[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"

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
	};
	const char **p;
	const char *warning = "warning: refname '%.*s' is ambiguous.\n";
	char *pathname;
	int already_found = 0;
	unsigned char *this_result;
	unsigned char sha1_from_ref[20];

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

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

	for (p = fmt; *p; p++) {
		this_result = already_found ? sha1_from_ref : sha1;
		pathname = git_path(*p, len, str);
		if (!read_ref(pathname, this_result)) {
			if (warn_ambiguous_refs) {
				if (already_found)
					fprintf(stderr, warning, len, str);
				already_found++;
			}
			else
				return 0;
		}
	}
	if (already_found)
		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 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;
			}
		}
		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"
9938af6a JH	7
	8	static int find_short_object_filename(int len, const char name, unsigned char sha1)
	9	{
99a19b43	10	struct alternate_object_database *alt;
9938af6a	11	char hex[40];
99a19b43 JH	12	int found = 0;
	13	static struct alternate_object_database *fakeent;
	14
	15	if (!fakeent) {
	16	const char *objdir = get_object_directory();
	17	int objdir_len = strlen(objdir);
	18	int entlen = objdir_len + 43;
	19	fakeent = xmalloc(sizeof(*fakeent) + entlen);
	20	memcpy(fakeent->base, objdir, objdir_len);
	21	fakeent->name = fakeent->base + objdir_len + 1;
	22	fakeent->name[-1] = '/';
	23	}
	24	fakeent->next = alt_odb_list;
9938af6a	25
9938af6a	26	sprintf(hex, "%.2s", name);
99a19b43	27	for (alt = fakeent; alt && found < 2; alt = alt->next) {
9938af6a	28	struct dirent *de;
99a19b43 JH	29	DIR *dir;
	30	sprintf(alt->name, "%.2s/", name);
	31	dir = opendir(alt->base);
	32	if (!dir)
	33	continue;
9938af6a JH	34	while ((de = readdir(dir)) != NULL) {
	35	if (strlen(de->d_name) != 38)
	36	continue;
99a19b43	37	if (memcmp(de->d_name, name + 2, len - 2))
9938af6a	38	continue;
99a19b43 JH	39	if (!found) {
	40	memcpy(hex + 2, de->d_name, 38);
	41	found++;
	42	}
	43	else if (memcmp(hex + 2, de->d_name, 38)) {
	44	found = 2;
9938af6a	45	break;
99a19b43	46	}
9938af6a JH	47	}
	48	closedir(dir);
	49	}
	50	if (found == 1)
	51	return get_sha1_hex(hex, sha1) == 0;
99a19b43	52	return found;
9938af6a JH	53	}
	54
	55	static int match_sha(unsigned len, const unsigned char a, const unsigned char b)
	56	{
	57	do {
	58	if (a != b)
	59	return 0;
	60	a++;
	61	b++;
	62	len -= 2;
	63	} while (len > 1);
	64	if (len)
	65	if ((a ^ b) & 0xf0)
	66	return 0;
	67	return 1;
	68	}
	69
	70	static int find_short_packed_object(int len, const unsigned char match, unsigned char sha1)
	71	{
	72	struct packed_git *p;
99a19b43 JH	73	unsigned char found_sha1[20];
99a19b43 JH	74	int found = 0;
9938af6a JH	75
9938af6a JH	76	prepare_packed_git();
99a19b43	77	for (p = packed_git; p && found < 2; p = p->next) {
9938af6a JH	78	unsigned num = num_packed_objects(p);
	79	unsigned first = 0, last = num;
	80	while (first < last) {
	81	unsigned mid = (first + last) / 2;
	82	unsigned char now[20];
	83	int cmp;
	84
	85	nth_packed_object_sha1(p, mid, now);
