trace mode fails with sh: /usr/bin/tar: No such file or directory

[Ryan Schmidt]

On Dec 19, 2017, at 08:23, Joshua Root wrote:
> 
> On 2017-12-20 01:09 , Rainer Müller 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?
> 
> Yep, looks like it. :(
> 
> % ls -l /tmp/tar
> lrwxr-xr-x  1 josh  wheel  6  1 Oct 06:07 /tmp/tar -> bsdtar

Did anybody file a bug report with Apple? If so, please add the information to this ticket:

https://trac.macports.org/ticket/55575