[thirdparty/git.git] / sha1_name.c

#include "cache.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.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 -2;
	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 < 4)
		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;
	static char hex[41];
	memcpy(hex, sha1_to_hex(sha1), 40);
	while (len < 40) {
		unsigned char sha1_ret[20];
		status = get_short_sha1(hex, len, sha1_ret, 1);
		if (!status) {
			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 *prefix[] = {
		"",
		"refs",
		"refs/tags",
		"refs/heads",
		NULL
	};
	const char **p;

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

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

	for (p = prefix; *p; p++) {
		char *pathname = git_path("%s/%.*s", *p, len, str);
		if (!read_ref(pathname, sha1))
			return 0;
	}
	return -1;
}

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 parent, ret;
	const char *cp;

	/* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
	if (len > 2 && name[len-2] == '^' &&
	    name[len-1] >= '0' && name[len-1] <= '9') {
		parent = name[len-1] - '0';
		len -= 2;
	}
	else if (len > 1 && name[len-1] == '^') {
		parent = 1;
		len--;
	} else
		parent = -1;

	if (parent >= 0)
		return get_parent(name, len, sha1, parent);

	/* "name~3" is "name^^^",
	 * "name~12" is "name^^^^^^^^^^^^", and
	 * "name~" and "name~0" are name -- not "name^0"!
	 */
	parent = 0;
	for (cp = name + len - 1; name <= cp; cp--) {
		int ch = *cp;
		if ('0' <= ch && ch <= '9')
			continue;
		if (ch != '~')
			parent = -1;
		break;
	}
	if (!parent && *cp == '~') {
		int len1 = cp - name;
		cp++;
		while (cp < name + len)
			parent = parent * 10 + *cp++ - '0';
		return get_nth_ancestor(name, len1, sha1, parent);
	}

