1# zx_vmo_read 2 3## NAME 4 5vmo_read - read bytes from the VMO 6 7## SYNOPSIS 8 9``` 10#include <zircon/syscalls.h> 11 12zx_status_t zx_vmo_read(zx_handle_t handle, void* buffer, uint64_t offset, size_t buffer_size); 13 14``` 15 16## DESCRIPTION 17 18**vmo_read**() attempts to read exactly *buffer_size* bytes from a VMO at *offset*. 19 20*buffer* pointer to a user buffer to read bytes into. 21 22*buffer_size* number of bytes to attempt to read. *buffer* buffer should be large 23enough for at least this many bytes. 24 25## RIGHTS 26 27TODO(ZX-2399) 28 29## RETURN VALUE 30 31**zx_vmo_read**() returns **ZX_OK** on success, and exactly *buffer_size* bytes will 32have been written to *buffer*. 33In the event of failure, a negative error value is returned, and the number of 34bytes written to *buffer* is undefined. 35 36## ERRORS 37 38**ZX_ERR_BAD_HANDLE** *handle* is not a valid handle. 39 40**ZX_ERR_WRONG_TYPE** *handle* is not a VMO handle. 41 42**ZX_ERR_ACCESS_DENIED** *handle* does not have the **ZX_RIGHT_READ** right. 43 44**ZX_ERR_INVALID_ARGS** *buffer* is an invalid pointer or NULL. 45 46**ZX_ERR_OUT_OF_RANGE** *offset* starts at or beyond the end of the VMO, 47 or VMO is shorter than *buffer_size*. 48 49**ZX_ERR_BAD_STATE** VMO has been marked uncached and is not directly readable. 50 51## SEE ALSO 52 53[vmo_create](vmo_create.md), 54[vmo_clone](vmo_clone.md), 55[vmo_write](vmo_write.md), 56[vmo_get_size](vmo_get_size.md), 57[vmo_set_size](vmo_set_size.md), 58[vmo_op_range](vmo_op_range.md). 59[vmo_set_cache_policy](vmo_set_cache_policy.md) 60