oidtree.c

   1 /*
   2  * A wrapper around cbtree which stores oids
   3  * May be used to replace oid-array for prefix (abbreviation) matches
   4  */
   5 #include "oidtree.h"
   6 #include "alloc.h"
   7 #include "hash.h"
   8
   9 struct oidtree_iter_data {
  10         oidtree_iter fn;
  11         void *arg;
  12         size_t *last_nibble_at;
  13         int algo;
  14         uint8_t last_byte;
  15 };
  16
  17 void oidtree_init(struct oidtree *ot)
  18 {
  19         cb_init(&ot->tree);
  20         mem_pool_init(&ot->mem_pool, 0);
  21 }
  22
  23 void oidtree_clear(struct oidtree *ot)
  24 {
  25         if (ot) {
  26                 mem_pool_discard(&ot->mem_pool, 0);
  27                 oidtree_init(ot);
  28         }
  29 }
  30
  31 void oidtree_insert(struct oidtree *ot, const struct object_id *oid)
  32 {
  33         struct cb_node *on;
  34
  35         if (!oid->algo)
  36                 BUG("oidtree_insert requires oid->algo");
  37
  38         on = mem_pool_alloc(&ot->mem_pool, sizeof(*on) + sizeof(*oid));
  39         oidcpy_with_padding((struct object_id *)on->k, oid);
  40
  41         /*
  42          * n.b. Current callers won't get us duplicates, here.  If a
  43          * future caller causes duplicates, there'll be a a small leak
  44          * that won't be freed until oidtree_clear.  Currently it's not
  45          * worth maintaining a free list
  46          */
  47         cb_insert(&ot->tree, on, sizeof(*oid));
  48 }
  49
  50
  51 int oidtree_contains(struct oidtree *ot, const struct object_id *oid)
  52 {
  53         struct object_id k;
  54         size_t klen = sizeof(k);
  55
  56         oidcpy_with_padding(&k, oid);
  57
  58         if (oid->algo == GIT_HASH_UNKNOWN)
  59                 klen -= sizeof(oid->algo);
  60
  61         /* cb_lookup relies on memcmp on the struct, so order matters: */
  62         klen += BUILD_ASSERT_OR_ZERO(offsetof(struct object_id, hash) <
  63                                 offsetof(struct object_id, algo));
  64
  65         return cb_lookup(&ot->tree, (const uint8_t *)&k, klen) ? 1 : 0;
  66 }
  67
  68 static enum cb_next iter(struct cb_node *n, void *arg)
  69 {
  70         struct oidtree_iter_data *x = arg;
  71         const struct object_id *oid = (const struct object_id *)n->k;
  72
  73         if (x->algo != GIT_HASH_UNKNOWN && x->algo != oid->algo)
  74                 return CB_CONTINUE;
  75
  76         if (x->last_nibble_at) {
  77                 if ((oid->hash[*x->last_nibble_at] ^ x->last_byte) & 0xf0)
  78                         return CB_CONTINUE;
  79         }
  80
  81         return x->fn(oid, x->arg);
  82 }
  83
  84 void oidtree_each(struct oidtree *ot, const struct object_id *oid,
  85                         size_t oidhexsz, oidtree_iter fn, void *arg)
  86 {
  87         size_t klen = oidhexsz / 2;
  88         struct oidtree_iter_data x = { 0 };
  89         assert(oidhexsz <= GIT_MAX_HEXSZ);
  90
  91         x.fn = fn;
  92         x.arg = arg;
  93         x.algo = oid->algo;
  94         if (oidhexsz & 1) {
  95                 x.last_byte = oid->hash[klen];
  96                 x.last_nibble_at = &klen;
  97         }
  98         cb_each(&ot->tree, (const uint8_t *)oid, klen, iter, &x);
  99 }