notes.con commit builtin/rebase.c: Remove pointless message (bf1e28e)
   1#include "cache.h"
   2#include "config.h"
   3#include "notes.h"
   4#include "object-store.h"
   5#include "blob.h"
   6#include "tree.h"
   7#include "utf8.h"
   8#include "strbuf.h"
   9#include "tree-walk.h"
  10#include "string-list.h"
  11#include "refs.h"
  12
  13/*
  14 * Use a non-balancing simple 16-tree structure with struct int_node as
  15 * internal nodes, and struct leaf_node as leaf nodes. Each int_node has a
  16 * 16-array of pointers to its children.
  17 * The bottom 2 bits of each pointer is used to identify the pointer type
  18 * - ptr & 3 == 0 - NULL pointer, assert(ptr == NULL)
  19 * - ptr & 3 == 1 - pointer to next internal node - cast to struct int_node *
  20 * - ptr & 3 == 2 - pointer to note entry - cast to struct leaf_node *
  21 * - ptr & 3 == 3 - pointer to subtree entry - cast to struct leaf_node *
  22 *
  23 * The root node is a statically allocated struct int_node.
  24 */
  25struct int_node {
  26        void *a[16];
  27};
  28
  29/*
  30 * Leaf nodes come in two variants, note entries and subtree entries,
  31 * distinguished by the LSb of the leaf node pointer (see above).
  32 * As a note entry, the key is the SHA1 of the referenced object, and the
  33 * value is the SHA1 of the note object.
  34 * As a subtree entry, the key is the prefix SHA1 (w/trailing NULs) of the
  35 * referenced object, using the last byte of the key to store the length of
  36 * the prefix. The value is the SHA1 of the tree object containing the notes
  37 * subtree.
  38 */
  39struct leaf_node {
  40        struct object_id key_oid;
  41        struct object_id val_oid;
  42};
  43
  44/*
  45 * A notes tree may contain entries that are not notes, and that do not follow
  46 * the naming conventions of notes. There are typically none/few of these, but
  47 * we still need to keep track of them. Keep a simple linked list sorted alpha-
  48 * betically on the non-note path. The list is populated when parsing tree
  49 * objects in load_subtree(), and the non-notes are correctly written back into
  50 * the tree objects produced by write_notes_tree().
  51 */
  52struct non_note {
  53        struct non_note *next; /* grounded (last->next == NULL) */
  54        char *path;
  55        unsigned int mode;
  56        struct object_id oid;
  57};
  58
  59#define PTR_TYPE_NULL     0
  60#define PTR_TYPE_INTERNAL 1
  61#define PTR_TYPE_NOTE     2
  62#define PTR_TYPE_SUBTREE  3
  63
  64#define GET_PTR_TYPE(ptr)       ((uintptr_t) (ptr) & 3)
  65#define CLR_PTR_TYPE(ptr)       ((void *) ((uintptr_t) (ptr) & ~3))
  66#define SET_PTR_TYPE(ptr, type) ((void *) ((uintptr_t) (ptr) | (type)))
  67
  68#define GET_NIBBLE(n, sha1) ((((sha1)[(n) >> 1]) >> ((~(n) & 0x01) << 2)) & 0x0f)
  69
  70#define KEY_INDEX (the_hash_algo->rawsz - 1)
  71#define FANOUT_PATH_SEPARATORS (the_hash_algo->rawsz - 1)
  72#define FANOUT_PATH_SEPARATORS_MAX ((GIT_MAX_HEXSZ / 2) - 1)
  73#define SUBTREE_SHA1_PREFIXCMP(key_sha1, subtree_sha1) \
  74        (memcmp(key_sha1, subtree_sha1, subtree_sha1[KEY_INDEX]))
  75
  76struct notes_tree default_notes_tree;
  77
  78static struct string_list display_notes_refs = STRING_LIST_INIT_NODUP;
  79static struct notes_tree **display_notes_trees;
  80
  81static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,
  82                struct int_node *node, unsigned int n);
  83
  84/*
  85 * Search the tree until the appropriate location for the given key is found:
  86 * 1. Start at the root node, with n = 0
  87 * 2. If a[0] at the current level is a matching subtree entry, unpack that
  88 *    subtree entry and remove it; restart search at the current level.
