[thirdparty/git.git] / sha1_name.c

#include "cache.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#include "tree-walk.h"
#include "refs.h"

static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
{
	struct alternate_object_database *alt;
	char hex[40];
	int found = 0;
	static struct alternate_object_database *fakeent;

	if (!fakeent) {
		const char *objdir = get_object_directory();
		int objdir_len = strlen(objdir);
		int entlen = objdir_len + 43;
		fakeent = xmalloc(sizeof(*fakeent) + entlen);
		memcpy(fakeent->base, objdir, objdir_len);
		fakeent->name = fakeent->base + objdir_len + 1;
		fakeent->name[-1] = '/';
	}
	fakeent->next = alt_odb_list;

	sprintf(hex, "%.2s", name);
	for (alt = fakeent; alt && found < 2; alt = alt->next) {
		struct dirent *de;
		DIR *dir;
		sprintf(alt->name, "%.2s/", name);
		dir = opendir(alt->base);
		if (!dir)
			continue;
		while ((de = readdir(dir)) != NULL) {
			if (strlen(de->d_name) != 38)
				continue;
			if (memcmp(de->d_name, name + 2, len - 2))
				continue;
			if (!found) {
				memcpy(hex + 2, de->d_name, 38);
				found++;
			}
			else if (memcmp(hex + 2, de->d_name, 38)) {
				found = 2;
				break;
			}
		}
		closedir(dir);
	}
	if (found == 1)
		return get_sha1_hex(hex, sha1) == 0;
	return found;
}

static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
{
	do {
		if (*a != *b)
			return 0;
		a++;
		b++;
		len -= 2;
	} while (len > 1);
	if (len)
		if ((*a ^ *b) & 0xf0)
			return 0;
	return 1;
}

static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
{
	struct packed_git *p;
	unsigned char found_sha1[20];
	int found = 0;

	prepare_packed_git();
	for (p = packed_git; p && found < 2; p = p->next) {
		unsigned num = num_packed_objects(p);
		unsigned first = 0, last = num;
		while (first < last) {
			unsigned mid = (first + last) / 2;
			unsigned char now[20];
			int cmp;

			nth_packed_object_sha1(p, mid, now);
			cmp = memcmp(match, now, 20);
			if (!cmp) {
				first = mid;
				break;
			}
			if (cmp > 0) {
				first = mid+1;
				continue;
			}
			last = mid;
		}
		if (first < num) {
			unsigned char now[20], next[20];
			nth_packed_object_sha1(p, first, now);
			if (match_sha(len, match, now)) {
				if (nth_packed_object_sha1(p, first+1, next) ||
				    !match_sha(len, match, next)) {
					/* unique within this pack */
					if (!found) {
						memcpy(found_sha1, now, 20);
						found++;
					}
					else if (memcmp(found_sha1, now, 20)) {
						found = 2;
						break;
					}
				}
				else {
					/* not even unique within this pack */
					found = 2;
					break;
				}
			}
		}
	}
	if (found == 1)
		memcpy(sha1, found_sha1, 20);
	return found;
}

#define SHORT_NAME_NOT_FOUND (-1)
#define SHORT_NAME_AMBIGUOUS (-2)

static int find_unique_short_object(int len, char *canonical,
				    unsigned char *res, unsigned char *sha1)
{
	int has_unpacked, has_packed;
	unsigned char unpacked_sha1[20], packed_sha1[20];

	has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
	has_packed = find_short_packed_object(len, res, packed_sha1);
	if (!has_unpacked && !has_packed)
		return SHORT_NAME_NOT_FOUND;
	if (1 < has_unpacked || 1 < has_packed)
		return SHORT_NAME_AMBIGUOUS;
	if (has_unpacked != has_packed) {
		memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
		return 0;
	}
	/* Both have unique ones -- do they match? */
	if (memcmp(packed_sha1, unpacked_sha1, 20))
		return SHORT_NAME_AMBIGUOUS;
	memcpy(sha1, packed_sha1, 20);
	return 0;
}

static int get_short_sha1(const char *name, int len, unsigned char *sha1,
			  int quietly)
{
	int i, status;
	char canonical[40];
	unsigned char res[20];

