midx: implement `midx_locate_pack()`

The multi-pack index API exposes a `midx_contains_pack()` function that
takes in a string ending in either ".idx" or ".pack" and returns whether
or not the MIDX contains a given pack corresponding to that string.

There is no corresponding function to locate the position of a pack
within the MIDX's pack order (sorted lexically by pack filename).

We could add an optional out parameter to `midx_contains_pack()` that is
filled out with the pack's position when the parameter is non-NULL. To
minimize the amount of fallout from this change, instead introduce a new
function by renaming `midx_contains_pack()` to `midx_locate_pack()`,
adding that output parameter, and then reimplementing
`midx_contains_pack()` in terms of it.

Future patches will make use of this new function.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/midx.c b/midx.c
index de25612b0c863d8544d04b943d50e55d4ab65f20..beaf0c0de4472c8c2fcf20902aa0aaf1ed3e4dab 100644 (file)
--- a/midx.c
+++ b/midx.c
@@ -428,7 +428,8 @@ static int cmp_idx_or_pack_name(const char *idx_or_pack_name,
        return strcmp(idx_or_pack_name, idx_name);
 }
 
-int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name)
+int midx_locate_pack(struct multi_pack_index *m, const char *idx_or_pack_name,
+                    uint32_t *pos)
 {
        uint32_t first = 0, last = m->num_packs;
 
@@ -439,8 +440,11 @@ int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name)
 
                current = m->pack_names[mid];
                cmp = cmp_idx_or_pack_name(idx_or_pack_name, current);
-               if (!cmp)
+               if (!cmp) {
+                       if (pos)
+                               *pos = mid;
                        return 1;
+               }
                if (cmp > 0) {
                        first = mid + 1;
                        continue;
@@ -451,6 +455,11 @@ int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name)
        return 0;
 }
 
+int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name)
+{
+       return midx_locate_pack(m, idx_or_pack_name, NULL);
+}
+
 int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local)
 {
        struct multi_pack_index *m;

diff --git a/midx.h b/midx.h
index b404235db535760cd64040abaaa6365a55c89be1..89c5aa637e0dbe7875235efd5476c02724a2afd9 100644 (file)
--- a/midx.h
+++ b/midx.h
@@ -70,7 +70,10 @@ struct object_id *nth_midxed_object_oid(struct object_id *oid,
                                        struct multi_pack_index *m,
                                        uint32_t n);
 int fill_midx_entry(struct repository *r, const struct object_id *oid, struct pack_entry *e, struct multi_pack_index *m);
-int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name);
+int midx_contains_pack(struct multi_pack_index *m,
+                      const char *idx_or_pack_name);
+int midx_locate_pack(struct multi_pack_index *m, const char *idx_or_pack_name,
+                    uint32_t *pos);
 int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local);
 
 /*