sha1_name.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "commit.h"
   4 #include "tree.h"
   5 #include "blob.h"
   6
   7 static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
   8 {
   9         struct alternate_object_database *alt;
  10         char hex[40];
  11         int found = 0;
  12         static struct alternate_object_database *fakeent;
  13
  14         if (!fakeent) {
  15                 const char *objdir = get_object_directory();
  16                 int objdir_len = strlen(objdir);
  17                 int entlen = objdir_len + 43;
  18                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
  19                 memcpy(fakeent->base, objdir, objdir_len);
  20                 fakeent->name = fakeent->base + objdir_len + 1;
  21                 fakeent->name[-1] = '/';
  22         }
  23         fakeent->next = alt_odb_list;
  24
  25         sprintf(hex, "%.2s", name);
  26         for (alt = fakeent; alt && found < 2; alt = alt->next) {
  27                 struct dirent *de;
  28                 DIR *dir;
  29                 sprintf(alt->name, "%.2s/", name);
  30                 dir = opendir(alt->base);
  31                 if (!dir)
  32                         continue;
  33                 while ((de = readdir(dir)) != NULL) {
  34                         if (strlen(de->d_name) != 38)
  35                                 continue;
  36                         if (memcmp(de->d_name, name + 2, len - 2))
  37                                 continue;
  38                         if (!found) {
  39                                 memcpy(hex + 2, de->d_name, 38);
  40                                 found++;
  41                         }
  42                         else if (memcmp(hex + 2, de->d_name, 38)) {
  43                                 found = 2;
  44                                 break;
  45                         }
  46                 }
  47                 closedir(dir);
  48         }
  49         if (found == 1)
  50                 return get_sha1_hex(hex, sha1) == 0;
  51         return found;
  52 }
  53
  54 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
  55 {
  56         do {
  57                 if (*a != *b)
  58                         return 0;
  59                 a++;
  60                 b++;
  61                 len -= 2;
  62         } while (len > 1);
  63         if (len)
  64                 if ((*a ^ *b) & 0xf0)
  65                         return 0;
  66         return 1;
  67 }
  68
  69 static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
  70 {
  71         struct packed_git *p;
  72         unsigned char found_sha1[20];
  73         int found = 0;
  74
  75         prepare_packed_git();
  76         for (p = packed_git; p && found < 2; p = p->next) {
  77                 unsigned num = num_packed_objects(p);
  78                 unsigned first = 0, last = num;
  79                 while (first < last) {
  80                         unsigned mid = (first + last) / 2;
  81                         unsigned char now[20];
  82                         int cmp;
  83
  84                         nth_packed_object_sha1(p, mid, now);
  85                         cmp = memcmp(match, now, 20);
  86                         if (!cmp) {
  87                                 first = mid;
  88                                 break;
  89                         }
  90                         if (cmp > 0) {
  91                                 first = mid+1;
  92                                 continue;
  93                         }
  94                         last = mid;
  95                 }
  96                 if (first < num) {
  97                         unsigned char now[20], next[20];
  98                         nth_packed_object_sha1(p, first, now);
  99                         if (match_sha(len, match, now)) {
 100                                 if (nth_packed_object_sha1(p, first+1, next) ||
 101                                     !match_sha(len, match, next)) {
 102                                         /* unique within this pack */
 103                                         if (!found) {
 104                                                 memcpy(found_sha1, now, 20);
 105                                                 found++;
 106                                         }
 107                                         else if (memcmp(found_sha1, now, 20)) {
 108                                                 found = 2;
 109                                                 break;
 110                                         }
 111                                 }
 112                                 else {
 113                                         /* not even unique within this pack */
 114                                         found = 2;
 115                                         break;
 116                                 }
 117                         }
 118                 }
 119         }
 120         if (found == 1)
 121                 memcpy(sha1, found_sha1, 20);
 122         return found;
 123 }
 124
 125 static int find_unique_short_object(int len, char *canonical,
