main/syscalls/iob_writev.md

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# zx_iob_writev

## Summary

Performs a mediated write to an IOBuffer region.

## Declaration
```c
#include <zircon/syscalls/iob.h>

zx_status_t zx_iob_write(zx_handle_t handle,
                         zx_iob_write_options_t options,
                         uint32_t region_index,
                         const zx_iovec_t* vectors,
                         size_t num_vectors);
```

## Description

Performs a mediated write to an IOBuffer region.

`options` must be zero.

The IOBuffer handle used to interact with the region must admit mediated write access.

There is a limit of 65535 bytes including any headers that the discipline might mandate, and
there can be no more than 8 vectors.

## Return value

On success, the data is written to the specified region according to the semantics of the
discipline.

## Errors

`ZX_ERR_ACCESS_DENIED`  The IOB handle does not have write permissions,
or the corresponding region does not have mediated write permissions.

`ZX_ERR_BAD_HANDLE`  *handle* is not a valid handle.

`ZX_ERR_INVALID_ARGS`  `options` was nonzero (there are no non-default options supported at
this time), the amount of data to write exceeds the limit, or the vectors are invalid.

`ZX_ERR_IO_DATA_INTEGRITY`  The region has been corrupted.

`ZX_ERR_NOT_FOUND`  A vector is invalid (e.g. points to invalid memory).

`ZX_ERR_NO_SPACE`  The region has insufficient space to write the message.

`ZX_ERR_OUT_OF_RANGE`  `region_index` exceeded the maximum region index.

`ZX_ERR_WRONG_TYPE`  The handle is not an IOBuffer handle, or the corresponding region is not
of the required discipline.