directory-rename-detection.txt: technical docs on abilities and limitations

diff --git a/builtin/pack-redundant.c b/builtin/pack-redundant.c
index 354478a12762d0b500cf7f56baf90ffc8d2b7c93..0494dceff73d672ee430f1c5bd0ce9f8b70c83f6 100644 (file)
--- a/builtin/pack-redundant.c
+++ b/builtin/pack-redundant.c
@@ -20,7 +20,7 @@ static int load_all_packs, verbose, alt_odb;
 
 struct llist_item {
        struct llist_item *next;
-       const unsigned char *sha1;
+       const struct object_id *oid;
 };
 static struct llist {
        struct llist_item *front;
@@ -90,14 +90,14 @@ static struct llist * llist_copy(struct llist *list)
                return ret;
 
        new_item = ret->front = llist_item_get();
-       new_item->sha1 = list->front->sha1;
+       new_item->oid = list->front->oid;
 
        old_item = list->front->next;
        while (old_item) {
                prev = new_item;
                new_item = llist_item_get();
                prev->next = new_item;
-               new_item->sha1 = old_item->sha1;
+               new_item->oid = old_item->oid;
                old_item = old_item->next;
        }
        new_item->next = NULL;
@@ -108,10 +108,10 @@ static struct llist * llist_copy(struct llist *list)
 
 static inline struct llist_item *llist_insert(struct llist *list,
                                              struct llist_item *after,
-                                              const unsigned char *sha1)
+                                             const struct object_id *oid)
 {
        struct llist_item *new_item = llist_item_get();
-       new_item->sha1 = sha1;
+       new_item->oid = oid;
        new_item->next = NULL;
 
        if (after != NULL) {
@@ -131,21 +131,21 @@ static inline struct llist_item *llist_insert(struct llist *list,
 }
 
 static inline struct llist_item *llist_insert_back(struct llist *list,
-                                                  const unsigned char *sha1)
+                                                  const struct object_id *oid)
 {
-       return llist_insert(list, list->back, sha1);
+       return llist_insert(list, list->back, oid);
 }
 
 static inline struct llist_item *llist_insert_sorted_unique(struct llist *list,
-                       const unsigned char *sha1, struct llist_item *hint)
+                       const struct object_id *oid, struct llist_item *hint)
 {
        struct llist_item *prev = NULL, *l;
 
        l = (hint == NULL) ? list->front : hint;
        while (l) {
-               int cmp = hashcmp(l->sha1, sha1);
+               int cmp = oidcmp(l->oid, oid);
                if (cmp > 0) { /* we insert before this entry */
-                       return llist_insert(list, prev, sha1);
+                       return llist_insert(list, prev, oid);
                }
                if (!cmp) { /* already exists */
                        return l;
@@ -154,11 +154,11 @@ static inline struct llist_item *llist_insert_sorted_unique(struct llist *list,
                l = l->next;
        }
        /* insert at the end */
-       return llist_insert_back(list, sha1);
+       return llist_insert_back(list, oid);
 }
 
 /* returns a pointer to an item in front of sha1 */
-static inline struct llist_item * llist_sorted_remove(struct llist *list, const unsigned char *sha1, struct llist_item *hint)
+static inline struct llist_item * llist_sorted_remove(struct llist *list, const struct object_id *oid, struct llist_item *hint)
 {
        struct llist_item *prev, *l;
 
@@ -166,7 +166,7 @@ static inline struct llist_item * llist_sorted_remove(struct llist *list, const
        l = (hint == NULL) ? list->front : hint;
        prev = NULL;
        while (l) {
-               int cmp = hashcmp(l->sha1, sha1);
+               int cmp = oidcmp(l->oid, oid);
                if (cmp > 0) /* not in list, since sorted */
                        return prev;
                if (!cmp) { /* found */
@@ -201,7 +201,7 @@ static void llist_sorted_difference_inplace(struct llist *A,
        b = B->front;
 
        while (b) {
-               hint = llist_sorted_remove(A, b->sha1, hint);
+               hint = llist_sorted_remove(A, b->oid, hint);
                b = b->next;
        }
 }
@@ -252,13 +252,14 @@ static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
        unsigned long p1_off = 0, p2_off = 0, p1_step, p2_step;
        const unsigned char *p1_base, *p2_base;
        struct llist_item *p1_hint = NULL, *p2_hint = NULL;
+       const unsigned int hashsz = the_hash_algo->rawsz;
 
