trace mode fails with sh: /usr/bin/tar: No such file or directory
Jan Stary
hans at stare.cz
Sun Dec 24 10:44:22 UTC 2017
On Dec 19 15:09:25, raimue at macports.org wrote:
> On 2017-12-18 00:20, Clemens Lang wrote:
> > We debugged this on IRC recently. Turns out the culprit is
> > https://github.com/macports/macports-base/commit/3d4c9b342d28abd0b7aaf7eb70fa4862e898542c#diff-94a7b4a6e8f8c93116146f83a92a7f44
> >
> > /usr/bin/tar is a symlink to bsdtar. copyfile(3) copies the symlink, the
> > previous method opened the file (dereferencing the symlink) and copied
> > its contents.
> >
> > When the symlink is copied (because copyfile(3) is used), the
> > destination of the symlink is not copied, which eventually leads to file
> > not found.
>
> According to the documentation of copyfile(3), it should always follow
> the symlink unless COPYFILE_NOFOLLOW was specified. I even checked its
> implementation [1]. Internally, clonefileat(2) will only be called with
> CLONE_NOFOLLOW when COPYFILE_NOFOLLOW was given – and we do not do that.
>
> I did a quick test with the following code snippet which should be
> roughly equivalent to what we use in our sip_copy_proc.c:
>
> ---8<---
>
> #include <copyfile.h>
> #include <stdio.h>
>
> int main(int argc, char *argv[]) {
> int ret;
>
> ret = copyfile("/usr/bin/tar", "/tmp/tar", NULL,
> COPYFILE_ALL | COPYFILE_CLONE);
> if (ret) {
> perror("copyfile");
> return 1;
> }
>
> return 0;
> }
>
> --->8---
>
> I could not reproduce the problem as described on 10.12.6 Sierra. After
> running this program, /tmp/tar is a regular file and contains the same
> contents as /usr/bin/bsdtar.
>
> I also tested on a VM with 10.13.0 High Sierra, as I still had that
> around. It also works there as expected.
>
> Does this mean Apple has a regression how copyfile(3) works with
> symlinks on macOS 10.13.2? Can somebody with 10.13.2 please test the
> code above and confirm this?
On my 10.13.2, this results in
$ ls -l /tmp/tar
lrwxr-xr-x 1 hans wheel 6 Dec 10 11:39 /tmp/tar -> bsdtar
Jan
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