@ -754,3 +754,154 @@ deleteLOfd(int fd)
{
cookies [ fd ] = NULL ;
}
/*****************************************************************************
* Wrappers oriented toward SQL callers
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* Read [ offset , offset + nbytes ) within LO ; when nbytes is - 1 , read to end .
*/
static bytea *
lo_get_fragment_internal ( Oid loOid , int64 offset , int32 nbytes )
{
LargeObjectDesc * loDesc ;
int64 loSize ;
int64 result_length ;
int total_read PG_USED_FOR_ASSERTS_ONLY ;
bytea * result = NULL ;
/*
* We don ' t actually need to store into fscxt , but create it anyway to
* ensure that AtEOXact_LargeObject knows there is state to clean up
*/
CreateFSContext ( ) ;
loDesc = inv_open ( loOid , INV_READ , fscxt ) ;
/* Permission check */
if ( ! lo_compat_privileges & &
pg_largeobject_aclcheck_snapshot ( loDesc - > id ,
GetUserId ( ) ,
ACL_SELECT ,
loDesc - > snapshot ) ! = ACLCHECK_OK )
ereport ( ERROR ,
( errcode ( ERRCODE_INSUFFICIENT_PRIVILEGE ) ,
errmsg ( " permission denied for large object %u " ,
loDesc - > id ) ) ) ;
/*
* Compute number of bytes we ' ll actually read , accommodating nbytes = = - 1
* and reads beyond the end of the LO .
*/
loSize = inv_seek ( loDesc , 0 , SEEK_END ) ;
if ( loSize > offset )
{
if ( nbytes > = 0 & & nbytes < = loSize - offset )
result_length = nbytes ; /* request is wholly inside LO */
else
result_length = loSize - offset ; /* adjust to end of LO */
}
else
result_length = 0 ; /* request is wholly outside LO */
/*
* A result_length calculated from loSize may not fit in a size_t . Check
* that the size will satisfy this and subsequently - enforced size limits .
*/
if ( result_length > MaxAllocSize - VARHDRSZ )
ereport ( ERROR ,
( errcode ( ERRCODE_PROGRAM_LIMIT_EXCEEDED ) ,
errmsg ( " large object read request is too large " ) ) ) ;
result = ( bytea * ) palloc ( VARHDRSZ + result_length ) ;
inv_seek ( loDesc , offset , SEEK_SET ) ;
total_read = inv_read ( loDesc , VARDATA ( result ) , result_length ) ;
Assert ( total_read = = result_length ) ;
SET_VARSIZE ( result , result_length + VARHDRSZ ) ;
inv_close ( loDesc ) ;
return result ;
}
/*
* Read entire LO
*/
Datum
lo_get ( PG_FUNCTION_ARGS )
{
Oid loOid = PG_GETARG_OID ( 0 ) ;
bytea * result ;
result = lo_get_fragment_internal ( loOid , 0 , - 1 ) ;
PG_RETURN_BYTEA_P ( result ) ;
}
/*
* Read range within LO
*/
Datum
lo_get_fragment ( PG_FUNCTION_ARGS )
{
Oid loOid = PG_GETARG_OID ( 0 ) ;
int64 offset = PG_GETARG_INT64 ( 1 ) ;
int32 nbytes = PG_GETARG_INT32 ( 2 ) ;
bytea * result ;
if ( nbytes < 0 )
ereport ( ERROR ,
( errcode ( ERRCODE_INVALID_PARAMETER_VALUE ) ,
errmsg ( " requested length cannot be negative " ) ) ) ;
result = lo_get_fragment_internal ( loOid , offset , nbytes ) ;
PG_RETURN_BYTEA_P ( result ) ;
}
/*
* Create LO with initial contents
*/
Datum
lo_create_bytea ( PG_FUNCTION_ARGS )
{
Oid loOid = PG_GETARG_OID ( 0 ) ;
bytea * str = PG_GETARG_BYTEA_PP ( 1 ) ;
LargeObjectDesc * loDesc ;
int written PG_USED_FOR_ASSERTS_ONLY ;
CreateFSContext ( ) ;
loOid = inv_create ( loOid ) ;
loDesc = inv_open ( loOid , INV_WRITE , fscxt ) ;
written = inv_write ( loDesc , VARDATA_ANY ( str ) , VARSIZE_ANY_EXHDR ( str ) ) ;
Assert ( written = = VARSIZE_ANY_EXHDR ( str ) ) ;
inv_close ( loDesc ) ;
PG_RETURN_OID ( loOid ) ;
}
/*
* Update range within LO
*/
Datum
lo_put ( PG_FUNCTION_ARGS )
{
Oid loOid = PG_GETARG_OID ( 0 ) ;
int64 offset = PG_GETARG_INT64 ( 1 ) ;
bytea * str = PG_GETARG_BYTEA_PP ( 2 ) ;
LargeObjectDesc * loDesc ;
int written PG_USED_FOR_ASSERTS_ONLY ;
CreateFSContext ( ) ;
loDesc = inv_open ( loOid , INV_WRITE , fscxt ) ;
inv_seek ( loDesc , offset , SEEK_SET ) ;
written = inv_write ( loDesc , VARDATA_ANY ( str ) , VARSIZE_ANY_EXHDR ( str ) ) ;
Assert ( written = = VARSIZE_ANY_EXHDR ( str ) ) ;
inv_close ( loDesc ) ;
PG_RETURN_VOID ( ) ;
}
Noah Misch
12 years ago