        p1_base = p1->pack->index_data;
        p2_base = p2->pack->index_data;
        p1_base += 256 * 4 + ((p1->pack->index_version < 2) ? 4 : 8);
        p2_base += 256 * 4 + ((p2->pack->index_version < 2) ? 4 : 8);
-       p1_step = (p1->pack->index_version < 2) ? 24 : 20;
-       p2_step = (p2->pack->index_version < 2) ? 24 : 20;
+       p1_step = hashsz + ((p1->pack->index_version < 2) ? 4 : 0);
+       p2_step = hashsz + ((p2->pack->index_version < 2) ? 4 : 0);
 
        while (p1_off < p1->pack->num_objects * p1_step &&
               p2_off < p2->pack->num_objects * p2_step)
@@ -267,9 +268,11 @@ static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
                /* cmp ~ p1 - p2 */
                if (cmp == 0) {
                        p1_hint = llist_sorted_remove(p1->unique_objects,
-                                       p1_base + p1_off, p1_hint);
+                                       (const struct object_id *)(p1_base + p1_off),
+                                       p1_hint);
                        p2_hint = llist_sorted_remove(p2->unique_objects,
-                                       p1_base + p1_off, p2_hint);
+                                       (const struct object_id *)(p1_base + p1_off),
+                                       p2_hint);
                        p1_off += p1_step;
                        p2_off += p2_step;
                        continue;
@@ -359,13 +362,14 @@ static size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
        size_t ret = 0;
        unsigned long p1_off = 0, p2_off = 0, p1_step, p2_step;
        const unsigned char *p1_base, *p2_base;
+       const unsigned int hashsz = the_hash_algo->rawsz;
 
        p1_base = p1->index_data;
        p2_base = p2->index_data;
        p1_base += 256 * 4 + ((p1->index_version < 2) ? 4 : 8);
        p2_base += 256 * 4 + ((p2->index_version < 2) ? 4 : 8);
-       p1_step = (p1->index_version < 2) ? 24 : 20;
-       p2_step = (p2->index_version < 2) ? 24 : 20;
+       p1_step = hashsz + ((p1->index_version < 2) ? 4 : 0);
+       p2_step = hashsz + ((p2->index_version < 2) ? 4 : 0);
 
        while (p1_off < p1->num_objects * p1_step &&
               p2_off < p2->num_objects * p2_step)
@@ -499,7 +503,7 @@ static void load_all_objects(void)
                l = pl->all_objects->front;
                while (l) {
                        hint = llist_insert_sorted_unique(all_objects,
-                                                         l->sha1, hint);
+                                                         l->oid, hint);
                        l = l->next;
                }
                pl = pl->next;
@@ -558,9 +562,9 @@ static struct pack_list * add_pack(struct packed_git *p)
 
        base = p->index_data;
        base += 256 * 4 + ((p->index_version < 2) ? 4 : 8);
-       step = (p->index_version < 2) ? 24 : 20;
+       step = the_hash_algo->rawsz + ((p->index_version < 2) ? 4 : 0);
        while (off < p->num_objects * step) {
-               llist_insert_back(l.all_objects, base + off);
+               llist_insert_back(l.all_objects, (const struct object_id *)(base + off));
                off += step;
        }
        /* this list will be pruned in cmp_two_packs later */
@@ -601,8 +605,8 @@ int cmd_pack_redundant(int argc, const char **argv, const char *prefix)
        int i;
        struct pack_list *min, *red, *pl;
        struct llist *ignore;
-       unsigned char *sha1;
-       char buf[42]; /* 40 byte sha1 + \n + \0 */
+       struct object_id *oid;
+       char buf[GIT_MAX_HEXSZ + 2]; /* hex hash + \n + \0 */
 
        if (argc == 2 && !strcmp(argv[1], "-h"))
                usage(pack_redundant_usage);
@@ -650,10 +654,10 @@ int cmd_pack_redundant(int argc, const char **argv, const char *prefix)
        llist_init(&ignore);
        if (!isatty(0)) {
                while (fgets(buf, sizeof(buf), stdin)) {
-                       sha1 = xmalloc(20);
-                       if (get_sha1_hex(buf, sha1))
-                               die("Bad sha1 on stdin: %s", buf);
-                       llist_insert_sorted_unique(ignore, sha1, NULL);
+                       oid = xmalloc(sizeof(*oid));
+                       if (get_oid_hex(buf, oid))
+                               die("Bad object ID on stdin: %s", buf);
+                       llist_insert_sorted_unique(ignore, oid, NULL);
                }
        }
        llist_sorted_difference_inplace(all_objects, ignore);