	86	cmp = memcmp(match, now, 20);
	87	if (!cmp) {
	88	first = mid;
	89	break;
	90	}
	91	if (cmp > 0) {
	92	first = mid+1;
	93	continue;
	94	}
	95	last = mid;
	96	}
	97	if (first < num) {
0bc45890	98	unsigned char now[20], next[20];
9938af6a JH	99	nth_packed_object_sha1(p, first, now);
9938af6a JH	100	if (match_sha(len, match, now)) {
0bc45890 JH	101	if (nth_packed_object_sha1(p, first+1, next) \|\|
	102	!match_sha(len, match, next)) {
	103	/* unique within this pack */
	104	if (!found) {
	105	memcpy(found_sha1, now, 20);
	106	found++;
	107	}
	108	else if (memcmp(found_sha1, now, 20)) {
	109	found = 2;
	110	break;
	111	}
99a19b43	112	}
0bc45890 JH	113	else {
0bc45890 JH	114	/* not even unique within this pack */
99a19b43 JH	115	found = 2;
99a19b43 JH	116	break;
9938af6a JH	117	}
	118	}
	119	}
	120	}
99a19b43 JH	121	if (found == 1)
	122	memcpy(sha1, found_sha1, 20);
	123	return found;
	124	}
	125
013f276e JH	126	#define SHORT_NAME_NOT_FOUND (-1)
	127	#define SHORT_NAME_AMBIGUOUS (-2)
	128
99a19b43 JH	129	static int find_unique_short_object(int len, char *canonical,
	130	unsigned char res, unsigned char sha1)
	131	{
	132	int has_unpacked, has_packed;
	133	unsigned char unpacked_sha1[20], packed_sha1[20];
	134
	135	has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
	136	has_packed = find_short_packed_object(len, res, packed_sha1);
	137	if (!has_unpacked && !has_packed)
013f276e	138	return SHORT_NAME_NOT_FOUND;
99a19b43	139	if (1 < has_unpacked \|\| 1 < has_packed)
013f276e	140	return SHORT_NAME_AMBIGUOUS;
99a19b43 JH	141	if (has_unpacked != has_packed) {
	142	memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
	143	return 0;
	144	}
	145	/* Both have unique ones -- do they match? */
	146	if (memcmp(packed_sha1, unpacked_sha1, 20))
e974c9ab	147	return SHORT_NAME_AMBIGUOUS;
99a19b43	148	memcpy(sha1, packed_sha1, 20);
9938af6a JH	149	return 0;
	150	}
	151
013f276e JH	152	static int get_short_sha1(const char name, int len, unsigned char sha1,
013f276e JH	153	int quietly)
9938af6a	154	{
013f276e	155	int i, status;
9938af6a JH	156	char canonical[40];
	157	unsigned char res[20];
	158
46a6c262	159	if (len < MINIMUM_ABBREV)
af61c6e0	160	return -1;
9938af6a JH	161	memset(res, 0, 20);
9938af6a JH	162	memset(canonical, 'x', 40);
af61c6e0	163	for (i = 0; i < len ;i++) {
9938af6a JH	164	unsigned char c = name[i];
9938af6a JH	165	unsigned char val;
9938af6a JH	166	if (c >= '0' && c <= '9')
	167	val = c - '0';
	168	else if (c >= 'a' && c <= 'f')
	169	val = c - 'a' + 10;
	170	else if (c >= 'A' && c <='F') {
	171	val = c - 'A' + 10;
	172	c -= 'A' - 'a';
	173	}
	174	else
	175	return -1;
	176	canonical[i] = c;
	177	if (!(i & 1))
	178	val <<= 4;
	179	res[i >> 1] \|= val;
	180	}
99a19b43	181
013f276e JH	182	status = find_unique_short_object(i, canonical, res, sha1);
	183	if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
	184	return error("short SHA1 %.*s is ambiguous.", len, canonical);
	185	return status;
	186	}
	187
	188	const char find_unique_abbrev(const unsigned char sha1, int len)
	189	{
297a1aad	190	int status, is_null;
013f276e	191	static char hex[41];
47dd0d59	192
