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Re: Fix nptl/tst-cancel7 for non-bash shells
On Mon, Oct 29, 2012 at 04:18:11PM -0400, Carlos O'Donell wrote:
> On Mon, Oct 29, 2012 at 12:02 PM, Rich Felker <dalias@aerifal.cx> wrote:
> > On Mon, Oct 29, 2012 at 09:37:34AM -0400, Carlos O'Donell wrote:
> >> On Sun, Oct 28, 2012 at 9:15 PM, Rich Felker <dalias@aerifal.cx> wrote:
> >> > This issue caused me to take a look at the implementation of system's
> >> > handling of cancellation, which turns out to have a serious bug:
> >> >
> >> > http://sourceware.org/bugzilla/show_bug.cgi?id=14782
> >> >
> >> > It should be easy to fix; the fix is a purely-red patch (all -'s).
> >>
> >> While your analysis looks correct the more interesting question to me
> >> is "Why was this added in the first place?" Can you dig a bit more and
> >> see if we can determine the reason for the deviation from the standard?
> >> Clearly we went to a lot of work to implement the current behaviour and
> >> I'd like to know why.
> >
> > Where would you suggest I start? "system" is not the easiest function
> > to search the bug tracker for, but I just did and the only resolved
> > bugs I found related to system were invalid (requests for it to close
> > the parent's file descriptors or catch the SIGCHLD). As such, I don't
> > think this code was written to fix any bug.
>
> I recommend:
>
> (1) Use gitweb to browse the history of the changes in the files
> and lines of code that implement the change. Alternatively use
> `git blame`, `git log` and `git diff ...`.
This turned up commit 6ee8d3345646ab0bea91891362a2bbf15503edec
http://sourceware.org/git/?p=glibc.git;a=commit;f=sysdeps/posix/system.c;h=6ee8d3345646ab0bea91891362a2bbf15503edec
The commit was by Drepper and he seems to have applied this exact same
pattern to a number of files to add cancellation support. The rest
were all syscalls; including system() seems to have just been a
mistake.
Rich