bytestring: Add bytestring_index and bytestring_rindex() functions

Add bytestring equivalents of the index() and rindex() standard functions
which search for characters/bytes within a bytestring.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

ccan/bytestring/_info

@@ -35,6 +35,7 @@ int main(int argc, char *argv[])
 
 	if (strcmp(argv[1], "depends") == 0) {
 		printf("ccan/array_size\n");
+		printf("ccan/mem\n");
 		return 0;
 	}
 

ccan/bytestring/bytestring.h

@@ -2,12 +2,15 @@
 #ifndef CCAN_BYTESTRING_H_
 #define CCAN_BYTESTRING_H_
 
+#include "config.h"
+
 #include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
 #include <assert.h>
 
 #include <ccan/array_size/array_size.h>
+#include <ccan/mem/mem.h>
 
 struct bytestring {
 	const char *ptr;
@@ -150,4 +153,32 @@ static inline bool bytestring_ends(struct bytestring s,
 						suffix.ptr, suffix.len) == 0);
 }
 
+/**
+ * bytestring_index - locate character in bytestring
+ * @haystack: a bytestring
+ * @needle: a character or byte value
+ *
+ * Returns a pointer to the first occurrence of @needle within
+ * @haystack, or NULL if @needle does not appear in @haystack.
+ */
+static inline const char *bytestring_index(struct bytestring haystack,
+					   char needle)
+{
+	return memchr(haystack.ptr, needle, haystack.len);
+}
+
+/**
+ * bytestring_rindex - locate character in bytestring
+ * @haystack: a bytestring
+ * @needle: a character or byte value
+ *
+ * Returns a pointer to the last occurrence of @needle within
+ * @haystack, or NULL if @needle does not appear in @haystack.
+ */
+static inline const char *bytestring_rindex(struct bytestring haystack,
+					   char needle)
+{
+	return memrchr(haystack.ptr, needle, haystack.len);
+}
+
 #endif /* CCAN_BYTESTRING_H_ */

ccan/bytestring/test/compile_fail-BYTESTRING-2.c

+#include "config.h"
+
 #include <stdio.h>
 
 #include <ccan/bytestring/bytestring.h>

ccan/bytestring/test/compile_fail-BYTESTRING.c

+#include "config.h"
+
 #include <stdio.h>
 
 #include <ccan/bytestring/bytestring.h>

ccan/bytestring/test/run.c

+#include "config.h"
+
 #include <ccan/bytestring/bytestring.h>
 #include <ccan/tap/tap.h>
 
@@ -12,7 +14,7 @@ int main(void)
 	struct bytestring bs, bs1, bs2, bs3, bs4, bs5;
 
 	/* This is how many tests you plan to run */
-	plan_tests(30);
+	plan_tests(42);
 
 	bs = bytestring(str1, sizeof(str1) - 1);
 	ok1(bs.ptr == str1);
@@ -59,6 +61,20 @@ int main(void)
 	ok1(!bytestring_starts(bs2, BYTESTRING("def")));
 	ok1(!bytestring_ends(bs2, BYTESTRING("abc")));
 
+	ok1(bytestring_index(bs1, ' ') == (bs1.ptr + 4));
+	ok1(bytestring_index(bs1, 't') == (bs1.ptr + 0));
+	ok1(bytestring_index(bs1, 0) == NULL);
+	ok1(bytestring_index(bs2, 0) == (bs2.ptr + 3));
+	ok1(bytestring_index(bs2, 'f') == (bs2.ptr + 6));
+	ok1(bytestring_index(bs2, 'q') == NULL);
+
+	ok1(bytestring_rindex(bs1, ' ') == (bs1.ptr + 4));
+	ok1(bytestring_rindex(bs1, 't') == (bs1.ptr + 6));
+	ok1(bytestring_rindex(bs1, 0) == NULL);
+	ok1(bytestring_rindex(bs2, 0) == (bs2.ptr + 3));
+	ok1(bytestring_rindex(bs2, 'f') == (bs2.ptr + 6));
+	ok1(bytestring_rindex(bs2, 'q') == NULL);
+
 	/* This exits depending on whether all tests passed */
 	return exit_status();
 }