• =?UTF-8?B?Tm9yZGzDtnc=?= (2/2) May 16 2017 What's the status of atomicity of file-copying and -moving
• FreeSlave (4/6) May 16 2017 Not sure about renaming but copying is not atomic on Posix
• Per =?UTF-8?B?Tm9yZGzDtnc=?= (5/8) May 17 2017 The standard way is to copy the source to a temporary file on the
• Per =?UTF-8?B?Tm9yZGzDtnc=?= (2/9) May 17 2017 Correction: should be renaming.
• =?UTF-8?B?Tm9yZGzDtnc=?= (4/7) May 17 2017 Here's an implementation in Python (3):
• H. S. Teoh via Digitalmars-d-learn (8/18) May 17 2017 Unfortunately it does suffer from the limitation that if the file is
• Andrew Godfrey (8/10) May 17 2017 For renaming that's a good question, but for copying, no-one
• Jerry (3/5) May 17 2017 Niall has a good talk about this on youtube:

=?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

What's the status of atomicity of file-copying and -moving 
(renaming) using std.file on different platforms?

FreeSlave <freeslave93 gmail.com> writes:

On Tuesday, 16 May 2017 at 08:32:56 UTC, Nordlöw wrote:
 What's the status of atomicity of file-copying and -moving 
 (renaming) using std.file on different platforms?

Not sure about renaming but copying is not atomic on Posix 
because it does not handle interruption by signal. I opened issue 
about that https://issues.dlang.org/show_bug.cgi?id=17296

Per =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

On Tuesday, 16 May 2017 at 10:57:08 UTC, FreeSlave wrote:
 Not sure about renaming but copying is not atomic on Posix 
 because it does not handle interruption by signal. I opened 
 issue about that https://issues.dlang.org/show_bug.cgi?id=17296

The standard way is to copy the source to a temporary file on the 
same file system as the target file followed by hardlinking the 
temporary to the target file. If an error occurs during copying 
you either retry or abort. That should be atomic.

Per =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

On Wednesday, 17 May 2017 at 19:56:52 UTC, Per Nordlöw wrote:
 On Tuesday, 16 May 2017 at 10:57:08 UTC, FreeSlave wrote:
 Not sure about renaming but copying is not atomic on Posix 
 because it does not handle interruption by signal. I opened 
 issue about that https://issues.dlang.org/show_bug.cgi?id=17296

 The standard way is to copy the source to a temporary file on 
 the same file system as the target file followed by hardlinking

Correction: should be renaming.

=?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

On Wednesday, 17 May 2017 at 20:02:44 UTC, Per Nordlöw wrote:
 The standard way is to copy the source to a temporary file on 
 the same file system as the target file followed by hardlinking

 Correction: should be renaming.

Here's an implementation in Python (3):

https://github.com/nordlow/containerize/blob/1dbcf57c1240882f8492f261962df0dfaa4edecb/containerize.py#L132

I would like to have it in D too. Any advice regarding the port?

"H. S. Teoh via Digitalmars-d-learn" <digitalmars-d-learn puremagic.com> writes:

On Wed, May 17, 2017 at 07:56:52PM +0000, Per Nordlöw via Digitalmars-d-learn
wrote:
 On Tuesday, 16 May 2017 at 10:57:08 UTC, FreeSlave wrote:
 
 Not sure about renaming but copying is not atomic on Posix because
 it does not handle interruption by signal. I opened issue about that
 https://issues.dlang.org/show_bug.cgi?id=17296

 
 The standard way is to copy the source to a temporary file on the same
 file system as the target file followed by hardlinking the temporary
 to the target file. If an error occurs during copying you either retry
 or abort.  That should be atomic.

Unfortunately it does suffer from the limitation that if the file is
large, you may run out of space on the target filesystem where you may
not have, had you overwritten the target file directly.  But I suppose
it's an acceptable tradeoff where atomicity of copying is desired.


T

-- 
"The number you have dialed is imaginary. Please rotate your phone 90 degrees
and try again."

Andrew Godfrey <X y.com> writes:

On Tuesday, 16 May 2017 at 08:32:56 UTC, Nordlöw wrote:
 What's the status of atomicity of file-copying and -moving 
 (renaming) using std.file on different platforms?

For renaming that's a good question, but for copying, no-one 
should make atomicity guarantees. It's inherently non-atomic, and 
if you try to build an atomic wrapper around it (by trying to 
catch failure cases and deleting the file), you'd be ignoring 
cases like power failure, system hang, process crash. Some of 
those could be achieved on some OSes, but I doubt all of them can 
on all OSes.

Jerry <Kickupx gmail.com> writes:

On Tuesday, 16 May 2017 at 08:32:56 UTC, Nordlöw wrote:
 What's the status of atomicity of file-copying and -moving 
 (renaming) using std.file on different platforms?

Niall has a good talk about this on youtube:
https://www.youtube.com/watch?v=uhRWMGBjlO8