  89 * 3. Use the nth nibble of the key as an index into a:
  90 *    - If a[n] is an int_node, recurse from #2 into that node and increment n
  91 *    - If a matching subtree entry, unpack that subtree entry (and remove it);
  92 *      restart search at the current level.
  93 *    - Otherwise, we have found one of the following:
  94 *      - a subtree entry which does not match the key
  95 *      - a note entry which may or may not match the key
  96 *      - an unused leaf node (NULL)
  97 *      In any case, set *tree and *n, and return pointer to the tree location.
  98 */
  99static void **note_tree_search(struct notes_tree *t, struct int_node **tree,
 100                unsigned char *n, const unsigned char *key_sha1)
 101{
 102        struct leaf_node *l;
 103        unsigned char i;
 104        void *p = (*tree)->a[0];
 105
 106        if (GET_PTR_TYPE(p) == PTR_TYPE_SUBTREE) {
 107                l = (struct leaf_node *) CLR_PTR_TYPE(p);
 108                if (!SUBTREE_SHA1_PREFIXCMP(key_sha1, l->key_oid.hash)) {
 109                        /* unpack tree and resume search */
 110                        (*tree)->a[0] = NULL;
 111                        load_subtree(t, l, *tree, *n);
 112                        free(l);
 113                        return note_tree_search(t, tree, n, key_sha1);
 114                }
 115        }
 116
 117        i = GET_NIBBLE(*n, key_sha1);
 118        p = (*tree)->a[i];
 119        switch (GET_PTR_TYPE(p)) {
 120        case PTR_TYPE_INTERNAL:
 121                *tree = CLR_PTR_TYPE(p);
 122                (*n)++;
 123                return note_tree_search(t, tree, n, key_sha1);
 124        case PTR_TYPE_SUBTREE:
 125                l = (struct leaf_node *) CLR_PTR_TYPE(p);
 126                if (!SUBTREE_SHA1_PREFIXCMP(key_sha1, l->key_oid.hash)) {
 127                        /* unpack tree and resume search */
 128                        (*tree)->a[i] = NULL;
 129                        load_subtree(t, l, *tree, *n);
 130                        free(l);
 131                        return note_tree_search(t, tree, n, key_sha1);
 132                }
 133                /* fall through */
 134        default:
 135                return &((*tree)->a[i]);
 136        }
 137}
 138
 139/*
 140 * To find a leaf_node:
 141 * Search to the tree location appropriate for the given key:
 142 * If a note entry with matching key, return the note entry, else return NULL.
 143 */
 144static struct leaf_node *note_tree_find(struct notes_tree *t,
 145                struct int_node *tree, unsigned char n,
 146                const unsigned char *key_sha1)
 147{
 148        void **p = note_tree_search(t, &tree, &n, key_sha1);
 149        if (GET_PTR_TYPE(*p) == PTR_TYPE_NOTE) {
 150                struct leaf_node *l = (struct leaf_node *) CLR_PTR_TYPE(*p);
 151                if (hasheq(key_sha1, l->key_oid.hash))
 152                        return l;
 153        }
 154        return NULL;
 155}
 156
 157/*
 158 * How to consolidate an int_node:
 159 * If there are > 1 non-NULL entries, give up and return non-zero.
 160 * Otherwise replace the int_node at the given index in the given parent node
 161 * with the only NOTE entry (or a NULL entry if no entries) from the given
 162 * tree, and return 0.