297a1aad	193	is_null = !memcmp(sha1, null_sha1, 20);
013f276e	194	memcpy(hex, sha1_to_hex(sha1), 40);
47dd0d59 JH	195	if (len == 40)
47dd0d59 JH	196	return hex;
013f276e JH	197	while (len < 40) {
	198	unsigned char sha1_ret[20];
	199	status = get_short_sha1(hex, len, sha1_ret, 1);
297a1aad JH	200	if (!status \|\|
297a1aad JH	201	(is_null && status != SHORT_NAME_AMBIGUOUS)) {
013f276e JH	202	hex[len] = 0;
	203	return hex;
	204	}
	205	if (status != SHORT_NAME_AMBIGUOUS)
	206	return NULL;
	207	len++;
	208	}
	209	return NULL;
9938af6a JH	210	}
9938af6a JH	211
6677c466	212	static int ambiguous_path(const char *path, int len)
af13cdf2 LT	213	{
af13cdf2 LT	214	int slash = 1;
6677c466	215	int cnt;
af13cdf2	216
6677c466	217	for (cnt = 0; cnt < len; cnt++) {
af13cdf2 LT	218	switch (*path++) {
	219	case '\0':
	220	break;
	221	case '/':
	222	if (slash)
	223	break;
	224	slash = 1;
	225	continue;
	226	case '.':
	227	continue;
	228	default:
	229	slash = 0;
	230	continue;
	231	}
c054d64e	232	break;
af13cdf2	233	}
6677c466	234	return slash;
af13cdf2 LT	235	}
af13cdf2 LT	236
9938af6a JH	237	static int get_sha1_basic(const char str, int len, unsigned char sha1)
9938af6a JH	238	{
c51d1369	239	static const char *fmt[] = {
84a9b58c	240	"%.*s",
c51d1369 JH	241	"refs/%.*s",
	242	"refs/tags/%.*s",
	243	"refs/heads/%.*s",
	244	"refs/remotes/%.*s",
	245	"refs/remotes/%.*s/HEAD",
9938af6a JH	246	NULL
	247	};
	248	const char **p;
2f8acdb3 JH	249	const char warning = "warning: refname '%.s' is ambiguous.\n";
	250	char *pathname;
	251	int already_found = 0;
c51d1369 JH	252	unsigned char *this_result;
c51d1369 JH	253	unsigned char sha1_from_ref[20];
9938af6a	254
3c3852e3	255	if (len == 40 && !get_sha1_hex(str, sha1))
9938af6a JH	256	return 0;
9938af6a JH	257
af13cdf2	258	/* Accept only unambiguous ref paths. */
6677c466	259	if (ambiguous_path(str, len))
af13cdf2 LT	260	return -1;
af13cdf2 LT	261
c51d1369 JH	262	for (p = fmt; *p; p++) {
	263	this_result = already_found ? sha1_from_ref : sha1;
	264	pathname = git_path(*p, len, str);
2f8acdb3 JH	265	if (!read_ref(pathname, this_result)) {
2f8acdb3 JH	266	if (warn_ambiguous_refs) {
84a9b58c	267	if (already_found)
2f8acdb3 JH	268	fprintf(stderr, warning, len, str);
	269	already_found++;
	270	}
	271	else
	272	return 0;
	273	}
6677c466	274	}
2f8acdb3 JH	275	if (already_found)
2f8acdb3 JH	276	return 0;
011fbc7f	277	return -1;
9938af6a JH	278	}
	279
	280	static int get_sha1_1(const char name, int len, unsigned char sha1);
	281
	282	static int get_parent(const char *name, int len,
	283	unsigned char *result, int idx)
	284	{
	285	unsigned char sha1[20];
	286	int ret = get_sha1_1(name, len, sha1);
	287	struct commit *commit;
	288	struct commit_list *p;
	289
	290	if (ret)
	291	return ret;
	292	commit = lookup_commit_reference(sha1);
	293	if (!commit)
	294	return -1;
	295	if (parse_commit(commit))
	296	return -1;
	297	if (!idx) {
	298	memcpy(result, commit->object.sha1, 20);
	299	return 0;
	300	}
	301	p = commit->parents;
	302	while (p) {
	303	if (!--idx) {
	304	memcpy(result, p->item->object.sha1, 20);
	305	return 0;
	306	}
	307	p = p->next;
	308	}
	309	return -1;
	310	}
	311
