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