Merge branch 'jc/how-to-document-api'
[git] / replace-object.c
1 #include "cache.h"
2 #include "oidmap.h"
3 #include "object-store.h"
4 #include "replace-object.h"
5 #include "refs.h"
6 #include "repository.h"
7 #include "commit.h"
8
9 static int register_replace_ref(struct repository *r,
10                                 const char *refname,
11                                 const struct object_id *oid,
12                                 int flag, void *cb_data)
13 {
14         /* Get sha1 from refname */
15         const char *slash = strrchr(refname, '/');
16         const char *hash = slash ? slash + 1 : refname;
17         struct replace_object *repl_obj = xmalloc(sizeof(*repl_obj));
18
19         if (get_oid_hex(hash, &repl_obj->original.oid)) {
20                 free(repl_obj);
21                 warning(_("bad replace ref name: %s"), refname);
22                 return 0;
23         }
24
25         /* Copy sha1 from the read ref */
26         oidcpy(&repl_obj->replacement, oid);
27
28         /* Register new object */
29         if (oidmap_put(r->objects->replace_map, repl_obj))
30                 die(_("duplicate replace ref: %s"), refname);
31
32         return 0;
33 }
34
35 void prepare_replace_object(struct repository *r)
36 {
37         if (r->objects->replace_map)
38                 return;
39
40         r->objects->replace_map =
41                 xmalloc(sizeof(*r->objects->replace_map));
42         oidmap_init(r->objects->replace_map, 0);
43
44         for_each_replace_ref(r, register_replace_ref, NULL);
45 }
46
47 /* We allow "recursive" replacement. Only within reason, though */
48 #define MAXREPLACEDEPTH 5
49
50 /*
51  * If a replacement for object oid has been set up, return the
52  * replacement object's name (replaced recursively, if necessary).
53  * The return value is either oid or a pointer to a
54  * permanently-allocated value.  This function always respects replace
55  * references, regardless of the value of read_replace_refs.
56  */
57 const struct object_id *do_lookup_replace_object(struct repository *r,
58                                                  const struct object_id *oid)
59 {
60         int depth = MAXREPLACEDEPTH;
61         const struct object_id *cur = oid;
62
63         prepare_replace_object(r);
64
65         /* Try to recursively replace the object */
66         while (depth-- > 0) {
67                 struct replace_object *repl_obj =
68                         oidmap_get(r->objects->replace_map, cur);
69                 if (!repl_obj)
70                         return cur;
71                 cur = &repl_obj->replacement;
72         }
73         die(_("replace depth too high for object %s"), oid_to_hex(oid));
74 }