Using access modes and flags with file streams
It is possible to open a file stream on an existing file descriptor by sending the on: message to the CfsFileStream class. The on: message answers an instance of the concrete stream class corresponding to the access mode of the file descriptor. An example of converting a file descriptor into a file stream is shown below:
| fd file |
fd := CfsFileDescriptor
open: 'new.fil'
oflag: ORDWR | OCREAT | OEXCL.
fd isCfsError
ifTrue: [^self error: fd printString].
file := CfsFileStream on: fd.
"Close the file stream - this will automatically close the file
descriptor as well"
file close.
The
on: message is also useful if the file is to be opened with a special share mode, using the
open:oflag:share: message, which was discussed in
"File locking". An example follows:
| file fd |
(fd := CfsFileDescriptor
open: 'a.fil'
oflag: ORDWR
share: ODENYRDWR) isCfsError
ifTrue: [^self error: fd message].
file := CfsFileStream on: fd.
file close.
Last modified date: 05/12/2020