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, unsigned char *sha1)
  88 {
  89         int i;
  90         char canonical[40];
  91         unsigned char res[20];
  92
  93         memset(res, 0, 20);
  94         memset(canonical, 'x', 40);
  95         for (i = 0;;i++) {
  96                 unsigned char c = name[i];
  97                 unsigned char val;
  98                 if (!c || i > 40)
  99                         break;
 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 (i < 4)
 116                 return -1;
 117         if (find_short_object_filename(i, canonical, sha1))
 118                 return 0;
 119         if (find_short_packed_object(i, res, sha1))
 120                 return 0;
 121         return -1;
 122 }
 123
 124 static int get_sha1_file(const char *path, unsigned char *result)
 125 {
 126         char buffer[60];
 127         int fd = open(path, O_RDONLY);
 128         int len;
 129
 130         if (fd < 0)
 131                 return -1;
 132         len = read(fd, buffer, sizeof(buffer));
 133         close(fd);
 134         if (len < 40)
 135                 return -1;
 136         return get_sha1_hex(buffer, result);
 137 }
 138
 139 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 140 {
 141         static const char *prefix[] = {
 142                 "",
 143                 "refs",
 144                 "refs/tags",
 145                 "refs/heads",
 146                 NULL
 147         };
 148         const char **p;
 149
 150         if (len == 40 && !get_sha1_hex(str, sha1))
 151                 return 0;
 152
 153         for (p = prefix; *p; p++) {
 154                 char *pathname = git_path("%s/%.*s", *p, len, str);
 155                 if (!get_sha1_file(pathname, sha1))
 156                         return 0;
 157         }
 158
 159         return -1;
 160 }
 161
 162 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 163
 164 static int get_parent(const char *name, int len,
 165                       unsigned char *result, int idx)
 166 {
 167         unsigned char sha1[20];
 168         int ret = get_sha1_1(name, len, sha1);
 169         struct commit *commit;
 170         struct commit_list *p;
 171
 172         if (ret)
 173                 return ret;
 174         commit = lookup_commit_reference(sha1);
 175         if (!commit)
 176                 return -1;
 177         if (parse_commit(commit))
 178                 return -1;
 179         if (!idx) {
 180                 memcpy(result, commit->object.sha1, 20);
 181                 return 0;
 182         }
 183         p = commit->parents;
 184         while (p) {
 185                 if (!--idx) {
 186                         memcpy(result, p->item->object.sha1, 20);
 187                         return 0;
 188                 }
 189                 p = p->next;
 190         }
 191         return -1;
 192 }
 193
 194 static int get_nth_ancestor(const char *name, int len,
 195                             unsigned char *result, int generation)
 196 {
 197         unsigned char sha1[20];
 198         int ret = get_sha1_1(name, len, sha1);
 199         if (ret)
 200                 return ret;
 201
 202         while (generation--) {
 203                 struct commit *commit = lookup_commit_reference(sha1);
 204
 205                 if (!commit || parse_commit(commit) || !commit->parents)
 206                         return -1;
 207                 memcpy(sha1, commit->parents->item->object.sha1, 20);
 208         }
 209         memcpy(result, sha1, 20);
 210         return 0;
 211 }
 212
 213 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 214 {
 215         int parent, ret;
 216         const char *cp;
 217
 218         /* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
 219         if (len > 2 && name[len-2] == '^' &&
 220             name[len-1] >= '0' && name[len-1] <= '9') {
 221                 parent = name[len-1] - '0';
 222                 len -= 2;
 223         }
 224         else if (len > 1 && name[len-1] == '^') {
 225                 parent = 1;
 226                 len--;
 227         } else
 228                 parent = -1;
 229
 230         if (parent >= 0)
 231                 return get_parent(name, len, sha1, parent);
 232
 233         /* "name~3" is "name^^^",
 234          * "name~12" is "name^^^^^^^^^^^^", and
 235          * "name~" and "name~0" are name -- not "name^0"!
 236          */
 237         parent = 0;
 238         for (cp = name + len - 1; name <= cp; cp--) {
 239                 int ch = *cp;
 240                 if ('0' <= ch && ch <= '9')
 241                         continue;
 242                 if (ch != '~')
 243                         parent = -1;
 244                 break;
 245         }
 246         if (!parent && *cp == '~') {
 247                 int len1 = cp - name;
 248                 cp++;
 249                 while (cp < name + len)
 250                         parent = parent * 10 + *cp++ - '0';
 251                 return get_nth_ancestor(name, len1, sha1, parent);
 252         }
 253
 254         ret = get_sha1_basic(name, len, sha1);
 255         if (!ret)
 256                 return 0;
 257         return get_short_sha1(name, sha1);
 258 }
 259
 260 /*
 261  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 262  * notably "xyz^" for "parent of xyz"
 263  */
 264 int get_sha1(const char *name, unsigned char *sha1)
 265 {
 266         return get_sha1_1(name, strlen(name), sha1);
 267 }