[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 = hashcmp(match, now);
			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) {
						hashcpy(found_sha1, now);
						found++;
					}
					else if (hashcmp(found_sha1, now)) {
						found = 2;
						break;
					}
				}
				else {
					/* not even unique within this pack */
					found = 2;
					break;
				}
			}
		}
	}
	if (found == 1)
		hashcpy(sha1, found_sha1);
	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) {
		hashcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1));
		return 0;
	}
	/* Both have unique ones -- do they match? */
	if (hashcmp(packed_sha1, unpacked_sha1))
		return SHORT_NAME_AMBIGUOUS;
	hashcpy(sha1, packed_sha1);
	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 || len > 40)
		return -1;
	hashclr(res);
	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 = is_null_sha1(sha1);
	memcpy(hex, sha1_to_hex(sha1), 40);
	if (len == 40 || !len)
		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 const char *ref_fmt[] = {
	"%.*s",
	"refs/%.*s",
	"refs/tags/%.*s",
	"refs/heads/%.*s",
	"refs/remotes/%.*s",
	"refs/remotes/%.*s/HEAD",
	NULL
};

int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
{
	const char **p, *r;
	int refs_found = 0;

	*ref = NULL;
	for (p = ref_fmt; *p; p++) {
		unsigned char sha1_from_ref[20];
		unsigned char *this_result;

		this_result = refs_found ? sha1_from_ref : sha1;
		r = resolve_ref(mkpath(*p, len, str), this_result, 1, NULL);
		if (r) {
			if (!refs_found++)
				*ref = xstrdup(r);
			if (!warn_ambiguous_refs)
				break;
		}
	}
	return refs_found;
}

static int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
{
	const char **p;
	int logs_found = 0;

	*log = NULL;
	for (p = ref_fmt; *p; p++) {
		struct stat st;
		char *path = mkpath(*p, len, str);
		if (!stat(git_path("logs/%s", path), &st) &&
		    S_ISREG(st.st_mode)) {
			if (!logs_found++) {
				*log = xstrdup(path);
				resolve_ref(path, sha1, 0, NULL);
			}
			if (!warn_ambiguous_refs)
				break;
		}
	}
	return logs_found;
}

static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
{
	static const char *warning = "warning: refname '%.*s' is ambiguous.\n";
	char *real_ref = NULL;
	int refs_found = 0;
	int at, reflog_len;

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

	/* basic@{time or number} format to query ref-log */
	reflog_len = at = 0;
	if (str[len-1] == '}') {
		for (at = 0; at < len - 1; at++) {
			if (str[at] == '@' && str[at+1] == '{') {
				reflog_len = (len-1) - (at+2);
				len = at;
				break;
			}
		}
	}

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

	if (!len && reflog_len) {
		/* allow "@{...}" to mean the current branch reflog */
		refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
	} else if (reflog_len)
		refs_found = dwim_log(str, len, sha1, &real_ref);
	else
		refs_found = dwim_ref(str, len, sha1, &real_ref);

	if (!refs_found)
		return -1;

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

	if (reflog_len) {
		int nth, i;
		unsigned long at_time;
		unsigned long co_time;
		int co_tz, co_cnt;

		/* Is it asking for N-th entry, or approxidate? */
		for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
			char ch = str[at+2+i];
			if ('0' <= ch && ch <= '9')
				nth = nth * 10 + ch - '0';
			else
				nth = -1;
		}
		if (0 <= nth)
			at_time = 0;
		else
			at_time = approxidate(str + at + 2);
		if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
				&co_time, &co_tz, &co_cnt)) {
			if (at_time)
				fprintf(stderr,
					"warning: Log for '%.*s' only goes "
					"back to %s.\n", len, str,
					show_rfc2822_date(co_time, co_tz));
			else
				fprintf(stderr,
					"warning: Log for '%.*s' only has "
					"%d entries.\n", len, str, co_cnt);
		}
	}

	free(real_ref);
	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) {
		hashcpy(result, commit->object.sha1);
		return 0;
	}
	p = commit->parents;
	while (p) {
		if (!--idx) {
			hashcpy(result, p->item->object.sha1);
			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;
		hashcpy(sha1, commit->parents->item->object.sha1);
	}
	hashcpy(result, sha1);
	return 0;
}

static int peel_onion(const char *name, int len, unsigned char *sha1)
{
	unsigned char outer[20];
	const char *sp;
	unsigned int expected_type = 0;
	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] == '}')
		expected_type = OBJ_COMMIT;
	else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
		expected_type = OBJ_TREE;
	else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
		expected_type = OBJ_BLOB;
	else if (sp[0] == '}')
		expected_type = OBJ_NONE;
	else
		return -1;

