/*
** Make sure pMem->z points to a writable allocation of at least
** n bytes.
**
** If the memory cell currently contains string or blob data
** and the third argument passed to this function is true, the
** current content of the cell is preserved. Otherwise, it may
** be discarded.
**
** This function sets the MEM_Dyn flag and clears any xDel callback.
** It also clears MEM_Ephem and MEM_Static. If the preserve flag is
** not set, Mem.n is zeroed.
*/
int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve){
assert( 1 >=
((pMem->zMalloc && pMem->zMalloc==pMem->z) ? 1 : 0) +
(((pMem->flags&MEM_Dyn)&&pMem->xDel) ? 1 : 0) +
((pMem->flags&MEM_Ephem) ? 1 : 0) +
((pMem->flags&MEM_Static) ? 1 : 0)
);
if( n<32 ) n = 32;
if( sqlite3DbMallocSize(pMem->db, pMem->zMalloc)<n ){
if( preserve && pMem->z==pMem->zMalloc ){
pMem->z = pMem->zMalloc = sqlite3DbReallocOrFree(pMem->db, pMem->z, n);
preserve = 0;
}else{
sqlite3DbFree(pMem->db, pMem->zMalloc);
pMem->zMalloc = sqlite3DbMallocRaw(pMem->db, n);
}
}
if( preserve && pMem->z && pMem->zMalloc && pMem->z!=pMem->zMalloc ){
memcpy(pMem->zMalloc, pMem->z, pMem->n);
}
if( pMem->flags&MEM_Dyn && pMem->xDel ){
pMem->xDel((void *)(pMem->z));
}
pMem->z = pMem->zMalloc;
if( pMem->z==0 ){
pMem->flags = MEM_Null;
}else{
pMem->flags &= ~(MEM_Ephem|MEM_Static);
}
pMem->xDel = 0;
return (pMem->z ? SQLITE_OK : SQLITE_NOMEM);
}
/*
** Advance iterator pIter to the next key in its PMA. Return SQLITE_OK if
** no error occurs, or an SQLite error code if one does.
*/
static int vdbeSorterIterNext(
sqlite3 *db, /* Database handle (for sqlite3DbMalloc() ) */
VdbeSorterIter *pIter /* Iterator to advance */
){
int rc; /* Return Code */
int nRead; /* Number of bytes read */
int nRec = 0; /* Size of record in bytes */
int iOff = 0; /* Size of serialized size varint in bytes */
assert( pIter->iEof>=pIter->iReadOff );
if( pIter->iEof-pIter->iReadOff>5 ){
nRead = 5;
}else{
nRead = (int)(pIter->iEof - pIter->iReadOff);
}
if( nRead<=0 ){
/* This is an EOF condition */
vdbeSorterIterZero(db, pIter);
return SQLITE_OK;
}
rc = sqlite3OsRead(pIter->pFile, pIter->aAlloc, nRead, pIter->iReadOff);
if( rc==SQLITE_OK ){
iOff = getVarint32(pIter->aAlloc, nRec);
if( (iOff+nRec)>nRead ){
int nRead2; /* Number of extra bytes to read */
if( (iOff+nRec)>pIter->nAlloc ){
int nNew = pIter->nAlloc*2;
while( (iOff+nRec)>nNew ) nNew = nNew*2;
pIter->aAlloc = sqlite3DbReallocOrFree(db, pIter->aAlloc, nNew);
if( !pIter->aAlloc ) return SQLITE_NOMEM;
pIter->nAlloc = nNew;
}
nRead2 = iOff + nRec - nRead;
rc = sqlite3OsRead(
pIter->pFile, &pIter->aAlloc[nRead], nRead2, pIter->iReadOff+nRead
);
}
}
assert( rc!=SQLITE_OK || nRec>0 );
pIter->iReadOff += iOff+nRec;
pIter->nKey = nRec;
pIter->aKey = &pIter->aAlloc[iOff];
return rc;
