Re: [GIT PULL v5.1] libfuse: run fuse servers as a contained service

[Bernd Schubert <bernd@bsbernd.com>]

On 5/2/26 17:59, Bernd Schubert wrote:
> 
> 
> On 5/1/26 00:49, Darrick J. Wong wrote:
>> On Thu, Apr 30, 2026 at 11:34:06PM +0200, Bernd Schubert wrote:
>>> Hi Darrick,
>>>
>>> On 4/30/26 23:18, Darrick J. Wong wrote:
>>>> Hi Bernd,
>>>>
>>>> Please pull this branch with changes for libfuse.
>>>>
>>>> As usual, I did a test-merge with the main upstream branch as of a few
>>>> minutes ago, and didn't see any conflicts.  Please let me know if you
>>>> encounter any problems.
>>>
>>> pushed to my github branch. BSD build fails with
>>>
>>> 2026-04-30T21:25:16.3874802Z FAILED: [code=1] lib/libfuse3.so.3.19.0 
>>> 2026-04-30T21:25:16.3906762Z cc  -o lib/libfuse3.so.3.19.0 lib/libfuse3.so.3.19.0.p/fuse.c.o lib/libfuse3.so.3.19.0.p/fuse_loop.c.o lib/libfuse3.so.3.19.0.p/fuse_loop_mt.c.o lib/libfuse3.so.3.19.0.p/fuse_lowlevel.c.o lib/libfuse3.so.3.19.0.p/fuse_opt.c.o lib/libfuse3.so.3.19.0.p/fuse_signals.c.o lib/libfuse3.so.3.19.0.p/buffer.c.o lib/libfuse3.so.3.19.0.p/cuse_lowlevel.c.o lib/libfuse3.so.3.19.0.p/helper.c.o lib/libfuse3.so.3.19.0.p/modules_subdir.c.o lib/libfuse3.so.3.19.0.p/mount_util.c.o lib/libfuse3.so.3.19.0.p/fuse_log.c.o lib/libfuse3.so.3.19.0.p/compat.c.o lib/libfuse3.so.3.19.0.p/util.c.o lib/libfuse3.so.3.19.0.p/mount_bsd.c.o lib/libfuse3.so.3.19.0.p/fuse_service_stub.c.o lib/libfuse3.so.3.19.0.p/modules_iconv.c.o -Wl,--as-needed -Wl,--no-undefined -shared -fPIC -Wl,-soname,libfuse3.so.4 -Wl,--version-script,/home/runner/work/libfuse/libfuse/lib/fuse_versionscript -pthread -Wl,--start-group -ldl -lrt -Wl,--end-group
>>> 2026-04-30T21:25:16.3939590Z ld: error: version script assignment of 'FUSE_3.19' to symbol 'fuse_service_can_allow_other' failed: symbol not defined
>>
>> Aha, that function got left out of the stub. :(
>>
>> Annoyingly, on Linux the build succeeds despite the missing symbol
>> when I tweak meson so that it doesn't build the service stuff.  I would
>> have thought that --no-undefined would have done that, but alas.
>>
>> Sorry about that too.  The following patch fixes it.
>>
>> diff --git i/lib/fuse_service_stub.c w/lib/fuse_service_stub.c
>> index d34df3891a6e31..231b98423df628 100644
>> --- i/lib/fuse_service_stub.c
>> +++ w/lib/fuse_service_stub.c
>> @@ -49,12 +49,17 @@ int fuse_service_send_goodbye(struct fuse_service *sf, int error)
>>  int fuse_service_accept(struct fuse_service **sfp)
>>  {
>>  	*sfp = NULL;
>>  	return 0;
>>  }
>>  
>> +bool fuse_service_can_allow_other(struct fuse_service *sf)
>> +{
>> +	return false;
>> +}
>> +
>>  int fuse_service_append_args(struct fuse_service *sf,
>>  			     struct fuse_args *existing_args)
>>  {
>>  	return -EOPNOTSUPP;
>>  }
>>  
>>
>>> 2026-04-30T21:25:16.3951874Z cc: error: linker command failed with exit code 1 (use -v to see invocation)
>>> 2026-04-30T21:25:16.4291582Z [44/82] cc -Itest/test_teardown_watchdog.p -Itest -I../test -Iinclude -I../include -Ilib -I../lib -I. -I.. -fdiagnostics-color=always -
>>>
>>>
>>> checkpatch, CodeChecker-cppcheck, CodeChecker-gcc also all fail. This CodeQL
>>
>> Not sure why checkpatch fails, this is what I got (Debian 13):
>>
>> $ git diff origin/master.. | ./checkpatch.pl --max-line-length=100 --no-tree --ignore MAINTAINERS,SPDX_LICENSE_TAG,COMMIT_MESSAGE,FILE_PATH_CHANGES,EMAIL_SUBJECT,AVOID_EXTERNS,GIT_COMMIT_ID,ENOSYS_SYSCALL,ENOSYS,FROM_SIGN_OFF_MISMATCH,QUOTED_COMMIT_ID,,PREFER_ATTRIBUTE_ALWAYS_UNUSED,PREFER_DEFINED_ATTRIBUTE_MACRO,STRCPY,STRNCPY -
>> No typos will be found - file '/storage/home/djwong/cdev/work/libfuse/spelling.txt': No such file or directory
>> No structs that should be const will be found - file '/storage/home/djwong/cdev/work/libfuse/const_structs.checkpatch': No such file or directory
