delta.c

   1 #include "object.h"
   2 #include "blob.h"
   3 #include "tree.h"
   4 #include "commit.h"
   5 #include "tag.h"
   6 #include "delta.h"
   7 #include "cache.h"
   8
   9 /* the delta object definition (it can alias any other object) */
  10 struct delta {
  11         union {
  12                 struct object object;
  13                 struct blob blob;
  14                 struct tree tree;
  15                 struct commit commit;
  16                 struct tag tag;
  17         } u;
  18 };
  19
  20 struct delta *lookup_delta(unsigned char *sha1)
  21 {
  22         struct object *obj = lookup_object(sha1);
  23         if (!obj) {
  24                 struct delta *ret = xmalloc(sizeof(struct delta));
  25                 memset(ret, 0, sizeof(struct delta));
  26                 created_object(sha1, &ret->u.object);
  27                 return ret;
  28         }
  29         return (struct delta *) obj;
  30 }
  31
  32 int parse_delta_buffer(struct delta *item, void *buffer, unsigned long size)
  33 {
  34         struct object *reference;
  35         struct object_list *p;
  36
  37         if (item->u.object.delta)
  38                 return 0;
  39         item->u.object.delta = 1;
  40         if (size <= 20)
  41                 return -1;
  42         reference = lookup_object(buffer);
  43         if (!reference) {
  44                 struct delta *ref = xmalloc(sizeof(struct delta));
  45                 memset(ref, 0, sizeof(struct delta));
  46                 created_object(buffer, &ref->u.object);
  47                 reference = &ref->u.object;
  48         }
  49
  50         p = xmalloc(sizeof(*p));
  51         p->item = &item->u.object;
  52         p->next = reference->attached_deltas;
  53         reference->attached_deltas = p;
  54         return 0;
  55 }
  56
  57 int process_deltas(void *src, unsigned long src_size, const char *src_type,
  58                    struct object_list *delta_list)
  59 {
  60         int deepest = 0;
  61         do {
  62                 struct object *obj = delta_list->item;
  63                 static char type[10];
  64                 void *map, *delta, *buf;
  65                 unsigned long map_size, delta_size, buf_size;
  66                 map = map_sha1_file(obj->sha1, &map_size);
  67                 if (!map)
  68                         continue;
  69                 delta = unpack_sha1_file(map, map_size, type, &delta_size);
  70                 munmap(map, map_size);
  71                 if (!delta)
  72                         continue;
  73                 if (strcmp(type, "delta") || delta_size <= 20) {
  74                         free(delta);
  75                         continue;
  76                 }
  77                 buf = patch_delta(src, src_size,
  78                                   delta+20, delta_size-20,
  79                                   &buf_size);
  80                 free(delta);
  81                 if (!buf)
  82                         continue;
  83                 if (check_sha1_signature(obj->sha1, buf, buf_size, src_type) < 0)
  84                         printf("sha1 mismatch for delta %s\n", sha1_to_hex(obj->sha1));
  85                 if (obj->type && obj->type != src_type) {
  86                         error("got %s when expecting %s for delta %s",
  87                               src_type, obj->type, sha1_to_hex(obj->sha1));
  88                         free(buf);
  89                         continue;
  90                 }
  91                 obj->type = src_type;
  92                 if (src_type == blob_type) {
  93                         parse_blob_buffer((struct blob *)obj, buf, buf_size);
  94                 } else if (src_type == tree_type) {
  95                         parse_tree_buffer((struct tree *)obj, buf, buf_size);
  96                 } else if (src_type == commit_type) {
  97                         parse_commit_buffer((struct commit *)obj, buf, buf_size);
  98                 } else if (src_type == tag_type) {
  99                         parse_tag_buffer((struct tag *)obj, buf, buf_size);
 100                 } else {
 101                         error("unknown object type %s", src_type);
 102                         free(buf);
 103                         continue;
 104                 }
 105                 if (obj->attached_deltas) {
 106                         int depth = process_deltas(buf, buf_size, src_type,
 107                                                    obj->attached_deltas);
 108                         if (deepest < depth)
 109                                 deepest = depth;
 110                 }
 111                 free(buf);
 112         } while ((delta_list = delta_list->next));
 113         return deepest + 1;
 114 }