Re: fts finds no files under mingw

[Jim Meyering]

address@hidden wrote:
...
> To find out what was happening, I took all of the gnulib code out of
> the picture by using the i686-pc-mingw32-gcc compiler to directly
> compile a simple test program, and found that the mingw opendir
> routine sets the dd_handle to -1 itself.
>
>     #include <dirent.h>
>     #include <errno.h>
>     #include <stdio.h>
>     int main(int argc, char **argv)
>     {
>       char **path, *paths[] = { ".", "m4", "lib", NULL };
>       for (path = paths; *path; path++)
>       {
>         DIR *d = opendir(*path);
>         printf("%p, %ld, %d: (%s) %s\n",
>           d, d->dd_handle, errno, d->dd_name, *path);
>       }
>       return 0;
>     }
>
>     Z:\home\kodis\fts> a
>     00116A68, -1, 0: (Z:\home\kodis\fts\*) .
>     00116CB8, -1, 0: (Z:\home\kodis\fts\m4\*) m4
>     00116F08, -1, 0: (Z:\home\kodis\fts\lib\*) lib
>
> It looks like the file descriptor returned by dirfd is used mainly by
> fts_safe_changedir to allow fts to work correctly even when parts of
> the file system are changed while being traversed.  I wonder if a
> fallback to the less robust changing directory by name would be the
> appropriate fix here?

Trying to do without a file descriptor looks like it'd add too
much complexity in already-hairy code.  Not worth it just for mingw.
If you're interested in pursuing it, I'd suggest trying harder to get a
file descriptor.  I.e., on mingw, if dirfd returns -1, resort to calling
openat or open on the directory name, similar to what's already done
above in this code:

    # define __opendir2(file, flag) \
            ( ! ISSET(FTS_NOCHDIR) && ISSET(FTS_CWDFD) \
              ? opendirat(sp->fts_cwd_fd, file)    \
              : opendir(file))
    #endif
           if ((dirp = __opendir2(cur->fts_accpath, oflag)) == NULL) {

Sure, it'll open up a window (between opendir and the last-resort
openat/open call) of vulnerability, but at least it'll compile and work
in a non-adversarial environment.  If you write the patch, be sure to
mention that in a comment.