pPage and write that byte sequence
* into pCell[]. Overflow pages are allocated and filled in as necessary. The calling procedure is
* responsible for making sure sufficient space has been allocated for pCell[].
*
* <p>Note that pCell does not necessary need to point to the pPage->aData area. pCell might point
* to some temporary storage. The cell will be constructed in this temporary area then copied into
* pPage->aData later.
*
* @param pCell Complete text of the cell
* @param pKey The key
* @param nKey The key
* @param pData The data
* @param nData The data
* @param nZero Extra zero bytes to append to pData
* @return cell size
* @throws SqlJetException
*/
public int fillInCell(
ISqlJetMemoryPointer pCell,
ISqlJetMemoryPointer pKey,
long nKey,
ISqlJetMemoryPointer pData,
int nData,
int nZero)
throws SqlJetException {
final SqlJetMemPage pPage = this;
int pnSize = 0;
int nPayload;
ISqlJetMemoryPointer pSrc;
int nSrc, n;
int spaceLeft;
SqlJetMemPage pOvfl = null;
SqlJetMemPage pToRelease = null;
ISqlJetMemoryPointer pPrior;
ISqlJetMemoryPointer pPayload;
SqlJetBtreeShared pBt = pPage.pBt;
int[] pgnoOvfl = {0};
int nHeader;
SqlJetBtreeCellInfo info;
assert (pPage.pBt.mutex.held());
/*
* pPage is not necessarily writeable since pCell might be auxiliary*
* buffer space that is separate from the pPage buffer area
*/
assert (pCell.getBuffer() != pPage.aData.getBuffer() || pPage.pDbPage.isWriteable());
/* Fill in the header. */
nHeader = 0;
if (!pPage.leaf) {
nHeader += 4;
}
if (pPage.hasData) {
nHeader += putVarint(pointer(pCell, nHeader), nData + nZero);
} else {
nData = nZero = 0;
}
nHeader += putVarint(pointer(pCell, nHeader), nKey);
info = pPage.parseCellPtr(pCell);
assert (info.nHeader == nHeader);
assert (info.nKey == nKey);
assert (info.nData == nData + nZero);
/* Fill in the payload */
nPayload = nData + nZero;
if (pPage.intKey) {
pSrc = pData;
nSrc = nData;
nData = 0;
} else {
/* TBD: Perhaps raise SQLITE_CORRUPT if nKey is larger than 31 bits? */
nPayload += (int) nKey;
pSrc = pKey;
nSrc = (int) nKey;
}
pnSize = info.nSize;
spaceLeft = info.nLocal;
pPayload = pointer(pCell, nHeader);
pPrior = pointer(pCell, info.iOverflow);
while (nPayload > 0) {
if (spaceLeft == 0) {
int pgnoPtrmap = pgnoOvfl[0]; /*
* Overflow page pointer-map entry
* page
*/
if (pBt.autoVacuum) {
do {
pgnoOvfl[0]++;
} while (pBt.PTRMAP_ISPAGE(pgnoOvfl[0]) || pgnoOvfl[0] == pBt.PENDING_BYTE_PAGE());
}
try {
pOvfl = pBt.allocatePage(pgnoOvfl, pgnoOvfl[0], false);
/*
* If the database supports auto-vacuum, and the second or
* subsequent* overflow page is being allocated, add an
* entry to the pointer-map* for that page now.** If this is
* the first overflow page, then write a partial entry* to
* the pointer-map. If we write nothing to this pointer-map
* slot,* then the optimistic overflow chain processing in
* clearCell()* may misinterpret the uninitialised values
* and delete the* wrong pages from the database.
*/
if (pBt.autoVacuum) {
byte eType =
(pgnoPtrmap != 0
? SqlJetBtreeShared.PTRMAP_OVERFLOW2
: SqlJetBtreeShared.PTRMAP_OVERFLOW1);
try {
pBt.ptrmapPut(pgnoOvfl[0], eType, pgnoPtrmap);
} catch (SqlJetException e) {
releasePage(pOvfl);
}
}
} catch (SqlJetException e) {
releasePage(pToRelease);
throw e;
}
/*
* If pToRelease is not zero than pPrior points into the data
* area* of pToRelease. Make sure pToRelease is still writeable.
*/
assert (pToRelease == null || pToRelease.pDbPage.isWriteable());
/*
* If pPrior is part of the data area of pPage, then make sure
* pPage* is still writeable
*/
assert (pPrior.getBuffer() != pPage.aData.getBuffer() || pPage.pDbPage.isWriteable());
put4byte(pPrior, pgnoOvfl[0]);
releasePage(pToRelease);
pToRelease = pOvfl;
pPrior = pOvfl.aData;
put4byte(pPrior, 0);
pPayload = pointer(pOvfl.aData, 4);
spaceLeft = pBt.usableSize - 4;
}
n = nPayload;
if (n > spaceLeft) n = spaceLeft;
/*
* If pToRelease is not zero than pPayload points into the data area
* * of pToRelease. Make sure pToRelease is still writeable.
*/
assert (pToRelease == null || pToRelease.pDbPage.isWriteable());
/*
* If pPayload is part of the data area of pPage, then make sure
* pPage* is still writeable
*/
assert (pPayload.getBuffer() != pPage.aData.getBuffer() || pPage.pDbPage.isWriteable());
if (nSrc > 0) {
if (n > nSrc) n = nSrc;
assert (pSrc != null);
memcpy(pPayload, pSrc, n);
} else {
memset(pPayload, (byte) 0, n);
}
nPayload -= n;
movePtr(pPayload, n);
pSrc = pointer(pSrc, n);
nSrc -= n;
spaceLeft -= n;
if (nSrc == 0) {
nSrc = nData;
pSrc = pData;
}
}
releasePage(pToRelease);
return pnSize;
}