string: Add strcspn()
Add an implementation of strcspn() which returns the number of initial
characters that do not match any in a rejection list.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/linux/string.h b/include/linux/string.h
index 718c372..3606620 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -76,6 +76,21 @@
#ifndef __HAVE_ARCH_STRNLEN
extern __kernel_size_t strnlen(const char *,__kernel_size_t);
#endif
+
+#ifndef __HAVE_ARCH_STRCSPN
+/**
+ * strcspn() - find span of string without given characters
+ *
+ * Calculates the length of the initial segment of @s which consists entirely
+ * of bsytes not in reject.
+ *
+ * @s: string to search
+ * @reject: strings which cause the search to halt
+ * @return number of characters at the start of @s which are not in @reject
+ */
+size_t strcspn(const char *s, const char *reject);
+#endif
+
#ifndef __HAVE_ARCH_STRDUP
extern char * strdup(const char *);
#endif
diff --git a/lib/string.c b/lib/string.c
index e6e749b..c4ca944 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -286,6 +286,30 @@
}
#endif
+#ifndef __HAVE_ARCH_STRCSPN
+/**
+ * strcspn - Calculate the length of the initial substring of @s which does
+ * not contain letters in @reject
+ * @s: The string to be searched
+ * @reject: The string to avoid
+ */
+size_t strcspn(const char *s, const char *reject)
+{
+ const char *p;
+ const char *r;
+ size_t count = 0;
+
+ for (p = s; *p != '\0'; ++p) {
+ for (r = reject; *r != '\0'; ++r) {
+ if (*p == *r)
+ return count;
+ }
+ ++count;
+ }
+ return count;
+}
+#endif
+
#ifndef __HAVE_ARCH_STRDUP
char * strdup(const char *s)
{