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

	o = parse_object(outer);
	if (!o)
		return -1;
	if (!expected_type) {
		o = deref_tag(o, name, sp - name - 2);
		if (!o || (!o->parsed && !parse_object(o->sha1)))
			return -1;
		hashcpy(sha1, o->sha1);
	}
	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 == expected_type) {
				hashcpy(sha1, o->sha1);
				return 0;
			}
			if (o->type == OBJ_TAG)
				o = ((struct tag*) o)->tagged;
			else if (o->type == OBJ_COMMIT)
				o = &(((struct commit *) o)->tree->object);
			else
				return error("%.*s: expected %s type, but the object dereferences to %s type",
					     len, name, typename(expected_type),
					     typename(o->type));
			if (!o->parsed)
				parse_object(o->sha1);
		}
	}
	return 0;
}

static int get_describe_name(const char *name, int len, unsigned char *sha1)
{
	const char *cp;

	for (cp = name + len - 1; name + 2 <= cp; cp--) {
		char ch = *cp;
		if (hexval(ch) & ~0377) {
			/* We must be looking at g in "SOMETHING-g"
			 * for it to be describe output.
			 */
			if (ch == 'g' && cp[-1] == '-') {
				cp++;
				len -= cp - name;
				return get_short_sha1(cp, len, sha1, 1);
			}
		}
	}
	return -1;
}

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;

