attr.c

   1 #include "cache.h"
   2 #include "attr.h"
   3
   4 /*
   5  * The basic design decision here is that we are not going to have
   6  * insanely large number of attributes.
   7  *
   8  * This is a randomly chosen prime.
   9  */
  10 #define HASHSIZE 257
  11
  12 #ifndef DEBUG_ATTR
  13 #define DEBUG_ATTR 0
  14 #endif
  15
  16 struct git_attr {
  17         struct git_attr *next;
  18         unsigned h;
  19         char name[FLEX_ARRAY];
  20 };
  21
  22 static struct git_attr *(git_attr_hash[HASHSIZE]);
  23
  24 static unsigned hash_name(const char *name, int namelen)
  25 {
  26         unsigned val = 0;
  27         unsigned char c;
  28
  29         while (namelen--) {
  30                 c = *name++;
  31                 val = ((val << 7) | (val >> 22)) ^ c;
  32         }
  33         return val;
  34 }
  35
  36 struct git_attr *git_attr(const char *name, int len)
  37 {
  38         unsigned hval = hash_name(name, len);
  39         unsigned pos = hval % HASHSIZE;
  40         struct git_attr *a;
  41
  42         for (a = git_attr_hash[pos]; a; a = a->next) {
  43                 if (a->h == hval &&
  44                     !memcmp(a->name, name, len) && !a->name[len])
  45                         return a;
  46         }
  47
  48         a = xmalloc(sizeof(*a) + len + 1);
  49         memcpy(a->name, name, len);
  50         a->name[len] = 0;
  51         a->h = hval;
  52         a->next = git_attr_hash[pos];
  53         git_attr_hash[pos] = a;
  54         return a;
  55 }
  56
  57 /*
  58  * .gitattributes file is one line per record, each of which is
  59  *
  60  * (1) glob pattern.
  61  * (2) whitespace
  62  * (3) whitespace separated list of attribute names, each of which
  63  *     could be prefixed with '!' to mean "not set".
  64  */
  65
  66 struct attr_state {
  67         int unset;
  68         struct git_attr *attr;
  69 };
  70
  71 struct match_attr {
  72         char *pattern;
  73         unsigned num_attr;
  74         struct attr_state state[FLEX_ARRAY];
  75 };
  76
  77 static const char blank[] = " \t\r\n";
  78
  79 static struct match_attr *parse_attr_line(const char *line)
  80 {
  81         int namelen;
  82         int num_attr;
  83         const char *cp, *name;
  84         struct match_attr *res = res;
  85         int pass;
  86
  87         cp = line + strspn(line, blank);
  88         if (!*cp || *cp == '#')
  89                 return NULL;
  90         name = cp;
  91         namelen = strcspn(name, blank);
  92
  93         for (pass = 0; pass < 2; pass++) {
  94                 /* pass 0 counts and allocates, pass 1 fills */
  95                 num_attr = 0;
  96                 cp = name + namelen;
  97                 cp = cp + strspn(cp, blank);
  98                 while (*cp) {
  99                         const char *ep;
 100                         ep = cp + strcspn(cp, blank);
 101                         if (pass) {
 102                                 struct attr_state *e;
 103
 104                                 e = &(res->state[num_attr]);
 105                                 if (*cp == '!') {
 106                                         e->unset = 1;
 107                                         cp++;
 108                                 }
 109                                 e->attr = git_attr(cp, ep - cp);
 110                         }
 111                         num_attr++;
 112                         cp = ep + strspn(ep, blank);
 113                 }
 114                 if (pass)
 115                         break;
 116                 res = xcalloc(1,
 117                               sizeof(*res) +
 118                               sizeof(struct attr_state) * num_attr +
 119                               namelen + 1);
 120                 res->pattern = (char*)&(res->state[num_attr]);
 121                 memcpy(res->pattern, name, namelen);
 122                 res->pattern[namelen] = 0;
 123                 res->num_attr = num_attr;
 124         }
 125         return res;
 126 }
 127
 128 /*
 129  * Like info/exclude and .gitignore, the attribute information can
 130  * come from many places.
 131  *
 132  * (1) .gitattribute file of the same directory;
 133  * (2) .gitattribute file of the parent directory if (1) does not have any match;
 134  *     this goes recursively upwards, just like .gitignore
 135  * (3) perhaps $GIT_DIR/info/attributes, as the final fallback.
