internal static void pageReinit(DbPage pData)
{
var pPage = Pager.sqlite3PagerGetExtra <MemPage>(pData);
Debug.Assert(Pager.GetPageRefCount(pData) > 0);
if (pPage.HasInit)
{
Debug.Assert(MutexEx.Held(pPage.Shared.Mutex));
pPage.HasInit = false;
if (Pager.GetPageRefCount(pData) > 1)
{
// pPage might not be a btree page; it might be an overflow page or ptrmap page or a free page. In those cases, the following
// call to btreeInitPage() will likely return SQLITE_CORRUPT. But no harm is done by this. And it is very important that
// btreeInitPage() be called on every btree page so we make the call for every page that comes in for re-initing.
pPage.btreeInitPage();
}
}
}
internal RC clearCell(int pCell)
{
Debug.Assert(MutexEx.Held(this.Shared.Mutex));
var info = new CellInfo();
btreeParseCellPtr(pCell, ref info);
if (info.iOverflow == 0)
{
return(RC.OK); // No overflow pages. Return without doing anything
}
var pBt = this.Shared;
var ovflPgno = (Pgno)ConvertEx.Get4(this.Data, pCell + info.iOverflow);
Debug.Assert(pBt.UsableSize > 4);
var ovflPageSize = (uint)(pBt.UsableSize - 4);
var nOvfl = (int)((info.nPayload - info.nLocal + ovflPageSize - 1) / ovflPageSize);
Debug.Assert(ovflPgno == 0 || nOvfl > 0);
RC rc;
while (nOvfl-- != 0)
{
Pgno iNext = 0;
MemPage pOvfl = null;
if (ovflPgno < 2 || ovflPgno > pBt.btreePagecount())
{
// 0 is not a legal page number and page 1 cannot be an overflow page. Therefore if ovflPgno<2 or past the end of the file the database must be corrupt.
return(SysEx.SQLITE_CORRUPT_BKPT());
}
if (nOvfl != 0)
{
rc = pBt.getOverflowPage(ovflPgno, out pOvfl, out iNext);
if (rc != RC.OK)
{
return(rc);
}
}
if ((pOvfl != null || ((pOvfl = pBt.btreePageLookup(ovflPgno)) != null)) && Pager.GetPageRefCount(pOvfl.DbPage) != 1)
{
// There is no reason any cursor should have an outstanding reference to an overflow page belonging to a cell that is being deleted/updated.
// So if there exists more than one reference to this page, then it must not really be an overflow page and the database must be corrupt.
// It is helpful to detect this before calling freePage2(), as freePage2() may zero the page contents if secure-delete mode is
// enabled. If this 'overflow' page happens to be a page that the caller is iterating through or using in some other way, this
// can be problematic.
rc = SysEx.SQLITE_CORRUPT_BKPT();
}
else
{
rc = pBt.freePage2(pOvfl, ovflPgno);
}
if (pOvfl != null)
{
Pager.Unref(pOvfl.DbPage);
}
if (rc != RC.OK)
{
return(rc);
}
ovflPgno = iNext;
}
return(RC.OK);
}
internal RC allocateBtreePage(ref MemPage ppPage, ref Pgno pPgno, Pgno nearby, byte exact)
{
MemPage pTrunk = null;
MemPage pPrevTrunk = null;
Debug.Assert(MutexEx.Held(this.Mutex));
var pPage1 = this.Page1;
var mxPage = btreePagecount(); // Total size of the database file
var n = ConvertEx.Get4(pPage1.Data, 36); // Number of pages on the freelist
if (n >= mxPage)
{
return(SysEx.SQLITE_CORRUPT_BKPT());
}
RC rc;
if (n > 0)
{
// There are pages on the freelist. Reuse one of those pages.
Pgno iTrunk;
byte searchList = 0; // If the free-list must be searched for 'nearby'
// If the 'exact' parameter was true and a query of the pointer-map shows that the page 'nearby' is somewhere on the free-list, then the entire-list will be searched for that page.
