port & root

[Joshua Root]

On 2018-4-6 03:25 , Rainer Müller wrote:
> On 2018-04-05 19:14, Joshua Root wrote:
>> My guess is that this is a bug in Tcl's file command. Deleting a
>> nonexistent file is not supposed to be considered an error. But by
>> starting two instances of port(1) at the same time, a race condition
>> arises. The 'file delete' command probably checks whether the file
>> exists, returns TCL_OK if not, and then attempts to delete the file. If
>> the file has been deleted by the other running instance (or indeed
>> anything else) between these two steps, then the actual deletion fails,
>> and it incorrectly returns an error.
> 
> You are right. We hit a race condition in the implementation of 'file
> delete' in Tcl.
> 
> It is missing another check for ENOENT here, as done in line 381:
> 
> https://github.com/macports/macports-base/blob/4b13207d9f7f9aba1cc9eba266b3071318637a8c/vendor/tcl8.5.19/generic/tclFCmd.c#L415

Still seems broken in 8.6 at first glance too.

- Josh