Warn (error?) about symlinks outside of package

[jgsogo]

I was packaging a gcc cross-compiler together with the sys-root of the target system. That sys-root contained a lot of symlinks, sometimes targeting files outside of the package (such as /etc/whatever). Conan packages this without complaining. However this created an error at conan install time with an access violation when trying to set some properties (timestamps?) on the target of these packages (which conan shouldn't be modifying anyway as they are outside of the package). You may want to
create another problem report for this specific issue.

Originally posted by @michiel-dewilde in #4051 (comment)

[lasote]

Probably checking always all the files to see if they belong to the package is costly. We could provide a tool maybe? how the files were packaged? by conan or by an external install? I don't know if the conan copy could check links pointing out of the package.

[danimtb]

IIRC the FileCopier class already clears the broken symlinks but I am not sure if it takes the outside symlinks into account

[jgsogo]

Maybe this can be a pre/post_package hook, what do you think?

[danimtb]

Did a small test and the FileCopier is copying the symlink correctly but it does not take into account that the "outside links" have to be copied too:

    def test_outside_link_copy(self):
        folder1 = temp_folder()
        sub1 = os.path.join(folder1, "subdir1")
        sub2 = os.path.join(folder1, "subdir2")
        file1_path = os.path.join(sub1, "file1.txt")
        file2_path = os.path.join(sub1, "file2.c")
        save(file1_path, "file1")
        save(file2_path, "file2")
        os.makedirs(sub2)
        os.symlink(file1_path, os.path.join(sub2, "file_subdir1_symlink.txt"))

        folder2 = temp_folder()
        copier = FileCopier(sub2, folder2)
        copier("*", links=True)
        self.assertEqual(os.listdir(folder2), ["file1.txt", "file2.c"])

However, I think this is the right behavior as we don't know if the user is doing this on purpose or not (for example in the case of a conanfile used to mimic a System package).

The most we could do is provide a tool for this, bu I think the user should be responsible for taking care of the symlinks on what they is trying to achieve

[jgsogo]

That's the reason I was suggesting a hook. Maybe we can provide an implementation that warns about links outside a package (traverse the packaged directory checking for links outside it), the user can activate/deactivate it, or even modify it to raise an error instead of a warning.

[danimtb]

Agree. I have opened an issue in the hooks repo conan-io/hooks#14

I think it is enough to close this one