	if (len < MINIMUM_ABBREV)
		return -1;
	memset(res, 0, 20);
	memset(canonical, 'x', 40);
	for (i = 0; i < len ;i++) {
		unsigned char c = name[i];
		unsigned char val;
		if (c >= '0' && c <= '9')
			val = c - '0';
		else if (c >= 'a' && c <= 'f')
			val = c - 'a' + 10;
		else if (c >= 'A' && c <='F') {
			val = c - 'A' + 10;
			c -= 'A' - 'a';
		}
		else
			return -1;
		canonical[i] = c;
		if (!(i & 1))
			val <<= 4;
		res[i >> 1] |= val;
	}

	status = find_unique_short_object(i, canonical, res, sha1);
	if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
		return error("short SHA1 %.*s is ambiguous.", len, canonical);
	return status;
}

const char *find_unique_abbrev(const unsigned char *sha1, int len)
{
	int status, is_null;
	static char hex[41];

	is_null = !memcmp(sha1, null_sha1, 20);
	memcpy(hex, sha1_to_hex(sha1), 40);
	if (len == 40)
		return hex;
	while (len < 40) {
		unsigned char sha1_ret[20];
		status = get_short_sha1(hex, len, sha1_ret, 1);
		if (!status ||
		    (is_null && status != SHORT_NAME_AMBIGUOUS)) {
			hex[len] = 0;
			return hex;
		}
		if (status != SHORT_NAME_AMBIGUOUS)
			return NULL;
		len++;
	}
	return NULL;
}

static int ambiguous_path(const char *path, int len)
{
	int slash = 1;
	int cnt;

	for (cnt = 0; cnt < len; cnt++) {
		switch (*path++) {
		case '\0':
			break;
		case '/':
			if (slash)
				break;
			slash = 1;
			continue;
		case '.':
			continue;
		default:
			slash = 0;
			continue;
		}
		break;
	}
	return slash;
}

static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
{
	static const char *fmt[] = {
		"%.*s",
		"refs/%.*s",
		"refs/tags/%.*s",
		"refs/heads/%.*s",
		"refs/remotes/%.*s",
		"refs/remotes/%.*s/HEAD",
		NULL
	};
	static const char *warning = "warning: refname '%.*s' is ambiguous.\n";
	const char **p, *pathname;
	char *real_path = NULL;
	int refs_found = 0, at_mark;
	unsigned long at_time = (unsigned long)-1;
	unsigned char *this_result;
	unsigned char sha1_from_ref[20];

	if (len == 40 && !get_sha1_hex(str, sha1))
		return 0;

	/* At a given period of time? "@2 hours ago" */
	for (at_mark = 1; at_mark < len; at_mark++) {
		if (str[at_mark] == '@') {
			int date_len = len - at_mark - 1;
			char *date_spec = xmalloc(date_len + 1);
			strncpy(date_spec, str + at_mark + 1, date_len);
			date_spec[date_len] = 0;
			at_time = approxidate(date_spec);
			free(date_spec);
			len = at_mark;
			break;
		}
	}

	/* Accept only unambiguous ref paths. */
	if (ambiguous_path(str, len))
		return -1;

	for (p = fmt; *p; p++) {
		this_result = refs_found ? sha1_from_ref : sha1;
		pathname = resolve_ref(git_path(*p, len, str), this_result, 1);
		if (pathname) {
			if (!refs_found++)
				real_path = strdup(pathname);
			if (!warn_ambiguous_refs)
				break;
		}
	}

	if (!refs_found)
		return -1;

	if (warn_ambiguous_refs && refs_found > 1)
		fprintf(stderr, warning, len, str);

	if (at_time != (unsigned long)-1) {
		read_ref_at(
			real_path + strlen(git_path(".")) - 1,
			at_time,
			sha1);
	}

	free(real_path);
	return 0;
}

static int get_sha1_1(const char *name, int len, unsigned char *sha1);

static int get_parent(const char *name, int len,
		      unsigned char *result, int idx)
{
	unsigned char sha1[20];
	int ret = get_sha1_1(name, len, sha1);
	struct commit *commit;
	struct commit_list *p;

	if (ret)
		return ret;
	commit = lookup_commit_reference(sha1);
	if (!commit)
		return -1;
	if (parse_commit(commit))
		return -1;
	if (!idx) {
		memcpy(result, commit->object.sha1, 20);
		return 0;
	}
	p = commit->parents;
	while (p) {
		if (!--idx) {
			memcpy(result, p->item->object.sha1, 20);
			return 0;
		}
		p = p->next;
	}
	return -1;
}

