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                 "refs/snap",
 147                 NULL
 148         };
 149         const char **p;
 150
 151         if (len == 40 && !get_sha1_hex(str, sha1))
 152                 return 0;
 153
 154         for (p = prefix; *p; p++) {
 155                 char *pathname = git_path("%s/%.*s", *p, len, str);
 156                 if (!get_sha1_file(pathname, sha1))
 157                         return 0;
 158         }
 159
 160         return -1;
 161 }
 162
 163 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 164
 165 static int get_parent(const char *name, int len,
 166                       unsigned char *result, int idx)
 167 {
 168         unsigned char sha1[20];
 169         int ret = get_sha1_1(name, len, sha1);
 170         struct commit *commit;
 171         struct commit_list *p;
 172
 173         if (ret)
 174                 return ret;
 175         commit = lookup_commit_reference(sha1);
 176         if (!commit)
 177                 return -1;
 178         if (parse_commit(commit))
 179                 return -1;
 180         if (!idx) {
 181                 memcpy(result, commit->object.sha1, 20);
 182                 return 0;
 183         }
 184         p = commit->parents;
 185         while (p) {
 186                 if (!--idx) {
 187                         memcpy(result, p->item->object.sha1, 20);
 188                         return 0;
 189                 }
 190                 p = p->next;
 191         }
 192         return -1;
 193 }
 194
 195 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 196 {
 197         int parent, ret;
 198
 199         /* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
 200         if (len > 2 && name[len-2] == '^' &&
 201             name[len-1] >= '0' && name[len-1] <= '9') {
 202                 parent = name[len-1] - '0';
 203                 len -= 2;
 204         }
 205         else if (len > 1 && name[len-1] == '^') {
 206                 parent = 1;
 207                 len--;
 208         } else
 209                 parent = -1;
 210
 211         if (parent >= 0)
 212                 return get_parent(name, len, sha1, parent);
 213
 214         ret = get_sha1_basic(name, len, sha1);
 215         if (!ret)
 216                 return 0;
 217         return get_short_sha1(name, sha1);
 218 }
 219
 220 /*
 221  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 222  * notably "xyz^" for "parent of xyz"
 223  */
 224 int get_sha1(const char *name, unsigned char *sha1)
 225 {
 226         return get_sha1_1(name, strlen(name), sha1);
 227 }