+/**
+ * bytestring_slice - extract a substring from a bytestring
+ * @s: bytestring
+ * @start, @end: indexes
+ *
+ * Return a sub-bytestring of @s, starting at byte index @start, and
+ * running to, but not including byte @end. If @end is before start,
+ * returns a zero-length bytestring. If @start is out of range,
+ * return a zero length bytestring at the end of @s.
+ *
+ * Note that this doesn't copy or allocate anything - the returned
+ * bytestring occupies (some of) the same memory as the given
+ * bytestring.
+ */
+static inline struct bytestring bytestring_slice(struct bytestring s,
+ size_t start, size_t end)
+{
+ if (start > s.len)
+ start = s.len;
+ if (end > s.len)
+ end = s.len;
+ if (end < start)
+ end = start;
+
+ return bytestring(s.ptr + start, end - start);
+}
+
+/**
+ * bytestring_starts - test if the start of one bytestring matches another
+ * @s, @prefix: bytestrings
+ *
+ * Returns true if @prefix appears as a substring at the beginning of
+ * @s, false otherwise.
+ */
+static inline bool bytestring_starts(struct bytestring s,
+ struct bytestring prefix)
+{
+ return (s.len >= prefix.len) && (memcmp(s.ptr,
+ prefix.ptr, prefix.len) == 0);
+}
+
+/**
+ * bytestring_ends - test if the end of one bytestring matches another
+ * @s, @suffix: bytestrings
+ *
+ * Returns true if @suffix appears as a substring at the end of @s,
+ * false otherwise.
+ */
+static inline bool bytestring_ends(struct bytestring s,
+ struct bytestring suffix)
+{
+ return (s.len >= suffix.len) && (memcmp(s.ptr + s.len - suffix.len,
+ 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);
+}
+
+/*
+ * bytestring_bytestring - search for a bytestring in another bytestring
+ * @haystack, @needle: bytestrings
+ *
+ * Returns a bytestring corresponding to the first occurrence of
+ * @needle in @haystack, or bytestring_NULL if @needle is not found
+ * within @haystack.
+ */
+static inline struct bytestring bytestring_bytestring(struct bytestring haystack,
+ struct bytestring needle)
+{
+ const char *p = memmem(haystack.ptr, haystack.len,
+ needle.ptr, needle.len);
+ if (p)
+ return bytestring(p, needle.len);
+ else
+ return bytestring_NULL;
+}
+