[PATCH] D93881: [llvm-objcopy] preserve file ownership when overwritten

[Jian Cai via Phabricator via llvm-commits]

jcai19 added a comment.

In D93881#2483674 <https://reviews.llvm.org/D93881#2483674>, @rupprecht wrote:

> From a user standpoint, I agree that "objcopy foo.o" should not be changing the ownership of a file, regardless of the implementation (which, in the case of llvm-objcopy, is getting it "wrong" compared to GNU objcopy, because we use temporary file and rename it at the end, without fixing ownership). Sounds like there's agreement there.

Thanks for the support!

> I also wonder if we should make this logic uniform to be least surprising, e.g. "llvm-objcopy foo.o bar.o" or "llvm-strip foo.o -o bar.o" should similarly have the same ownership for foo.o and bar.o. Also, if "llvm-objcopy foo.o --split-dwo=foo.dwo" should propagate ownership of foo.o to foo.dwo. As a user, that may be the most intuitive. This seems to break from what GNU objcopy does, however.

This sounds interesting and probably is worth another thread for discussion.

> If so, I think we'd want to move some of this elsewhere, e.g. into FileOutputBuffer (chown the temporary file immediately instead of patching it at the end), or restoreStatOnFile (so it runs on both the object file and the split dwo file), so that it doesn't apply just to this narrow use case.

IMO it's probably safer to decouple the GNU-compatible and GNU-incompatible changes in case the latter breaks existing code and we need to revert it before we find a long-term solution.


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