ag 2 <(echo 2) gets assertion "p >= path" failed: .. /cygwin-3.1.7 ... /cygwin/path.cc", line 3065, function: int symlink_info::check
Eliot Moss
moss@cs.umass.edu
Sun Sep 6 23:19:25 GMT 2020
On 9/6/2020 6:15 PM, David Dyck wrote:
>
>
> On Sun, Sep 6, 2020 at 12:07 PM Eliot Moss <moss@cs.umass.edu <mailto:moss@cs.umass.edu>> wrote:
> >
> > On 9/6/2020 2:43 PM, David Dyck via Cygwin wrote:
> > > This command triggers an assertion failure
> > > "ag" is from the_silver_searcher
> > >
> > > $ ag 2 <(echo 2)
> > > assertion "p >= path" failed: file
> > >
> "/home/corinna/src/cygwin/cygwin-3.1.7/cygwin-3.1.7-1.x86_64/src/newlib-cygwin/winsup/cygwin/path.cc",
> > > line 3065, function: int symlink_info::check(char*, const
> > > suffix_info*, fs_info&, path_conv_handle&)
>
> >
> > I just tried this:
> >
> > grep 2 <(echo 2)
> >
> > on cygwin 3.1.7 and it worked fine. I am not familiar with Silver Searcher, but it would
> > seem that the problem is more idiosyncratic to that program than to Cygwin more generally.
> > I am _not_ saying the problem is not in Cygwin - only that ag must be doing something
> > somewhat different from what grep does with <( ) command input. Perhaps ag is testing
> > what sort of "thing" (device, etc.) the input file is, while grep does not - something
> > like that might give different behavior.
> >
> > Now I have CYGWIN=winsymlinks:native, which may (almost certainly does) affect what
> > path.cc is doing (the error message is concerned about symlinks; presumably Cygwin
> > is trying to check whether /dev/fd/63 is a symlink.
> >
> > Well, those are the clues I can offer :-) ... EM
>
> Thanks, I tried
> export CYGWIN=winsymlinks:native
> and it still asserted
>
> I think the "ag" uses mmap and pthreads - at least that is what the manual page indicated -
> though even when I passed --nommap I still got the assertion,
>
> From man ag:
>
> How is it so fast?
> * Searching for literals (no regex) uses Boyer-Moore-Horspool strstr.
> * Files are mmap()ed instead of read into a buffer.
> * If you're building with PCRE 8.21 or greater, regex searches use the JIT compiler.
> * Ag calls pcre_study() before executing the regex on a jillion files.
> * Instead of calling fnmatch() on every pattern in your ignore files, non-regex patterns are
> loaded into an array and binary searched.
> * Ag uses Pthreads to take advantage of multiple CPU cores and search files in parallel.
Yes, mmap would fail on a device file like this, but the failure is when trying to open a
.ignore file under the device file (which won't exist), as I recall. As others indicated,
there is a problem in cygwin. It might have to do with flavors of symlink, but maybe not.
Anyway, seems folks are onto it.
Best wishes - EM
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