 126                                     unsigned char *res, unsigned char *sha1)
 127 {
 128         int has_unpacked, has_packed;
 129         unsigned char unpacked_sha1[20], packed_sha1[20];
 130
 131         has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
 132         has_packed = find_short_packed_object(len, res, packed_sha1);
 133         if (!has_unpacked && !has_packed)
 134                 return -1;
 135         if (1 < has_unpacked || 1 < has_packed)
 136                 return error("short SHA1 %.*s is ambiguous.", len, canonical);
 137         if (has_unpacked != has_packed) {
 138                 memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
 139                 return 0;
 140         }
 141         /* Both have unique ones -- do they match? */
 142         if (memcmp(packed_sha1, unpacked_sha1, 20))
 143                 return error("short SHA1 %.*s is ambiguous.", len, canonical);
 144         memcpy(sha1, packed_sha1, 20);
 145         return 0;
 146 }
 147
 148 static int get_short_sha1(const char *name, int len, unsigned char *sha1)
 149 {
 150         int i;
 151         char canonical[40];
 152         unsigned char res[20];
 153
 154         if (len < 4)
 155                 return -1;
 156         memset(res, 0, 20);
 157         memset(canonical, 'x', 40);
 158         for (i = 0; i < len ;i++) {
 159                 unsigned char c = name[i];
 160                 unsigned char val;
 161                 if (c >= '0' && c <= '9')
 162                         val = c - '0';
 163                 else if (c >= 'a' && c <= 'f')
 164                         val = c - 'a' + 10;
 165                 else if (c >= 'A' && c <='F') {
 166                         val = c - 'A' + 10;
 167                         c -= 'A' - 'a';
 168                 }
 169                 else
 170                         return -1;
 171                 canonical[i] = c;
 172                 if (!(i & 1))
 173                         val <<= 4;
 174                 res[i >> 1] |= val;
 175         }
 176
 177         return find_unique_short_object(i, canonical, res, sha1);
 178 }
 179
 180 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 181 {
 182         static const char *prefix[] = {
 183                 "",
 184                 "refs",
 185                 "refs/tags",
 186                 "refs/heads",
 187                 NULL
 188         };
 189         const char **p;
 190
 191         if (len == 40 && !get_sha1_hex(str, sha1))
 192                 return 0;
 193
 194         for (p = prefix; *p; p++) {
 195                 char *pathname = git_path("%s/%.*s", *p, len, str);
 196                 if (!read_ref(pathname, sha1))
 197                         return 0;
 198         }
 199
 200         return -1;
 201 }
 202
 203 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 204
 205 static int get_parent(const char *name, int len,
 206                       unsigned char *result, int idx)
 207 {
 208         unsigned char sha1[20];
 209         int ret = get_sha1_1(name, len, sha1);
 210         struct commit *commit;
 211         struct commit_list *p;
 212
 213         if (ret)
 214                 return ret;
 215         commit = lookup_commit_reference(sha1);
 216         if (!commit)
 217                 return -1;
 218         if (parse_commit(commit))
 219                 return -1;
 220         if (!idx) {
 221                 memcpy(result, commit->object.sha1, 20);
 222                 return 0;
 223         }
 224         p = commit->parents;
 225         while (p) {
 226                 if (!--idx) {
 227                         memcpy(result, p->item->object.sha1, 20);
 228                         return 0;
 229                 }
 230                 p = p->next;
 231         }
 232         return -1;
 233 }
 234
 235 static int get_nth_ancestor(const char *name, int len,
 236                             unsigned char *result, int generation)
 237 {
 238         unsigned char sha1[20];
 239         int ret = get_sha1_1(name, len, sha1);
 240         if (ret)
 241                 return ret;
 242
 243         while (generation--) {
 244                 struct commit *commit = lookup_commit_reference(sha1);
 245
 246                 if (!commit || parse_commit(commit) || !commit->parents)
 247                         return -1;
 248                 memcpy(sha1, commit->parents->item->object.sha1, 20);
 249         }
 250         memcpy(result, sha1, 20);
 251         return 0;
 252 }
 253
 254 static int peel_onion(const char *name, int len, unsigned char *sha1)
 255 {
 256         unsigned char outer[20];
 257         const char *sp;
 258         const char *type_string = NULL;
 259         struct object *o;
 260
 261         /*
 262          * "ref^{type}" dereferences ref repeatedly until you cannot
 263          * dereference anymore, or you get an object of given type,
 264          * whichever comes first.  "ref^{}" means just dereference
 265          * tags until you get a non-tag.  "ref^0" is a shorthand for
 266          * "ref^{commit}".  "commit^{tree}" could be used to find the
 267          * top-level tree of the given commit.
