summaryrefslogtreecommitdiff
path: root/attr.c
blob: 741db3b468c6a6ebbcd1414e42b4ef7d6ab3cc9d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
#include "cache.h"
#include "attr.h"

const char git_attr__true[] = "(builtin)true";
const char git_attr__false[] = "\0(builtin)false";
static const char git_attr__unknown[] = "(builtin)unknown";
#define ATTR__TRUE git_attr__true
#define ATTR__FALSE git_attr__false
#define ATTR__UNSET NULL
#define ATTR__UNKNOWN git_attr__unknown

/*
 * The basic design decision here is that we are not going to have
 * insanely large number of attributes.
 *
 * This is a randomly chosen prime.
 */
#define HASHSIZE 257

#ifndef DEBUG_ATTR
#define DEBUG_ATTR 0
#endif

struct git_attr {
	struct git_attr *next;
	unsigned h;
	int attr_nr;
	char name[FLEX_ARRAY];
};
static int attr_nr;

static struct git_attr_check *check_all_attr;
static struct git_attr *(git_attr_hash[HASHSIZE]);

static unsigned hash_name(const char *name, int namelen)
{
	unsigned val = 0;
	unsigned char c;

	while (namelen--) {
		c = *name++;
		val = ((val << 7) | (val >> 22)) ^ c;
	}
	return val;
}

static int invalid_attr_name(const char *name, int namelen)
{
	/*
	 * Attribute name cannot begin with '-' and from
	 * [-A-Za-z0-9_.].  We'd specifically exclude '=' for now,
	 * as we might later want to allow non-binary value for
	 * attributes, e.g. "*.svg	merge=special-merge-program-for-svg"
	 */
	if (*name == '-')
		return -1;
	while (namelen--) {
		char ch = *name++;
		if (! (ch == '-' || ch == '.' || ch == '_' ||
		       ('0' <= ch && ch <= '9') ||
		       ('a' <= ch && ch <= 'z') ||
		       ('A' <= ch && ch <= 'Z')) )
			return -1;
	}
	return 0;
}

struct git_attr *git_attr(const char *name, int len)
{
	unsigned hval = hash_name(name, len);
	unsigned pos = hval % HASHSIZE;
	struct git_attr *a;

	for (a = git_attr_hash[pos]; a; a = a->next) {
		if (a->h == hval &&
		    !memcmp(a->name, name, len) && !a->name[len])
			return a;
	}

	if (invalid_attr_name(name, len))
		return NULL;

	a = xmalloc(sizeof(*a) + len + 1);
	memcpy(a->name, name, len);
	a->name[len] = 0;
	a->h = hval;
	a->next = git_attr_hash[pos];
	a->attr_nr = attr_nr++;
	git_attr_hash[pos] = a;

	check_all_attr = xrealloc(check_all_attr,
				  sizeof(*check_all_attr) * attr_nr);
	check_all_attr[a->attr_nr].attr = a;
	check_all_attr[a->attr_nr].value = ATTR__UNKNOWN;
	return a;
}

/*
 * .gitattributes file is one line per record, each of which is
 *
 * (1) glob pattern.
 * (2) whitespace
 * (3) whitespace separated list of attribute names, each of which
 *     could be prefixed with '-' to mean "set to false", '!' to mean
 *     "unset".
 */

/* What does a matched pattern decide? */
struct attr_state {
	struct git_attr *attr;
	const char *setto;
};

struct match_attr {
	union {
		char *pattern;
		struct git_attr *attr;
	} u;
	char is_macro;
	unsigned num_attr;
	struct attr_state state[FLEX_ARRAY];
};

static const char blank[] = " \t\r\n";

static const char *parse_attr(const char *src, int lineno, const char *cp,
			      int *num_attr, struct match_attr *res)
{
	const char *ep, *equals;
	int len;

	ep = cp + strcspn(cp, blank);
	equals = strchr(cp, '=');
	if (equals && ep < equals)
		equals = NULL;
	if (equals)
		len = equals - cp;
	else
		len = ep - cp;
	if (!res) {
		if (*cp == '-' || *cp == '!') {
			cp++;
			len--;
		}
		if (invalid_attr_name(cp, len)) {
			fprintf(stderr,
				"%.*s is not a valid attribute name: %s:%d\n",
				len, cp, src, lineno);
			return NULL;
		}
	} else {
		struct attr_state *e;

		e = &(res->state[*num_attr]);
		if (*cp == '-' || *cp == '!') {
			e->setto = (*cp == '-') ? ATTR__FALSE : ATTR__UNSET;
			cp++;
			len--;
		}
		else if (!equals)
			e->setto = ATTR__TRUE;
		else {
			e->setto = xmemdupz(equals + 1, ep - equals - 1);
		}
		e->attr = git_attr(cp, len);
	}
	(*num_attr)++;
	return ep + strspn(ep, blank);
}

