Re: file is already open & file wasn't open
Re: file is already open & file wasn't open
- Subject: Re: file is already open & file wasn't open
- From: Emmanuel <email@hidden>
- Date: Sat, 21 Apr 2007 18:54:16 +0200
At 9:38 AM -0600 4/21/07, Doug McNutt wrote:
At 14:22 +0200 4/21/07, Emmanuel wrote:
This suggests that you can open a given file for access with write
permission from two different applications, which may be misleading
as such. The facts on OSX are the following.
Once an application A has opened a given file with write permission:
- any app may access the file in read-only mode (simple open for access),
- attempting to open the file with write permission from the same
app results in error number -49,
- attempting to open the file with write permission from another
app on the same machine results in error number -54,
Hmmm. UNIX - the one I learned before 1984 - has no such
protection. Cooperative file locking is all there is.
Has Apple modified the "It's UNIX underneath" kernel? Or is the
performance above a part of the HFS+ file system which does other
violence to UNIX conventions like case-insensitive file names?
Are resource forks different? If I have a data fork open for writing
can someone else have the resource fork open for writing? Not that
it matters much for OS neXt but for OS 9. . .
For me - but Chris would tell us for sure - it's just that the
locking scheme that we are using here is 100% AppleScript-internal.
The good point is, it's veeeery handy as long as you're not accessing
a given file from several machines at the same time. The bad point
is, it's of little use if you are.
Emmanuel
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