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 #define SHORT_NAME_NOT_FOUND (-1)
 126 #define SHORT_NAME_AMBIGUOUS (-2)
 127
 128 static int find_unique_short_object(int len, char *canonical,
 129                                     unsigned char *res, unsigned char *sha1)
 130 {
 131         int has_unpacked, has_packed;
 132         unsigned char unpacked_sha1[20], packed_sha1[20];
 133
 134         has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
 135         has_packed = find_short_packed_object(len, res, packed_sha1);
 136         if (!has_unpacked && !has_packed)
 137                 return SHORT_NAME_NOT_FOUND;
 138         if (1 < has_unpacked || 1 < has_packed)
 139                 return SHORT_NAME_AMBIGUOUS;
 140         if (has_unpacked != has_packed) {
 141                 memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
 142                 return 0;
 143         }
 144         /* Both have unique ones -- do they match? */
 145         if (memcmp(packed_sha1, unpacked_sha1, 20))
 146                 return -2;
 147         memcpy(sha1, packed_sha1, 20);
 148         return 0;
 149 }
 150
 151 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 152                           int quietly)
 153 {
 154         int i, status;
 155         char canonical[40];
 156         unsigned char res[20];
 157
 158         if (len < 4)
 159                 return -1;
 160         memset(res, 0, 20);
 161         memset(canonical, 'x', 40);
 162         for (i = 0; i < len ;i++) {
 163                 unsigned char c = name[i];
 164                 unsigned char val;
 165                 if (c >= '0' && c <= '9')
 166                         val = c - '0';
 167                 else if (c >= 'a' && c <= 'f')
 168                         val = c - 'a' + 10;
 169                 else if (c >= 'A' && c <='F') {
 170                         val = c - 'A' + 10;
 171                         c -= 'A' - 'a';
 172                 }
 173                 else
 174                         return -1;
 175                 canonical[i] = c;
 176                 if (!(i & 1))
 177                         val <<= 4;
 178                 res[i >> 1] |= val;
 179         }
 180
 181         status = find_unique_short_object(i, canonical, res, sha1);
 182         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 183                 return error("short SHA1 %.*s is ambiguous.", len, canonical);
 184         return status;
 185 }
 186
 187 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 188 {
 189         int status;
 190         static char hex[41];
 191         memcpy(hex, sha1_to_hex(sha1), 40);
 192         while (len < 40) {
 193                 unsigned char sha1_ret[20];
 194                 status = get_short_sha1(hex, len, sha1_ret, 1);
 195                 if (!status) {
 196                         hex[len] = 0;
 197                         return hex;
 198                 }
 199                 if (status != SHORT_NAME_AMBIGUOUS)
 200                         return NULL;
 201                 len++;
 202         }
 203         return NULL;
 204 }
 205
 206 static int ambiguous_path(const char *path)
 207 {
 208         int slash = 1;
 209
 210         for (;;) {
 211                 switch (*path++) {
 212                 case '\0':
 213                         break;
 214                 case '/':
 215                         if (slash)
 216                                 break;
 217                         slash = 1;
 218                         continue;
 219                 case '.':
 220                         continue;
 221                 default:
 222                         slash = 0;
 223                         continue;
 224                 }
 225                 return slash;
 226         }
 227 }
 228
 229 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 230 {
 231         static const char *prefix[] = {
 232                 "",
 233                 "refs",
 234                 "refs/tags",
 235                 "refs/heads",
 236                 NULL
 237         };
 238         const char **p;
 239         int found = 0;
 240
 241         if (len == 40 && !get_sha1_hex(str, sha1))
 242                 return 0;
 243
 244         /* Accept only unambiguous ref paths. */
 245         if (ambiguous_path(str))
 246                 return -1;
 247
 248         for (p = prefix; *p; p++) {
 249                 char *pathname = git_path("%s/%.*s", *p, len, str);
 250                 if (!read_ref(pathname, sha1)) {
 251                         /* Must be unique; i.e. when heads/foo and
 252                          * tags/foo are both present, reject "foo".
 253                          * Note that read_ref() eventually calls
 254                          * get_sha1_hex() which can smudge initial
 255                          * part of the buffer even if what is read
 256                          * is found to be invalid halfway.
