1 files changed, 214 insertions, 35 deletions

diff --git a/sha1_name.c b/sha1_name.c
index b4fed92..be1755a 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -1,33 +1,54 @@
 #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)
 {
-	static char dirname[PATH_MAX];
+	struct alternate_object_database *alt;
 	char hex[40];
-	DIR *dir;
-	int found;
+	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;
 
-	snprintf(dirname, sizeof(dirname), "%s/%.2s", get_object_directory(), name);
-	dir = opendir(dirname);
 	sprintf(hex, "%.2s", name);
-	found = 0;
-	if (dir) {
+	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))
+			if (memcmp(de->d_name, name + 2, len - 2))
 				continue;
-			memcpy(hex + 2, de->d_name, 38);
-			if (++found > 1)
+			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 0;
+	return found;
 }
 
 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
@@ -48,9 +69,11 @@ static int match_sha(unsigned len, const unsigned char *a, const unsigned char *
 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; p = p->next) {
+	for (p = packed_git; p && found < 2; p = p->next) {
 		unsigned num = num_packed_objects(p);
 		unsigned first = 0, last = num;
 		while (first < last) {
@@ -74,19 +97,61 @@ static int find_short_packed_object(int len, const unsigned char *match, unsigne
 			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)) {
-					memcpy(sha1, now, 20);
-					return 1;
+				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)
+static int get_short_sha1(const char *name, int len, unsigned char *sha1,
+			  int quietly)
 {
-	int i;
+	int i, status;
 	char canonical[40];
 	unsigned char res[20];
 
@@ -112,26 +177,53 @@ static int get_short_sha1(const char *name, int len, unsigned char *sha1)
 			val <<= 4;
 		res[i >> 1] |= val;
 	}
-	if (find_short_object_filename(i, canonical, sha1))
-		return 0;
-	if (find_short_packed_object(i, res, sha1))
-		return 0;
-	return -1;
+
+	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;
 }
 
-static int get_sha1_file(const char *path, unsigned char *result)
+const char *find_unique_abbrev(const unsigned char *sha1, int len)
 {
-	char buffer[60];
-	int fd = open(path, O_RDONLY);
-	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;
+}
 
-	if (fd < 0)
-		return -1;
-	len = read(fd, buffer, sizeof(buffer));
-	close(fd);
-	if (len < 40)
-		return -1;
-	return get_sha1_hex(buffer, result);
+static int ambiguous_path(const char *path)
+{
+	int slash = 1;
+
+	for (;;) {
+		switch (*path++) {
+		case '\0':
+			break;
+		case '/':
+			if (slash)
+				break;
+			slash = 1;
+			continue;
+		case '.':
+			continue;
+		default:
+			slash = 0;
+			continue;
+		}
+		return slash;
+	}
 }
 
 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
@@ -148,9 +240,13 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 	if (len == 40 && !get_sha1_hex(str, sha1))
 		return 0;
 
+	/* Accept only unambiguous ref paths. */
+	if (ambiguous_path(str))
+		return -1;
+
 	for (p = prefix; *p; p++) {
 		char *pathname = git_path("%s/%.*s", *p, len, str);
-		if (!get_sha1_file(pathname, sha1))
+		if (!read_ref(pathname, sha1))
 			return 0;
 	}
 
@@ -208,6 +304,84 @@ static int get_nth_ancestor(const char *name, int len,
 	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;
@@ -249,10 +423,14 @@ static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 		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);
+	return get_short_sha1(name, len, sha1, 0);
 }
 
 /*
@@ -261,5 +439,6 @@ static int get_sha1_1(const char *name, int len, unsigned char *sha1)
  */
 int get_sha1(const char *name, unsigned char *sha1)
 {
+	prepare_alt_odb();
 	return get_sha1_1(name, strlen(name), sha1);
 }