cfsctl: Add cmd to get object ref for a file by Johan-Liebert1 · Pull Request #236 · composefs/composefs-rs

Johan-Liebert1 · 2026-02-23T04:31:56Z

Add a command GetFileObjectRef that accepts an absolute file path and returns the ref in objects directory corresponding to that file

crates/cfsctl/src/main.rs

cgwalters · 2026-02-23T18:07:49Z

Add a command GetFileObjectRef that accepts an absolute file path and returns the ref in objects directory corresponding to that file

Also: this commit message only says "what" not why. The "why" could be very short, something like "I wanted this to access the underlying file for a kernel binary so I could..."

Johan-Liebert1 · 2026-02-24T12:34:46Z

Also: this commit message only says "what" not why. The "why" could be very short, something like "I wanted this to access the underlying file for a kernel binary so I could..."

My bad, should've added context. Added some in the new commit message

Johan-Liebert1 · 2026-02-24T14:14:49Z

Rebased and fixed conflicts

cgwalters · 2026-02-24T15:56:10Z

crates/cfsctl/src/main.rs

+#[derive(Debug, Serialize)]
+pub struct ObjectRef {
+    /// Whether the file is stored inline in the EROFS image
+    pub stored_inline: bool,


What problem did you hit in making this an enum? serde supports that https://serde.rs/enum-representations.html

I had it as

enum ObjectRef { Internal, External { digest: String, path: String } }

serde serialised Internal as just "Internal".

I didn't know about the untagged trait. Do you think an Enum would be better here?

crates/cfsctl/src/main.rs

cgwalters · 2026-02-25T14:47:19Z

crates/composefs/src/generic_tree.rs

+where
+    S: serde::Serializer,
+{
+    s.serialize_str(v.to_string_lossy().as_ref())


I'm not usually a fan of to_string_lossy except for human output. The problem is it just means the data isn't usable for machines in the general case.

cgwalters · 2026-02-25T14:47:48Z

crates/composefs/src/generic_tree.rs


 /// Content types for leaf nodes (non-directory files).
-#[derive(Debug)]
+#[derive(Debug, Clone, Serialize)]


I know I asked for this but let me argue to undo it with a different suggestion.

cgwalters · 2026-02-25T14:49:53Z

crates/cfsctl/src/main.rs

    },
+    /// Given a file path, get the file corresponding to it in the object store
+    /// If the file if stored inline, returns an empty string
+    StatFile {


OK I thought about this more and I have a suggestion that solves the "non-UTF8 filename" problem and would align better with the "LayerInspect" verb: let's have this output a single line in composefs dump file format.

That includes all relevant metadata (backing file path, file metadata) in a "standard" format.

We could then call it dump-single-file perhaps? Or since we're here we could easily have it support multiple files (why not?) so how about

dump-files <image> [files]

And I'd also suggest we add a --with-parents so the output is a truly valid dump file that could be used to make new EROFS files in theory if desired.

And we can just drop the enum serialization stuff - we already have a textual serialization of a composefs filesystem tree.

(maybe --with-parents is on by default...it's only a bit more verbose)

we already have a textual serialization of a composefs filesystem tree

I was not aware of this? Where do we have it?

OK I thought about this more and I have a suggestion that solves the "non-UTF8 filename" problem and would align better with the "LayerInspect" verb: let's have this output a single line in composefs dump file format.

that would be great, but that's not quite the intent here. The intent is more so just getting the corresponding file in the objects directory. Maybe I'm misunderstanding this but your suggestion is to output something like the following?