	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)
{
	prepare_alt_odb();
	return get_sha1_1(name, strlen(name), sha1);
}
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"
9938af6a JH	6
	7	static int find_short_object_filename(int len, const char name, unsigned char sha1)
	8	{
99a19b43	9	struct alternate_object_database *alt;
9938af6a	10	char hex[40];
99a19b43 JH	11	int found = 0;
	12	static struct alternate_object_database *fakeent;
	13
	14	if (!fakeent) {
	15	const char *objdir = get_object_directory();
	16	int objdir_len = strlen(objdir);
	17	int entlen = objdir_len + 43;
	18	fakeent = xmalloc(sizeof(*fakeent) + entlen);
	19	memcpy(fakeent->base, objdir, objdir_len);
	20	fakeent->name = fakeent->base + objdir_len + 1;
	21	fakeent->name[-1] = '/';
	22	}
	23	fakeent->next = alt_odb_list;
9938af6a	24
9938af6a	25	sprintf(hex, "%.2s", name);
99a19b43	26	for (alt = fakeent; alt && found < 2; alt = alt->next) {
9938af6a	27	struct dirent *de;
99a19b43 JH	28	DIR *dir;
	29	sprintf(alt->name, "%.2s/", name);
	30	dir = opendir(alt->base);
	31	if (!dir)
	32	continue;
9938af6a JH	33	while ((de = readdir(dir)) != NULL) {
	34	if (strlen(de->d_name) != 38)
	35	continue;
99a19b43	36	if (memcmp(de->d_name, name + 2, len - 2))
9938af6a	37	continue;
99a19b43 JH	38	if (!found) {
	39	memcpy(hex + 2, de->d_name, 38);
	40	found++;
	41	}
	42	else if (memcmp(hex + 2, de->d_name, 38)) {
	43	found = 2;
9938af6a	44	break;
99a19b43	45	}
9938af6a JH	46	}
	47	closedir(dir);
	48	}
	49	if (found == 1)
	50	return get_sha1_hex(hex, sha1) == 0;
99a19b43	51	return found;
9938af6a JH	52	}
	53
	54	static int match_sha(unsigned len, const unsigned char a, const unsigned char b)
	55	{
	56	do {
	57	if (a != b)
	58	return 0;
	59	a++;
	60	b++;
	61	len -= 2;
	62	} while (len > 1);
	63	if (len)
	64	if ((a ^ b) & 0xf0)
	65	return 0;
	66	return 1;
	67	}
	68
	69	static int find_short_packed_object(int len, const unsigned char match, unsigned char sha1)
	70	{
	71	struct packed_git *p;
99a19b43 JH	72	unsigned char found_sha1[20];
99a19b43 JH	73	int found = 0;
9938af6a JH	74
9938af6a JH	75	prepare_packed_git();
99a19b43	76	for (p = packed_git; p && found < 2; p = p->next) {
9938af6a JH	77	unsigned num = num_packed_objects(p);
	78	unsigned first = 0, last = num;
	79	while (first < last) {
	80	unsigned mid = (first + last) / 2;
	81	unsigned char now[20];
	82	int cmp;
	83
	84	nth_packed_object_sha1(p, mid, now);
	85	cmp = memcmp(match, now, 20);
	86	if (!cmp) {
	87	first = mid;
	88	break;
	89	}
	90	if (cmp > 0) {
	91	first = mid+1;
	92	continue;
	93	}
	94	last = mid;
	95	}
	96	if (first < num) {
0bc45890	97	unsigned char now[20], next[20];
9938af6a JH	98	nth_packed_object_sha1(p, first, now);
9938af6a JH	99	if (match_sha(len, match, now)) {
0bc45890 JH	100	if (nth_packed_object_sha1(p, first+1, next) \|\|
	101	!match_sha(len, match, next)) {
	102	/* unique within this pack */
	103	if (!found) {
	104	memcpy(found_sha1, now, 20);
	105	found++;
	106	}
	107	else if (memcmp(found_sha1, now, 20)) {
	108	found = 2;
	109	break;
	110	}
99a19b43	111	}
0bc45890 JH	112	else {
0bc45890 JH	113	/* not even unique within this pack */
99a19b43 JH	114	found = 2;
99a19b43 JH	115	break;
9938af6a JH	116	}
	117	}
	118	}
	119	}
99a19b43 JH	120	if (found == 1)
	121	memcpy(sha1, found_sha1, 20);
	122	return found;
	123	}
	124
013f276e JH	125	#define SHORT_NAME_NOT_FOUND (-1)
	126	#define SHORT_NAME_AMBIGUOUS (-2)
	127
99a19b43 JH	128	static int find_unique_short_object(int len, char *canonical,
	129	unsigned char res, unsigned char sha1)
	130	{
	131	int has_unpacked, has_packed;
	132	unsigned char unpacked_sha1[20], packed_sha1[20];
	133
	134	has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
	135	has_packed = find_short_packed_object(len, res, packed_sha1);
	136	if (!has_unpacked && !has_packed)
013f276e	137	return SHORT_NAME_NOT_FOUND;
99a19b43	138	if (1 < has_unpacked \|\| 1 < has_packed)
013f276e	139	return SHORT_NAME_AMBIGUOUS;
99a19b43 JH	140	if (has_unpacked != has_packed) {
	141	memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
	142	return 0;
	143	}
	144	/* Both have unique ones -- do they match? */
