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authorPeter Rosin2019-07-17 01:27:15 +0200
committerLinus Torvalds2019-07-17 04:23:22 +0200
commitb09757104e433447226a95eff4b92583acc0b0fb (patch)
tree35e349432b94a5351aa5dc958b40f3dd337ac897 /lib
parentlib/list: tweak LIST_POISON2 for better code generation on x86_64 (diff)
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lib/string.c: allow searching for NUL with strnchr
Patch series "lib/string: search for NUL with strchr/strnchr". I noticed an inconsistency where strchr and strnchr do not behave the same with respect to the trailing NUL. strchr is standardised and the kernel function conforms, and the kernel relies on the behavior. So, naturally strchr stays as-is and strnchr is what I change. While writing a few tests to verify that my new strnchr loop was sane, I noticed that the tests for memset16/32/64 had a problem. Since it's all about the lib/string.c file I made a short series of it all... This patch (of 3): strchr considers the terminating NUL to be part of the string, and NUL can thus be searched for with that function. For consistency, do the same with strnchr. Link: http://lkml.kernel.org/r/20190506124634.6807-2-peda@axentia.se Signed-off-by: Peter Rosin <peda@axentia.se> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/string.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/lib/string.c b/lib/string.c
index 6016eb3ac73d..461fb620f85f 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -400,6 +400,9 @@ EXPORT_SYMBOL(strncmp);
* strchr - Find the first occurrence of a character in a string
* @s: The string to be searched
* @c: The character to search for
+ *
+ * Note that the %NUL-terminator is considered part of the string, and can
+ * be searched for.
*/
char *strchr(const char *s, int c)
{
@@ -453,12 +456,18 @@ EXPORT_SYMBOL(strrchr);
* @s: The string to be searched
* @count: The number of characters to be searched
* @c: The character to search for
+ *
+ * Note that the %NUL-terminator is considered part of the string, and can
+ * be searched for.
*/
char *strnchr(const char *s, size_t count, int c)
{
- for (; count-- && *s != '\0'; ++s)
+ while (count--) {
if (*s == (char)c)
return (char *)s;
+ if (*s++ == '\0')
+ break;
+ }
return NULL;
}
EXPORT_SYMBOL(strnchr);