replace_object.c

   1 #include "cache.h"
   2 #include "sha1-lookup.h"
   3 #include "refs.h"
   4 #include "commit.h"
   5
   6 static struct replace_object {
   7         unsigned char sha1[2][20];
   8 } **replace_object;
   9
  10 static int replace_object_alloc, replace_object_nr;
  11
  12 static const unsigned char *replace_sha1_access(size_t index, void *table)
  13 {
  14         struct replace_object **replace = table;
  15         return replace[index]->sha1[0];
  16 }
  17
  18 static int replace_object_pos(const unsigned char *sha1)
  19 {
  20         return sha1_pos(sha1, replace_object, replace_object_nr,
  21                         replace_sha1_access);
  22 }
  23
  24 static int register_replace_object(struct replace_object *replace,
  25                                    int ignore_dups)
  26 {
  27         int pos = replace_object_pos(replace->sha1[0]);
  28
  29         if (0 <= pos) {
  30                 if (ignore_dups)
  31                         free(replace);
  32                 else {
  33                         free(replace_object[pos]);
  34                         replace_object[pos] = replace;
  35                 }
  36                 return 1;
  37         }
  38         pos = -pos - 1;
  39         ALLOC_GROW(replace_object, replace_object_nr + 1, replace_object_alloc);
  40         replace_object_nr++;
  41         if (pos < replace_object_nr)
  42                 memmove(replace_object + pos + 1,
  43                         replace_object + pos,
  44                         (replace_object_nr - pos - 1) *
  45                         sizeof(*replace_object));
  46         replace_object[pos] = replace;
  47         return 0;
  48 }
  49
  50 static int register_replace_ref(const char *refname,
  51                                 const unsigned char *sha1,
  52                                 int flag, void *cb_data)
  53 {
  54         /* Get sha1 from refname */
  55         const char *slash = strrchr(refname, '/');
  56         const char *hash = slash ? slash + 1 : refname;
  57         struct replace_object *repl_obj = xmalloc(sizeof(*repl_obj));
  58
  59         if (strlen(hash) != 40 || get_sha1_hex(hash, repl_obj->sha1[0])) {
  60                 free(repl_obj);
  61                 warning("bad replace ref name: %s", refname);
  62                 return 0;
  63         }
  64
  65         /* Copy sha1 from the read ref */
  66         hashcpy(repl_obj->sha1[1], sha1);
  67
  68         /* Register new object */
  69         if (register_replace_object(repl_obj, 1))
  70                 die("duplicate replace ref: %s", refname);
  71
  72         return 0;
  73 }
  74
  75 static void prepare_replace_object(void)
  76 {
  77         static int replace_object_prepared;
  78
  79         if (replace_object_prepared)
  80                 return;
  81
  82         for_each_replace_ref(register_replace_ref, NULL);
  83         replace_object_prepared = 1;
  84         if (!replace_object_nr)
  85                 read_replace_refs = 0;
  86 }
  87
  88 /* We allow "recursive" replacement. Only within reason, though */
  89 #define MAXREPLACEDEPTH 5
  90
  91 const unsigned char *do_lookup_replace_object(const unsigned char *sha1)
  92 {
  93         int pos, depth = MAXREPLACEDEPTH;
  94         const unsigned char *cur = sha1;
  95
  96         prepare_replace_object();
  97
  98         /* Try to recursively replace the object */
  99         do {
 100                 if (--depth < 0)
 101                         die("replace depth too high for object %s",
 102                             sha1_to_hex(sha1));
 103
 104                 pos = replace_object_pos(cur);
 105                 if (0 <= pos)
 106                         cur = replace_object[pos]->sha1[1];
 107         } while (0 <= pos);
 108
 109         return cur;
 110 }