Messages in this thread Patch in this message | | | From | André Goddard Rosa <> | Subject | [PATCH v5 10/12] string: factorize skip_spaces and export it to be generally available | Date | Sat, 14 Nov 2009 05:11:58 -0200 |
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On the following sentence: while (*s && isspace(*s)) s++;
If *s == 0, isspace() evaluates to ((_ctype[*s] & 0x20) != 0), which evaluates to ((0x08 & 0x20) != 0) which equals to 0 as well. If *s == 1, we depend on isspace() result anyway. In other words, "a char equals zero is never a space", so remove this check.
Also, *s != 0 is most common case (non-null string).
Fixed const return as noticed by Jan Engelhardt and James Bottomley. Fixed unnecessary extra cast on strstrip() as noticed by Jan Engelhardt.
Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com> --- include/linux/ctype.h | 1 + include/linux/string.h | 1 + lib/string.c | 19 +++++++++++++++---- 3 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/include/linux/ctype.h b/include/linux/ctype.h index 6dec944..a3d6ee0 100644 --- a/include/linux/ctype.h +++ b/include/linux/ctype.h @@ -27,6 +27,7 @@ extern const unsigned char _ctype[]; #define islower(c) ((__ismask(c)&(_L)) != 0) #define isprint(c) ((__ismask(c)&(_P|_U|_L|_D|_SP)) != 0) #define ispunct(c) ((__ismask(c)&(_P)) != 0) +/* Note: isspace() must return false for %NUL-terminator */ #define isspace(c) ((__ismask(c)&(_S)) != 0) #define isupper(c) ((__ismask(c)&(_U)) != 0) #define isxdigit(c) ((__ismask(c)&(_D|_X)) != 0) diff --git a/include/linux/string.h b/include/linux/string.h index b850886..168dad1 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -62,6 +62,7 @@ extern char * strnchr(const char *, size_t, int); #ifndef __HAVE_ARCH_STRRCHR extern char * strrchr(const char *,int); #endif +extern char * __must_check skip_spaces(const char *); extern char * __must_check strstrip(char *); #ifndef __HAVE_ARCH_STRSTR extern char * strstr(const char *,const char *); diff --git a/lib/string.c b/lib/string.c index b19b87a..087d33b 100644 --- a/lib/string.c +++ b/lib/string.c @@ -330,6 +330,20 @@ EXPORT_SYMBOL(strnchr); #endif /** + * skip_spaces - Removes leading whitespace from @s. + * @s: The string to be stripped. + * + * Returns a pointer to the first non-whitespace character in @s. + */ +char *skip_spaces(const char *str) +{ + while (isspace(*str)) + ++str; + return (char *)str; +} +EXPORT_SYMBOL(skip_spaces); + +/** * strstrip - Removes leading and trailing whitespace from @s. * @s: The string to be stripped. * @@ -352,10 +366,7 @@ char *strstrip(char *s) end--; *(end + 1) = '\0'; - while (*s && isspace(*s)) - s++; - - return s; + return skip_spaces(s); } EXPORT_SYMBOL(strstrip); -- 1.6.5.2.180.gc5b3e.dirty -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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