#if !SQLITE_OMIT_AUTOVACUUM
if (exact != 0 && nearby <= mxPage)
{
Debug.Assert(nearby > 0);
Debug.Assert(this.AutoVacuum);
PTRMAP eType = 0;
uint dummy0 = 0;
rc = ptrmapGet(nearby, ref eType, ref dummy0);
if (rc != RC.OK)
{
return(rc);
}
if (eType == PTRMAP.FREEPAGE)
{
searchList = 1;
}
pPgno = nearby;
}
#endif
// Decrement the free-list count by 1. Set iTrunk to the index of the first free-list trunk page. iPrevTrunk is initially 1.
rc = Pager.Write(pPage1.DbPage);
if (rc != RC.OK)
{
return(rc);
}
ConvertEx.Put4(pPage1.Data, 36, n - 1);
// The code within this loop is run only once if the 'searchList' variable is not true. Otherwise, it runs once for each trunk-page on the
// free-list until the page 'nearby' is located.
do
{
pPrevTrunk = pTrunk;
iTrunk = (pPrevTrunk != null ? ConvertEx.Get4(pPrevTrunk.Data, 0) : ConvertEx.Get4(pPage1.Data, 32));
rc = (iTrunk > mxPage ? SysEx.SQLITE_CORRUPT_BKPT() : btreeGetPage(iTrunk, ref pTrunk, 0));
if (rc != RC.OK)
{
pTrunk = null;
goto end_allocate_page;
}
var k = ConvertEx.Get4(pTrunk.Data, 4); // # of leaves on this trunk page
if (k == 0 && searchList == 0)
{
// The trunk has no leaves and the list is not being searched. So extract the trunk page itself and use it as the newly allocated page
Debug.Assert(pPrevTrunk == null);
rc = Pager.Write(pTrunk.DbPage);
if (rc != RC.OK)
{
goto end_allocate_page;
}
pPgno = iTrunk;
Buffer.BlockCopy(pTrunk.Data, 0, pPage1.Data, 32, 4);
ppPage = pTrunk;
pTrunk = null;
Btree.TRACE("ALLOCATE: %d trunk - %d free pages left\n", pPgno, n - 1);
}
else if (k > (uint)(this.UsableSize / 4 - 2))
{
// Value of k is out of range. Database corruption
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto end_allocate_page;
#if !SQLITE_OMIT_AUTOVACUUM
}
else if (searchList != 0 && nearby == iTrunk)
{
// The list is being searched and this trunk page is the page to allocate, regardless of whether it has leaves.
Debug.Assert(pPgno == iTrunk);
ppPage = pTrunk;
searchList = 0;
rc = Pager.Write(pTrunk.DbPage);
if (rc != RC.OK)
{
goto end_allocate_page;
}
if (k == 0)
{
if (pPrevTrunk == null)
{
pPage1.Data[32 + 0] = pTrunk.Data[0 + 0];
pPage1.Data[32 + 1] = pTrunk.Data[0 + 1];
pPage1.Data[32 + 2] = pTrunk.Data[0 + 2];
pPage1.Data[32 + 3] = pTrunk.Data[0 + 3];
}
else
{
rc = Pager.Write(pPrevTrunk.DbPage);
if (rc != RC.OK)
{
goto end_allocate_page;
}
pPrevTrunk.Data[0 + 0] = pTrunk.Data[0 + 0];
pPrevTrunk.Data[0 + 1] = pTrunk.Data[0 + 1];
pPrevTrunk.Data[0 + 2] = pTrunk.Data[0 + 2];
pPrevTrunk.Data[0 + 3] = pTrunk.Data[0 + 3];
}
}
else
{
// The trunk page is required by the caller but it contains pointers to free-list leaves. The first leaf becomes a trunk page in this case.