 163 */
 164static int note_tree_consolidate(struct int_node *tree,
 165        struct int_node *parent, unsigned char index)
 166{
 167        unsigned int i;
 168        void *p = NULL;
 169
 170        assert(tree && parent);
 171        assert(CLR_PTR_TYPE(parent->a[index]) == tree);
 172
 173        for (i = 0; i < 16; i++) {
 174                if (GET_PTR_TYPE(tree->a[i]) != PTR_TYPE_NULL) {
 175                        if (p) /* more than one entry */
 176                                return -2;
 177                        p = tree->a[i];
 178                }
 179        }
 180
 181        if (p && (GET_PTR_TYPE(p) != PTR_TYPE_NOTE))
 182                return -2;
 183        /* replace tree with p in parent[index] */
 184        parent->a[index] = p;
 185        free(tree);
 186        return 0;
 187}
 188
 189/*
 190 * To remove a leaf_node:
 191 * Search to the tree location appropriate for the given leaf_node's key:
 192 * - If location does not hold a matching entry, abort and do nothing.
 193 * - Copy the matching entry's value into the given entry.
 194 * - Replace the matching leaf_node with a NULL entry (and free the leaf_node).
 195 * - Consolidate int_nodes repeatedly, while walking up the tree towards root.
 196 */
 197static void note_tree_remove(struct notes_tree *t,
 198                struct int_node *tree, unsigned char n,
 199                struct leaf_node *entry)
 200{
 201        struct leaf_node *l;
 202        struct int_node *parent_stack[GIT_MAX_RAWSZ];
 203        unsigned char i, j;
 204        void **p = note_tree_search(t, &tree, &n, entry->key_oid.hash);
 205
 206        assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
 207        if (GET_PTR_TYPE(*p) != PTR_TYPE_NOTE)
 208                return; /* type mismatch, nothing to remove */
 209        l = (struct leaf_node *) CLR_PTR_TYPE(*p);
 210        if (!oideq(&l->key_oid, &entry->key_oid))
 211                return; /* key mismatch, nothing to remove */
 212
 213        /* we have found a matching entry */
 214        oidcpy(&entry->val_oid, &l->val_oid);
 215        free(l);
 216        *p = SET_PTR_TYPE(NULL, PTR_TYPE_NULL);
 217
 218        /* consolidate this tree level, and parent levels, if possible */
 219        if (!n)
 220                return; /* cannot consolidate top level */
 221        /* first, build stack of ancestors between root and current node */
 222        parent_stack[0] = t->root;
 223        for (i = 0; i < n; i++) {
 224                j = GET_NIBBLE(i, entry->key_oid.hash);
 225                parent_stack[i + 1] = CLR_PTR_TYPE(parent_stack[i]->a[j]);
 226        }
 227        assert(i == n && parent_stack[i] == tree);
 228        /* next, unwind stack until note_tree_consolidate() is done */
 229        while (i > 0 &&
 230               !note_tree_consolidate(parent_stack[i], parent_stack[i - 1],
 231                                      GET_NIBBLE(i - 1, entry->key_oid.hash)))
 232                i--;
 233}
 234
 235/*
 236 * To insert a leaf_node:
 237 * Search to the tree location appropriate for the given leaf_node's key:
 238 * - If location is unused (NULL), store the tweaked pointer directly there
 239 * - If location holds a note entry that matches the note-to-be-inserted, then
 240 *   combine the two notes (by calling the given combine_notes function).
 241 * - If location holds a note entry that matches the subtree-to-be-inserted,
 242 *   then unpack the subtree-to-be-inserted into the location.
 243 * - If location holds a matching subtree entry, unpack the subtree at that
 244 *   location, and restart the insert operation from that level.
 245 * - Else, create a new int_node, holding both the node-at-location and the
 246 *   node-to-be-inserted, and store the new int_node into the location.