	/* It could be describe output that is "SOMETHING-gXXXX" */
	ret = get_describe_name(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, bracket_depth;
	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) {
				hashcpy(sha1, ce->sha1);
				return 0;
			}
			pos++;
		}
		return -1;
	}
	for (cp = name, bracket_depth = 0; *cp; cp++) {
		if (*cp == '{')
			bracket_depth++;
		else if (bracket_depth && *cp == '}')
			bracket_depth--;
		else if (!bracket_depth && *cp == ':')
			break;
	}
	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);
a89fccd2	87	cmp = hashcmp(match, now);
9938af6a JH	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) {
e702496e	106	hashcpy(found_sha1, now);
0bc45890 JH	107	found++;
0bc45890 JH	108	}
a89fccd2	109	else if (hashcmp(found_sha1, now)) {
0bc45890 JH	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	122	if (found == 1)
e702496e	123	hashcpy(sha1, found_sha1);
99a19b43 JH	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	142	if (has_unpacked != has_packed) {
e702496e	143	hashcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1));
99a19b43 JH	144	return 0;
	145	}
	146	/* Both have unique ones -- do they match? */
a89fccd2	147	if (hashcmp(packed_sha1, unpacked_sha1))
e974c9ab	148	return SHORT_NAME_AMBIGUOUS;
e702496e	149	hashcpy(sha1, packed_sha1);
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
8a83157e	160	if (len < MINIMUM_ABBREV \|\| len > 40)
af61c6e0	161	return -1;
a8e0d16d	162	hashclr(res);
9938af6a	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
0bef57ee	194	is_null = is_null_sha1(sha1);
013f276e	195	memcpy(hex, sha1_to_hex(sha1), 40);
02c5cba2	196	if (len == 40 \|\| !len)
47dd0d59	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
f2eba66d NP	238	static const char *ref_fmt[] = {
	239	"%.*s",
	240	"refs/%.*s",
	241	"refs/tags/%.*s",
	242	"refs/heads/%.*s",
	243	"refs/remotes/%.*s",
	244	"refs/remotes/%.*s/HEAD",
	245	NULL
	246	};
	247
e86eb666	248	int dwim_ref(const char str, int len, unsigned char sha1, char **ref)
9938af6a	249	{
e86eb666 JH	250	const char *p, r;
	251	int refs_found = 0;
	252
	253	*ref = NULL;
f2eba66d	254	for (p = ref_fmt; *p; p++) {
e86eb666 JH	255	unsigned char sha1_from_ref[20];
	256	unsigned char *this_result;
	257
	258	this_result = refs_found ? sha1_from_ref : sha1;
	259	r = resolve_ref(mkpath(*p, len, str), this_result, 1, NULL);
	260	if (r) {
	261	if (!refs_found++)
	262	*ref = xstrdup(r);
	263	if (!warn_ambiguous_refs)
	264	break;
	265	}
	266	}
	267	return refs_found;
	268	}
	269
f2eba66d NP	270	static int dwim_log(const char str, int len, unsigned char sha1, char **log)
	271	{
	272	const char **p;
	273	int logs_found = 0;
	274
	275	*log = NULL;
	276	for (p = ref_fmt; *p; p++) {
	277	struct stat st;
	278	char path = mkpath(p, len, str);
	279	if (!stat(git_path("logs/%s", path), &st) &&
	280	S_ISREG(st.st_mode)) {
	281	if (!logs_found++) {
	282	*log = xstrdup(path);
	283	resolve_ref(path, sha1, 0, NULL);
	284	}
	285	if (!warn_ambiguous_refs)
	286	break;
	287	}
	288	}
	289	return logs_found;
	290	}
	291
e86eb666 JH	292	static int get_sha1_basic(const char str, int len, unsigned char sha1)
e86eb666 JH	293	{
d556fae2	294	static const char warning = "warning: refname '%.s' is ambiguous.\n";
ed378ec7	295	char *real_ref = NULL;
ab2a1a32 JH	296	int refs_found = 0;
ab2a1a32 JH	297	int at, reflog_len;
9938af6a	298
3c3852e3	299	if (len == 40 && !get_sha1_hex(str, sha1))
9938af6a JH	300	return 0;
9938af6a JH	301
ab2a1a32	302	/* basic@{time or number} format to query ref-log */
694500ed	303	reflog_len = at = 0;
ab2a1a32	304	if (str[len-1] == '}') {
11cf8801	305	for (at = 0; at < len - 1; at++) {
ab2a1a32 JH	306	if (str[at] == '@' && str[at+1] == '{') {
	307	reflog_len = (len-1) - (at+2);
	308	len = at;
	309	break;
	310	}
d556fae2 SP	311	}
	312	}
	313
af13cdf2	314	/* Accept only unambiguous ref paths. */
11cf8801	315	if (len && ambiguous_path(str, len))
af13cdf2 LT	316	return -1;
af13cdf2 LT	317
11cf8801 NP	318	if (!len && reflog_len) {
	319	/* allow "@{...}" to mean the current branch reflog */
	320	refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
f2eba66d NP	321	} else if (reflog_len)
	322	refs_found = dwim_log(str, len, sha1, &real_ref);
	323	else
11cf8801	324	refs_found = dwim_ref(str, len, sha1, &real_ref);
d556fae2 SP	325
	326	if (!refs_found)
	327	return -1;
	328
	329	if (warn_ambiguous_refs && refs_found > 1)
	330	fprintf(stderr, warning, len, str);
