docs/syscalls/vmo_write.md

# zx_vmo_write

## NAME

vmo_write - write bytes to the VMO

## SYNOPSIS

```
#include <zircon/syscalls.h>

zx_status_t zx_vmo_write(zx_handle_t handle, const void* data, uint64_t offset,
                         size_t len, size_t* actual);

```

## DESCRIPTION

**vmo_write**() attempts to write *len* bytes to a VMO at *offset*. The number of actual
bytes written is returned in *actual*.

*data* pointer to a user buffer to write bytes from.

*len* number of bytes to attempt to write.

*actual* returns the actual number of bytes written, which may be anywhere from 0 to *len*. If
a write extends beyond the size of the VMO, the actual bytes written will be trimmed to the end
of the VMO. If the write starts at or beyond the size of the VMO, **ZX_ERR_OUT_OF_RANGE** will be
returned.

## RETURN VALUE

**zx_vmo_write**() returns **ZX_OK** on success. In the event of failure, a negative error
value is returned.

## ERRORS

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

**ZX_ERR_WRONG_TYPE**  *handle* is not a VMO handle.

**ZX_ERR_ACCESS_DENIED**  *handle* does not have the **ZX_RIGHT_WRITE** right.

**ZX_ERR_INVALID_ARGS**  *actual* or *data* is an invalid pointer or NULL.

**ZX_ERR_NO_MEMORY**  Failure to allocate system memory to complete write.

**ZX_ERR_OUT_OF_RANGE**  *offset* starts at or beyond the end of the VMO.

## SEE ALSO

[vmo_create](vmo_create.md),
[vmo_clone](vmo_clone.md),
[vmo_read](vmo_read.md),
[vmo_get_size](vmo_get_size.md),
[vmo_set_size](vmo_set_size.md),
[vmo_op_range](vmo_op_range.md).