refs/packed-backend.c: refactor `find_reference_location()`

The function `find_reference_location()` is used to perform a
binary search-like function over the contents of a repository's
`$GIT_DIR/packed-refs` file.

The search it implements is unlike a standard binary search in that the
records it searches over are not of a fixed width, so the comparison
must locate the end of a record before comparing it.

Extract the core routine of `find_reference_location()` in order to
implement a function in the following patch which will find the first
location in the `packed-refs` file that *doesn't* match the given
pattern.

The behavior of `find_reference_location()` is unchanged.

Co-authored-by: Jeff King <peff@peff.net>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index 176bd3905b31ee3e575c77e84fc4872cc45edf27..33639f73e167d47f021716b5fb7ea46cd2130ddf 100644 (file)
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -527,22 +527,8 @@ static int load_contents(struct snapshot *snapshot)
        return 1;
 }
 
-/*
- * Find the place in `snapshot->buf` where the start of the record for
- * `refname` starts. If `mustexist` is true and the reference doesn't
- * exist, then return NULL. If `mustexist` is false and the reference
- * doesn't exist, then return the point where that reference would be
- * inserted, or `snapshot->eof` (which might be NULL) if it would be
- * inserted at the end of the file. In the latter mode, `refname`
- * doesn't have to be a proper reference name; for example, one could
- * search for "refs/replace/" to find the start of any replace
- * references.
- *
- * The record is sought using a binary search, so `snapshot->buf` must
- * be sorted.
- */
-static const char *find_reference_location(struct snapshot *snapshot,
-                                          const char *refname, int mustexist)
+static const char *find_reference_location_1(struct snapshot *snapshot,
+                                            const char *refname, int mustexist)
 {
        /*
         * This is not *quite* a garden-variety binary search, because
@@ -588,6 +574,26 @@ static const char *find_reference_location(struct snapshot *snapshot,
                return lo;
 }
 
+/*
+ * Find the place in `snapshot->buf` where the start of the record for
+ * `refname` starts. If `mustexist` is true and the reference doesn't
+ * exist, then return NULL. If `mustexist` is false and the reference
+ * doesn't exist, then return the point where that reference would be
+ * inserted, or `snapshot->eof` (which might be NULL) if it would be
+ * inserted at the end of the file. In the latter mode, `refname`
+ * doesn't have to be a proper reference name; for example, one could
+ * search for "refs/replace/" to find the start of any replace
+ * references.
+ *
+ * The record is sought using a binary search, so `snapshot->buf` must
+ * be sorted.
+ */
+static const char *find_reference_location(struct snapshot *snapshot,
+                                          const char *refname, int mustexist)
+{
+       return find_reference_location_1(snapshot, refname, mustexist);
+}
+
 /*
  * Create a newly-allocated `snapshot` of the `packed-refs` file in
  * its current state and return it. The return value will already have