sha1_name.c

   1 #include "cache.h"
   2 #include "commit.h"
   3
   4 static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
   5 {
   6         struct alternate_object_database *alt;
   7         char hex[40];
   8         int found = 0;
   9         static struct alternate_object_database *fakeent;
  10
  11         if (!fakeent) {
  12                 const char *objdir = get_object_directory();
  13                 int objdir_len = strlen(objdir);
  14                 int entlen = objdir_len + 43;
  15                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
  16                 memcpy(fakeent->base, objdir, objdir_len);
  17                 fakeent->name = fakeent->base + objdir_len + 1;
  18                 fakeent->name[-1] = '/';
  19         }
  20         fakeent->next = alt_odb_list;
  21
  22         sprintf(hex, "%.2s", name);
  23         for (alt = fakeent; alt && found < 2; alt = alt->next) {
  24                 struct dirent *de;
  25                 DIR *dir;
  26                 sprintf(alt->name, "%.2s/", name);
  27                 dir = opendir(alt->base);
  28                 if (!dir)
  29                         continue;
  30                 while ((de = readdir(dir)) != NULL) {
  31                         if (strlen(de->d_name) != 38)
  32                                 continue;
  33                         if (memcmp(de->d_name, name + 2, len - 2))
  34                                 continue;
  35                         if (!found) {
  36                                 memcpy(hex + 2, de->d_name, 38);
  37                                 found++;
  38                         }
  39                         else if (memcmp(hex + 2, de->d_name, 38)) {
  40                                 found = 2;
  41                                 break;
  42                         }
  43                 }
  44                 closedir(dir);
  45         }
  46         if (found == 1)
  47                 return get_sha1_hex(hex, sha1) == 0;
  48         return found;
  49 }
  50
  51 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
  52 {
  53         do {
  54                 if (*a != *b)
  55                         return 0;
  56                 a++;
  57                 b++;
  58                 len -= 2;
  59         } while (len > 1);
  60         if (len)
  61                 if ((*a ^ *b) & 0xf0)
  62                         return 0;
  63         return 1;
  64 }
  65
  66 static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
  67 {
  68         struct packed_git *p;
  69         unsigned char found_sha1[20];
  70         int found = 0;
  71
  72         prepare_packed_git();
  73         for (p = packed_git; p && found < 2; p = p->next) {
  74                 unsigned num = num_packed_objects(p);
  75                 unsigned first = 0, last = num;
  76                 while (first < last) {
  77                         unsigned mid = (first + last) / 2;
  78                         unsigned char now[20];
  79                         int cmp;
  80
  81                         nth_packed_object_sha1(p, mid, now);
  82                         cmp = memcmp(match, now, 20);
  83                         if (!cmp) {
  84                                 first = mid;
  85                                 break;
  86                         }
  87                         if (cmp > 0) {
  88                                 first = mid+1;
  89                                 continue;
  90                         }
  91                         last = mid;
  92                 }
  93                 if (first < num) {
  94                         unsigned char now[20], next[20];
  95                         nth_packed_object_sha1(p, first, now);
  96                         if (match_sha(len, match, now)) {
  97                                 if (nth_packed_object_sha1(p, first+1, next) ||
  98                                     !match_sha(len, match, next)) {
  99                                         /* unique within this pack */
 100                                         if (!found) {
 101                                                 memcpy(found_sha1, now, 20);
 102                                                 found++;
 103                                         }
 104                                         else if (memcmp(found_sha1, now, 20)) {
 105                                                 found = 2;
 106                                                 break;
 107                                         }
 108                                 }
 109                                 else {
 110                                         /* not even unique within this pack */
 111                                         found = 2;
 112                                         break;
 113                                 }
 114                         }
 115                 }
 116         }
 117         if (found == 1)
 118                 memcpy(sha1, found_sha1, 20);
 119         return found;
 120 }
 121
 122 static int find_unique_short_object(int len, char *canonical,
 123                                     unsigned char *res, unsigned char *sha1)
 124 {
 125         int has_unpacked, has_packed;
 126         unsigned char unpacked_sha1[20], packed_sha1[20];
 127
 128         has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
 129         has_packed = find_short_packed_object(len, res, packed_sha1);
 130         if (!has_unpacked && !has_packed)
 131                 return -1;
 132         if (1 < has_unpacked || 1 < has_packed)
 133                 return error("short SHA1 %.*s is ambiguous.", len, canonical);
 134         if (has_unpacked != has_packed) {
 135                 memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
