public static Backup Init(Context destCtx, string destDbName, Context srcCtx, string srcDbName)
{
// Lock the source database handle. The destination database handle is not locked in this routine, but it is locked in
// sqlite3_backup_step(). The user is required to ensure that no other thread accesses the destination handle for the duration
// of the backup operation. Any attempt to use the destination database connection while a backup is in progress may cause
// a malfunction or a deadlock.
MutexEx.Enter(srcCtx.Mutex);
MutexEx.Enter(destCtx.Mutex);
Backup p;
if (srcCtx == destCtx)
{
Main.Error(destCtx, RC.ERROR, "source and destination must be distinct");
p = null;
}
else
{
// Allocate space for a new sqlite3_backup object... EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a
// call to sqlite3_backup_init() and is destroyed by a call to sqlite3_backup_finish().
p = new Backup();
if (p == null)
Main.Error(destCtx, RC.NOMEM, null);
}
// If the allocation succeeded, populate the new object.
if (p != null)
{
p.Src = FindBtree(destCtx, srcCtx, srcDbName);
p.Dest = FindBtree(destCtx, destCtx, destDbName);
p.DestCtx = destCtx;
p.SrcCtx = srcCtx;
p.NextId = 1;
p.IsAttached = false;
if (p.Src == null || p.Dest == null || SetDestPgsz(p) == RC.NOMEM)
{
// One (or both) of the named databases did not exist or an OOM error was hit. The error has already been written into the
// pDestDb handle. All that is left to do here is free the sqlite3_backup structure.
//C._free(ref p);
p = null;
}
}
if (p != null)
p.Src.Backups++;
MutexEx.Leave(destCtx.Mutex);
MutexEx.Leave(srcCtx.Mutex);
return p;
}
static RC SetDestPgsz(Backup p)
{
RC rc = p.Dest.SetPageSize(p.Src.GetPageSize(), -1, false);
return rc;
}
static void AttachBackupObject(Backup p)
{
Debug.Assert(p.Src.HoldsMutex());
Backup pp = (Backup)p.Src.get_Pager().Backup;
p.Next = pp;
p.Src.get_Pager().Backup = p;
p.IsAttached = true;
}
public static RC Finish(Backup p)
{
// Enter the mutexes
if (p == null) return RC.OK;
Context srcCtx = p.SrcCtx; // Source database connection
MutexEx.Enter(srcCtx.Mutex);
p.Src.Enter();
if (p.DestCtx != null)
MutexEx.Enter(p.DestCtx.Mutex);
// Detach this backup from the source pager.
if (p.DestCtx != null)
p.Src.Backups--;
if (p.IsAttached)
{
Backup pp = (Backup)p.Src.get_Pager().Backup;
while (pp != p)
pp = (pp).Next;
p.Src.get_Pager().Backup = p.Next;
}
// If a transaction is still open on the Btree, roll it back.
p.Dest.Rollback(RC.OK);
// Set the error code of the destination database handle.
RC rc = (p.RC_ == RC.DONE ? RC.OK : p.RC_);
Main.Error(p.DestCtx, rc, null);
// Exit the mutexes and free the backup context structure.
if (p.DestCtx != null)
Main.LeaveMutexAndCloseZombie(p.DestCtx.Mutex);
p.Src.Leave();
//// EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a call to sqlite3_backup_init() and is destroyed by a call to sqlite3_backup_finish().
//if (p.DestCtx != null)
// C._free(ref p);
Main.LeaveMutexAndCloseZombie(mutex);
return rc;
}
static RC BackupOnePage(Backup p, Pid srcPg, byte[] srcData, bool update)
{
Pager destPager = p.Dest.get_Pager();
int srcPgsz = p.Src.GetPageSize();
int destPgsz = p.Dest.GetPageSize();
int copy = Math.Min(srcPgsz, destPgsz);
long end = (long)srcPg * (long)srcPgsz;
RC rc = RC.OK;
Debug.Assert(p.Src.GetReserveNoMutex() >= 0);
Debug.Assert(p.DestLocked);
Debug.Assert(!IsFatalError(p.RC_));
Debug.Assert(srcPg != Btree.PENDING_BYTE_PAGE(p.Src.Bt));
Debug.Assert(srcData != null);
// Catch the case where the destination is an in-memory database and the page sizes of the source and destination differ.
if (srcPgsz != destPgsz && destPager.get_MemoryDB)
rc = RC.READONLY;
#if HAS_CODEC
int srcReserve = p.Src.GetReserveNoMutex();
int destReserve = p.Dest.GetReserve();
// Backup is not possible if the page size of the destination is changing and a codec is in use.
if (srcPgsz != destPgsz && Pager.GetCodec(destPager) != null)
rc = RC.READONLY;
// Backup is not possible if the number of bytes of reserve space differ between source and destination. If there is a difference, try to
// fix the destination to agree with the source. If that is not possible, then the backup cannot proceed.
if (srcReserve != destReserve)
{
uint newPgsz = (uint)srcPgsz;
rc = destPager.SetPageSize(ref newPgsz, srcReserve);
if (rc == RC.OK && newPgsz != srcPgsz)
rc = RC.READONLY;
}
#endif
// This loop runs once for each destination page spanned by the source page. For each iteration, variable iOff is set to the byte offset
// of the destination page.
for (long off = end - (long)srcPgsz; rc == RC.OK && off < end; off += destPgsz)
{
IPage destPg = null;
uint dest = (uint)(off / destPgsz) + 1;
if (dest == Btree.PENDING_BYTE_PAGE(p.Dest.Bt))
continue;
if ((rc = destPager.Acquire(dest, ref destPg, false)) == RC.OK && (rc = Pager.Write(destPg)) == RC.OK)
{
byte[] destData = Pager.GetData(destPg);
// Copy the data from the source page into the destination page. Then clear the Btree layer MemPage.isInit flag. Both this module
// and the pager code use this trick (clearing the first byte of the page 'extra' space to invalidate the Btree layers
// cached parse of the page). MemPage.isInit is marked "MUST BE FIRST" for this purpose.
Buffer.BlockCopy(srcData, (int)(off % srcPgsz), destData, (int)(off % destPgsz), copy);
Pager.GetExtra(destPg).IsInit = false;
}
Pager.Unref(destPg);
}
return rc;
}
