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    SubjectRe: [PATCH] lib/string: Introduce sysfs_streqcase
    On Fri, Apr 02, 2021 at 11:17:13AM -0700, Nick Desaulniers wrote:
    > Thanks for the patch!
    >
    > + akpm (please remember to run ./scripts/get_maintainer.pl on your patch files)
    >
    > On Fri, Apr 2, 2021 at 2:41 AM Gioh Kim <gi-oh.kim@ionos.com> wrote:
    > >
    > > As the name shows, it checks if strings are equal in case insensitive
    > > manner. I found some cases using strncasecmp to check the entire
    > > strings and they would not work as intended.
    > >
    > > For example, drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c uses
    > > strncasecmp to check that the input via sysfs is "mi". But it would
    > > work even-if the input is "min-wrongcommand".
    > > And also drivers/pnp/interface.c checks "disable" command with
    > > strncasecmp but it would also work if the command is "disable-wrong".
    >
    > Perhaps those callers should be using strcasecmp then, rather than strncasecmp?
    >
    > Also, if they're being liberal in accepting either case, I don't see
    > why the sysfs nodes should be strict in rejecting trailing input at
    > that point.

    I think this shouldn't be prefixed "sysfs_" -- name it for what it does,
    not where it gets used, if it's a general utility function.

    -Kees

    >
    > >
    > > Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
    > > ---
    > > lib/string.c | 23 +++++++++++++++++++++++
    > > 1 file changed, 23 insertions(+)
    > >
    > > diff --git a/lib/string.c b/lib/string.c
    > > index 7548eb715ddb..5e6bc0d3d5c6 100644
    > > --- a/lib/string.c
    > > +++ b/lib/string.c
    > > @@ -714,6 +714,29 @@ bool sysfs_streq(const char *s1, const char *s2)
    > > }
    > > EXPORT_SYMBOL(sysfs_streq);
    > >
    > > +/**
    > > + * sysfs_streqcase - same to sysfs_streq and case insensitive
    > > + * @s1: one string
    > > + * @s2: another string
    > > + *
    > > + */
    > > +bool sysfs_streqcase(const char *s1, const char *s2)
    > > +{
    > > + while (*s1 && tolower(*s1) == tolower(*s2)) {
    > > + s1++;
    > > + s2++;
    > > + }
    > > +
    > > + if (*s1 == *s2)
    > > + return true;
    > > + if (!*s1 && *s2 == '\n' && !s2[1])
    > > + return true;
    > > + if (*s1 == '\n' && !s1[1] && !*s2)
    > > + return true;
    > > + return false;
    > > +}
    > > +EXPORT_SYMBOL(sysfs_streqcase);
    >
    > This should be declared in
    > include/linux/string.h
    > in order for others to use this (as 0day bot notes).
    >
    > > +
    > > /**
    > > * match_string - matches given string in an array
    > > * @array: array of strings
    > > --
    > > 2.25.1
    > >
    >
    >
    > --
    > Thanks,
    > ~Nick Desaulniers

    --
    Kees Cook

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