Requests that a file be opened for reading or writing.
| Item | Description |
|---|---|
| vp | Points to the virtual node (v-node) associated with the desired file. The v-node is held for the duration of the open process. |
| flag | Specifies the type of access. Access modes are defined in
the /usr/include/sys/fcntl.h file. Note: The vnop_open entry
point does not use the FCREAT mode.
|
| ext | Points to external data. This parameter is used if the subroutine is opening a device. |
| vinfop | This parameter is not currently used. |
| crp | Points to the cred structure. This structure contains data that the file system can use to validate access permission. |
The vnop_open entry point is called to initiate a process access to a v-node and its underlying file system object. The operation of the vnop_open entry point varies between virtual file system (VFS) implementations. A successful vnop_open entry point must leave a v-node count of at least 1.
The logical file system ensures that the process is not requesting write access (with the FWRITE or FTRUNC mode) to a read-only file system.
The vnop_open entry point can be called from the process environment only.
| Item | Description |
|---|---|
| 0 | Indicates success. |
Nonzero return values are returned from the /usr/include/sys/errno.h file to indicate failure.