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digitalmars.D.learn - The std.file rename method fails in the docker environment.

reply zoujiaqing <zoujiaqing gmail.com> writes:
upload file to server in docker, but upload directory volume to 
host machine.

Exception error:
```
Invalid cross-device link
```

Have other function like move(a, b) ?

https://github.com/huntlabs/hunt-framework/blob/master/source/hunt/framework/file/File.d#L102
Mar 13
parent reply Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:
On Wednesday, March 13, 2024 3:03:30 PM MDT zoujiaqing via Digitalmars-d-learn 
wrote:

 upload file to server in docker, but upload directory volume to
 host machine.

 Exception error:
 ```
 Invalid cross-device link
 ```

 Have other function like move(a, b) ?

 https://github.com/huntlabs/hunt-framework/blob/master/source/hunt/framework
 /file/File.d#L102


Well, the subject of your post mentions std.file, and then you link to a
framework that does basically the same thing. So, I don't know what you're
actually using.

However, both of those functions use the OS function, rename, which renames
the file within a file system, but it can't move files across file systems.
Strictly speaking, it's not possible to move a file across file systems.
What a program like mv does when the destination is on a different file
system from the source file is copy the file and then delete the original.
So, if you want to "move" a file across file systems within your program,
you'll have to do the same thing.

There may be a projcet on code.dlang.org which has a function which tries to
move the file within the file system and then does a copy and remove instead
if moving within the file system doesn't work, but otherwise, you'll have to
implement that yourself, which could be as simple as catching the any
exceptions from move and then attempting to copy the file and then remove it
if an exception was thrown.

- Jonathan M Davis
Mar 13
parent reply zoujiaqing <zoujiaqing gmail.com> writes:
On Wednesday, 13 March 2024 at 21:21:21 UTC, Jonathan M Davis 
wrote:

 On Wednesday, March 13, 2024 3:03:30 PM MDT zoujiaqing via 
 Digitalmars-d-learn wrote:

 upload file to server in docker, but upload directory volume 
 to host machine.

 Exception error:
 ```
 Invalid cross-device link
 ```

 Have other function like move(a, b) ?

 https://github.com/huntlabs/hunt-framework/blob/master/source/hunt/framework
/file/File.d#L102


 Well, the subject of your post mentions std.file, and then you 
 link to a framework that does basically the same thing. So, I 
 don't know what you're actually using.

 However, both of those functions use the OS function, rename, 
 which renames the file within a file system, but it can't move 
 files across file systems. Strictly speaking, it's not possible 
 to move a file across file systems. What a program like mv does 
 when the destination is on a different file system from the 
 source file is copy the file and then delete the original. So, 
 if you want to "move" a file across file systems within your 
 program, you'll have to do the same thing.

 There may be a projcet on code.dlang.org which has a function 
 which tries to move the file within the file system and then 
 does a copy and remove instead if moving within the file system 
 doesn't work, but otherwise, you'll have to implement that 
 yourself, which could be as simple as catching the any 
 exceptions from move and then attempting to copy the file and 
 then remove it if an exception was thrown.

 - Jonathan M Davis


this is bug in D.

Docker run app code:
```d
reanme("/tmp/aaa", "/data/attachments/aaa");
```

docker volume path:
```txt
VOLUME /data/attachments
```

docker compose yml:
```yml
     volumes:
       - /data/attachments:/data/attachments
```

Error exception:
```
Invalid cross-device link
```
Mar 13
next sibling parent Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:
On Wednesday, March 13, 2024 3:49:55 PM MDT zoujiaqing via Digitalmars-d-learn 
wrote:

 On Wednesday, 13 March 2024 at 21:21:21 UTC, Jonathan M Davis

 wrote:

 On Wednesday, March 13, 2024 3:03:30 PM MDT zoujiaqing via

 Digitalmars-d-learn wrote:

 upload file to server in docker, but upload directory volume
 to host machine.