static struct match_attr *parse_attr_line(const char *line, const char *src,
					  int lineno, int macro_ok)
{
	int namelen;
	int num_attr;
	const char *cp, *name;
	struct match_attr *res = NULL;
	int pass;
	int is_macro;

	cp = line + strspn(line, blank);
	if (!*cp || *cp == '#')
		return NULL;
	name = cp;
	namelen = strcspn(name, blank);
	if (strlen(ATTRIBUTE_MACRO_PREFIX) < namelen &&
	    !prefixcmp(name, ATTRIBUTE_MACRO_PREFIX)) {
		if (!macro_ok) {
			fprintf(stderr, "%s not allowed: %s:%d\n",
				name, src, lineno);
			return NULL;
		}
		is_macro = 1;
		name += strlen(ATTRIBUTE_MACRO_PREFIX);
		name += strspn(name, blank);
		namelen = strcspn(name, blank);
		if (invalid_attr_name(name, namelen)) {
			fprintf(stderr,
				"%.*s is not a valid attribute name: %s:%d\n",
				namelen, name, src, lineno);
			return NULL;
		}
	}
	else
		is_macro = 0;

	for (pass = 0; pass < 2; pass++) {
		/* pass 0 counts and allocates, pass 1 fills */
		num_attr = 0;
		cp = name + namelen;
		cp = cp + strspn(cp, blank);
		while (*cp) {
			cp = parse_attr(src, lineno, cp, &num_attr, res);
			if (!cp)
				return NULL;
		}
		if (pass)
			break;
		res = xcalloc(1,
			      sizeof(*res) +
			      sizeof(struct attr_state) * num_attr +
			      (is_macro ? 0 : namelen + 1));
		if (is_macro)
			res->u.attr = git_attr(name, namelen);
		else {
			res->u.pattern = (char*)&(res->state[num_attr]);
			memcpy(res->u.pattern, name, namelen);
			res->u.pattern[namelen] = 0;
		}
		res->is_macro = is_macro;
		res->num_attr = num_attr;
	}
	return res;
}

/*
 * Like info/exclude and .gitignore, the attribute information can
 * come from many places.
 *
 * (1) .gitattribute file of the same directory;
 * (2) .gitattribute file of the parent directory if (1) does not have
 *      any match; this goes recursively upwards, just like .gitignore.
 * (3) $GIT_DIR/info/attributes, which overrides both of the above.
 *
 * In the same file, later entries override the earlier match, so in the
 * global list, we would have entries from info/attributes the earliest
 * (reading the file from top to bottom), .gitattribute of the root
 * directory (again, reading the file from top to bottom) down to the
 * current directory, and then scan the list backwards to find the first match.
 * This is exactly the same as what excluded() does in dir.c to deal with
 * .gitignore
 */

static struct attr_stack {
	struct attr_stack *prev;
	char *origin;
	unsigned num_matches;
	unsigned alloc;
	struct match_attr **attrs;
} *attr_stack;

static void free_attr_elem(struct attr_stack *e)
{
	int i;
	free(e->origin);
	for (i = 0; i < e->num_matches; i++) {
		struct match_attr *a = e->attrs[i];
		int j;
		for (j = 0; j < a->num_attr; j++) {
			const char *setto = a->state[j].setto;
			if (setto == ATTR__TRUE ||
			    setto == ATTR__FALSE ||
			    setto == ATTR__UNSET ||
			    setto == ATTR__UNKNOWN)
				;
			else
				free((char*) setto);
		}
		free(a);
	}
	free(e);
}

static const char *builtin_attr[] = {
	"[attr]binary -diff -crlf",
	NULL,
};

static void handle_attr_line(struct attr_stack *res,
			     const char *line,
			     const char *src,
			     int lineno,
			     int macro_ok)
{
	struct match_attr *a;

	a = parse_attr_line(line, src, lineno, macro_ok);
	if (!a)
		return;
	if (res->alloc <= res->num_matches) {
		res->alloc = alloc_nr(res->num_matches);
		res->attrs = xrealloc(res->attrs,
				      sizeof(struct match_attr *) *
				      res->alloc);
	}
	res->attrs[res->num_matches++] = a;
}

static struct attr_stack *read_attr_from_array(const char **list)
{
	struct attr_stack *res;
	const char *line;
	int lineno = 0;

	res = xcalloc(1, sizeof(*res));
	while ((line = *(list++)) != NULL)
		handle_attr_line(res, line, "[builtin]", ++lineno, 1);
	return res;
}