static int get_nth_ancestor(const char *name, int len,
			    unsigned char *result, int generation)
{
	unsigned char sha1[20];
	int ret = get_sha1_1(name, len, sha1);
	if (ret)
		return ret;

	while (generation--) {
		struct commit *commit = lookup_commit_reference(sha1);

		if (!commit || parse_commit(commit) || !commit->parents)
			return -1;
		memcpy(sha1, commit->parents->item->object.sha1, 20);
	}
	memcpy(result, sha1, 20);
	return 0;
}

static int peel_onion(const char *name, int len, unsigned char *sha1)
{
	unsigned char outer[20];
	const char *sp;
	const char *type_string = NULL;
	struct object *o;

	/*
	 * "ref^{type}" dereferences ref repeatedly until you cannot
	 * dereference anymore, or you get an object of given type,
	 * whichever comes first.  "ref^{}" means just dereference
	 * tags until you get a non-tag.  "ref^0" is a shorthand for
	 * "ref^{commit}".  "commit^{tree}" could be used to find the
	 * top-level tree of the given commit.
	 */
	if (len < 4 || name[len-1] != '}')
		return -1;

	for (sp = name + len - 1; name <= sp; sp--) {
		int ch = *sp;
		if (ch == '{' && name < sp && sp[-1] == '^')
			break;
	}
	if (sp <= name)
		return -1;

	sp++; /* beginning of type name, or closing brace for empty */
	if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
		type_string = commit_type;
	else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
		type_string = tree_type;
	else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
		type_string = blob_type;
	else if (sp[0] == '}')
		type_string = NULL;
	else
		return -1;

	if (get_sha1_1(name, sp - name - 2, outer))
		return -1;

	o = parse_object(outer);
	if (!o)
		return -1;
	if (!type_string) {
		o = deref_tag(o, name, sp - name - 2);
		if (!o || (!o->parsed && !parse_object(o->sha1)))
			return -1;
		memcpy(sha1, o->sha1, 20);
	}
	else {
		/* At this point, the syntax look correct, so
		 * if we do not get the needed object, we should
		 * barf.
		 */

		while (1) {
			if (!o || (!o->parsed && !parse_object(o->sha1)))
				return -1;
			if (o->type == type_string) {
				memcpy(sha1, o->sha1, 20);
				return 0;
			}
			if (o->type == tag_type)
				o = ((struct tag*) o)->tagged;
			else if (o->type == commit_type)
				o = &(((struct commit *) o)->tree->object);
			else
				return error("%.*s: expected %s type, but the object dereferences to %s type",
					     len, name, type_string,
					     o->type);
			if (!o->parsed)
				parse_object(o->sha1);
		}
	}
	return 0;
}

static int get_sha1_1(const char *name, int len, unsigned char *sha1)
{
	int ret, has_suffix;
	const char *cp;

	/* "name~3" is "name^^^",
	 * "name~" and "name~0" are name -- not "name^0"!
	 * "name^" is not "name^0"; it is "name^1".
	 */
	has_suffix = 0;
	for (cp = name + len - 1; name <= cp; cp--) {
		int ch = *cp;
		if ('0' <= ch && ch <= '9')
			continue;
		if (ch == '~' || ch == '^')
			has_suffix = ch;
		break;
	}

	if (has_suffix) {
		int num = 0;
		int len1 = cp - name;
		cp++;
		while (cp < name + len)
			num = num * 10 + *cp++ - '0';
		if (has_suffix == '^') {
			if (!num && len1 == len - 1)
				num = 1;
			return get_parent(name, len1, sha1, num);
		}
		/* else if (has_suffix == '~') -- goes without saying */
		return get_nth_ancestor(name, len1, sha1, num);
	}

	ret = peel_onion(name, len, sha1);
	if (!ret)
		return 0;

	ret = get_sha1_basic(name, len, sha1);
	if (!ret)
		return 0;
	return get_short_sha1(name, len, sha1, 0);
}