var pNewTrunk = new MemPage();
var iNewTrunk = (Pgno)ConvertEx.Get4(pTrunk.Data, 8);
if (iNewTrunk > mxPage)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto end_allocate_page;
}
rc = btreeGetPage(iNewTrunk, ref pNewTrunk, 0);
if (rc != RC.OK)
{
goto end_allocate_page;
}
rc = Pager.Write(pNewTrunk.DbPage);
if (rc != RC.OK)
{
pNewTrunk.releasePage();
goto end_allocate_page;
}
pNewTrunk.Data[0 + 0] = pTrunk.Data[0 + 0];
pNewTrunk.Data[0 + 1] = pTrunk.Data[0 + 1];
pNewTrunk.Data[0 + 2] = pTrunk.Data[0 + 2];
pNewTrunk.Data[0 + 3] = pTrunk.Data[0 + 3];
ConvertEx.Put4(pNewTrunk.Data, 4, (uint)(k - 1));
Buffer.BlockCopy(pTrunk.Data, 12, pNewTrunk.Data, 8, (int)(k - 1) * 4);
pNewTrunk.releasePage();
if (pPrevTrunk == null)
{
Debug.Assert(Pager.IsPageWriteable(pPage1.DbPage));
ConvertEx.Put4(pPage1.Data, 32, iNewTrunk);
}
else
{
rc = Pager.Write(pPrevTrunk.DbPage);
if (rc != RC.OK)
{
goto end_allocate_page;
}
ConvertEx.Put4(pPrevTrunk.Data, 0, iNewTrunk);
}
}
pTrunk = null;
Btree.TRACE("ALLOCATE: %d trunk - %d free pages left\n", pPgno, n - 1);
#endif
}
else if (k > 0)
{
// Extract a leaf from the trunk
uint closest;
var aData = pTrunk.Data;
if (nearby > 0)
{
closest = 0;
var dist = Math.Abs((int)(ConvertEx.Get4(aData, 8) - nearby));
for (uint i = 1; i < k; i++)
{
int dist2 = Math.Abs((int)(ConvertEx.Get4(aData, 8 + i * 4) - nearby));
if (dist2 < dist)
{
closest = i;
dist = dist2;
}
}
}
else
{
closest = 0;
}
//
var iPage = (Pgno)ConvertEx.Get4(aData, 8 + closest * 4);
if (iPage > mxPage)
{
rc = SysEx.SQLITE_CORRUPT_BKPT();
goto end_allocate_page;
}
if (searchList == 0 || iPage == nearby)
{
pPgno = iPage;
Btree.TRACE("ALLOCATE: %d was leaf %d of %d on trunk %d" + ": %d more free pages\n", pPgno, closest + 1, k, pTrunk.ID, n - 1);
rc = Pager.Write(pTrunk.DbPage);
if (rc != RC.OK)
{
goto end_allocate_page;
}
if (closest < k - 1)
{
Buffer.BlockCopy(aData, (int)(4 + k * 4), aData, 8 + (int)closest * 4, 4);
}
ConvertEx.Put4(aData, 4, (k - 1));
var noContent = (!btreeGetHasContent(pPgno) ? 1 : 0);
rc = btreeGetPage(pPgno, ref ppPage, noContent);
if (rc == RC.OK)
{
rc = Pager.Write((ppPage).DbPage);
if (rc != RC.OK)
{
ppPage.releasePage();
}
}
searchList = 0;
}
}
pPrevTrunk.releasePage();
pPrevTrunk = null;
} while (searchList != 0);
}
else
{
// There are no pages on the freelist, so create a new page at the end of the file
rc = Pager.Write(this.Page1.DbPage);
if (rc != RC.OK)
{
return(rc);
}
this.Pages++;
if (this.Pages == MemPage.PENDING_BYTE_PAGE(this))
{
this.Pages++;
}
#if !SQLITE_OMIT_AUTOVACUUM
if (this.AutoVacuum && MemPage.PTRMAP_ISPAGE(this, this.Pages))
{
// If pPgno refers to a pointer-map page, allocate two new pages at the end of the file instead of one. The first allocated page
// becomes a new pointer-map page, the second is used by the caller.
MemPage pPg = null;
Btree.TRACE("ALLOCATE: %d from end of file (pointer-map page)\n", pPgno);
Debug.Assert(this.Pages != MemPage.PENDING_BYTE_PAGE(this));
rc = btreeGetPage(this.Pages, ref pPg, 1);
if (rc == RC.OK)
{
rc = Pager.Write(pPg.DbPage);
pPg.releasePage();
}
if (rc != RC.OK)
{
return(rc);
}
this.Pages++;
if (this.Pages == MemPage.PENDING_BYTE_PAGE(this))
{
this.Pages++;
}
}
#endif
ConvertEx.Put4(this.Page1.Data, 28, this.Pages);
pPgno = this.Pages;
Debug.Assert(pPgno != MemPage.PENDING_BYTE_PAGE(this));
rc = btreeGetPage(pPgno, ref ppPage, 1);
if (rc != RC.OK)
{
return(rc);
}
rc = Pager.Write((ppPage).DbPage);
if (rc != RC.OK)
{
ppPage.releasePage();
}
Btree.TRACE("ALLOCATE: %d from end of file\n", pPgno);
}
Debug.Assert(pPgno != MemPage.PENDING_BYTE_PAGE(this));
end_allocate_page:
pTrunk.releasePage();
pPrevTrunk.releasePage();
if (rc == RC.OK)
{
if (Pager.GetPageRefCount((ppPage).DbPage) > 1)
{
ppPage.releasePage();
return(SysEx.SQLITE_CORRUPT_BKPT());
}
(ppPage).HasInit = false;
}
else
{
ppPage = null;
}
Debug.Assert(rc != RC.OK || Pager.IsPageWriteable((ppPage).DbPage));
return(rc);
}
