lkml.org 
[lkml]   [2018]   [Dec]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4] string.h: Add str_has_prefix() helper function
On Sat, 22 Dec 2018 18:33:46 +0900
Namhyung Kim <namhyung@kernel.org> wrote:

> > +static __always_inline size_t str_has_prefix(const char *str, const char *prefix)
> > +{
> > + size_t len = strlen(prefix);
> > + return strncmp(str, prefix, len) == 0 ? len : 0;
>
> As it already knows the length (and it needs to use it for return
> value), isn't it (slightly) better using memcmp() instead?

No, because we don't know the length of str.


[ str = "h\0[bad memory]" ]


str_has_prefix(str, "TEST THIS BIG STRING AT FRONT")


If we use memcmp(), then we are testing way after str has ended, and
that can cause a memory fault.

-- Steve

\
 
 \ /
  Last update: 2018-12-22 18:50    [W:0.086 / U:12.156 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site