 Exception error:
 ```
 Invalid cross-device link
 ```

 Have other function like move(a, b) ?

 https://github.com/huntlabs/hunt-framework/blob/master/source/hunt/framew
 ork /file/File.d#L102>


 Well, the subject of your post mentions std.file, and then you
 link to a framework that does basically the same thing. So, I
 don't know what you're actually using.

 However, both of those functions use the OS function, rename,
 which renames the file within a file system, but it can't move
 files across file systems. Strictly speaking, it's not possible
 to move a file across file systems. What a program like mv does
 when the destination is on a different file system from the
 source file is copy the file and then delete the original. So,
 if you want to "move" a file across file systems within your
 program, you'll have to do the same thing.

 There may be a projcet on code.dlang.org which has a function
 which tries to move the file within the file system and then
 does a copy and remove instead if moving within the file system
 doesn't work, but otherwise, you'll have to implement that
 yourself, which could be as simple as catching the any
 exceptions from move and then attempting to copy the file and
 then remove it if an exception was thrown.

 - Jonathan M Davis


 this is bug in D.

 Docker run app code:
 ```d
 reanme("/tmp/aaa", "/data/attachments/aaa");
 ```

 docker volume path:
 ```txt
 VOLUME /data/attachments
 ```

 docker compose yml:
 ```yml
      volumes:
        - /data/attachments:/data/attachments
 ```

 Error exception:
 ```
 Invalid cross-device link
 ```


How is it a bug in D? You are attempting to rename a file across
filesystems, and that's not possible. The error is coming from the OS
function - https://www.man7.org/linux/man-pages/man2/rename.2.html - and
it's telling you what the problem is. You are attempting to rename a file
across devices / filesystems, which rename does not support. Linux's rename
doesn't even support renaming across different mount points if that
filesystem is mounted in multiple places. It's designed to do an atomic move
within a filesystem, and that's it.

The documentation for std.file's rename even explains that it won't work
across filesystems / mount points / drives:

https://dlang.org/phobos/std_file.html#rename

If you want to move a file between two separate filesystems, then you need
to copy the file, not rename it, and then if you want the original to be
gone, you can then remove it.

You may not like that, but you're trying to use rename to do something that
it does not support, because the OS function that it's a wrapper for does
not support it. std.file could theoretically add a higher level wrapper that
attempted to use rename and then copied the file and removed the original if
rename failed, but std.file does not currently provide such a function, and
rename is not intended to be that function. It's just a cross-platform
wrapper around the OS function, rename.

So, while rename may not do what you want, it is working as intended, and
it's not a bug.

- Jonathan M Davis
Mar 13
prev sibling parent reply Sergey <kornburn yandex.ru> writes:
On Wednesday, 13 March 2024 at 21:49:55 UTC, zoujiaqing wrote:

 this is bug in D.


It seems like a bug in Hunt-framework.
And Hunt - is an abandoned project.
Mar 13
parent reply zoujiaqing <zoujiaqing gmail.com> writes:
On Wednesday, 13 March 2024 at 22:16:13 UTC, Sergey wrote:

 On Wednesday, 13 March 2024 at 21:49:55 UTC, zoujiaqing wrote:

 this is bug in D.


 It seems like a bug in Hunt-framework.
 And Hunt - is an abandoned project.


Hunt Framework call std.file rename function.
but this function can't move file from docker container to host 
machine.
Mar 13
parent Paolo Invernizzi <paolo.invernizzi gmail.com> writes:
On Wednesday, 13 March 2024 at 23:59:24 UTC, zoujiaqing wrote:

 On Wednesday, 13 March 2024 at 22:16:13 UTC, Sergey wrote:

 On Wednesday, 13 March 2024 at 21:49:55 UTC, zoujiaqing wrote:

 this is bug in D.


 It seems like a bug in Hunt-framework.
 And Hunt - is an abandoned project.


 Hunt Framework call std.file rename function.
 but this function can't move file from docker container to host 
 machine.


As Jonathan said, it's NOT possible to move aka rename files 
across different filesystems.
You can NOT do that in D, in C, in Python, every language ... is 
a OS error.

Try to copy the file, and then delete the original one.

/P
Mar 14