/*
 * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 * notably "xyz^" for "parent of xyz"
 */
int get_sha1(const char *name, unsigned char *sha1)
{
	int ret;
	unsigned unused;
	int namelen = strlen(name);
	const char *cp;

	prepare_alt_odb();
	ret = get_sha1_1(name, namelen, sha1);
	if (!ret)
		return ret;
	/* sha1:path --> object name of path in ent sha1
	 * :path -> object name of path in index
	 * :[0-3]:path -> object name of path in index at stage
	 */
	if (name[0] == ':') {
		int stage = 0;
		struct cache_entry *ce;
		int pos;
		if (namelen < 3 ||
		    name[2] != ':' ||
		    name[1] < '0' || '3' < name[1])
			cp = name + 1;
		else {
			stage = name[1] - '0';
			cp = name + 3;
		}
		namelen = namelen - (cp - name);
		if (!active_cache)
			read_cache();
		if (active_nr < 0)
			return -1;
		pos = cache_name_pos(cp, namelen);
		if (pos < 0)
			pos = -pos - 1;
		while (pos < active_nr) {
			ce = active_cache[pos];
			if (ce_namelen(ce) != namelen ||
			    memcmp(ce->name, cp, namelen))
				break;
			if (ce_stage(ce) == stage) {
				memcpy(sha1, ce->sha1, 20);
				return 0;
			}
			pos++;
		}
		return -1;
	}
	cp = strchr(name, ':');
	if (cp) {
		unsigned char tree_sha1[20];
		if (!get_sha1_1(name, cp-name, tree_sha1))
			return get_tree_entry(tree_sha1, cp+1, sha1,
					      &unused);
	}
	return ret;
}
Commit	Line	Data
9938af6a	1	#include "cache.h"
5385f52d	2	#include "tag.h"
9938af6a	3	#include "commit.h"
5385f52d JH	4	#include "tree.h"
5385f52d JH	5	#include "blob.h"
f3ab49db	6	#include "tree-walk.h"
d556fae2	7	#include "refs.h"
9938af6a JH	8
	9	static int find_short_object_filename(int len, const char name, unsigned char sha1)
	10	{
99a19b43	11	struct alternate_object_database *alt;
9938af6a	12	char hex[40];
99a19b43 JH	13	int found = 0;
	14	static struct alternate_object_database *fakeent;
	15
	16	if (!fakeent) {
	17	const char *objdir = get_object_directory();
	18	int objdir_len = strlen(objdir);
	19	int entlen = objdir_len + 43;
	20	fakeent = xmalloc(sizeof(*fakeent) + entlen);
	21	memcpy(fakeent->base, objdir, objdir_len);
	22	fakeent->name = fakeent->base + objdir_len + 1;
	23	fakeent->name[-1] = '/';
	24	}
	25	fakeent->next = alt_odb_list;
9938af6a	26
9938af6a	27	sprintf(hex, "%.2s", name);
99a19b43	28	for (alt = fakeent; alt && found < 2; alt = alt->next) {
9938af6a	29	struct dirent *de;
99a19b43 JH	30	DIR *dir;
	31	sprintf(alt->name, "%.2s/", name);
	32	dir = opendir(alt->base);
	33	if (!dir)
	34	continue;
9938af6a JH	35	while ((de = readdir(dir)) != NULL) {
	36	if (strlen(de->d_name) != 38)
	37	continue;
99a19b43	38	if (memcmp(de->d_name, name + 2, len - 2))
9938af6a	39	continue;
99a19b43 JH	40	if (!found) {
	41	memcpy(hex + 2, de->d_name, 38);
	42	found++;
	43	}
	44	else if (memcmp(hex + 2, de->d_name, 38)) {
	45	found = 2;
9938af6a	46	break;
99a19b43	47	}
9938af6a JH	48	}
	49	closedir(dir);
	50	}
	51	if (found == 1)
	52	return get_sha1_hex(hex, sha1) == 0;
99a19b43	53	return found;
9938af6a JH	54	}
	55
	56	static int match_sha(unsigned len, const unsigned char a, const unsigned char b)
	57	{
	58	do {
	59	if (a != b)
	60	return 0;
	61	a++;
	62	b++;
	63	len -= 2;
	64	} while (len > 1);
	65	if (len)
	66	if ((a ^ b) & 0xf0)
	67	return 0;
	68	return 1;
	69	}
	70
	71	static int find_short_packed_object(int len, const unsigned char match, unsigned char sha1)
