utils: Add strstr

The strstr API searches for s2 in s1 and returns the pointer to the
substring found in s1.

Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>

BUG=none
BRANCH=none
TEST=make run-utils_str

Change-Id: I30f5e8d03e304d28dd6e9bfeebfcaeee2e79ea85
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1818727
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
Auto-Submit: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Jett Rink <jettrink@chromium.org>
Commit-Queue: Jett Rink <jettrink@chromium.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/util.h b/include/util.h
index 60bb00510a..10d9b3661d 100644
--- a/include/util.h
+++ b/include/util.h
@@ -95,6 +95,16 @@ void *memmove(void *dest, const void *src, size_t len);
 void *memchr(const void *buffer, int c, size_t n);
 int strcasecmp(const char *s1, const char *s2);
 int strncasecmp(const char *s1, const char *s2, size_t size);
+
+/**
+ * Find the first occurrence of the substring <s2> in the string <s1>
+ *
+ * @param s1	String where <s2> is searched.
+ * @param s2	Substring to be located in <s1>
+ * @return	Pointer to the located substring or NULL if not found.
+ */
+char *strstr(const char *s1, const char *s2);
+
 size_t strlen(const char *s);
 size_t strnlen(const char *s, size_t maxlen);
 char *strncpy(char *dest, const char *src, size_t n);