4f7599ac JH	312	static int get_nth_ancestor(const char *name, int len,
	313	unsigned char *result, int generation)
	314	{
	315	unsigned char sha1[20];
	316	int ret = get_sha1_1(name, len, sha1);
	317	if (ret)
	318	return ret;
	319
	320	while (generation--) {
	321	struct commit *commit = lookup_commit_reference(sha1);
	322
	323	if (!commit \|\| parse_commit(commit) \|\| !commit->parents)
	324	return -1;
	325	memcpy(sha1, commit->parents->item->object.sha1, 20);
	326	}
	327	memcpy(result, sha1, 20);
	328	return 0;
	329	}
	330
5385f52d JH	331	static int peel_onion(const char name, int len, unsigned char sha1)
	332	{
	333	unsigned char outer[20];
	334	const char *sp;
	335	const char *type_string = NULL;
	336	struct object *o;
	337
	338	/*
	339	* "ref^{type}" dereferences ref repeatedly until you cannot
	340	* dereference anymore, or you get an object of given type,
	341	* whichever comes first. "ref^{}" means just dereference
	342	* tags until you get a non-tag. "ref^0" is a shorthand for
	343	* "ref^{commit}". "commit^{tree}" could be used to find the
	344	* top-level tree of the given commit.
	345	*/
	346	if (len < 4 \|\| name[len-1] != '}')
	347	return -1;
	348
	349	for (sp = name + len - 1; name <= sp; sp--) {
	350	int ch = *sp;
	351	if (ch == '{' && name < sp && sp[-1] == '^')
	352	break;
	353	}
	354	if (sp <= name)
	355	return -1;
	356
	357	sp++; /* beginning of type name, or closing brace for empty */
	358	if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
	359	type_string = commit_type;
	360	else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
	361	type_string = tree_type;
	362	else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
	363	type_string = blob_type;
	364	else if (sp[0] == '}')
	365	type_string = NULL;
	366	else
	367	return -1;
	368
	369	if (get_sha1_1(name, sp - name - 2, outer))
	370	return -1;
	371
	372	o = parse_object(outer);
	373	if (!o)
	374	return -1;
	375	if (!type_string) {
9534f40b	376	o = deref_tag(o, name, sp - name - 2);
6e1c6c10 JH	377	if (!o \|\| (!o->parsed && !parse_object(o->sha1)))
6e1c6c10 JH	378	return -1;
5385f52d JH	379	memcpy(sha1, o->sha1, 20);
	380	}
	381	else {
	382	/* At this point, the syntax look correct, so
	383	* if we do not get the needed object, we should
	384	* barf.
	385	*/
	386
	387	while (1) {
6e1c6c10	388	if (!o \|\| (!o->parsed && !parse_object(o->sha1)))
5385f52d JH	389	return -1;
	390	if (o->type == type_string) {
	391	memcpy(sha1, o->sha1, 20);
	392	return 0;
	393	}
	394	if (o->type == tag_type)
	395	o = ((struct tag*) o)->tagged;
	396	else if (o->type == commit_type)
	397	o = &(((struct commit *) o)->tree->object);
	398	else
	399	return error("%.*s: expected %s type, but the object dereferences to %s type",
	400	len, name, type_string,
	401	o->type);
	402	if (!o->parsed)
	403	parse_object(o->sha1);
	404	}
	405	}
	406	return 0;
	407	}
	408
9938af6a JH	409	static int get_sha1_1(const char name, int len, unsigned char sha1)
9938af6a JH	410	{
0601dbe1	411	int ret, has_suffix;
4f7599ac	412	const char *cp;
9938af6a	413
4f7599ac	414	/* "name~3" is "name^^^",
4f7599ac	415	* "name~" and "name~0" are name -- not "name^0"!