	72	{
	73	struct packed_git *p;
99a19b43 JH	74	unsigned char found_sha1[20];
99a19b43 JH	75	int found = 0;
9938af6a JH	76
9938af6a JH	77	prepare_packed_git();
99a19b43	78	for (p = packed_git; p && found < 2; p = p->next) {
9938af6a JH	79	unsigned num = num_packed_objects(p);
	80	unsigned first = 0, last = num;
	81	while (first < last) {
	82	unsigned mid = (first + last) / 2;
	83	unsigned char now[20];
	84	int cmp;
	85
	86	nth_packed_object_sha1(p, mid, now);
	87	cmp = memcmp(match, now, 20);
	88	if (!cmp) {
	89	first = mid;
	90	break;
	91	}
	92	if (cmp > 0) {
	93	first = mid+1;
	94	continue;
	95	}
	96	last = mid;
	97	}
	98	if (first < num) {
0bc45890	99	unsigned char now[20], next[20];
9938af6a JH	100	nth_packed_object_sha1(p, first, now);
9938af6a JH	101	if (match_sha(len, match, now)) {
0bc45890 JH	102	if (nth_packed_object_sha1(p, first+1, next) \|\|
	103	!match_sha(len, match, next)) {
	104	/* unique within this pack */
	105	if (!found) {
	106	memcpy(found_sha1, now, 20);
	107	found++;
	108	}
	109	else if (memcmp(found_sha1, now, 20)) {
	110	found = 2;
	111	break;
	112	}
99a19b43	113	}
0bc45890 JH	114	else {
0bc45890 JH	115	/* not even unique within this pack */
99a19b43 JH	116	found = 2;
99a19b43 JH	117	break;
9938af6a JH	118	}
	119	}
	120	}
	121	}
99a19b43 JH	122	if (found == 1)
	123	memcpy(sha1, found_sha1, 20);
	124	return found;
	125	}
	126
013f276e JH	127	#define SHORT_NAME_NOT_FOUND (-1)
	128	#define SHORT_NAME_AMBIGUOUS (-2)
	129
99a19b43 JH	130	static int find_unique_short_object(int len, char *canonical,
	131	unsigned char res, unsigned char sha1)
	132	{
	133	int has_unpacked, has_packed;
	134	unsigned char unpacked_sha1[20], packed_sha1[20];
	135
	136	has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
	137	has_packed = find_short_packed_object(len, res, packed_sha1);
	138	if (!has_unpacked && !has_packed)
013f276e	139	return SHORT_NAME_NOT_FOUND;
99a19b43	140	if (1 < has_unpacked \|\| 1 < has_packed)
013f276e	141	return SHORT_NAME_AMBIGUOUS;
99a19b43 JH	142	if (has_unpacked != has_packed) {
	143	memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
	144	return 0;
	145	}
	146	/* Both have unique ones -- do they match? */
	147	if (memcmp(packed_sha1, unpacked_sha1, 20))
e974c9ab	148	return SHORT_NAME_AMBIGUOUS;
99a19b43	149	memcpy(sha1, packed_sha1, 20);
9938af6a JH	150	return 0;
	151	}
	152
013f276e JH	153	static int get_short_sha1(const char name, int len, unsigned char sha1,
013f276e JH	154	int quietly)
9938af6a	155	{
013f276e	156	int i, status;
9938af6a JH	157	char canonical[40];
	158	unsigned char res[20];
	159
46a6c262	160	if (len < MINIMUM_ABBREV)
af61c6e0	161	return -1;
9938af6a JH	162	memset(res, 0, 20);
9938af6a JH	163	memset(canonical, 'x', 40);
af61c6e0	164	for (i = 0; i < len ;i++) {
9938af6a JH	165	unsigned char c = name[i];
9938af6a JH	166	unsigned char val;
9938af6a JH	167	if (c >= '0' && c <= '9')
	168	val = c - '0';
	169	else if (c >= 'a' && c <= 'f')
	170	val = c - 'a' + 10;
	171	else if (c >= 'A' && c <='F') {
	172	val = c - 'A' + 10;
	173	c -= 'A' - 'a';
	174	}
	175	else
	176	return -1;
	177	canonical[i] = c;
	178	if (!(i & 1))
	179	val <<= 4;
	180	res[i >> 1] \|= val;
	181	}
99a19b43	182
013f276e JH	183	status = find_unique_short_object(i, canonical, res, sha1);
	184	if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