 247 */
 248static int note_tree_insert(struct notes_tree *t, struct int_node *tree,
 249                unsigned char n, struct leaf_node *entry, unsigned char type,
 250                combine_notes_fn combine_notes)
 251{
 252        struct int_node *new_node;
 253        struct leaf_node *l;
 254        void **p = note_tree_search(t, &tree, &n, entry->key_oid.hash);
 255        int ret = 0;
 256
 257        assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
 258        l = (struct leaf_node *) CLR_PTR_TYPE(*p);
 259        switch (GET_PTR_TYPE(*p)) {
 260        case PTR_TYPE_NULL:
 261                assert(!*p);
 262                if (is_null_oid(&entry->val_oid))
 263                        free(entry);
 264                else
 265                        *p = SET_PTR_TYPE(entry, type);
 266                return 0;
 267        case PTR_TYPE_NOTE:
 268                switch (type) {
 269                case PTR_TYPE_NOTE:
 270                        if (oideq(&l->key_oid, &entry->key_oid)) {
 271                                /* skip concatenation if l == entry */
 272                                if (oideq(&l->val_oid, &entry->val_oid))
 273                                        return 0;
 274
 275                                ret = combine_notes(&l->val_oid,
 276                                                    &entry->val_oid);
 277                                if (!ret && is_null_oid(&l->val_oid))
 278                                        note_tree_remove(t, tree, n, entry);
 279                                free(entry);
 280                                return ret;
 281                        }
 282                        break;
 283                case PTR_TYPE_SUBTREE:
 284                        if (!SUBTREE_SHA1_PREFIXCMP(l->key_oid.hash,
 285                                                    entry->key_oid.hash)) {
 286                                /* unpack 'entry' */
 287                                load_subtree(t, entry, tree, n);
 288                                free(entry);
 289                                return 0;
 290                        }
 291                        break;
 292                }
 293                break;
 294        case PTR_TYPE_SUBTREE:
 295                if (!SUBTREE_SHA1_PREFIXCMP(entry->key_oid.hash, l->key_oid.hash)) {
 296                        /* unpack 'l' and restart insert */
 297                        *p = NULL;
 298                        load_subtree(t, l, tree, n);
 299                        free(l);
 300                        return note_tree_insert(t, tree, n, entry, type,
 301                                                combine_notes);
 302                }
 303                break;
 304        }
 305
 306        /* non-matching leaf_node */
 307        assert(GET_PTR_TYPE(*p) == PTR_TYPE_NOTE ||
 308               GET_PTR_TYPE(*p) == PTR_TYPE_SUBTREE);
 309        if (is_null_oid(&entry->val_oid)) { /* skip insertion of empty note */
 310                free(entry);
 311                return 0;
 312        }
 313        new_node = (struct int_node *) xcalloc(1, sizeof(struct int_node));
 314        ret = note_tree_insert(t, new_node, n + 1, l, GET_PTR_TYPE(*p),
 315                               combine_notes);
 316        if (ret)
 317                return ret;
 318        *p = SET_PTR_TYPE(new_node, PTR_TYPE_INTERNAL);
 319        return note_tree_insert(t, new_node, n + 1, entry, type, combine_notes);
 320}
 321
 322/* Free the entire notes data contained in the given tree */
 323static void note_tree_free(struct int_node *tree)
 324{
 325        unsigned int i;
 326        for (i = 0; i < 16; i++) {
 327                void *p = tree->a[i];
 328                switch (GET_PTR_TYPE(p)) {
 329                case PTR_TYPE_INTERNAL:
 330                        note_tree_free(CLR_PTR_TYPE(p));
 331                        /* fall through */
 332                case PTR_TYPE_NOTE:
 333                case PTR_TYPE_SUBTREE:
 334                        free(CLR_PTR_TYPE(p));
 335                }
 336        }
 337}
 338
 339static int non_note_cmp(const struct non_note *a, const struct non_note *b)
 340{
 341        return strcmp(a->path, b->path);
 342}
 343
 344/* note: takes ownership of path string */
 345static void add_non_note(struct notes_tree *t, char *path,
 346                unsigned int mode, const unsigned char *sha1)
 347{
 348        struct non_note *p = t->prev_non_note, *n;
