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>

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>
Simon Glass
1 parent 6b45ba45fb
Showing 2 changed files with 39 additions and 0 deletions Side-by-side Diff
include/linux/string.h
lib/string.c
@@ -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
@@ -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)
 {
...	...	@@ -76,6 +76,21 @@
76	76	#ifndef __HAVE_ARCH_STRNLEN
77	77	extern __kernel_size_t strnlen(const char *,__kernel_size_t);
78	78	#endif
	79	+
	80	+#ifndef __HAVE_ARCH_STRCSPN
	81	+/**
	82	+ * strcspn() - find span of string without given characters
	83	+ *
	84	+ * Calculates the length of the initial segment of @s which consists entirely
	85	+ * of bsytes not in reject.
	86	+ *
	87	+ * @s: string to search
	88	+ * @reject: strings which cause the search to halt
	89	+ * @return number of characters at the start of @s which are not in @reject
	90	+ */
	91	+size_t strcspn(const char s, const char reject);
	92	+#endif
	93	+
79	94	#ifndef __HAVE_ARCH_STRDUP
80	95	extern char * strdup(const char *);
81	96	#endif
...	...	@@ -286,6 +286,30 @@
286	286	}
287	287	#endif
288	288
	289	+#ifndef __HAVE_ARCH_STRCSPN
	290	+/**
	291	+ * strcspn - Calculate the length of the initial substring of @s which does
	292	+ * not contain letters in @reject
	293	+ * @s: The string to be searched
	294	+ * @reject: The string to avoid
	295	+ */
	296	+size_t strcspn(const char s, const char reject)
	297	+{
	298	+ const char *p;
	299	+ const char *r;
	300	+ size_t count = 0;
	301	+
	302	+ for (p = s; *p != '\0'; ++p) {
	303	+ for (r = reject; *r != '\0'; ++r) {
	304	+ if (p == r)
	305	+ return count;
	306	+ }
	307	+ ++count;
	308	+ }
	309	+ return count;
	310	+}
	311	+#endif
	312	+
289	313	#ifndef __HAVE_ARCH_STRDUP
290	314	char * strdup(const char *s)
291	315	{