	185	return error("short SHA1 %.*s is ambiguous.", len, canonical);
	186	return status;
	187	}
	188
	189	const char find_unique_abbrev(const unsigned char sha1, int len)
	190	{
297a1aad	191	int status, is_null;
013f276e	192	static char hex[41];
47dd0d59	193
297a1aad	194	is_null = !memcmp(sha1, null_sha1, 20);
013f276e	195	memcpy(hex, sha1_to_hex(sha1), 40);
47dd0d59 JH	196	if (len == 40)
47dd0d59 JH	197	return hex;
013f276e JH	198	while (len < 40) {
	199	unsigned char sha1_ret[20];
	200	status = get_short_sha1(hex, len, sha1_ret, 1);
297a1aad JH	201	if (!status \|\|
297a1aad JH	202	(is_null && status != SHORT_NAME_AMBIGUOUS)) {
013f276e JH	203	hex[len] = 0;
	204	return hex;
	205	}
	206	if (status != SHORT_NAME_AMBIGUOUS)
	207	return NULL;
	208	len++;
	209	}
	210	return NULL;
9938af6a JH	211	}
9938af6a JH	212
6677c466	213	static int ambiguous_path(const char *path, int len)
af13cdf2 LT	214	{
af13cdf2 LT	215	int slash = 1;
6677c466	216	int cnt;
af13cdf2	217
6677c466	218	for (cnt = 0; cnt < len; cnt++) {
af13cdf2 LT	219	switch (*path++) {
	220	case '\0':
	221	break;
	222	case '/':
	223	if (slash)
	224	break;
	225	slash = 1;
	226	continue;
	227	case '.':
	228	continue;
	229	default:
	230	slash = 0;
	231	continue;
	232	}
c054d64e	233	break;
af13cdf2	234	}
6677c466	235	return slash;
af13cdf2 LT	236	}
af13cdf2 LT	237
9938af6a JH	238	static int get_sha1_basic(const char str, int len, unsigned char sha1)
9938af6a JH	239	{
c51d1369	240	static const char *fmt[] = {
84a9b58c	241	"%.*s",
c51d1369 JH	242	"refs/%.*s",
	243	"refs/tags/%.*s",
	244	"refs/heads/%.*s",
	245	"refs/remotes/%.*s",
	246	"refs/remotes/%.*s/HEAD",
9938af6a JH	247	NULL
9938af6a JH	248	};
d556fae2 SP	249	static const char warning = "warning: refname '%.s' is ambiguous.\n";
	250	const char *p, pathname;
	251	char *real_path = NULL;
	252	int refs_found = 0, at_mark;
	253	unsigned long at_time = (unsigned long)-1;
c51d1369 JH	254	unsigned char *this_result;
c51d1369 JH	255	unsigned char sha1_from_ref[20];
9938af6a	256
3c3852e3	257	if (len == 40 && !get_sha1_hex(str, sha1))
9938af6a JH	258	return 0;
9938af6a JH	259
d556fae2 SP	260	/* At a given period of time? "@2 hours ago" */
	261	for (at_mark = 1; at_mark < len; at_mark++) {
	262	if (str[at_mark] == '@') {
	263	int date_len = len - at_mark - 1;
	264	char *date_spec = xmalloc(date_len + 1);
	265	strncpy(date_spec, str + at_mark + 1, date_len);
	266	date_spec[date_len] = 0;
	267	at_time = approxidate(date_spec);
	268	free(date_spec);
	269	len = at_mark;
70e34b2d	270	break;
d556fae2 SP	271	}
	272	}
	273
af13cdf2	274	/* Accept only unambiguous ref paths. */
6677c466	275	if (ambiguous_path(str, len))
af13cdf2 LT	276	return -1;
af13cdf2 LT	277
c51d1369	278	for (p = fmt; *p; p++) {
d556fae2 SP	279	this_result = refs_found ? sha1_from_ref : sha1;
	280	pathname = resolve_ref(git_path(*p, len, str), this_result, 1);
	281	if (pathname) {
	282	if (!refs_found++)
	283	real_path = strdup(pathname);
	284	if (!warn_ambiguous_refs)
	285	break;
2f8acdb3	286	}
6677c466	287	}
d556fae2 SP	288
	289	if (!refs_found)
	290	return -1;
	291
	292	if (warn_ambiguous_refs && refs_found > 1)
	293	fprintf(stderr, warning, len, str);
	294
	295	if (at_time != (unsigned long)-1) {
	296	read_ref_at(
	297	real_path + strlen(git_path(".")) - 1,
	298	at_time,
	299	sha1);
	300	}
	301