/usr/share/apk/keys/alpine-devel@lists.alpinelinux.org-66ba20fe.rsa.pub 800 100644 1 0 0 0 1758215632.0 1b/60ad29665d7a6c58e5dfc74d8bbfab074543c866820e5d3e4368054b62a263aba2bc157624305f2c8402 c446a6921d9e84d3d0409fd9731a9503a9982e872c - 1b60ad29665d7a6c58e5dfc74d8bbfab074543c866820e5d3e4368054b62a263aba2bc157624305f2c8402c446a6921d9e84d3d0409fd9731a9503a9982e872c

I was not aware of this? Where do we have it?

https://github.com/composefs/composefs-rs/blob/main/crates/composefs/src/dumpfile.rs

How about dump-files --backing-path which outputs just the path(s) newline separated and quoted in composefs dumpfile format?

But the default would be full dumpfile metadata.

Added a new command that operates on the EROFS and outputs in a dumpfile format

This is what the output looks like

$ ./cfsctl --repo /tmp/.tmpqzyqeM dump-files refs/my-image / --recursive / 0 40755 4 1000 1000 0 1773135856.0 - - - /etc 0 40755 2 1000 1000 0 1773135856.0 - - - /usr 0 40755 4 1000 1000 0 1773135856.0 - - - /usr/bin 0 40755 2 1000 1000 0 1773135856.0 - - - /usr/lib 0 40755 2 1000 1000 0 1773135856.0 - - - /etc/hostname 17 100644 1 1000 1000 0 1773135856.0 - integration-test\x0a - /usr/bin/hello 131072 100644 1 1000 1000 0 1773135856.0 18/c6776e8d37d2076bd66e7160f2c3cab90ce064dc8cdb1d10954c2c7007fd1e83963da6c78fcfb30783c1a37ff36d7255718324e64f414acfd5cefc1ade05a3 - 18c 6776e8d37d2076bd66e7160f2c3cab90ce064dc8cdb1d10954c2c7007fd1e83963da6c78fcfb30783c1a37ff36d7255718324e64f414acfd5cefc1ade05a3 trusted.overlay.metacopy=\x00D\x00\x02\x18\xc6wn\x8d7\xd2\x07k\xd 6nq`\xf2\xc3\xca\xb9\x0c\xe0d\xdc\x8c\xdb\x1d\x10\x95L,p\x07\xfd\x1e\x83\x96\x3d\xa6\xc7\x8f\xcf\xb3\x07\x83\xc1\xa3\x7f\xf3mrUq\x83$\xe6OAJ\xcf\xd5\xce\xfc\x1a\xde\x05\xa3 trusted.overlay.re direct=/18/c6776e8d37d2076bd66e7160f2c3cab90ce064dc8cdb1d10954c2c7007fd1e83963da6c78fcfb30783c1a37ff36d7255718324e64f414acfd5cefc1ade05a3 /usr/lib/readme.txt 13 100644 1 1000 1000 0 1773135856.0 - test\x20fixture\x0a -

With only backing path

$ ./cfsctl --repo /tmp/.tmpqzyqeM dump-files refs/my-image /usr/bin/hello --backing-path /usr/bin/hello /18/c6776e8d37d2076bd66e7160f2c3cab90ce064dc8cdb1d10954c2c7007fd1e83963da6c78fcfb30783c1a37ff36d7255718324e64f414acfd5cefc1ade05a3

cgwalters · 2026-03-02T14:16:35Z

Also we should unify and fix https://github.com/composefs/composefs-rs/blob/main/crates/composefs-oci/src/oci_image.rs#L1015 to operate in terms of the erofs not the tar I think

cgwalters

There's a lot of code churn in the last commit that seems unrelated to "use sha512" - I think it'd make sense to squash.

cgwalters · 2026-03-10T11:21:13Z

crates/composefs/src/erofs/get_file.rs

-            let data = extract_file_data(inode, img);
-            LeafContent::Regular(RegularFile::Inline(data.into()))
-        }
+    // TODO: Sha256HashValue not handled here because the trait FsVerityHashValue


This relates to #181 - instead of using generics after that we'll need the repo itself to handle this.

cgwalters · 2026-03-10T12:37:13Z

crates/composefs/src/erofs/get_file.rs

+}
+
+/// Extract xattrs from an inode
+fn extract_xattrs_from_inode(


Hmmm... do we not already have code that creates a Tree from erofs? I think it would make sense to do instead of this basically

There's one that creates a Tree from a dumpfile, but I'm not sure if there's code that creates a Tree from an erofs image. We do have an erofs debugger, but that prints output in a different format

Right...ok I can take a crack at that but let's get #247 in first?