 136  *
 137  * In the same file, later entries override the earlier match, so in the
 138  * global list, we would have entries from info/attributes the earliest
 139  * (reading the file from top to bottom), .gitattribute of the root
 140  * directory (again, reading the file from top to bottom) down to the
 141  * current directory, and then scan the list backwards to find the first match.
 142  * This is exactly the same as what excluded() does in dir.c to deal with
 143  * .gitignore
 144  */
 145
 146 static struct attr_stack {
 147         struct attr_stack *prev;
 148         char *origin;
 149         unsigned num_matches;
 150         struct match_attr **attrs;
 151 } *attr_stack;
 152
 153 static void free_attr_elem(struct attr_stack *e)
 154 {
 155         int i;
 156         free(e->origin);
 157         for (i = 0; i < e->num_matches; i++)
 158                 free(e->attrs[i]);
 159         free(e);
 160 }
 161
 162 static const char *builtin_attr[] = {
 163         NULL,
 164 };
 165
 166 static struct attr_stack *read_attr_from_array(const char **list)
 167 {
 168         struct attr_stack *res;
 169         const char *line;
 170
 171         res = xcalloc(1, sizeof(*res));
 172         while ((line = *(list++)) != NULL) {
 173                 struct match_attr *a = parse_attr_line(line);
 174                 if (!a)
 175                         continue;
 176                 res->attrs = xrealloc(res->attrs, res->num_matches + 1);
 177                 res->attrs[res->num_matches++] = a;
 178         }
 179         return res;
 180 }
 181
 182 static struct attr_stack *read_attr_from_file(const char *path)
 183 {
 184         FILE *fp;
 185         struct attr_stack *res;
 186         char buf[2048];
 187
 188         res = xcalloc(1, sizeof(*res));
 189         fp = fopen(path, "r");
 190         if (!fp)
 191                 return res;
 192
 193         while (fgets(buf, sizeof(buf), fp)) {
 194                 struct match_attr *a = parse_attr_line(buf);
 195                 if (!a)
 196                         continue;
 197                 res->attrs = xrealloc(res->attrs, res->num_matches + 1);
 198                 res->attrs[res->num_matches++] = a;
 199         }
 200         fclose(fp);
 201         return res;
 202 }
 203
 204 #if DEBUG_ATTR
 205 static void debug_info(const char *what, struct attr_stack *elem)
 206 {
 207         fprintf(stderr, "%s: %s\n", what, elem->origin ? elem->origin : "()");
 208 }
 209 #define debug_push(a) debug_info("push", (a))
 210 #define debug_pop(a) debug_info("pop", (a))
 211 #else
 212 #define debug_push(a) do { ; } while (0)
 213 #define debug_pop(a) do { ; } while (0)
 214 #endif
 215
 216 static void prepare_attr_stack(const char *path, int dirlen)
 217 {
 218         struct attr_stack *elem, *info;
 219         int len;
 220         char pathbuf[PATH_MAX];
 221
 222         /*
 223          * At the bottom of the attribute stack is the built-in
 224          * set of attribute definitions.  Then, contents from
 225          * .gitattribute files from directories closer to the
 226          * root to the ones in deeper directories are pushed
 227          * to the stack.  Finally, at the very top of the stack
 228          * we always keep the contents of $GIT_DIR/info/attributes.
 229          *
 230          * When checking, we use entries from near the top of the
 231          * stack, preferring $GIT_DIR/info/attributes, then
 232          * .gitattributes in deeper directories to shallower ones,
 233          * and finally use the built-in set as the default.
 234          */
 235         if (!attr_stack) {
 236                 elem = read_attr_from_array(builtin_attr);
 237                 elem->origin = NULL;
 238                 elem->prev = attr_stack;
 239                 attr_stack = elem;
 240
 241                 elem = read_attr_from_file(GITATTRIBUTES_FILE);
 242                 elem->origin = strdup("");
 243                 elem->prev = attr_stack;
 244                 attr_stack = elem;
 245                 debug_push(elem);
 246
 247                 elem = read_attr_from_file(git_path(INFOATTRIBUTES_FILE));
 248                 elem->origin = NULL;
 249                 elem->prev = attr_stack;
 250                 attr_stack = elem;
 251         }
 252
 253         /*
 254          * Pop the "info" one that is always at the top of the stack.