 257                          */
 258                         if (1 < found++)
 259                                 return -1;
 260                 }
 261         }
 262         if (found == 1)
 263                 return 0;
 264         return -1;
 265 }
 266
 267 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 268
 269 static int get_parent(const char *name, int len,
 270                       unsigned char *result, int idx)
 271 {
 272         unsigned char sha1[20];
 273         int ret = get_sha1_1(name, len, sha1);
 274         struct commit *commit;
 275         struct commit_list *p;
 276
 277         if (ret)
 278                 return ret;
 279         commit = lookup_commit_reference(sha1);
 280         if (!commit)
 281                 return -1;
 282         if (parse_commit(commit))
 283                 return -1;
 284         if (!idx) {
 285                 memcpy(result, commit->object.sha1, 20);
 286                 return 0;
 287         }
 288         p = commit->parents;
 289         while (p) {
 290                 if (!--idx) {
 291                         memcpy(result, p->item->object.sha1, 20);
 292                         return 0;
 293                 }
 294                 p = p->next;
 295         }
 296         return -1;
 297 }
 298
 299 static int get_nth_ancestor(const char *name, int len,
 300                             unsigned char *result, int generation)
 301 {
 302         unsigned char sha1[20];
 303         int ret = get_sha1_1(name, len, sha1);
 304         if (ret)
 305                 return ret;
 306
 307         while (generation--) {
 308                 struct commit *commit = lookup_commit_reference(sha1);
 309
 310                 if (!commit || parse_commit(commit) || !commit->parents)
 311                         return -1;
 312                 memcpy(sha1, commit->parents->item->object.sha1, 20);
 313         }
 314         memcpy(result, sha1, 20);
 315         return 0;
 316 }
 317
 318 static int peel_onion(const char *name, int len, unsigned char *sha1)
 319 {
 320         unsigned char outer[20];
 321         const char *sp;
 322         const char *type_string = NULL;
 323         struct object *o;
 324
 325         /*
 326          * "ref^{type}" dereferences ref repeatedly until you cannot
 327          * dereference anymore, or you get an object of given type,
 328          * whichever comes first.  "ref^{}" means just dereference
 329          * tags until you get a non-tag.  "ref^0" is a shorthand for
 330          * "ref^{commit}".  "commit^{tree}" could be used to find the
 331          * top-level tree of the given commit.
 332          */
 333         if (len < 4 || name[len-1] != '}')
 334                 return -1;
 335
 336         for (sp = name + len - 1; name <= sp; sp--) {
 337                 int ch = *sp;
 338                 if (ch == '{' && name < sp && sp[-1] == '^')
 339                         break;
 340         }
 341         if (sp <= name)
 342                 return -1;
 343
 344         sp++; /* beginning of type name, or closing brace for empty */
 345         if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
 346                 type_string = commit_type;
 347         else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
 348                 type_string = tree_type;
 349         else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
 350                 type_string = blob_type;
 351         else if (sp[0] == '}')
 352                 type_string = NULL;
 353         else
 354                 return -1;
 355
 356         if (get_sha1_1(name, sp - name - 2, outer))
 357                 return -1;
 358
 359         o = parse_object(outer);
 360         if (!o)
 361                 return -1;
 362         if (!type_string) {
 363                 o = deref_tag(o, name, sp - name - 2);
 364                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 365                         return -1;
 366                 memcpy(sha1, o->sha1, 20);
 367         }
 368         else {
 369                 /* At this point, the syntax look correct, so
 370                  * if we do not get the needed object, we should
 371                  * barf.
 372                  */
 373
 374                 while (1) {
 375                         if (!o || (!o->parsed && !parse_object(o->sha1)))
 376                                 return -1;
 377                         if (o->type == type_string) {
 378                                 memcpy(sha1, o->sha1, 20);
 379                                 return 0;
 380                         }
 381                         if (o->type == tag_type)
 382                                 o = ((struct tag*) o)->tagged;
 383                         else if (o->type == commit_type)
 384                                 o = &(((struct commit *) o)->tree->object);
 385                         else
 386                                 return error("%.*s: expected %s type, but the object dereferences to %s type",
 387                                              len, name, type_string,
 388                                              o->type);
 389                         if (!o->parsed)
 390                                 parse_object(o->sha1);
 391                 }
 392         }
 393         return 0;
 394 }
 395
 396 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 397 {
 398         int parent, ret;
 399         const char *cp;
 400
 401         /* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
 402         if (len > 2 && name[len-2] == '^' &&
 403             name[len-1] >= '0' && name[len-1] <= '9') {
 404                 parent = name[len-1] - '0';
 405                 len -= 2;
 406         }
 407         else if (len > 1 && name[len-1] == '^') {
 408                 parent = 1;
 409                 len--;
 410         } else
 411                 parent = -1;
 412
 413         if (parent >= 0)
 414                 return get_parent(name, len, sha1, parent);
 415
 416         /* "name~3" is "name^^^",
 417          * "name~12" is "name^^^^^^^^^^^^", and
 418          * "name~" and "name~0" are name -- not "name^0"!
 419          */
 420         parent = 0;
 421         for (cp = name + len - 1; name <= cp; cp--) {
 422                 int ch = *cp;
 423                 if ('0' <= ch && ch <= '9')
 424                         continue;
 425                 if (ch != '~')
 426                         parent = -1;
 427                 break;
 428         }
 429         if (!parent && *cp == '~') {
 430                 int len1 = cp - name;
 431                 cp++;
 432                 while (cp < name + len)
 433                         parent = parent * 10 + *cp++ - '0';
 434                 return get_nth_ancestor(name, len1, sha1, parent);
 435         }
 436
 437         ret = peel_onion(name, len, sha1);
 438         if (!ret)
 439                 return 0;
 440
 441         ret = get_sha1_basic(name, len, sha1);
 442         if (!ret)
 443                 return 0;
 444         return get_short_sha1(name, len, sha1, 0);
 445 }
 446
 447 /*
 448  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 449  * notably "xyz^" for "parent of xyz"
 450  */
 451 int get_sha1(const char *name, unsigned char *sha1)
 452 {
 453         prepare_alt_odb();
 454         return get_sha1_1(name, strlen(name), sha1);
 455 }