---
title: copyPhysicalExtent
framework: kernel
role: pseudoSymbol
path: kernel/iomedia/1813424-copyphysicalextent
---

# copyPhysicalExtent

## Declaration

```occ
virtual IOStorage * copyPhysicalExtent(
 IOService *client, 
 UInt64 *byteStart, 
 UInt64 *byteCount); 
```

## Parameters

- `client`: Client requesting the operation.
- `byteStart`: Starting byte offset for the operation. Returns a physical byte offset, relative to the physical storage object, on success.
- `byteCount`: Size of the operation. Returns the actual number of bytes which can be transferred, relative to the physical storage object, on success.

## Return Value

Return Value A reference to the physical storage object, which should be released by the caller, or a null on error.

## Overview

Overview Convert the specified byte offset into a physical byte offset, relative to a physical storage object. This call should only be made within the context of lockPhysicalExtents().

## See Also

### Miscellaneous

- [getAttributes](kernel/iomedia/1813444-getattributes.md)
- [getBase](kernel/iomedia/1813468-getbase.md)
- [getContent](kernel/iomedia/1813495-getcontent.md)
- [getContentHint](kernel/iomedia/1813522-getcontenthint.md)
- [getPreferredBlockSize](kernel/iomedia/1813553-getpreferredblocksize.md)
- [getSize](kernel/iomedia/1813585-getsize.md)
- [handleClose](kernel/iomedia/1813614-handleclose.md)
- [handleIsOpen](kernel/iomedia/1813630-handleisopen.md)
- [handleOpen](kernel/iomedia/1813647-handleopen.md)
- [init](kernel/iomedia/1813657-init.md)
- [isEjectable](kernel/iomedia/1813664-isejectable.md)
- [isFormatted](kernel/iomedia/1813670-isformatted.md)
- [isWhole](kernel/iomedia/1813677-iswhole.md)
- [isWritable](kernel/iomedia/1813683-iswritable.md)
- [lockPhysicalExtents](kernel/iomedia/1813689-lockphysicalextents.md)
- [read](kernel/iomedia/1813696-read.md)
- [synchronizeCache](kernel/iomedia/1813702-synchronizecache.md)
- [unlockPhysicalExtents](kernel/iomedia/1813710-unlockphysicalextents.md)
- [unmap](kernel/iomedia/1813719-unmap.md)
- [write](kernel/iomedia/1813725-write.md)