Changed return value of git_oid_match to be consistent with the other compare methods (0 means oids match). Added method to compare prefixes of hex formatted oids.

include/git2/oid.h

@@ -142,7 +142,7 @@ GIT_EXTERN(int) git_oid_cmp(const git_oid *a, const git_oid *b);
  * @param len the number of hex chars to compare
  * @param a first oid structure.
  * @param b second oid structure.
- * @return 1 in case of a match
+ * @return 0 in case of a match
  */
 GIT_EXTERN(int) gid_oid_match(unsigned int len, git_oid *a, git_oid *b);
 

src/oid.c

@@ -177,15 +177,20 @@ int git_oid_match_raw(unsigned int len, const unsigned char *a, const unsigned c
 {
         do {
                 if (*a != *b)
-                        return 0;
+                        return 1;
                 a++;
                 b++;
                 len -= 2;
         } while (len > 1);
         if (len)
                 if ((*a ^ *b) & 0xf0)
-                        return 0;
+                        return 1;
-        return 1;
+        return 0;
+}
+
+int git_oid_match_hex(unsigned int len, const unsigned char *a, const unsigned char *b)
+{
+	return memcmp(a, b, len);
 }
 
 int gid_oid_match(unsigned int len, git_oid *a, git_oid *b)

src/oid.h

@@ -1,7 +1,17 @@
 #ifndef INCLUDE_oid_h__
 #define INCLUDE_oid_h__
 
-/* This can be useful for internal use */
+/**
+ * Compare the first ('len'*4) bits of two raw formatted oids.
+ * This can be useful for internal use.
+ * Return 0 if they match.
+ */
 int git_oid_match_raw(unsigned int len, const unsigned char *a, const unsigned char *b);
 
+/**
+ * Compare the first 'len' characters of two hex formatted oids.
+ * Return 0 if they match.
+ */
+int git_oid_match_hex(unsigned int len, const unsigned char *a, const unsigned char *b);
+
 #endif