}
/*
** Make sure pMem->z points to a writable allocation of at least
** n bytes.
**
** If the third argument passed to this function is true, then memory
** cell pMem must contain a string or blob. In this case the content is
** preserved. Otherwise, if the third parameter to this function is false,
** any current string or blob value may be discarded.
**
** This function sets the MEM_Dyn flag and clears any xDel callback.
** It also clears MEM_Ephem and MEM_Static. If the preserve flag is
** not set, Mem.n is zeroed.
*/
int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve){
assert( 1 >=
((pMem->zMalloc && pMem->zMalloc==pMem->z) ? 1 : 0) +
(((pMem->flags&MEM_Dyn)&&pMem->xDel) ? 1 : 0) +
((pMem->flags&MEM_Ephem) ? 1 : 0) +
((pMem->flags&MEM_Static) ? 1 : 0)
);
assert( (pMem->flags&MEM_RowSet)==0 );
/* If the preserve flag is set to true, then the memory cell must already
** contain a valid string or blob value. */
assert( preserve==0 || pMem->flags&(MEM_Blob|MEM_Str) );
if( n<32 ) n = 32;
if( sqlite3DbMallocSize(pMem->db, pMem->zMalloc)<n ){
if( preserve && pMem->z==pMem->zMalloc ){
pMem->z = pMem->zMalloc = sqlite3DbReallocOrFree(pMem->db, pMem->z, n);
preserve = 0;
}else{
sqlite3DbFree(pMem->db, pMem->zMalloc);
pMem->zMalloc = sqlite3DbMallocRaw(pMem->db, n);
}
}
if( pMem->z && preserve && pMem->zMalloc && pMem->z!=pMem->zMalloc ){
memcpy(pMem->zMalloc, pMem->z, pMem->n);
}
if( pMem->flags&MEM_Dyn && pMem->xDel ){
assert( pMem->xDel!=SQLITE_DYNAMIC );
pMem->xDel((void *)(pMem->z));
}
pMem->z = pMem->zMalloc;
if( pMem->z==0 ){
pMem->flags = MEM_Null;
}else{
pMem->flags &= ~(MEM_Ephem|MEM_Static);
}
pMem->xDel = 0;
return (pMem->z ? SQLITE_OK : SQLITE_NOMEM);
}
/*
** Read nByte bytes of data from the stream of data iterated by object p.
** If successful, set *ppOut to point to a buffer containing the data
** and return SQLITE_OK. Otherwise, if an error occurs, return an SQLite
** error code.
**
** The buffer indicated by *ppOut may only be considered valid until the
** next call to this function.
*/
static int vdbeSorterIterRead(
sqlite3 *db, /* Database handle (for malloc) */
VdbeSorterIter *p, /* Iterator */
int nByte, /* Bytes of data to read */
u8 **ppOut /* OUT: Pointer to buffer containing data */
){
int iBuf; /* Offset within buffer to read from */
int nAvail; /* Bytes of data available in buffer */
assert( p->aBuffer );
/* If there is no more data to be read from the buffer, read the next
** p->nBuffer bytes of data from the file into it. Or, if there are less
** than p->nBuffer bytes remaining in the PMA, read all remaining data. */
iBuf = p->iReadOff % p->nBuffer;
if( iBuf==0 ){
int nRead; /* Bytes to read from disk */
int rc; /* sqlite3OsRead() return code */
/* Determine how many bytes of data to read. */
if( (p->iEof - p->iReadOff) > (i64)p->nBuffer ){
nRead = p->nBuffer;
}else{
nRead = (int)(p->iEof - p->iReadOff);
}
assert( nRead>0 );
/* Read data from the file. Return early if an error occurs. */
rc = sqlite3OsRead(p->pFile, p->aBuffer, nRead, p->iReadOff);
assert( rc!=SQLITE_IOERR_SHORT_READ );
if( rc!=SQLITE_OK ) return rc;
}
nAvail = p->nBuffer - iBuf;
if( nByte<=nAvail ){
/* The requested data is available in the in-memory buffer. In this
** case there is no need to make a copy of the data, just return a
** pointer into the buffer to the caller. */
*ppOut = &p->aBuffer[iBuf];
p->iReadOff += nByte;
}else{
/* The requested data is not all available in the in-memory buffer.
** In this case, allocate space at p->aAlloc[] to copy the requested
** range into. Then return a copy of pointer p->aAlloc to the caller. */
int nRem; /* Bytes remaining to copy */
/* Extend the p->aAlloc[] allocation if required. */
if( p->nAlloc<nByte ){
int nNew = p->nAlloc*2;
while( nByte>nNew ) nNew = nNew*2;
p->aAlloc = sqlite3DbReallocOrFree(db, p->aAlloc, nNew);
if( !p->aAlloc ) return SQLITE_NOMEM;
p->nAlloc = nNew;
}
/* Copy as much data as is available in the buffer into the start of
** p->aAlloc[]. */
memcpy(p->aAlloc, &p->aBuffer[iBuf], nAvail);
p->iReadOff += nAvail;
nRem = nByte - nAvail;
/* The following loop copies up to p->nBuffer bytes per iteration into
** the p->aAlloc[] buffer. */
while( nRem>0 ){
int rc; /* vdbeSorterIterRead() return code */
int nCopy; /* Number of bytes to copy */
u8 *aNext; /* Pointer to buffer to copy data from */
nCopy = nRem;
if( nRem>p->nBuffer ) nCopy = p->nBuffer;
rc = vdbeSorterIterRead(db, p, nCopy, &aNext);
if( rc!=SQLITE_OK ) return rc;
assert( aNext!=p->aAlloc );
memcpy(&p->aAlloc[nByte - nRem], aNext, nCopy);
nRem -= nCopy;
}
*ppOut = p->aAlloc;
}
return SQLITE_OK;
}