	331
ab2a1a32	332	if (reflog_len) {
ab2a1a32 JH	333	int nth, i;
ab2a1a32 JH	334	unsigned long at_time;
16d7cc90 JH	335	unsigned long co_time;
	336	int co_tz, co_cnt;
	337
fe558516	338	/* Is it asking for N-th entry, or approxidate? */
ab2a1a32 JH	339	for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
	340	char ch = str[at+2+i];
	341	if ('0' <= ch && ch <= '9')
	342	nth = nth * 10 + ch - '0';
	343	else
	344	nth = -1;
	345	}
	346	if (0 <= nth)
	347	at_time = 0;
	348	else
	349	at_time = approxidate(str + at + 2);
16d7cc90 JH	350	if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
	351	&co_time, &co_tz, &co_cnt)) {
	352	if (at_time)
	353	fprintf(stderr,
	354	"warning: Log for '%.*s' only goes "
	355	"back to %s.\n", len, str,
	356	show_rfc2822_date(co_time, co_tz));
	357	else
	358	fprintf(stderr,
	359	"warning: Log for '%.*s' only has "
	360	"%d entries.\n", len, str, co_cnt);
	361	}
d556fae2 SP	362	}
d556fae2 SP	363
ed378ec7	364	free(real_ref);
d556fae2	365	return 0;
9938af6a JH	366	}
	367
	368	static int get_sha1_1(const char name, int len, unsigned char sha1);
	369
	370	static int get_parent(const char *name, int len,
	371	unsigned char *result, int idx)
	372	{
	373	unsigned char sha1[20];
	374	int ret = get_sha1_1(name, len, sha1);
	375	struct commit *commit;
	376	struct commit_list *p;
	377
	378	if (ret)
	379	return ret;
	380	commit = lookup_commit_reference(sha1);
	381	if (!commit)
	382	return -1;
	383	if (parse_commit(commit))
	384	return -1;
	385	if (!idx) {
e702496e	386	hashcpy(result, commit->object.sha1);
9938af6a JH	387	return 0;
	388	}
	389	p = commit->parents;
	390	while (p) {
	391	if (!--idx) {
e702496e	392	hashcpy(result, p->item->object.sha1);
9938af6a JH	393	return 0;
	394	}
	395	p = p->next;
	396	}
	397	return -1;
	398	}
	399
4f7599ac JH	400	static int get_nth_ancestor(const char *name, int len,
	401	unsigned char *result, int generation)
	402	{
	403	unsigned char sha1[20];
	404	int ret = get_sha1_1(name, len, sha1);
	405	if (ret)
	406	return ret;
	407
	408	while (generation--) {
	409	struct commit *commit = lookup_commit_reference(sha1);
	410
	411	if (!commit \|\| parse_commit(commit) \|\| !commit->parents)
	412	return -1;
e702496e	413	hashcpy(sha1, commit->parents->item->object.sha1);
4f7599ac	414	}
e702496e	415	hashcpy(result, sha1);
4f7599ac JH	416	return 0;
	417	}
	418
5385f52d JH	419	static int peel_onion(const char name, int len, unsigned char sha1)
	420	{
	421	unsigned char outer[20];
	422	const char *sp;
885a86ab	423	unsigned int expected_type = 0;
5385f52d JH	424	struct object *o;
	425
	426	/*
	427	* "ref^{type}" dereferences ref repeatedly until you cannot
	428	* dereference anymore, or you get an object of given type,
	429	* whichever comes first. "ref^{}" means just dereference
	430	* tags until you get a non-tag. "ref^0" is a shorthand for
	431	* "ref^{commit}". "commit^{tree}" could be used to find the
	432	* top-level tree of the given commit.
	433	*/
	434	if (len < 4 \|\| name[len-1] != '}')
	435	return -1;
	436
	437	for (sp = name + len - 1; name <= sp; sp--) {
	438	int ch = *sp;
	439	if (ch == '{' && name < sp && sp[-1] == '^')
	440	break;
	441	}
	442	if (sp <= name)
	443	return -1;
	444
	445	sp++; /* beginning of type name, or closing brace for empty */
	446	if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
1974632c	447	expected_type = OBJ_COMMIT;
5385f52d	448	else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
1974632c	449	expected_type = OBJ_TREE;
5385f52d	450	else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
1974632c	451	expected_type = OBJ_BLOB;
5385f52d	452	else if (sp[0] == '}')
1974632c	453	expected_type = OBJ_NONE;
5385f52d JH	454	else
	455	return -1;
	456
	457	if (get_sha1_1(name, sp - name - 2, outer))
	458	return -1;
	459
	460	o = parse_object(outer);
	461	if (!o)
	462	return -1;
885a86ab	463	if (!expected_type) {
9534f40b	464	o = deref_tag(o, name, sp - name - 2);
6e1c6c10 JH	465	if (!o \|\| (!o->parsed && !parse_object(o->sha1)))
6e1c6c10 JH	466	return -1;
e702496e	467	hashcpy(sha1, o->sha1);
5385f52d JH	468	}
	469	else {
	470	/* At this point, the syntax look correct, so
	471	* if we do not get the needed object, we should
	472	* barf.
	473	*/
	474
	475	while (1) {
6e1c6c10	476	if (!o \|\| (!o->parsed && !parse_object(o->sha1)))
5385f52d	477	return -1;
885a86ab	478	if (o->type == expected_type) {
e702496e	479	hashcpy(sha1, o->sha1);
5385f52d JH	480	return 0;
