From: David Brownell Date: Thu, 1 May 2008 11:34:42 +0000 (-0700) Subject: Add a new sysfs_streq() string comparison function X-Git-Tag: v2.6.26-rc1~78 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=34990cf702bdf2b4964e0629dab4af7669f8b2c5;p=linux-2.6 Add a new sysfs_streq() string comparison function Add a new sysfs_streq() string comparison function, which ignores the trailing newlines found in sysfs inputs. By example: sysfs_streq("a", "b") ==> false sysfs_streq("a", "a") ==> true sysfs_streq("a", "a\n") ==> true sysfs_streq("a\n", "a") ==> true This is intended to simplify parsing of sysfs inputs, letting them avoid the need to manually strip off newlines from inputs. Signed-off-by: David Brownell Acked-by: Greg KH Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/linux/string.h b/include/linux/string.h index c5d3fcad7b..efdc44593b 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -109,5 +109,7 @@ extern void *kmemdup(const void *src, size_t len, gfp_t gfp); extern char **argv_split(gfp_t gfp, const char *str, int *argcp); extern void argv_free(char **argv); +extern bool sysfs_streq(const char *s1, const char *s2); + #endif #endif /* _LINUX_STRING_H_ */ diff --git a/lib/string.c b/lib/string.c index 5efafed3d6..b19b87af65 100644 --- a/lib/string.c +++ b/lib/string.c @@ -493,6 +493,33 @@ char *strsep(char **s, const char *ct) EXPORT_SYMBOL(strsep); #endif +/** + * sysfs_streq - return true if strings are equal, modulo trailing newline + * @s1: one string + * @s2: another string + * + * This routine returns true iff two strings are equal, treating both + * NUL and newline-then-NUL as equivalent string terminations. It's + * geared for use with sysfs input strings, which generally terminate + * with newlines but are compared against values without newlines. + */ +bool sysfs_streq(const char *s1, const char *s2) +{ + while (*s1 && *s1 == *s2) { + s1++; + s2++; + } + + if (*s1 == *s2) + return true; + if (!*s1 && *s2 == '\n' && !s2[1]) + return true; + if (*s1 == '\n' && !s1[1] && !*s2) + return true; + return false; +} +EXPORT_SYMBOL(sysfs_streq); + #ifndef __HAVE_ARCH_MEMSET /** * memset - Fill a region of memory with the given value