 255          */
 256         info = attr_stack;
 257         attr_stack = info->prev;
 258
 259         /*
 260          * Pop the ones from directories that are not the prefix of
 261          * the path we are checking.
 262          */
 263         while (attr_stack && attr_stack->origin) {
 264                 int namelen = strlen(attr_stack->origin);
 265
 266                 elem = attr_stack;
 267                 if (namelen <= dirlen &&
 268                     !strncmp(elem->origin, path, namelen))
 269                         break;
 270
 271                 debug_pop(elem);
 272                 attr_stack = elem->prev;
 273                 free_attr_elem(elem);
 274         }
 275
 276         /*
 277          * Read from parent directories and push them down
 278          */
 279         while (1) {
 280                 char *cp;
 281
 282                 len = strlen(attr_stack->origin);
 283                 if (dirlen <= len)
 284                         break;
 285                 memcpy(pathbuf, path, dirlen);
 286                 memcpy(pathbuf + dirlen, "/", 2);
 287                 cp = strchr(pathbuf + len + 1, '/');
 288                 strcpy(cp + 1, GITATTRIBUTES_FILE);
 289                 elem = read_attr_from_file(pathbuf);
 290                 *cp = '\0';
 291                 elem->origin = strdup(pathbuf);
 292                 elem->prev = attr_stack;
 293                 attr_stack = elem;
 294                 debug_push(elem);
 295         }
 296
 297         /*
 298          * Finally push the "info" one at the top of the stack.
 299          */
 300         info->prev = attr_stack;
 301         attr_stack = info;
 302 }
 303
 304 static int path_matches(const char *pathname, int pathlen,
 305                         const char *pattern,
 306                         const char *base, int baselen)
 307 {
 308         if (!strchr(pattern, '/')) {
 309                 /* match basename */
 310                 const char *basename = strrchr(pathname, '/');
 311                 basename = basename ? basename + 1 : pathname;
 312                 return (fnmatch(pattern, basename, 0) == 0);
 313         }
 314         /*
 315          * match with FNM_PATHNAME; the pattern has base implicitly
 316          * in front of it.
 317          */
 318         if (*pattern == '/')
 319                 pattern++;
 320         if (pathlen < baselen ||
 321             (baselen && pathname[baselen - 1] != '/') ||
 322             strncmp(pathname, base, baselen))
 323                 return 0;
 324         return fnmatch(pattern, pathname + baselen, FNM_PATHNAME) == 0;
 325 }
 326
 327 /*
 328  * I do not like this at all.  Only because we allow individual
 329  * attribute to be set or unset incrementally by individual
 330  * lines in .gitattribute files, we need to do this triple
 331  * loop which looks quite wasteful.
 332  */
 333 static int fill(const char *path, int pathlen,
 334                 struct attr_stack *stk, struct git_attr_check *check,
 335                 int num, int rem)
 336 {
 337         int i, j, k;
 338         const char *base = stk->origin ? stk->origin : "";
 339
 340         for (i = stk->num_matches - 1; 0 < rem && 0 <= i; i--) {
 341                 struct match_attr *a = stk->attrs[i];
 342                 if (path_matches(path, pathlen,
 343                                  a->pattern, base, strlen(base))) {
 344                         for (j = 0; j < a->num_attr; j++) {
 345                                 struct git_attr *attr = a->state[j].attr;
 346                                 int set = !a->state[j].unset;
 347                                 for (k = 0; k < num; k++) {
 348                                         if (0 <= check[k].isset ||
 349                                             check[k].attr != attr)
 350                                                 continue;
 351                                         check[k].isset = set;
 352                                         rem--;
 353                                 }
 354                         }
 355                 }
 356         }
 357         return rem;
 358 }
 359
 360 int git_checkattr(const char *path, int num, struct git_attr_check *check)
 361 {
 362         struct attr_stack *stk;
 363         const char *cp;
 364         int dirlen, pathlen, i, rem;
 365
 366         for (i = 0; i < num; i++)
 367                 check[i].isset = -1;
 368
 369         pathlen = strlen(path);
 370         cp = strrchr(path, '/');
 371         if (!cp)
 372                 dirlen = 0;
 373         else
 374                 dirlen = cp - path;
 375         prepare_attr_stack(path, dirlen);
 376         rem = num;
 377         for (stk = attr_stack; 0 < rem && stk; stk = stk->prev)
 378                 rem = fill(path, pathlen, stk, check, num, rem);
 379         return 0;
 380 }