zx_vmo_read

Summary

Read bytes from the VMO.

Declaration

#include <zircon/syscalls.h>

zx_status_t zx_vmo_read(zx_handle_t handle,
                        void* buffer,
                        uint64_t offset,
                        size_t buffer_size);

Description

zx_vmo_read() attempts to read exactly buffer_size bytes from a virtual memory object (VMO) at offset.

buffer pointer to a user buffer to read bytes into.

buffer_size number of bytes to attempt to read. buffer buffer should be large enough for at least this many bytes.

Rights

handle must be of type ZX_OBJ_TYPE_VMO and have ZX_RIGHT_READ.

Return value

zx_vmo_read() returns ZX_OK on success, and exactly buffer_size bytes will have been written to buffer. In the event of failure, a negative error value is returned, and the number of bytes written to buffer is undefined.

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_READ right or or [buffer, buffer + buffer_size) is not writable.

ZX_ERR_INVALID_ARGS buffer is an invalid pointer or NULL.

ZX_ERR_NOT_FOUND buffer address does not map to address in address space.

ZX_ERR_OUT_OF_RANGE offset + buffer_size is greater than the size of the VMO.

ZX_ERR_BAD_STATE VMO has been marked uncached and is not directly readable, or the VMO is backed by a pager and the pager or the VMO is in a bad state preventing requested pages from being populated.

ZX_ERR_IO The VMO is backed by a pager and the pager encountered an I/O error while reading in the requested pages.

ZX_ERR_IO_DATA_INTEGRITY The VMO is backed by a pager and the contents that were read in by the pager are corrupted.