	145	if (memcmp(packed_sha1, unpacked_sha1, 20))
013f276e	146	return -2;
99a19b43	147	memcpy(sha1, packed_sha1, 20);
9938af6a JH	148	return 0;
	149	}
	150
013f276e JH	151	static int get_short_sha1(const char name, int len, unsigned char sha1,
013f276e JH	152	int quietly)
9938af6a	153	{
013f276e	154	int i, status;
9938af6a JH	155	char canonical[40];
	156	unsigned char res[20];
	157
af61c6e0 LT	158	if (len < 4)
af61c6e0 LT	159	return -1;
9938af6a JH	160	memset(res, 0, 20);
9938af6a JH	161	memset(canonical, 'x', 40);
af61c6e0	162	for (i = 0; i < len ;i++) {
9938af6a JH	163	unsigned char c = name[i];
9938af6a JH	164	unsigned char val;
9938af6a JH	165	if (c >= '0' && c <= '9')
	166	val = c - '0';
	167	else if (c >= 'a' && c <= 'f')
	168	val = c - 'a' + 10;
	169	else if (c >= 'A' && c <='F') {
	170	val = c - 'A' + 10;
	171	c -= 'A' - 'a';
	172	}
	173	else
	174	return -1;
	175	canonical[i] = c;
	176	if (!(i & 1))
	177	val <<= 4;
	178	res[i >> 1] \|= val;
	179	}
99a19b43	180
013f276e JH	181	status = find_unique_short_object(i, canonical, res, sha1);
	182	if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
	183	return error("short SHA1 %.*s is ambiguous.", len, canonical);
	184	return status;
	185	}
	186
	187	const char find_unique_abbrev(const unsigned char sha1, int len)
	188	{
	189	int status;
	190	static char hex[41];
	191	memcpy(hex, sha1_to_hex(sha1), 40);
	192	while (len < 40) {
	193	unsigned char sha1_ret[20];
	194	status = get_short_sha1(hex, len, sha1_ret, 1);
	195	if (!status) {
	196	hex[len] = 0;
	197	return hex;
	198	}
	199	if (status != SHORT_NAME_AMBIGUOUS)
	200	return NULL;
	201	len++;
	202	}
	203	return NULL;
9938af6a JH	204	}
9938af6a JH	205
6677c466	206	static int ambiguous_path(const char *path, int len)
af13cdf2 LT	207	{
af13cdf2 LT	208	int slash = 1;
6677c466	209	int cnt;
af13cdf2	210
6677c466	211	for (cnt = 0; cnt < len; cnt++) {
af13cdf2 LT	212	switch (*path++) {
	213	case '\0':
	214	break;
	215	case '/':
	216	if (slash)
	217	break;
	218	slash = 1;
	219	continue;
	220	case '.':
	221	continue;
	222	default:
	223	slash = 0;
	224	continue;
	225	}
c054d64e	226	break;
af13cdf2	227	}
6677c466	228	return slash;
af13cdf2 LT	229	}
af13cdf2 LT	230
9938af6a JH	231	static int get_sha1_basic(const char str, int len, unsigned char sha1)
	232	{
	233	static const char *prefix[] = {
	234	"",
	235	"refs",
	236	"refs/tags",
	237	"refs/heads",
9938af6a JH	238	NULL
	239	};
	240	const char **p;
	241
3c3852e3	242	if (len == 40 && !get_sha1_hex(str, sha1))
9938af6a JH	243	return 0;
9938af6a JH	244
af13cdf2	245	/* Accept only unambiguous ref paths. */
6677c466	246	if (ambiguous_path(str, len))
af13cdf2 LT	247	return -1;
af13cdf2 LT	248
9938af6a JH	249	for (p = prefix; *p; p++) {
9938af6a JH	250	char pathname = git_path("%s/%.s", *p, len, str);
011fbc7f JH	251	if (!read_ref(pathname, sha1))
011fbc7f JH	252	return 0;
6677c466	253	}
011fbc7f	254	return -1;
9938af6a JH	255	}
	256
	257	static int get_sha1_1(const char name, int len, unsigned char sha1);
	258
	259	static int get_parent(const char *name, int len,
	260	unsigned char *result, int idx)
	261	{
	262	unsigned char sha1[20];
	263	int ret = get_sha1_1(name, len, sha1);
	264	struct commit *commit;
	265	struct commit_list *p;
	266
	267	if (ret)
	268	return ret;
	269	commit = lookup_commit_reference(sha1);
	270	if (!commit)
	271	return -1;
	272	if (parse_commit(commit))
	273	return -1;
	274	if (!idx) {
	275	memcpy(result, commit->object.sha1, 20);
	276	return 0;
	277	}
	278	p = commit->parents;
	279	while (p) {
	280	if (!--idx) {
	281	memcpy(result, p->item->object.sha1, 20);
	282	return 0;
	283	}
	284	p = p->next;
	285	}
	286	return -1;
	287	}
	288
4f7599ac JH	289	static int get_nth_ancestor(const char *name, int len,
	290	unsigned char *result, int generation)
	291	{
	292	unsigned char sha1[20];
	293	int ret = get_sha1_1(name, len, sha1);
	294	if (ret)
	295	return ret;
	296
	297	while (generation--) {
	298	struct commit *commit = lookup_commit_reference(sha1);
	299
	300	if (!commit \|\| parse_commit(commit) \|\| !commit->parents)
	301	return -1;
	302	memcpy(sha1, commit->parents->item->object.sha1, 20);