Actually...OK I am sorry about this I really scope creeped your PR. I think the larger issues are valid, but maybe we should just get in the feature you originally requested and then tackle the larger erofs/dumpfile stuff after?

How about this: We making --backing-path a required option for now, and always output the backing paths in dumpfile format?

Actually I am going to take a crack at adding erofs -> Tree code

OK I'm liking #252

This command recevies an EROFS image and file paths, and produces a dump file like ouput. If `--backing-path-only` is provided, only the backing object digest is outputted in the format `<file name> <digest>` If a directory is passed as input instead of a file, it works like the `ls` command printing information for all files/directories inside Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com> refactor: Refactor duplicated code in cfsctl Move out duplicated filesystem creation code blocks to separate functions Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Johan-Liebert1 · 2026-03-11T08:27:40Z

Rebased on top of #252. Makes the code much simpler

cgwalters · 2026-03-11T12:34:07Z

This one also relates to #225

cgwalters closed this Feb 23, 2026

cgwalters reopened this Feb 23, 2026

cgwalters requested changes Feb 23, 2026

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Johan-Liebert1 force-pushed the cmd-get-objref branch 2 times, most recently from 1eaca87 to 588570f Compare February 24, 2026 11:18

Johan-Liebert1 requested a review from cgwalters February 24, 2026 14:06

Johan-Liebert1 force-pushed the cmd-get-objref branch from 588570f to 81861f2 Compare February 24, 2026 14:14

Johan-Liebert1 force-pushed the cmd-get-objref branch from 81861f2 to 08caf94 Compare February 24, 2026 15:08

cgwalters reviewed Feb 24, 2026

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Johan-Liebert1 force-pushed the cmd-get-objref branch from 3de3226 to 67d1f35 Compare February 25, 2026 10:39

Johan-Liebert1 requested a review from cgwalters February 25, 2026 10:41

Johan-Liebert1 force-pushed the cmd-get-objref branch from 67d1f35 to c619bbe Compare February 25, 2026 10:45

Johan-Liebert1 mentioned this pull request Feb 25, 2026

cfsctl: Create lib target #239

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cgwalters requested changes Feb 25, 2026

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Johan-Liebert1 force-pushed the cmd-get-objref branch from c619bbe to a75d67d Compare February 27, 2026 08:01

Johan-Liebert1 force-pushed the cmd-get-objref branch 3 times, most recently from f2d26f1 to 5cd008c Compare March 10, 2026 10:09

Johan-Liebert1 requested a review from cgwalters March 10, 2026 10:11

Johan-Liebert1 force-pushed the cmd-get-objref branch 3 times, most recently from 66902dd to 94eeb96 Compare March 10, 2026 10:35

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cgwalters mentioned this pull request Mar 10, 2026

erofs: Add erofs_to_filesystem to convert EROFS images back to tree::FileSystem #252

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Johan-Liebert1 added 2 commits March 11, 2026 13:55

Johan-Liebert1 force-pushed the cmd-get-objref branch from 94eeb96 to feb81b1 Compare March 11, 2026 08:26

Johan-Liebert1 requested a review from cgwalters March 11, 2026 08:27

cgwalters approved these changes Mar 11, 2026

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cgwalters merged commit 999033a into composefs:main Mar 11, 2026
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Johan-Liebert1 Mar 10, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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cgwalters commented Mar 2, 2026

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Johan-Liebert1 commented Mar 11, 2026

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Johan-Liebert1 Mar 10, 2026 •

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