replace_object.c

   1 #include "cache.h"
   2 #include "oidmap.h"
   3 #include "refs.h"
   4 #include "commit.h"
   5
   6 struct replace_object {
   7         struct oidmap_entry original;
   8         struct object_id replacement;
   9 };
  10
  11 static struct oidmap replace_map = OIDMAP_INIT;
  12
  13 static int register_replace_ref(const char *refname,
  14                                 const struct object_id *oid,
  15                                 int flag, void *cb_data)
  16 {
  17         /* Get sha1 from refname */
  18         const char *slash = strrchr(refname, '/');
  19         const char *hash = slash ? slash + 1 : refname;
  20         struct replace_object *repl_obj = xmalloc(sizeof(*repl_obj));
  21
  22         if (get_oid_hex(hash, &repl_obj->original.oid)) {
  23                 free(repl_obj);
  24                 warning("bad replace ref name: %s", refname);
  25                 return 0;
  26         }
  27
  28         /* Copy sha1 from the read ref */
  29         oidcpy(&repl_obj->replacement, oid);
  30
  31         /* Register new object */
  32         if (oidmap_put(&replace_map, repl_obj))
  33                 die("duplicate replace ref: %s", refname);
  34
  35         return 0;
  36 }
  37
  38 static void prepare_replace_object(void)
  39 {
  40         static int replace_object_prepared;
  41
  42         if (replace_object_prepared)
  43                 return;
  44
  45         for_each_replace_ref(register_replace_ref, NULL);
  46         replace_object_prepared = 1;
  47         if (!replace_map.map.tablesize)
  48                 check_replace_refs = 0;
  49 }
  50
  51 /* We allow "recursive" replacement. Only within reason, though */
  52 #define MAXREPLACEDEPTH 5
  53
  54 /*
  55  * If a replacement for object oid has been set up, return the
  56  * replacement object's name (replaced recursively, if necessary).
  57  * The return value is either oid or a pointer to a
  58  * permanently-allocated value.  This function always respects replace
  59  * references, regardless of the value of check_replace_refs.
  60  */
  61 const struct object_id *do_lookup_replace_object(const struct object_id *oid)
  62 {
  63         int depth = MAXREPLACEDEPTH;
  64         const struct object_id *cur = oid;
  65
  66         prepare_replace_object();
  67
  68         /* Try to recursively replace the object */
  69         while (depth-- > 0) {
  70                 struct replace_object *repl_obj = oidmap_get(&replace_map, cur);
  71                 if (!repl_obj)
  72                         return cur;
  73                 cur = &repl_obj->replacement;
  74         }
  75         die("replace depth too high for object %s", oid_to_hex(oid));
  76 }