Re: [PATCH v5 proxmox-backup 10/16] client: treat minus sign as stdin

[Christian Ebner <c.ebner@proxmox.com>]

On 2/4/26 3:00 PM, Robert Obkircher wrote:
> 
> On 2/2/26 13:14, Christian Ebner wrote:
>> On 1/30/26 5:45 PM, Robert Obkircher wrote:
>>> Treat "-" as an alias for "/dev/stdin". If there is an actual file
>>> with that name it can still be read via "./-".
>>>
>>> Signed-off-by: Robert Obkircher <r.obkircher@proxmox.com>
>>> ---
>>>    proxmox-backup-client/src/main.rs | 7 +++++++
>>>    1 file changed, 7 insertions(+)
>>>
>>> diff --git a/proxmox-backup-client/src/main.rs
>>> b/proxmox-backup-client/src/main.rs
>>> index 7fc711fd..37878b01 100644
>>> --- a/proxmox-backup-client/src/main.rs
>>> +++ b/proxmox-backup-client/src/main.rs
>>> @@ -845,6 +845,13 @@ async fn create_backup(
>>>            }
>>>            target_set.insert(target.clone());
>>>    +        // one can still use ./- to refer to an actual file with
>>> that name
>>> +        let filename = if filename == "-" {
>>> +            String::from("/dev/stdin")
>>
>> should we add a warning here?
>>
>> This is actually a breaking change, but guarding it behind a flag is
>> maybe a bit overkill. We could check if the file exists before
>> continuing and if so fail with an appropriate warning/error?
> 
> Another option would be to just require /dev/stdin and print a hint
> about that if the user tries to specify "-". What do you think about that?

Might be the better option for the time being, yes. And must be 
documented correctly of course. The '-' shortcut could still be added as 
breaking change in a future version.

But now I'm wondering, how is the multi archive case handled if reading 
from stdin?

To extend your example in the cover letter: `ssh host cmd | 
proxmox-backup-client backup a.img:/dev/stdin b.img:/dev/stdin`

Without having tested it I guess this will fail on the second archive 
creation since that will be empty?

This should be checked and fail on command invocation instead.

 > The only real advantage of "-" is that it could be implemented in a> 
platform independent way by reading from io::stdin(). That would
> require a lot of changes though.
> 
>>
>>> +        } else {
>>> +            filename
>>> +        };
>>> +
>>>            use std::os::unix::fs::FileTypeExt;
>>>              let metadata = std::fs::metadata(&filename)
>>