	302	free(real_path);
	303	return 0;
9938af6a JH	304	}
	305
	306	static int get_sha1_1(const char name, int len, unsigned char sha1);
	307
	308	static int get_parent(const char *name, int len,
	309	unsigned char *result, int idx)
	310	{
	311	unsigned char sha1[20];
	312	int ret = get_sha1_1(name, len, sha1);
	313	struct commit *commit;
	314	struct commit_list *p;
	315
	316	if (ret)
	317	return ret;
	318	commit = lookup_commit_reference(sha1);
	319	if (!commit)
	320	return -1;
	321	if (parse_commit(commit))
	322	return -1;
	323	if (!idx) {
	324	memcpy(result, commit->object.sha1, 20);
	325	return 0;
	326	}
	327	p = commit->parents;
	328	while (p) {
	329	if (!--idx) {
	330	memcpy(result, p->item->object.sha1, 20);
	331	return 0;
	332	}
	333	p = p->next;
	334	}
	335	return -1;
	336	}
	337
4f7599ac JH	338	static int get_nth_ancestor(const char *name, int len,
	339	unsigned char *result, int generation)
	340	{
	341	unsigned char sha1[20];
	342	int ret = get_sha1_1(name, len, sha1);
	343	if (ret)
	344	return ret;
	345
	346	while (generation--) {
	347	struct commit *commit = lookup_commit_reference(sha1);
	348
	349	if (!commit \|\| parse_commit(commit) \|\| !commit->parents)
	350	return -1;
	351	memcpy(sha1, commit->parents->item->object.sha1, 20);
	352	}
	353	memcpy(result, sha1, 20);
	354	return 0;
	355	}
	356
5385f52d JH	357	static int peel_onion(const char name, int len, unsigned char sha1)
	358	{
	359	unsigned char outer[20];
	360	const char *sp;
	361	const char *type_string = NULL;
	362	struct object *o;
	363
	364	/*
	365	* "ref^{type}" dereferences ref repeatedly until you cannot
	366	* dereference anymore, or you get an object of given type,
	367	* whichever comes first. "ref^{}" means just dereference
	368	* tags until you get a non-tag. "ref^0" is a shorthand for
	369	* "ref^{commit}". "commit^{tree}" could be used to find the
	370	* top-level tree of the given commit.
	371	*/
	372	if (len < 4 \|\| name[len-1] != '}')
	373	return -1;
	374
	375	for (sp = name + len - 1; name <= sp; sp--) {
	376	int ch = *sp;
	377	if (ch == '{' && name < sp && sp[-1] == '^')
	378	break;
	379	}
	380	if (sp <= name)
	381	return -1;
	382
	383	sp++; /* beginning of type name, or closing brace for empty */
	384	if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
	385	type_string = commit_type;
	386	else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
	387	type_string = tree_type;
	388	else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
	389	type_string = blob_type;
	390	else if (sp[0] == '}')
	391	type_string = NULL;
	392	else
	393	return -1;
	394
	395	if (get_sha1_1(name, sp - name - 2, outer))
	396	return -1;
	397
	398	o = parse_object(outer);
	399	if (!o)
	400	return -1;
	401	if (!type_string) {
9534f40b	402	o = deref_tag(o, name, sp - name - 2);
6e1c6c10 JH	403	if (!o \|\| (!o->parsed && !parse_object(o->sha1)))
6e1c6c10 JH	404	return -1;
5385f52d JH	405	memcpy(sha1, o->sha1, 20);
	406	}
	407	else {
	408	/* At this point, the syntax look correct, so
	409	* if we do not get the needed object, we should
	410	* barf.
	411	*/
	412
	413	while (1) {
6e1c6c10	414	if (!o \|\| (!o->parsed && !parse_object(o->sha1)))
5385f52d JH	415	return -1;
	416	if (o->type == type_string) {
	417	memcpy(sha1, o->sha1, 20);
	418	return 0;
	419	}
	420	if (o->type == tag_type)
	421	o = ((struct tag*) o)->tagged;