 268          */
 269         if (len < 4 || name[len-1] != '}')
 270                 return -1;
 271
 272         for (sp = name + len - 1; name <= sp; sp--) {
 273                 int ch = *sp;
 274                 if (ch == '{' && name < sp && sp[-1] == '^')
 275                         break;
 276         }
 277         if (sp <= name)
 278                 return -1;
 279
 280         sp++; /* beginning of type name, or closing brace for empty */
 281         if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
 282                 type_string = commit_type;
 283         else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
 284                 type_string = tree_type;
 285         else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
 286                 type_string = blob_type;
 287         else if (sp[0] == '}')
 288                 type_string = NULL;
 289         else
 290                 return -1;
 291
 292         if (get_sha1_1(name, sp - name - 2, outer))
 293                 return -1;
 294
 295         o = parse_object(outer);
 296         if (!o)
 297                 return -1;
 298         if (!type_string) {
 299                 o = deref_tag(o);
 300                 memcpy(sha1, o->sha1, 20);
 301         }
 302         else {
 303                 /* At this point, the syntax look correct, so
 304                  * if we do not get the needed object, we should
 305                  * barf.
 306                  */
 307
 308                 while (1) {
 309                         if (!o)
 310                                 return -1;
 311                         if (o->type == type_string) {
 312                                 memcpy(sha1, o->sha1, 20);
 313                                 return 0;
 314                         }
 315                         if (o->type == tag_type)
 316                                 o = ((struct tag*) o)->tagged;
 317                         else if (o->type == commit_type)
 318                                 o = &(((struct commit *) o)->tree->object);
 319                         else
 320                                 return error("%.*s: expected %s type, but the object dereferences to %s type",
 321                                              len, name, type_string,
 322                                              o->type);
 323                         if (!o->parsed)
 324                                 parse_object(o->sha1);
 325                 }
 326         }
 327         return 0;
 328 }
 329
 330 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 331 {
 332         int parent, ret;
 333         const char *cp;
 334
 335         /* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
 336         if (len > 2 && name[len-2] == '^' &&
 337             name[len-1] >= '0' && name[len-1] <= '9') {
 338                 parent = name[len-1] - '0';
 339                 len -= 2;
 340         }
 341         else if (len > 1 && name[len-1] == '^') {
 342                 parent = 1;
 343                 len--;
 344         } else
 345                 parent = -1;
 346
 347         if (parent >= 0)
 348                 return get_parent(name, len, sha1, parent);
 349
 350         /* "name~3" is "name^^^",
 351          * "name~12" is "name^^^^^^^^^^^^", and
 352          * "name~" and "name~0" are name -- not "name^0"!
 353          */
 354         parent = 0;
 355         for (cp = name + len - 1; name <= cp; cp--) {
 356                 int ch = *cp;
 357                 if ('0' <= ch && ch <= '9')
 358                         continue;
 359                 if (ch != '~')
 360                         parent = -1;
 361                 break;
 362         }
 363         if (!parent && *cp == '~') {
 364                 int len1 = cp - name;
 365                 cp++;
 366                 while (cp < name + len)
 367                         parent = parent * 10 + *cp++ - '0';
 368                 return get_nth_ancestor(name, len1, sha1, parent);
 369         }
 370
 371         ret = peel_onion(name, len, sha1);
 372         if (!ret)
 373                 return 0;
 374
 375         ret = get_sha1_basic(name, len, sha1);
 376         if (!ret)
 377                 return 0;
 378         return get_short_sha1(name, len, sha1);
 379 }
 380
 381 /*
 382  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 383  * notably "xyz^" for "parent of xyz"
 384  */
 385 int get_sha1(const char *name, unsigned char *sha1)
 386 {
 387         prepare_alt_odb();
 388         return get_sha1_1(name, strlen(name), sha1);
 389 }