[PATCH] lib: parse_area_spec: don't modify *start and *size values if parse failed
Peter Mamonov
pmamonov at gmail.com
Thu Jan 11 09:28:00 PST 2018
Hi, Sasha,
On Thu, Jan 11, 2018 at 09:15:31AM +0100, Sascha Hauer wrote:
> Hi Peter,
>
> On Tue, Jan 09, 2018 at 05:21:20PM +0300, Peter Mamonov wrote:
> > Signed-off-by: Peter Mamonov <pmamonov at gmail.com>
> > ---
> > lib/misc.c | 46 ++++++++++++++++++++++++++++++++--------------
> > 1 file changed, 32 insertions(+), 14 deletions(-)
> >
> > diff --git a/lib/misc.c b/lib/misc.c
> > index 62ddd6677..c7d5a0ca5 100644
> > --- a/lib/misc.c
> > +++ b/lib/misc.c
> > @@ -79,38 +79,56 @@ EXPORT_SYMBOL(strtoul_suffix);
> > int parse_area_spec(const char *str, loff_t *start, loff_t *size)
> > {
> > char *endp;
> > - loff_t end;
> > + loff_t end, _start, _size;
> > + int ret = -1;
> >
> > if (!isdigit(*str))
> > return -1;
> >
> > - *start = strtoull_suffix(str, &endp, 0);
> > + _start = strtoull_suffix(str, &endp, 0);
> >
> > str = endp;
> >
> > if (!*str) {
> > /* beginning given, but no size, assume maximum size */
> > - *size = ~0;
> > - return 0;
> > + _size = ~0;
> > + ret = 0;
> > }
> >
> > - if (*str == '-') {
> > + if (ret && *str == '-') {
> > /* beginning and end given */
> > - end = strtoull_suffix(str + 1, NULL, 0);
> > - if (end < *start) {
> > + if (!isdigit(*(str + 1)))
> > + return ret;
> > +
> > + end = strtoull_suffix(str + 1, &endp, 0);
> > + str = endp;
> > + if (end < _start) {
> > printf("end < start\n");
> > - return -1;
> > + return ret;
> > }
> > - *size = end - *start + 1;
> > - return 0;
> > + _size = end - _start + 1;
> > + ret = 0;
> > }
> >
> > - if (*str == '+') {
> > + if (ret && *str == '+') {
> > /* beginning and size given */
> > - *size = strtoull_suffix(str + 1, NULL, 0);
> > - return 0;
> > + if (!isdigit(*(str + 1)))
> > + return ret;
> > +
> > + _size = strtoull_suffix(str + 1, &endp, 0);
> > + str = endp;
> > + ret = 0;
> > + }
> > +
> > + if (!ret && *str)
> > + /* trailing symbols indicate invalid area spec */
> > + ret = -1;
>
> Is this correct? I would assume a whitespace should be fine. We only
> do not get trailing whitespaces in here because current users pass in
> argv[] elements which are split up at whitespaces.
Ok, whitespaces " \n\r\t" are fine too. Will fix it in the next revision.
> The check would
> also deserve a separate patch.
My proposal is to fix `parse_area_spec` so it can distinguish a valid memory
area specification from the following sample file names:
4k.bin
4k-8k.txt
4096+1k_of_random_bytes
Without this final check parse_area_spec would return 0 for the last two
samples, which are not valid area specifications.
>
> > +
> > + if (!ret) {
> > + *start = _start;
> > + *size = _size;
> > }
> >
> > - return -1;
> > + return ret;
>
> I find this patch unnecessarily hard to review and also the end result
> doesn't look optimal. Could you create a 'success:' label and jump to it
> when everything is fine? That would make the additional if(ret) and
> if(!ret) checks unnecessary.
Sounds good, will fix it as well.
Regards,
Peter
>
> Sascha
>
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