0601dbe1	416	* "name^" is not "name^0"; it is "name^1".
4f7599ac	417	*/
0601dbe1	418	has_suffix = 0;
4f7599ac JH	419	for (cp = name + len - 1; name <= cp; cp--) {
	420	int ch = *cp;
	421	if ('0' <= ch && ch <= '9')
	422	continue;
0601dbe1 JH	423	if (ch == '~' \|\| ch == '^')
0601dbe1 JH	424	has_suffix = ch;
4f7599ac JH	425	break;
4f7599ac JH	426	}
0601dbe1 JH	427
	428	if (has_suffix) {
	429	int num = 0;
4f7599ac JH	430	int len1 = cp - name;
	431	cp++;
	432	while (cp < name + len)
0601dbe1 JH	433	num = num * 10 + *cp++ - '0';
	434	if (has_suffix == '^') {
	435	if (!num && len1 == len - 1)
	436	num = 1;
	437	return get_parent(name, len1, sha1, num);
	438	}
	439	/* else if (has_suffix == '~') -- goes without saying */
	440	return get_nth_ancestor(name, len1, sha1, num);
4f7599ac JH	441	}
4f7599ac JH	442
5385f52d JH	443	ret = peel_onion(name, len, sha1);
	444	if (!ret)
	445	return 0;
	446
9938af6a JH	447	ret = get_sha1_basic(name, len, sha1);
	448	if (!ret)
	449	return 0;
013f276e	450	return get_short_sha1(name, len, sha1, 0);
9938af6a JH	451	}
	452
	453	/*
	454	* This is like "get_sha1_basic()", except it allows "sha1 expressions",
	455	* notably "xyz^" for "parent of xyz"
	456	*/
	457	int get_sha1(const char name, unsigned char sha1)
	458	{
5119602a	459	int ret;
041a7308	460	unsigned unused;
73b0e5af JH	461	int namelen = strlen(name);
73b0e5af JH	462	const char *cp;
5119602a	463
99a19b43	464	prepare_alt_odb();
73b0e5af JH	465	ret = get_sha1_1(name, namelen, sha1);
	466	if (!ret)
	467	return ret;
	468	/* sha1:path --> object name of path in ent sha1
	469	* :path -> object name of path in index
	470	* :[0-3]:path -> object name of path in index at stage
	471	*/
	472	if (name[0] == ':') {
	473	int stage = 0;
	474	struct cache_entry *ce;
	475	int pos;
	476	if (namelen < 3 \|\|
	477	name[2] != ':' \|\|
	478	name[1] < '0' \|\| '3' < name[1])
	479	cp = name + 1;
	480	else {
	481	stage = name[1] - '0';
	482	cp = name + 3;
5119602a	483	}
73b0e5af JH	484	namelen = namelen - (cp - name);
	485	if (!active_cache)
	486	read_cache();
	487	if (active_nr < 0)
	488	return -1;
	489	pos = cache_name_pos(cp, namelen);
	490	if (pos < 0)
	491	pos = -pos - 1;
	492	while (pos < active_nr) {
	493	ce = active_cache[pos];
	494	if (ce_namelen(ce) != namelen \|\|
	495	memcmp(ce->name, cp, namelen))
	496	break;
	497	if (ce_stage(ce) == stage) {
	498	memcpy(sha1, ce->sha1, 20);
	499	return 0;
	500	}
	501	}
	502	return -1;
	503	}
	504	cp = strchr(name, ':');
	505	if (cp) {
	506	unsigned char tree_sha1[20];
	507	if (!get_sha1_1(name, cp-name, tree_sha1))
	508	return get_tree_entry(tree_sha1, cp+1, sha1,
	509	&unused);
5119602a LT	510	}
5119602a LT	511	return ret;
9938af6a	512	}