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 #include <string.h>
   9
  10 /* the delta object definition (it can alias any other object) */
  11 struct delta {
  12         union {
  13                 struct object object;
  14                 struct blob blob;
  15                 struct tree tree;
  16                 struct commit commit;
  17                 struct tag tag;
  18         } u;
  19 };
  20
  21 struct delta *lookup_delta(unsigned char *sha1)
  22 {
  23         struct object *obj = lookup_object(sha1);
  24         if (!obj) {
  25                 struct delta *ret = xmalloc(sizeof(struct delta));
  26                 memset(ret, 0, sizeof(struct delta));
  27                 created_object(sha1, &ret->u.object);
  28                 return ret;
  29         }
  30         return (struct delta *) obj;
  31 }
  32
  33 int parse_delta_buffer(struct delta *item, void *buffer, unsigned long size)
  34 {
  35         struct object *reference;
  36         struct object_list *p;
  37
  38         if (item->u.object.delta)
  39                 return 0;
  40         item->u.object.delta = 1;
  41         if (size <= 20)
  42                 return -1;
  43         reference = lookup_object(buffer);
  44         if (!reference) {
  45                 struct delta *ref = xmalloc(sizeof(struct delta));
  46                 memset(ref, 0, sizeof(struct delta));
  47                 created_object(buffer, &ref->u.object);
  48                 reference = &ref->u.object;
  49         }
  50
  51         p = xmalloc(sizeof(*p));
  52         p->item = &item->u.object;
  53         p->next = reference->attached_deltas;
  54         reference->attached_deltas = p;
  55         return 0;
  56 }
  57
  58 int process_deltas(void *src, unsigned long src_size, const char *src_type,
  59                    struct object_list *delta_list)
  60 {
  61         int deepest = 0;
  62         do {
  63                 struct object *obj = delta_list->item;
  64                 static char type[10];
  65                 void *map, *delta, *buf;
  66                 unsigned long map_size, delta_size, buf_size;
  67                 map = map_sha1_file(obj->sha1, &map_size);
  68                 if (!map)
  69                         continue;
  70                 delta = unpack_sha1_file(map, map_size, type, &delta_size);
  71                 munmap(map, map_size);
  72                 if (!delta)
  73                         continue;
  74                 if (strcmp(type, "delta") || delta_size <= 20) {
  75                         free(delta);
  76                         continue;
  77                 }
  78                 buf = patch_delta(src, src_size,
  79                                   delta+20, delta_size-20,
  80                                   &buf_size);
  81                 free(delta);
  82                 if (!buf)
  83                         continue;
  84                 if (check_sha1_signature(obj->sha1, buf, buf_size, src_type) < 0)
  85                         printf("sha1 mismatch for delta %s\n", sha1_to_hex(obj->sha1));
  86                 if (obj->type && obj->type != src_type) {
  87                         error("got %s when expecting %s for delta %s",
  88                               src_type, obj->type, sha1_to_hex(obj->sha1));
  89                         free(buf);
  90                         continue;
  91                 }
  92                 obj->type = src_type;
  93                 if (src_type == blob_type) {
  94                         parse_blob_buffer((struct blob *)obj, buf, buf_size);
  95                 } else if (src_type == tree_type) {
  96                         parse_tree_buffer((struct tree *)obj, buf, buf_size);
  97                 } else if (src_type == commit_type) {
  98                         parse_commit_buffer((struct commit *)obj, buf, buf_size);
  99                 } else if (src_type == tag_type) {
 100                         parse_tag_buffer((struct tag *)obj, buf, buf_size);
 101                 } else {
 102                         error("unknown object type %s", src_type);
 103                         free(buf);
 104                         continue;
 105                 }
 106                 if (obj->attached_deltas) {
 107                         int depth = process_deltas(buf, buf_size, src_type,
 108                                                    obj->attached_deltas);
 109                         if (deepest < depth)
 110                                 deepest = depth;
 111                 }
 112                 free(buf);
 113         } while ((delta_list = delta_list->next));
 114         return deepest + 1;
 115 }