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         if (replace_object_alloc <= ++replace_object_nr) {
  40                 replace_object_alloc = alloc_nr(replace_object_alloc);
  41                 replace_object = xrealloc(replace_object,
  42                                           sizeof(*replace_object) *
  43                                           replace_object_alloc);
  44         }
  45         if (pos < replace_object_nr)
  46                 memmove(replace_object + pos + 1,
  47                         replace_object + pos,
  48                         (replace_object_nr - pos - 1) *
  49                         sizeof(*replace_object));
  50         replace_object[pos] = replace;
  51         return 0;
  52 }
  53
  54 static int register_replace_ref(const char *refname,
  55                                 const unsigned char *sha1,
  56                                 int flag, void *cb_data)
  57 {
  58         /* Get sha1 from refname */
  59         const char *slash = strrchr(refname, '/');
  60         const char *hash = slash ? slash + 1 : refname;
  61         struct replace_object *repl_obj = xmalloc(sizeof(*repl_obj));
  62
  63         if (strlen(hash) != 40 || get_sha1_hex(hash, repl_obj->sha1[0])) {
  64                 free(repl_obj);
  65                 warning("bad replace ref name: %s", refname);
  66                 return 0;
  67         }
  68
  69         /* Copy sha1 from the read ref */
  70         hashcpy(repl_obj->sha1[1], sha1);
  71
  72         /* Register new object */
  73         if (register_replace_object(repl_obj, 1))
  74                 die("duplicate replace ref: %s", refname);
  75
  76         return 0;
  77 }
  78
  79 static void prepare_replace_object(void)
  80 {
  81         static int replace_object_prepared;
  82
  83         if (replace_object_prepared)
  84                 return;
  85
  86         for_each_replace_ref(register_replace_ref, NULL);
  87         replace_object_prepared = 1;
  88         if (!replace_object_nr)
  89                 read_replace_refs = 0;
  90 }
  91
  92 /* We allow "recursive" replacement. Only within reason, though */
  93 #define MAXREPLACEDEPTH 5
  94
  95 const unsigned char *do_lookup_replace_object(const unsigned char *sha1)
  96 {
  97         int pos, depth = MAXREPLACEDEPTH;
  98         const unsigned char *cur = sha1;
  99
 100         if (!read_replace_refs)
 101                 return sha1;
 102
 103         prepare_replace_object();
 104
 105         /* Try to recursively replace the object */
 106         do {
 107                 if (--depth < 0)
 108                         die("replace depth too high for object %s",
 109                             sha1_to_hex(sha1));
 110
 111                 pos = replace_object_pos(cur);
 112                 if (0 <= pos)
 113                         cur = replace_object[pos]->sha1[1];
 114         } while (0 <= pos);
 115
 116         return cur;
 117 }