On 12/30/18 12:09 PM, Richard W.M. Jones wrote:
> On FreeBSD 11.2:
>
> $ ./qemu-io -f raw -c "aio_write 0 512" "nbd:localhost:10809"
> Parsing error: non-numeric argument, or extraneous/unrecognized suffix --
> aio_write
>
> After main option parsing, we reinitialize optind so we can parse each
> command. The error happens when parsing the aio_write command. After
> the aio_write getopt loop, optind == 0 and argv[optind] points to the
> command name ("aio_write" in this case). The code fails because it
> tries to parse argv[optind] (which it thinks is the first argument) as
> an integer.
>
> In fact optind _starts_ the loop as 0, because we set it to 0.
>
> The FreeBSD manual page says:
>
> In order to use getopt() to evaluate multiple sets of arguments, or to
> evaluate a single set of arguments multiple times, the variable optreset
> must be set to 1 before the second and each additional set of calls to
> getopt(), and the variable optind must be reinitialized.
>
> (From the rest of the man page it is clear that optind must be
> reinitialized to 1).
>
> Unfortunately this conflicts with the glibc man page which says:
>
> A program that scans multiple argument vectors, or rescans the same
> vector more than once, and wants to make use of GNU extensions such as
> '+' and '-' at the start of optstring, or changes the value of
> POSIXLY_CORRECT between scans, must reinitialize getopt() by resetting
> optind to 0, rather than the traditional value of 1. (Resetting to 0
> forces the invocation of an internal initialization routine that
> rechecks POSIXLY_CORRECT and checks for GNU extensions in optstring.)The glibc manual implies that setting optind = 1 is a weak reset (sufficient if you are NOT using either leading '+' or '-', and if you do NOT expect POSIXLY_CORRECT to have changed value since the last time), and that optind = 0 is a hard reset needed only when the weak reset is insufficient. > > Reinitialize optind to either 0 or 1 depending on whether we're using > glibc or not. > > I didn't set optreset - it's not present in glibc and it doesn't seem > to make any difference on FreeBSD. BSD has optreset as its way of forcing hard reset (instead of optind=0), but both platforms allow optind=1 for soft reset. > > Signed-off-by: Richard W.M. Jones <[email protected]> > --- > qemu-io-cmds.c | 4 ++++ > 1 file changed, 4 insertions(+) > Given that none of our uses of getopt() in qemu-io-cmds.c rely on leading '+' or '-', and that we don't call setenv() to change POSIXLY_CORRECT on the fly, I think the simpler patch is to just blindly set optind = 1 when we want a soft reset, as a hard reset is overkill for our needs. > diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c > index 2c39124036..ca4e258579 100644 > --- a/qemu-io-cmds.c > +++ b/qemu-io-cmds.c > @@ -114,7 +114,11 @@ static int command(BlockBackend *blk, const cmdinfo_t > *ct, int argc, > } > } > > +#ifdef __GNU_LIBRARY__ > optind = 0; > +#else > + optind = 1; > +#endif and thus we don't need the #ifdef __GNU_LIBRARY__ code, nor the syntax check violation. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
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