Messages in this thread Patch in this message | | | Subject | Re: [PATCH 08/12] printk: Replace strncmp with str_has_prefix | From | Joe Perches <> | Date | Thu, 01 Aug 2019 10:51:22 -0700 |
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On Thu, 2019-08-01 at 23:23 +0800, Chuhong Yuan wrote: > Joe Perches <joe@perches.com> 于2019年7月30日周二 上午8:16写道: > > On Mon, 2019-07-29 at 23:15 +0800, Chuhong Yuan wrote: > > > strncmp(str, const, len) is error-prone. > > > We had better use newly introduced > > > str_has_prefix() instead of it. > > [] > > > diff --git a/kernel/printk/braille.c b/kernel/printk/braille.c > > [] > > > @@ -11,10 +11,10 @@ > > > > > > int _braille_console_setup(char **str, char **brl_options) > > > { > > > - if (!strncmp(*str, "brl,", 4)) { > > > + if (str_has_prefix(*str, "brl,")) { > > > *brl_options = ""; > > > *str += 4; > > > - } else if (!strncmp(*str, "brl=", 4)) { > > > + } else if (str_has_prefix(*str, "brl=")) { > > > *brl_options = *str + 4; > > > > Better to get rid of the += 4 uses too by storing the result > > of str_has_prefix and using that as the addend. > > > > Perhaps > > size_t len; > > > > if ((len = str_has_prefix(*str, "brl,"))) { > > *brl_options = ""; > > *str += len; > > } else if ((len = str_has_prefix(*str, "brl="))) { > > etc... > > > > I find that checkpatch.pl forbids assignment in if condition. > So this seems to be infeasible...
So the code could be rewritten like below: (though it's trivial as-is) --- kernel/printk/braille.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-)
diff --git a/kernel/printk/braille.c b/kernel/printk/braille.c index 1d21ebacfdb8..46dd9fcc7525 100644 --- a/kernel/printk/braille.c +++ b/kernel/printk/braille.c @@ -11,19 +11,29 @@ int _braille_console_setup(char **str, char **brl_options) { - if (!strncmp(*str, "brl,", 4)) { + size_t len; + + len = str_has_prefix(*str, "brl,"); + if (len) { *brl_options = ""; - *str += 4; - } else if (!strncmp(*str, "brl=", 4)) { - *brl_options = *str + 4; - *str = strchr(*brl_options, ','); - if (!*str) { - pr_err("need port name after brl=\n"); - return -EINVAL; - } - *((*str)++) = 0; + *str += len; + return 0; + } + + len = str_has_prefix(*str, "brl="); + if (!len) + return 0; + + *brl_options = *str + len; + + *str = strchr(*brl_options, ','); + if (!*str) { + pr_err("need port name after brl=\n"); + return -EINVAL; } + *((*str)++) = 0; + return 0; }
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