Buffer-oriented synchronous random-access write device requirements

In the table below, a denotes a synchronous random-access write device object, o denotes an offset of type boost::uint64_t, cb denotes an object satisfying constant buffer sequence requirements, and ec denotes an object of type error_code.

Table 30. Buffer-oriented synchronous random-access write device requirements

operation	type	semantics, pre/post-conditions
`a.write_some_at(o, cb);`	`size_t`	Equivalent to: error_code ec; size_t s = a.write_some(o, cb, ec); if (ec) throw system_error(ec); return s;
`a.write_some_at(o, cb, ec);`	`size_t`	Writes one or more bytes of data to the device `a` at offset `o`. The constant buffer sequence `cb` specifies memory where the data to be written is located. The `write_some_at` operation shall always write a buffer in the sequence completely before proceeding to the next. If successful, returns the number of bytes written and sets `ec` such that `!ec` is true. If an error occurred, returns `0` and sets `ec` such that `!!ec` is true. If the total size of all buffers in the sequence `cb` is `0`, the function shall return `0` immediately.

operation

type

semantics, pre/post-conditions

a.write_some_at(o, cb);

size_t

Equivalent to:

error_code ec;
size_t s = a.write_some(o, cb, ec);
if (ec) throw system_error(ec);
return s;

a.write_some_at(o, cb, ec);

size_t

Writes one or more bytes of data to the device a at offset o.

The constant buffer sequence cb specifies memory where the data to be written is located. The write_some_at operation shall always write a buffer in the sequence completely before proceeding to the next.

If successful, returns the number of bytes written and sets ec such that !ec is true. If an error occurred, returns 0 and sets ec such that !!ec is true.

If the total size of all buffers in the sequence cb is 0, the function shall return 0 immediately.