/*
* 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);
/*
* 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;
}
/*
* Update range within LO
*/
Datum
be_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);
/* Permission check */
if (!lo_compat_privileges &&
pg_largeobject_aclcheck_snapshot(loDesc->id,
GetUserId(),
ACL_UPDATE,
loDesc->snapshot) != ACLCHECK_OK)
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied for large object %u",
loDesc->id)));
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();
}
Datum
lo_lseek64(PG_FUNCTION_ARGS)
{
int32 fd = PG_GETARG_INT32(0);
int64 offset = PG_GETARG_INT64(1);
int32 whence = PG_GETARG_INT32(2);
int64 status;
#ifdef PGXC
#ifdef XCP
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("Postgres-XL does not yet support large objects"),
errdetail("The feature is not currently supported")));
#else
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("Postgres-XC does not support large object yet"),
errdetail("The feature is not currently supported")));
#endif
#endif
if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("invalid large-object descriptor: %d", fd)));
status = inv_seek(cookies[fd], offset, whence);
PG_RETURN_INT64(status);
}
Datum
lo_lseek(PG_FUNCTION_ARGS)
{
int32 fd = PG_GETARG_INT32(0);
int32 offset = PG_GETARG_INT32(1);
int32 whence = PG_GETARG_INT32(2);
int64 status;
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("large objects are not supported")));
if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("invalid large-object descriptor: %d", fd)));
status = inv_seek(cookies[fd], offset, whence);
/* guard against result overflow */
if (status != (int32) status)
ereport(ERROR,
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
errmsg("lo_lseek result out of range for large-object descriptor %d",
fd)));
PG_RETURN_INT32((int32) status);
}
Datum
lo_lseek(PG_FUNCTION_ARGS)
{
int32 fd = PG_GETARG_INT32(0);
int32 offset = PG_GETARG_INT32(1);
int32 whence = PG_GETARG_INT32(2);
int status;
if (fd < 0 || fd >= cookies_size || cookies[fd] == NULL)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("invalid large-object descriptor: %d", fd)));
status = inv_seek(cookies[fd], offset, whence);
PG_RETURN_INT32(status);
}
/*
* 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();
}
