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lib: add glibc style strchrnul() variant 

The strchrnul() variant helpfully returns a the end of the string
instead of a NULL if the requested character is not found. This can
simplify string parsing code since it doesn't need to expicitly check
for a NULL return. If a valid string pointer is passed in, then a valid
null terminated string will always come back out.

Signed-off-by: Grant Likely <grant.likely@linaro.org>
This commit is contained in:
Grant Likely 2014-03-14 17:00:14 +00:00
parent b44aa25d20
commit 11d200e95f
2 changed files with 21 additions and 0 deletions
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3
include/linux/string.h
View File

@ -52,6 +52,9 @@ extern int strncasecmp(const char *s1, const char *s2, size_t n);
#ifndef __HAVE_ARCH_STRCHR
extern char * strchr(const char *,int);
#endif
#ifndef __HAVE_ARCH_STRCHRNUL
extern char * strchrnul(const char *,int);
#endif
#ifndef __HAVE_ARCH_STRNCHR
extern char * strnchr(const char *, size_t, int);
#endif

18
lib/string.c
View File

@ -301,6 +301,24 @@ char *strchr(const char *s, int c)
EXPORT_SYMBOL(strchr);
#endif
#ifndef __HAVE_ARCH_STRCHRNUL
/**
* strchrnul - Find and return a character in a string, or end of string
* @s: The string to be searched
* @c: The character to search for
*
* Returns pointer to first occurrence of 'c' in s. If c is not found, then
* return a pointer to the null byte at the end of s.
*/
char *strchrnul(const char *s, int c)
{
while (*s && *s != (char)c)
s++;
return (char *)s;
}
EXPORT_SYMBOL(strchrnul);
#endif
#ifndef __HAVE_ARCH_STRRCHR
/**
* strrchr - Find the last occurrence of a character in a string