5385f52d JH	481	}
1974632c	482	if (o->type == OBJ_TAG)
5385f52d	483	o = ((struct tag*) o)->tagged;
1974632c	484	else if (o->type == OBJ_COMMIT)
5385f52d JH	485	o = &(((struct commit *) o)->tree->object);
	486	else
	487	return error("%.*s: expected %s type, but the object dereferences to %s type",
885a86ab LT	488	len, name, typename(expected_type),
885a86ab LT	489	typename(o->type));
5385f52d JH	490	if (!o->parsed)
	491	parse_object(o->sha1);
	492	}
	493	}
	494	return 0;
	495	}
	496
7dd45e15 JH	497	static int get_describe_name(const char name, int len, unsigned char sha1)
	498	{
	499	const char *cp;
	500
	501	for (cp = name + len - 1; name + 2 <= cp; cp--) {
	502	char ch = *cp;
	503	if (hexval(ch) & ~0377) {
	504	/* We must be looking at g in "SOMETHING-g"
	505	* for it to be describe output.
	506	*/
	507	if (ch == 'g' && cp[-1] == '-') {
	508	cp++;
	509	len -= cp - name;
	510	return get_short_sha1(cp, len, sha1, 1);
	511	}
	512	}
	513	}
	514	return -1;
	515	}
	516
9938af6a JH	517	static int get_sha1_1(const char name, int len, unsigned char sha1)
9938af6a JH	518	{
0601dbe1	519	int ret, has_suffix;
4f7599ac	520	const char *cp;
9938af6a	521
4f7599ac	522	/* "name~3" is "name^^^",
4f7599ac	523	* "name~" and "name~0" are name -- not "name^0"!
0601dbe1	524	* "name^" is not "name^0"; it is "name^1".
4f7599ac	525	*/
0601dbe1	526	has_suffix = 0;
4f7599ac JH	527	for (cp = name + len - 1; name <= cp; cp--) {
	528	int ch = *cp;
	529	if ('0' <= ch && ch <= '9')
	530	continue;
0601dbe1 JH	531	if (ch == '~' \|\| ch == '^')
0601dbe1 JH	532	has_suffix = ch;
4f7599ac JH	533	break;
4f7599ac JH	534	}
0601dbe1 JH	535
	536	if (has_suffix) {
	537	int num = 0;
4f7599ac JH	538	int len1 = cp - name;
	539	cp++;
	540	while (cp < name + len)
0601dbe1 JH	541	num = num * 10 + *cp++ - '0';
	542	if (has_suffix == '^') {
	543	if (!num && len1 == len - 1)
	544	num = 1;
	545	return get_parent(name, len1, sha1, num);
	546	}
	547	/* else if (has_suffix == '~') -- goes without saying */
	548	return get_nth_ancestor(name, len1, sha1, num);
4f7599ac JH	549	}
4f7599ac JH	550
5385f52d JH	551	ret = peel_onion(name, len, sha1);
	552	if (!ret)
	553	return 0;
	554
9938af6a JH	555	ret = get_sha1_basic(name, len, sha1);
	556	if (!ret)
	557	return 0;
7dd45e15 JH	558
	559	/* It could be describe output that is "SOMETHING-gXXXX" */
	560	ret = get_describe_name(name, len, sha1);
	561	if (!ret)
	562	return 0;
	563
013f276e	564	return get_short_sha1(name, len, sha1, 0);
9938af6a JH	565	}
	566
	567	/*
	568	* This is like "get_sha1_basic()", except it allows "sha1 expressions",
	569	* notably "xyz^" for "parent of xyz"
	570	*/
	571	int get_sha1(const char name, unsigned char sha1)
	572	{
cce91a2c	573	int ret, bracket_depth;
041a7308	574	unsigned unused;
73b0e5af JH	575	int namelen = strlen(name);
73b0e5af JH	576	const char *cp;
5119602a	577
99a19b43	578	prepare_alt_odb();
73b0e5af JH	579	ret = get_sha1_1(name, namelen, sha1);
	580	if (!ret)
	581	return ret;
	582	/* sha1:path --> object name of path in ent sha1
	583	* :path -> object name of path in index
	584	* :[0-3]:path -> object name of path in index at stage
	585	*/
	586	if (name[0] == ':') {
	587	int stage = 0;
	588	struct cache_entry *ce;
	589	int pos;
	590	if (namelen < 3 \|\|
	591	name[2] != ':' \|\|
	592	name[1] < '0' \|\| '3' < name[1])
	593	cp = name + 1;
	594	else {
	595	stage = name[1] - '0';
	596	cp = name + 3;
5119602a	597	}
73b0e5af JH	598	namelen = namelen - (cp - name);
	599	if (!active_cache)
	600	read_cache();
	601	if (active_nr < 0)
	602	return -1;
	603	pos = cache_name_pos(cp, namelen);
	604	if (pos < 0)
	605	pos = -pos - 1;
	606	while (pos < active_nr) {
	607	ce = active_cache[pos];
	608	if (ce_namelen(ce) != namelen \|\|
	609	memcmp(ce->name, cp, namelen))
	610	break;
	611	if (ce_stage(ce) == stage) {
e702496e	612	hashcpy(sha1, ce->sha1);
73b0e5af JH	613	return 0;
73b0e5af JH	614	}
e7cef45f	615	pos++;
73b0e5af JH	616	}
	617	return -1;
	618	}
cce91a2c SP	619	for (cp = name, bracket_depth = 0; *cp; cp++) {
	620	if (*cp == '{')
	621	bracket_depth++;
	622	else if (bracket_depth && *cp == '}')
	623	bracket_depth--;
	624	else if (!bracket_depth && *cp == ':')
	625	break;
	626	}
	627	if (*cp == ':') {
73b0e5af JH	628	unsigned char tree_sha1[20];
	629	if (!get_sha1_1(name, cp-name, tree_sha1))
	630	return get_tree_entry(tree_sha1, cp+1, sha1,
	631	&unused);
5119602a LT	632	}
5119602a LT	633	return ret;
9938af6a	634	}