static struct attr_stack *read_attr_from_file(const char *path, int macro_ok)
{
	FILE *fp = fopen(path, "r");
	struct attr_stack *res;
	char buf[2048];
	int lineno = 0;

	if (!fp)
		return NULL;
	res = xcalloc(1, sizeof(*res));
	while (fgets(buf, sizeof(buf), fp))
		handle_attr_line(res, buf, path, ++lineno, macro_ok);
	fclose(fp);
	return res;
}

static void *read_index_data(const char *path)
{
	int pos, len;
	unsigned long sz;
	enum object_type type;
	void *data;

	len = strlen(path);
	pos = cache_name_pos(path, len);
	if (pos < 0) {
		/*
		 * We might be in the middle of a merge, in which
		 * case we would read stage #2 (ours).
		 */
		int i;
		for (i = -pos - 1;
		     (pos < 0 && i < active_nr &&
		      !strcmp(active_cache[i]->name, path));
		     i++)
			if (ce_stage(active_cache[i]) == 2)
				pos = i;
	}
	if (pos < 0)
		return NULL;
	data = read_sha1_file(active_cache[pos]->sha1, &type, &sz);
	if (!data || type != OBJ_BLOB) {
		free(data);
		return NULL;
	}
	return data;
}

static struct attr_stack *read_attr(const char *path, int macro_ok)
{
	struct attr_stack *res;
	char *buf, *sp;
	int lineno = 0;

	res = read_attr_from_file(path, macro_ok);
	if (res)
		return res;

	res = xcalloc(1, sizeof(*res));

	/*
	 * There is no checked out .gitattributes file there, but
	 * we might have it in the index.  We allow operation in a
	 * sparsely checked out work tree, so read from it.
	 */
	buf = read_index_data(path);
	if (!buf)
		return res;

	for (sp = buf; *sp; ) {
		char *ep;
		int more;
		for (ep = sp; *ep && *ep != '\n'; ep++)
			;
		more = (*ep == '\n');
		*ep = '\0';
		handle_attr_line(res, sp, path, ++lineno, macro_ok);
		sp = ep + more;
	}
	free(buf);
	return res;
}

#if DEBUG_ATTR
static void debug_info(const char *what, struct attr_stack *elem)
{
	fprintf(stderr, "%s: %s\n", what, elem->origin ? elem->origin : "()");
}
static void debug_set(const char *what, const char *match, struct git_attr *attr, void *v)
{
	const char *value = v;

	if (ATTR_TRUE(value))
		value = "set";
	else if (ATTR_FALSE(value))
		value = "unset";
	else if (ATTR_UNSET(value))
		value = "unspecified";

	fprintf(stderr, "%s: %s => %s (%s)\n",
		what, attr->name, (char *) value, match);
}
#define debug_push(a) debug_info("push", (a))
#define debug_pop(a) debug_info("pop", (a))
#else
#define debug_push(a) do { ; } while (0)
#define debug_pop(a) do { ; } while (0)
#define debug_set(a,b,c,d) do { ; } while (0)
#endif

static void bootstrap_attr_stack(void)
{
	if (!attr_stack) {
		struct attr_stack *elem;

		elem = read_attr_from_array(builtin_attr);
		elem->origin = NULL;
		elem->prev = attr_stack;
		attr_stack = elem;

		elem = read_attr(GITATTRIBUTES_FILE, 1);
		elem->origin = strdup("");
		elem->prev = attr_stack;
		attr_stack = elem;
		debug_push(elem);

		elem = read_attr_from_file(git_path(INFOATTRIBUTES_FILE), 1);
		if (!elem)
			elem = xcalloc(1, sizeof(*elem));
		elem->origin = NULL;
		elem->prev = attr_stack;
		attr_stack = elem;
	}
}

static void prepare_attr_stack(const char *path, int dirlen)
{
	struct attr_stack *elem, *info;
	int len;
	char pathbuf[PATH_MAX];

	/*
	 * At the bottom of the attribute stack is the built-in
	 * set of attribute definitions.  Then, contents from
	 * .gitattribute files from directories closer to the
	 * root to the ones in deeper directories are pushed
	 * to the stack.  Finally, at the very top of the stack
	 * we always keep the contents of $GIT_DIR/info/attributes.
	 *
	 * When checking, we use entries from near the top of the
	 * stack, preferring $GIT_DIR/info/attributes, then
	 * .gitattributes in deeper directories to shallower ones,
	 * and finally use the built-in set as the default.
	 */
	if (!attr_stack)
		bootstrap_attr_stack();