>> total: 0 errors, 0 warnings, 3908 lines checked
>>
>> Your patch has no obvious style problems and is ready for submission.
>>
>> NOTE: Ignored message types: AVOID_EXTERNS COMMIT_MESSAGE EMAIL_SUBJECT ENOSYS ENOSYS_SYSCALL FILE_PATH_CHANGES FROM_SIGN_OFF_MISMATCH GIT_COMMIT_ID MAINTAINERS PREFER_ATTRIBUTE_ALWAYS_UNUSED PREFER_DEFINED_ATTRIBUTE_MACRO QUOTED_COMMIT_ID SPDX_LICENSE_TAG STRCPY STRNCPY
>>
>> cppcheck had a few things to say, but none of it was about the changed
>> lines.
>>
>>> report is funny
>>>
>>>> int mount_service_main(int argc, char *argv[])
>>>> Warning
>>>> Poorly documented large function
>>>> Poorly documented function: fewer than 2% comments for a function of 113 lines.
>>>> CodeQL
>>
>> Hrmm.  I guess I'll have to figure out how to get those things running.
>> That said, the stuff in mount_service.c is internal to libfuse (i.e.
>> it's not public library API) so I didn't comment them as intensely.
>> Would you like more?
>>
>>> I think I'm going to merge my sync fuse init series tomorrow.
>>
>> Yay!
>>
>>> Are you ok if skip posting another version of the series?
>>
>>                ^ is there an "I" here?  e.g. "...if I skip posting..."?
>>
>> /My/ normal practice (from xfs) was to repost the series as it was
>> merged, followed by an announcement.  That way the mailing list is a
>> complete record of what was merged.  However, very very few people
>> actually do that, even in the kernel.
>>
>> I'm ok with you not posting another version of the series.
>>
>>> Or do you prefer to review the recent changes and last piece I'm going
>>> to do tomorrow?
>>
>> Nah, just merge it.  I'll look over the changes once it's in the branch
>> and if there's anything weird, you or I or anyone else can send patches.
>> As long as you're not planning to tag it as a release, nothing's set in
>> stone.
>>
>>> Basically my goal is to rebase your series against it immediately and
>>> to merge your series during the next few days.
>>
>> <nod> Let me know what you want changed, I'll be around since I am not
>> travelling anywhere for a couple of weeks. :)
>>
>> I can reflow changes into the patchset, or if you'd prefer, I can add
>> them as new patches that would go on the end of the series.
>>
> 
> Hi Darrick,
> 
> eventually merged my patches and made a quick rebase and conflict 
> resolving with your branch. Github still reports plenty of issues ;)
> 
> Could you fix all of the checkpatch isssues? This one shows plenty
> "util: hoist the fuse.conf parsing and setuid mode enforcement code"
> 
> bschubert2@imesrv6 libfuse.git>stg series
> + mount_service-add-systemd
> + mount_service-create-high
> + mount_service-use-the-new
> + mount_service-update-mtab
>> util-hoist-the-fuse.conf
> - util-fix-checkpatch-complaints
> - mount_service-enable
> - mount.fuse3-integrate-systemd
> - mount_service-allow
> - example-service_ll-create-a
> - example-service-create-a
> - nullfs-support-fuse-systemd
> - meson-show-feature-summary
> bschubert2@imesrv6 libfuse.git>.github/workflows/run-checkpatch.sh 
> No typos will be found - file '/home/bschubert2/src/libfuse/libfuse.git/spelling.txt': No such file or directory
> No structs that should be const will be found - file '/home/bschubert2/src/libfuse/libfuse.git/const_structs.checkpatch': No such file or directory
> ERROR:GLOBAL_INITIALISERS: do not initialise globals to 0
> #61: FILE: util/fuser_conf.c:33:
> +int user_allow_other = 0;
> 
> WARNING:LINE_SPACING: Missing a blank line after declarations
> #74: FILE: util/fuser_conf.c:46:
> +	char *dest = buf;
> +	while (1) {
> 
> ...
> 
> I don't have a strong opinion about these two above - feel 
> free to disable them. However, in order to merge it, it would
> be good to run without any checkpatch report.
> And everything that cppcheck and gcc-checker reports, definitely 
> need to be fixed.

