On 01/25/2012 03:23 PM, Ronnie Sahlberg wrote: > Update the readconfig filename parsing to allow specifying an existing, > inherited, filedescriptor as 'fd:<n>' > This is useful when you want to pass potentially sensitive onfiguration data > to qemu without having it hit the filesystem/stable-storage > > Signed-off-by: Ronnie Sahlberg <ronniesahlb...@gmail.com> > --- > qemu-config.c | 15 +++++++++++++-- > qemu-options.hx | 3 ++- > 2 files changed, 15 insertions(+), 3 deletions(-)
Reviewed-by: Eric Blake <ebl...@redhat.com>
>
> diff --git a/qemu-config.c b/qemu-config.c
> index b030205..c12c5eb 100644
> --- a/qemu-config.c
> +++ b/qemu-config.c
> @@ -770,8 +770,19 @@ out:
>
> int qemu_read_config_file(const char *filename)
> {
> - FILE *f = fopen(filename, "r");
> - int ret;
> + FILE *f;
> + int ret, fd;
> +
> + if (strncmp(filename, "fd:", 3)) {
> + f = fopen(filename, "r");
> + } else {
> + errno = 0;
> + fd = strtol(filename + 3, NULL, 10);
This means
-readconfig fd:4junk
will read fd 4. I don't know if there is a policy on ignoring vs.
rejecting ill-formed command line, which is why I'm okay with the patch
as-is if it meets project policy; but you might want to consider passing
a non-NULL pointer for the second argument and rejecting an empty string
or trailing junk.
> + if (errno != 0) {
> + return -errno;
> + }
POSIX says that strtol("", NULL, 10) may return 0 without setting errno
(that is, you can't rely on EINVAL in that case). That's another
argument for _always_ passing a non-NULL pointer and to see if you
accidentally parsed an empty string, since you don't want to have
another FILE* competing with stdin. [Libvirt forbids the direct use of
strtol and friends, and instead provides wrapper functions that take
care of the sanity checking that is not mandated by POSIX; it may be
worth introducing a qemu_strtol that does likewise, but that's a
different cleanup project with wider scope.]
--
Eric Blake ebl...@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
signature.asc
Description: OpenPGP digital signature
