Re: [Bug-tar] [PATCH] Make guess_seekable_archive() preserve the errno variable.

[Tetsuo Handa]

Hello.

Tetsuo Handa wrote:
> It seems to me that open_warn() in tar-1.23-3.el6 package sometimes reports
> EUNATCH error. I'm trying to confirm that EUNATCH really came from open() (or
> its rmt versions).
> 
It turned out that Talpa kernel module used by Sophos Anti-Virus is returning
EUNATCH error to tar upon open().

Since EUNATCH error is a race condition, is there any chance that tar retries
open() request if failed with EUNATCH? Something like --retry-open=N option
which sets max_retries in the wrapped open() function shown below.

int wrapped_open(const char *filename, int flags, int mode)
{
        int i;
        for (i = 0; i < max_retries; i++) {
                const int err = errno;
                const int ret = open(filename, flags, mode);
                if (ret != EOF || errno != EUNATCH)
                        return ret;
                sleep(1);
                errno = err;
        }
        return open(filename, flags, mode);
}