Could not find adapter for file-like object for empty result

[OlafHaalstra]

rdump returns a fatal error even when target-query returns 0 records without any errors. To me this seems incorrect because if there are 0 records to be parsed this should for example generate a warning or at least a different type of error. Not sure what is the best approach here but happy to submit a pull request with some feedback on how the team thinks this should be handled.

Example output with error:

target-query -f firewall.logs ../cache/Collection-workstation-03 | rdump -vvvv -w "jsonfile://test.json"
2026-01-18T06:47:57.776788Z [debug    ] Creating <class 'flow.record.adapter.jsonfile.JsonfileWriter'> for 'jsonfile://test.json' with args {'clobber': True} [flow.record.base]
2026-01-18T06:47:57.780143Z [debug    ] Record stream with selector: None [flow.record.stream]
[reading from stdin]
2026-01-18T06:47:58.658826Z [error    ] rdump encountered a fatal error: Could not find adapter for file-like object [flow.record.tools.rdump]
2026-01-18T06:47:58.658906Z [error    ] Full traceback                 [flow.record.tools.rdump]
Traceback (most recent call last):
  File "/opt/homebrew/Caskroom/miniforge/base/envs/dissect/lib/python3.12/site-packages/flow/record/tools/rdump.py", line 397, in main
    for count, rec in enumerate(record_iterator, start=1):  # noqa: B007
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Caskroom/miniforge/base/envs/dissect/lib/python3.12/site-packages/flow/record/stream.py", line 169, in record_stream
    reader = RecordReader(src, selector=selector)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Caskroom/miniforge/base/envs/dissect/lib/python3.12/site-packages/flow/record/base.py", line 925, in RecordReader
    return RecordAdapter(url=url, out=False, selector=selector, fileobj=fileobj, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Caskroom/miniforge/base/envs/dissect/lib/python3.12/site-packages/flow/record/base.py", line 894, in RecordAdapter
    raise RecordAdapterNotFound("Could not find adapter for file-like object")
flow.record.exceptions.RecordAdapterNotFound: Could not find adapter for file-like object

Easiest way to reproduce this locally is to run:

echo | rdump -vvv
2026-01-18T06:51:06.740634Z [debug    ] Creating <class 'flow.record.adapter.text.TextWriter'> for 'text://?' with args {'clobber': True} [flow.record.base]
2026-01-18T06:51:06.740892Z [debug    ] Record stream with selector: None [flow.record.stream]
[reading from stdin]
2026-01-18T06:51:06.740951Z [error    ] rdump encountered a fatal error: Could not find adapter for file-like object [flow.record.tools.rdump]
2026-01-18T06:51:06.740981Z [error    ] Full traceback                 [flow.record.tools.rdump]
Traceback (most recent call last):
  File "/opt/homebrew/Caskroom/miniforge/base/envs/dissect/lib/python3.12/site-packages/flow/record/tools/rdump.py", line 397, in main
    for count, rec in enumerate(record_iterator, start=1):  # noqa: B007
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Caskroom/miniforge/base/envs/dissect/lib/python3.12/site-packages/flow/record/stream.py", line 169, in record_stream
    reader = RecordReader(src, selector=selector)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Caskroom/miniforge/base/envs/dissect/lib/python3.12/site-packages/flow/record/base.py", line 925, in RecordReader
    return RecordAdapter(url=url, out=False, selector=selector, fileobj=fileobj, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Caskroom/miniforge/base/envs/dissect/lib/python3.12/site-packages/flow/record/base.py", line 894, in RecordAdapter
    raise RecordAdapterNotFound("Could not find adapter for file-like object")
flow.record.exceptions.RecordAdapterNotFound: Could not find adapter for file-like object

[yunzheng]

Hi @OlafHaalstra,

I pushed a fix in #203, please test the branch and let me know if this works for you. It will now raise a warning when the input stream is empty and thus 0 records. I agree that this should not error.

Note that: echo | rdump -vvv will still trigger the error, because it reads a newline \n, and is a unrecognized stream.

The following does work, by ensuring echo doesn't add a newline:

$ echo -n '' | uv run rdump -l
[reading from stdin]
2026-01-19T09:58:32.699493Z [warning  ] RecordReader('-'): Empty input stream [flow.record.stream]
Processed 0 records (matched=0, unmatched=0)

[yunzheng]

Merged into main, should be fixed in dev/pre packages.

[OlafHaalstra]

Thanks for taking care of this so quickly!