	303	}
	304	memcpy(result, sha1, 20);
	305	return 0;
	306	}
	307
5385f52d JH	308	static int peel_onion(const char name, int len, unsigned char sha1)
	309	{
	310	unsigned char outer[20];
	311	const char *sp;
	312	const char *type_string = NULL;
	313	struct object *o;
	314
	315	/*
	316	* "ref^{type}" dereferences ref repeatedly until you cannot
	317	* dereference anymore, or you get an object of given type,
	318	* whichever comes first. "ref^{}" means just dereference
	319	* tags until you get a non-tag. "ref^0" is a shorthand for
	320	* "ref^{commit}". "commit^{tree}" could be used to find the
	321	* top-level tree of the given commit.
	322	*/
	323	if (len < 4 \|\| name[len-1] != '}')
	324	return -1;
	325
	326	for (sp = name + len - 1; name <= sp; sp--) {
	327	int ch = *sp;
	328	if (ch == '{' && name < sp && sp[-1] == '^')
	329	break;
	330	}
	331	if (sp <= name)
	332	return -1;
	333
	334	sp++; /* beginning of type name, or closing brace for empty */
	335	if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
	336	type_string = commit_type;
	337	else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
	338	type_string = tree_type;
	339	else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
	340	type_string = blob_type;
	341	else if (sp[0] == '}')
	342	type_string = NULL;
	343	else
	344	return -1;
	345
	346	if (get_sha1_1(name, sp - name - 2, outer))
	347	return -1;
	348
	349	o = parse_object(outer);
	350	if (!o)
	351	return -1;
	352	if (!type_string) {
9534f40b	353	o = deref_tag(o, name, sp - name - 2);
6e1c6c10 JH	354	if (!o \|\| (!o->parsed && !parse_object(o->sha1)))
6e1c6c10 JH	355	return -1;
5385f52d JH	356	memcpy(sha1, o->sha1, 20);
	357	}
	358	else {
	359	/* At this point, the syntax look correct, so
	360	* if we do not get the needed object, we should
	361	* barf.
	362	*/
	363
	364	while (1) {
6e1c6c10	365	if (!o \|\| (!o->parsed && !parse_object(o->sha1)))
5385f52d JH	366	return -1;
	367	if (o->type == type_string) {
	368	memcpy(sha1, o->sha1, 20);
	369	return 0;
	370	}
	371	if (o->type == tag_type)
	372	o = ((struct tag*) o)->tagged;
	373	else if (o->type == commit_type)
	374	o = &(((struct commit *) o)->tree->object);
	375	else
	376	return error("%.*s: expected %s type, but the object dereferences to %s type",
	377	len, name, type_string,
	378	o->type);
	379	if (!o->parsed)
	380	parse_object(o->sha1);
	381	}
	382	}
	383	return 0;
	384	}
	385
9938af6a JH	386	static int get_sha1_1(const char name, int len, unsigned char sha1)
	387	{
	388	int parent, ret;
4f7599ac	389	const char *cp;
9938af6a JH	390
	391	/* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
	392	if (len > 2 && name[len-2] == '^' &&
	393	name[len-1] >= '0' && name[len-1] <= '9') {
	394	parent = name[len-1] - '0';
	395	len -= 2;
	396	}
ef0bd2e6	397	else if (len > 1 && name[len-1] == '^') {
9938af6a	398	parent = 1;
ef0bd2e6 JS	399	len--;
ef0bd2e6 JS	400	} else
9938af6a JH	401	parent = -1;
9938af6a JH	402
02a4a32c LT	403	if (parent >= 0)
	404	return get_parent(name, len, sha1, parent);
	405
4f7599ac JH	406	/* "name~3" is "name^^^",
	407	* "name~12" is "name^^^^^^^^^^^^", and
	408	* "name~" and "name~0" are name -- not "name^0"!
	409	*/
	410	parent = 0;
	411	for (cp = name + len - 1; name <= cp; cp--) {
	412	int ch = *cp;
	413	if ('0' <= ch && ch <= '9')
	414	continue;
	415	if (ch != '~')
	416	parent = -1;
	417	break;
	418	}
	419	if (!parent && *cp == '~') {
	420	int len1 = cp - name;
	421	cp++;
	422	while (cp < name + len)
	423	parent = parent * 10 + *cp++ - '0';
	424	return get_nth_ancestor(name, len1, sha1, parent);
	425	}
	426
5385f52d JH	427	ret = peel_onion(name, len, sha1);
	428	if (!ret)
	429	return 0;
	430
9938af6a JH	431	ret = get_sha1_basic(name, len, sha1);
	432	if (!ret)
	433	return 0;
013f276e	434	return get_short_sha1(name, len, sha1, 0);
9938af6a JH	435	}
	436
	437	/*
	438	* This is like "get_sha1_basic()", except it allows "sha1 expressions",
	439	* notably "xyz^" for "parent of xyz"
	440	*/
	441	int get_sha1(const char name, unsigned char sha1)
	442	{
99a19b43	443	prepare_alt_odb();
9938af6a JH	444	return get_sha1_1(name, strlen(name), sha1);
9938af6a JH	445	}