	/*
	 * Pop the "info" one that is always at the top of the stack.
	 */
	info = attr_stack;
	attr_stack = info->prev;

	/*
	 * Pop the ones from directories that are not the prefix of
	 * the path we are checking.
	 */
	while (attr_stack && attr_stack->origin) {
		int namelen = strlen(attr_stack->origin);

		elem = attr_stack;
		if (namelen <= dirlen &&
		    !strncmp(elem->origin, path, namelen))
			break;

		debug_pop(elem);
		attr_stack = elem->prev;
		free_attr_elem(elem);
	}

	/*
	 * Read from parent directories and push them down
	 */
	while (1) {
		char *cp;

		len = strlen(attr_stack->origin);
		if (dirlen <= len)
			break;
		memcpy(pathbuf, path, dirlen);
		memcpy(pathbuf + dirlen, "/", 2);
		cp = strchr(pathbuf + len + 1, '/');
		strcpy(cp + 1, GITATTRIBUTES_FILE);
		elem = read_attr(pathbuf, 0);
		*cp = '\0';
		elem->origin = strdup(pathbuf);
		elem->prev = attr_stack;
		attr_stack = elem;
		debug_push(elem);
	}

	/*
	 * Finally push the "info" one at the top of the stack.
	 */
	info->prev = attr_stack;
	attr_stack = info;
}

static int path_matches(const char *pathname, int pathlen,
			const char *pattern,
			const char *base, int baselen)
{
	if (!strchr(pattern, '/')) {
		/* match basename */
		const char *basename = strrchr(pathname, '/');
		basename = basename ? basename + 1 : pathname;
		return (fnmatch(pattern, basename, 0) == 0);
	}
	/*
	 * match with FNM_PATHNAME; the pattern has base implicitly
	 * in front of it.
	 */
	if (*pattern == '/')
		pattern++;
	if (pathlen < baselen ||
	    (baselen && pathname[baselen - 1] != '/') ||
	    strncmp(pathname, base, baselen))
		return 0;
	return fnmatch(pattern, pathname + baselen, FNM_PATHNAME) == 0;
}

static int fill_one(const char *what, struct match_attr *a, int rem)
{
	struct git_attr_check *check = check_all_attr;
	int i;

	for (i = 0; 0 < rem && i < a->num_attr; i++) {
		struct git_attr *attr = a->state[i].attr;
		const char **n = &(check[attr->attr_nr].value);
		const char *v = a->state[i].setto;

		if (*n == ATTR__UNKNOWN) {
			debug_set(what, a->u.pattern, attr, v);
			*n = v;
			rem--;
		}
	}
	return rem;
}

static int fill(const char *path, int pathlen, struct attr_stack *stk, int rem)
{
	int i;
	const char *base = stk->origin ? stk->origin : "";

	for (i = stk->num_matches - 1; 0 < rem && 0 <= i; i--) {
		struct match_attr *a = stk->attrs[i];
		if (a->is_macro)
			continue;
		if (path_matches(path, pathlen,
				 a->u.pattern, base, strlen(base)))
			rem = fill_one("fill", a, rem);
	}
	return rem;
}

static int macroexpand(struct attr_stack *stk, int rem)
{
	int i;
	struct git_attr_check *check = check_all_attr;

	for (i = stk->num_matches - 1; 0 < rem && 0 <= i; i--) {
		struct match_attr *a = stk->attrs[i];
		if (!a->is_macro)
			continue;
		if (check[a->u.attr->attr_nr].value != ATTR__TRUE)
			continue;
		rem = fill_one("expand", a, rem);
	}
	return rem;
}

int git_checkattr(const char *path, int num, struct git_attr_check *check)
{
	struct attr_stack *stk;
	const char *cp;
	int dirlen, pathlen, i, rem;

	bootstrap_attr_stack();
	for (i = 0; i < attr_nr; i++)
		check_all_attr[i].value = ATTR__UNKNOWN;

	pathlen = strlen(path);
	cp = strrchr(path, '/');
	if (!cp)
		dirlen = 0;
	else
		dirlen = cp - path;
	prepare_attr_stack(path, dirlen);
	rem = attr_nr;
	for (stk = attr_stack; 0 < rem && stk; stk = stk->prev)
		rem = fill(path, pathlen, stk, rem);

	for (stk = attr_stack; 0 < rem && stk; stk = stk->prev)
		rem = macroexpand(stk, rem);

	for (i = 0; i < num; i++) {
		const char *value = check_all_attr[check[i].attr->attr_nr].value;
		if (value == ATTR__UNKNOWN)
			value = ATTR__UNSET;
		check[i].value = value;
	}

	return 0;
}