Basically

cd <$FUSEDIR>
BUILDDIR="build-without-examples"
mkdir -p ${BUILDDIR}
meson setup ${BUILDDIR} -Dexamples=false 
ninja -C ${BUILDDIR}
./.github/workflows/codechecker.sh --gcc --codechecker --build-dir ${BUILDDIR}

gcc reports are starting here

bschubert2@imesrv6 libfuse.git>stg series
+ mount_service-add-systemd
+ mount_service-create-high
+ mount_service-use-the-new
+ mount_service-update-mtab
+ util-hoist-the-fuse.conf
+ util-fix-checkpatch-complaints
+ mount_service-enable
> mount.fuse3-integrate-systemd


bschubert2@imesrv6 libfuse.git>git show |head -n5
commit f908bb1504eca167e156671dde957c2e7192b7d2
Author: Darrick J. Wong <djwong@kernel.org>
Date:   Wed Mar 4 13:48:55 2026 -0800

    mount.fuse3: integrate systemd service startup


---==== Severity Statistics ====----
----------------------------
Severity | Number of reports
----------------------------
MEDIUM   |                 1
----------------------------
----=================----

----==== Checker Statistics ====----
-----------------------------------------------------
Checker name           | Severity | Number of reports
-----------------------------------------------------
gcc-deref-before-check | MEDIUM   |                 1
-----------------------------------------------------
----=================----

----==== File Statistics ====----
--------------------------------
File name    | Number of reports
--------------------------------
mount.fuse.c |                 1
--------------------------------
----=================----

----======== Summary ========----
----------------------------------------------
Number of processed analyzer result files | 45
Number of analyzer reports                | 1 
----------------------------------------------
----=================----

To view statistics in a browser run:
> firefox /home/bschubert2/src/libfuse/libfuse.git/build-without-examples/codechecker-html/statistics.html

To view the results in a browser run:
> firefox /home/bschubert2/src/libfuse/libfuse.git/build-without-examples/codechecker-html/index.html
[INFO 2026-05-02 18:25] - ----==== Summary ====----
[INFO 2026-05-02 18:25] - Up-to-date analysis results
[INFO 2026-05-02 18:25] -   gcc: 37
[INFO 2026-05-02 18:25] - Outdated analysis results
[INFO 2026-05-02 18:25] - Failed to analyze
[INFO 2026-05-02 18:25] - Missing analysis results
[INFO 2026-05-02 18:25] -   clangsa: 37
[INFO 2026-05-02 18:25] -   clang-tidy: 37
[INFO 2026-05-02 18:25] -   cppcheck: 37
[INFO 2026-05-02 18:25] -   infer: 37
[INFO 2026-05-02 18:25] - Total analyzed compilation commands: 45
[INFO 2026-05-02 18:25] - Total available compilation commands: 45
[INFO 2026-05-02 18:25] - ----=================----
bschubert2@imesrv6 libfuse.git>