DAOS-15388 tools: daos fs copy: error when src is dst

[daltonbohning]

Features: daos_fs_copy

Check if the source and destination are the same.
Check if the source is a subset of the destination.

Required-githooks: true

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[github-actions]

Ticket title is 'daos fs copy should detect copying a directory into itself'
Status is 'In Progress'
Labels: 'scrubbed,triaged'
https://daosio.atlassian.net/browse/DAOS-15388

[daosbuild1]

Test stage Functional Hardware Medium completed with status FAILURE. https://build.hpdd.intel.com/job/daos-stack/job/daos/job/PR-13962/2/display/redirect

[daosbuild1]

Test stage Functional Hardware Medium Verbs Provider completed with status FAILURE. https://build.hpdd.intel.com/job/daos-stack/job/daos/job/PR-13962/2/display/redirect

[daosbuild1]

Test stage Functional Hardware Medium Verbs Provider completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-13962/5/execution/node/836/log

[daosbuild1]

Test stage Functional on EL 8.8 completed with status UNSTABLE. https://build.hpdd.intel.com/job/daos-stack/job/daos//view/change-requests/job/PR-13962/6/testReport/

[daosbuild1]

Test stage Functional Hardware Medium completed with status UNSTABLE. https://build.hpdd.intel.com/job/daos-stack/job/daos//view/change-requests/job/PR-13962/9/testReport/

[daosbuild1]

Test stage Functional Hardware Medium Verbs Provider completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-13962/9/execution/node/1540/log

[daosbuild1]

Test stage Functional Hardware Medium Verbs Provider completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-13962/10/execution/node/1435/log

[daltonbohning]

Failures in https://build.hpdd.intel.com/blue/organizations/jenkins/daos-stack%2Fdaos/detail/PR-13962/10/tests
are
https://daosio.atlassian.net/browse/DAOS-15431

[mchaarawi]

should check tmp_src != NULL, but do you really need an extra allocation and a tmp string here?
why not just compare:
(strncmp(src_path, dst_path, src_path_len) == 0 && dst_path[src_path_len] == "/") ?

im not sure though if this is correct though, because consider
what if src == dst == /d1/d2
I see that the same as
src == /d1/d2 and dst == /d1/d2/
but the result is different in this case, no?

[ashleypittman]

Alternatively you could stat the src and dest and if the st_dev and st_ino fields are the same then they two are the same. This has the advantage that it'll work if you access the same tree via different paths, full vs relative or in the presence of symlinks etc.

[daltonbohning]

why not just compare:
(strncmp(src_path, dst_path, src_path_len) == 0 && dst_path[src_path_len] == "/") ?

You're right. I tested locally and that works the same (with minor tweaks).

Per my other comment to @wiliamhuang: #13962 (comment)

At this point, dst_path is either /, has a / at the same location as src_path, or src_path is not a subpath of dst_path.

For my previous implementation and your suggestion, all four of these error as expected:

daos fs copy --src src  --dst src
daos fs copy --src src  --dst src/
daos fs copy --src src/ --dst src/
daos fs copy --src src/ --dst src

I pushed your suggestion and added more comments here

[daltonbohning]

Alternatively you could stat the src and dest and if the st_dev and st_ino fields are the same

That would be more complete, but I think we'd have to do some recursive parse + stat to detect subpaths. E.g.

src_path = /some/deep/dir
dst_path = /some/deep/dir/that/keeps/going

We'd have to stat like this to figure it out (unless I'm missing something)

src - /some/deep/dir
dst - /some/deep/dir/that/keeps/going
dst - /some/deep/dir/that/keeps
dst - /some/deep/dir/that
dst - /some/deep/dir

[daosbuild1]

Test stage Functional Hardware Medium completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-13962/14/execution/node/616/log

[daltonbohning]

Failure in https://build.hpdd.intel.com/blue/organizations/jenkins/daos-stack%2Fdaos/detail/PR-13962/14/tests
is
https://daosio.atlassian.net/browse/DAOS-15547