bytestring: Implement bytestring_bytestring()

[ccan] / ccan / bytestring / bytestring.h

diff --git a/ccan/bytestring/bytestring.h b/ccan/bytestring/bytestring.h
index ee4087d44cb4c9dc864e632973e917cafb768ea9..62141bea41149a30bd61214e8804d50c23e4c971 100644 (file)
--- a/ccan/bytestring/bytestring.h
+++ b/ccan/bytestring/bytestring.h
@@ -2,11 +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;
@@ -62,6 +66,8 @@ static inline struct bytestring bytestring(const char *p, size_t l)
  */
 static inline struct bytestring bytestring_from_string(const char *s)
 {
+       if (!s)
+               return bytestring_NULL;
        return bytestring(s, strlen(s));
 }
 
@@ -78,4 +84,120 @@ static inline bool bytestring_eq(struct bytestring a, struct bytestring b)
                && (memcmp(a.ptr, b.ptr, a.len) == 0);
 }
 
+/**
+ * bytestring_byte - get a byte from a bytestring
+ * @s: bytestring
+ * @n: index
+ *
+ * Return the @n-th byte from @s.  Aborts (via assert) if @n is out of
+ * range for the length of @s.
+ */
+static inline char bytestring_byte(struct bytestring s, size_t n)
+{
+       assert(n < s.len);
+       return s.ptr[n];
+}
+
+/**
+ * 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;
+}
+
 #endif /* CCAN_BYTESTRING_H_ */