	422	else if (o->type == commit_type)
	423	o = &(((struct commit *) o)->tree->object);
	424	else
	425	return error("%.*s: expected %s type, but the object dereferences to %s type",
	426	len, name, type_string,
	427	o->type);
	428	if (!o->parsed)
	429	parse_object(o->sha1);
	430	}
	431	}
	432	return 0;
	433	}
	434
9938af6a JH	435	static int get_sha1_1(const char name, int len, unsigned char sha1)
9938af6a JH	436	{
0601dbe1	437	int ret, has_suffix;
4f7599ac	438	const char *cp;
9938af6a	439
4f7599ac	440	/* "name~3" is "name^^^",
4f7599ac	441	* "name~" and "name~0" are name -- not "name^0"!
0601dbe1	442	* "name^" is not "name^0"; it is "name^1".
4f7599ac	443	*/
0601dbe1	444	has_suffix = 0;
4f7599ac JH	445	for (cp = name + len - 1; name <= cp; cp--) {
	446	int ch = *cp;
	447	if ('0' <= ch && ch <= '9')
	448	continue;
0601dbe1 JH	449	if (ch == '~' \|\| ch == '^')
0601dbe1 JH	450	has_suffix = ch;
4f7599ac JH	451	break;
4f7599ac JH	452	}
0601dbe1 JH	453
	454	if (has_suffix) {
	455	int num = 0;
4f7599ac JH	456	int len1 = cp - name;
	457	cp++;
	458	while (cp < name + len)
0601dbe1 JH	459	num = num * 10 + *cp++ - '0';
	460	if (has_suffix == '^') {
	461	if (!num && len1 == len - 1)
	462	num = 1;
	463	return get_parent(name, len1, sha1, num);
	464	}
	465	/* else if (has_suffix == '~') -- goes without saying */
	466	return get_nth_ancestor(name, len1, sha1, num);
4f7599ac JH	467	}
4f7599ac JH	468
5385f52d JH	469	ret = peel_onion(name, len, sha1);
	470	if (!ret)
	471	return 0;
	472
9938af6a JH	473	ret = get_sha1_basic(name, len, sha1);
	474	if (!ret)
	475	return 0;
013f276e	476	return get_short_sha1(name, len, sha1, 0);
9938af6a JH	477	}
	478
	479	/*
	480	* This is like "get_sha1_basic()", except it allows "sha1 expressions",
	481	* notably "xyz^" for "parent of xyz"
	482	*/
	483	int get_sha1(const char name, unsigned char sha1)
	484	{
5119602a	485	int ret;
041a7308	486	unsigned unused;
73b0e5af JH	487	int namelen = strlen(name);
73b0e5af JH	488	const char *cp;
5119602a	489
99a19b43	490	prepare_alt_odb();
73b0e5af JH	491	ret = get_sha1_1(name, namelen, sha1);
	492	if (!ret)
	493	return ret;
	494	/* sha1:path --> object name of path in ent sha1
	495	* :path -> object name of path in index
	496	* :[0-3]:path -> object name of path in index at stage
	497	*/
	498	if (name[0] == ':') {
	499	int stage = 0;
	500	struct cache_entry *ce;
	501	int pos;
	502	if (namelen < 3 \|\|
	503	name[2] != ':' \|\|
	504	name[1] < '0' \|\| '3' < name[1])
	505	cp = name + 1;
	506	else {
	507	stage = name[1] - '0';
	508	cp = name + 3;
5119602a	509	}
73b0e5af JH	510	namelen = namelen - (cp - name);
	511	if (!active_cache)
	512	read_cache();
	513	if (active_nr < 0)
	514	return -1;
	515	pos = cache_name_pos(cp, namelen);
	516	if (pos < 0)
	517	pos = -pos - 1;
	518	while (pos < active_nr) {
	519	ce = active_cache[pos];
	520	if (ce_namelen(ce) != namelen \|\|
	521	memcmp(ce->name, cp, namelen))
	522	break;
	523	if (ce_stage(ce) == stage) {
	524	memcpy(sha1, ce->sha1, 20);
	525	return 0;
	526	}
e7cef45f	527	pos++;
73b0e5af JH	528	}
	529	return -1;
	530	}
	531	cp = strchr(name, ':');
	532	if (cp) {
	533	unsigned char tree_sha1[20];
	534	if (!get_sha1_1(name, cp-name, tree_sha1))
	535	return get_tree_entry(tree_sha1, cp+1, sha1,
	536	&unused);
5119602a LT	537	}
5119602a LT	538	return ret;
9938af6a	539	}