string: factorize skip_spaces and export it to be generally available
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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f653398c86
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@ -27,6 +27,7 @@ extern const unsigned char _ctype[];
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#define islower(c) ((__ismask(c)&(_L)) != 0)
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#define isprint(c) ((__ismask(c)&(_P|_U|_L|_D|_SP)) != 0)
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#define ispunct(c) ((__ismask(c)&(_P)) != 0)
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/* Note: isspace() must return false for %NUL-terminator */
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#define isspace(c) ((__ismask(c)&(_S)) != 0)
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#define isupper(c) ((__ismask(c)&(_U)) != 0)
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#define isxdigit(c) ((__ismask(c)&(_D|_X)) != 0)
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@ -62,6 +62,7 @@ extern char * strnchr(const char *, size_t, int);
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#ifndef __HAVE_ARCH_STRRCHR
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extern char * strrchr(const char *,int);
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#endif
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extern char * __must_check skip_spaces(const char *);
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extern char * __must_check strstrip(char *);
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#ifndef __HAVE_ARCH_STRSTR
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extern char * strstr(const char *,const char *);
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19
lib/string.c
19
lib/string.c
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@ -337,6 +337,20 @@ char *strnchr(const char *s, size_t count, int c)
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EXPORT_SYMBOL(strnchr);
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#endif
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/**
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* skip_spaces - Removes leading whitespace from @s.
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* @s: The string to be stripped.
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*
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* Returns a pointer to the first non-whitespace character in @s.
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*/
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char *skip_spaces(const char *str)
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{
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while (isspace(*str))
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++str;
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return (char *)str;
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}
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EXPORT_SYMBOL(skip_spaces);
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/**
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* strstrip - Removes leading and trailing whitespace from @s.
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* @s: The string to be stripped.
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@ -360,10 +374,7 @@ char *strstrip(char *s)
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end--;
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*(end + 1) = '\0';
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while (*s && isspace(*s))
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s++;
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return s;
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return skip_spaces(s);
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}
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EXPORT_SYMBOL(strstrip);
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