 136                 return 0;
 137         }
 138         /* Both have unique ones -- do they match? */
 139         if (memcmp(packed_sha1, unpacked_sha1, 20))
 140                 return error("short SHA1 %.*s is ambiguous.", len, canonical);
 141         memcpy(sha1, packed_sha1, 20);
 142         return 0;
 143 }
 144
 145 static int get_short_sha1(const char *name, int len, unsigned char *sha1)
 146 {
 147         int i;
 148         char canonical[40];
 149         unsigned char res[20];
 150
 151         if (len < 4)
 152                 return -1;
 153         memset(res, 0, 20);
 154         memset(canonical, 'x', 40);
 155         for (i = 0; i < len ;i++) {
 156                 unsigned char c = name[i];
 157                 unsigned char val;
 158                 if (c >= '0' && c <= '9')
 159                         val = c - '0';
 160                 else if (c >= 'a' && c <= 'f')
 161                         val = c - 'a' + 10;
 162                 else if (c >= 'A' && c <='F') {
 163                         val = c - 'A' + 10;
 164                         c -= 'A' - 'a';
 165                 }
 166                 else
 167                         return -1;
 168                 canonical[i] = c;
 169                 if (!(i & 1))
 170                         val <<= 4;
 171                 res[i >> 1] |= val;
 172         }
 173
 174         return find_unique_short_object(i, canonical, res, sha1);
 175 }
 176
 177 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 178 {
 179         static const char *prefix[] = {
 180                 "",
 181                 "refs",
 182                 "refs/tags",
 183                 "refs/heads",
 184                 NULL
 185         };
 186         const char **p;
 187
 188         if (len == 40 && !get_sha1_hex(str, sha1))
 189                 return 0;
 190
 191         for (p = prefix; *p; p++) {
 192                 char *pathname = git_path("%s/%.*s", *p, len, str);
 193                 if (!read_ref(pathname, sha1))
 194                         return 0;
 195         }
 196
 197         return -1;
 198 }
 199
 200 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 201
 202 static int get_parent(const char *name, int len,
 203                       unsigned char *result, int idx)
 204 {
 205         unsigned char sha1[20];
 206         int ret = get_sha1_1(name, len, sha1);
 207         struct commit *commit;
 208         struct commit_list *p;
 209
 210         if (ret)
 211                 return ret;
 212         commit = lookup_commit_reference(sha1);
 213         if (!commit)
 214                 return -1;
 215         if (parse_commit(commit))
 216                 return -1;
 217         if (!idx) {
 218                 memcpy(result, commit->object.sha1, 20);
 219                 return 0;
 220         }
 221         p = commit->parents;
 222         while (p) {
 223                 if (!--idx) {
 224                         memcpy(result, p->item->object.sha1, 20);
 225                         return 0;
 226                 }
 227                 p = p->next;
 228         }
 229         return -1;
 230 }
 231
 232 static int get_nth_ancestor(const char *name, int len,
 233                             unsigned char *result, int generation)
 234 {
 235         unsigned char sha1[20];
 236         int ret = get_sha1_1(name, len, sha1);
 237         if (ret)
 238                 return ret;
 239
 240         while (generation--) {
 241                 struct commit *commit = lookup_commit_reference(sha1);
 242
 243                 if (!commit || parse_commit(commit) || !commit->parents)
 244                         return -1;
 245                 memcpy(sha1, commit->parents->item->object.sha1, 20);
 246         }
 247         memcpy(result, sha1, 20);
 248         return 0;
 249 }
 250
 251 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 252 {
 253         int parent, ret;
 254         const char *cp;
 255
 256         /* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
 257         if (len > 2 && name[len-2] == '^' &&
 258             name[len-1] >= '0' && name[len-1] <= '9') {
 259                 parent = name[len-1] - '0';
 260                 len -= 2;
 261         }
 262         else if (len > 1 && name[len-1] == '^') {
 263                 parent = 1;
 264                 len--;
 265         } else
 266                 parent = -1;
 267
 268         if (parent >= 0)
 269                 return get_parent(name, len, sha1, parent);
 270
 271         /* "name~3" is "name^^^",
 272          * "name~12" is "name^^^^^^^^^^^^", and
 273          * "name~" and "name~0" are name -- not "name^0"!
 274          */
 275         parent = 0;
 276         for (cp = name + len - 1; name <= cp; cp--) {
 277                 int ch = *cp;
 278                 if ('0' <= ch && ch <= '9')
 279                         continue;
 280                 if (ch != '~')
 281                         parent = -1;
 282                 break;
 283         }
 284         if (!parent && *cp == '~') {
 285                 int len1 = cp - name;
 286                 cp++;
 287                 while (cp < name + len)
 288                         parent = parent * 10 + *cp++ - '0';
 289                 return get_nth_ancestor(name, len1, sha1, parent);
 290         }
 291
 292         ret = get_sha1_basic(name, len, sha1);
 293         if (!ret)
 294                 return 0;
 295         return get_short_sha1(name, len, sha1);
 296 }
 297
 298 /*
 299  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 300  * notably "xyz^" for "parent of xyz"
 301  */
 302 int get_sha1(const char *name, unsigned char *sha1)
 303 {
 304         prepare_alt_odb();
 305         return get_sha1_1(name, strlen(name), sha1);
 306 }