 349        n = (struct non_note *) xmalloc(sizeof(struct non_note));
 350        n->next = NULL;
 351        n->path = path;
 352        n->mode = mode;
 353        hashcpy(n->oid.hash, sha1);
 354        t->prev_non_note = n;
 355
 356        if (!t->first_non_note) {
 357                t->first_non_note = n;
 358                return;
 359        }
 360
 361        if (non_note_cmp(p, n) < 0)
 362                ; /* do nothing  */
 363        else if (non_note_cmp(t->first_non_note, n) <= 0)
 364                p = t->first_non_note;
 365        else {
 366                /* n sorts before t->first_non_note */
 367                n->next = t->first_non_note;
 368                t->first_non_note = n;
 369                return;
 370        }
 371
 372        /* n sorts equal or after p */
 373        while (p->next && non_note_cmp(p->next, n) <= 0)
 374                p = p->next;
 375
 376        if (non_note_cmp(p, n) == 0) { /* n ~= p; overwrite p with n */
 377                assert(strcmp(p->path, n->path) == 0);
 378                p->mode = n->mode;
 379                oidcpy(&p->oid, &n->oid);
 380                free(n);
 381                t->prev_non_note = p;
 382                return;
 383        }
 384
 385        /* n sorts between p and p->next */
 386        n->next = p->next;
 387        p->next = n;
 388}
 389
 390static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,
 391                struct int_node *node, unsigned int n)
 392{
 393        struct object_id object_oid;
 394        size_t prefix_len;
 395        void *buf;
 396        struct tree_desc desc;
 397        struct name_entry entry;
 398        const unsigned hashsz = the_hash_algo->rawsz;
 399
 400        buf = fill_tree_descriptor(the_repository, &desc, &subtree->val_oid);
 401        if (!buf)
 402                die("Could not read %s for notes-index",
 403                     oid_to_hex(&subtree->val_oid));
 404
 405        prefix_len = subtree->key_oid.hash[KEY_INDEX];
 406        if (prefix_len >= hashsz)
 407                BUG("prefix_len (%"PRIuMAX") is out of range", (uintmax_t)prefix_len);
 408        if (prefix_len * 2 < n)
 409                BUG("prefix_len (%"PRIuMAX") is too small", (uintmax_t)prefix_len);
 410        memcpy(object_oid.hash, subtree->key_oid.hash, prefix_len);
 411        while (tree_entry(&desc, &entry)) {
 412                unsigned char type;
 413                struct leaf_node *l;
 414                size_t path_len = strlen(entry.path);
 415
 416                if (path_len == 2 * (hashsz - prefix_len)) {
 417                        /* This is potentially the remainder of the SHA-1 */
 418
 419                        if (!S_ISREG(entry.mode))
 420                                /* notes must be blobs */
 421                                goto handle_non_note;
 422
 423                        if (hex_to_bytes(object_oid.hash + prefix_len, entry.path,
 424                                         hashsz - prefix_len))
 425                                goto handle_non_note; /* entry.path is not a SHA1 */
 426
 427                        type = PTR_TYPE_NOTE;
 428                } else if (path_len == 2) {
 429                        /* This is potentially an internal node */
 430                        size_t len = prefix_len;
 431
 432                        if (!S_ISDIR(entry.mode))
 433                                /* internal nodes must be trees */
 434                                goto handle_non_note;
 435
 436                        if (hex_to_bytes(object_oid.hash + len++, entry.path, 1))
 437                                goto handle_non_note; /* entry.path is not a SHA1 */
 438
 439                        /*
 440                         * Pad the rest of the SHA-1 with zeros,
 441                         * except for the last byte, where we write
 442                         * the length:
 443                         */
 444                        memset(object_oid.hash + len, 0, hashsz - len - 1);
 445                        object_oid.hash[KEY_INDEX] = (unsigned char)len;
 446
 447                        type = PTR_TYPE_SUBTREE;
 448                } else {
 449                        /* This can't be part of a note */
 450                        goto handle_non_note;
 451                }
 452
 453                l = xcalloc(1, sizeof(*l));
 454                oidcpy(&l->key_oid, &object_oid);
 455                oidcpy(&l->val_oid, &entry.oid);
 456                if (note_tree_insert(t, node, n, l, type,
 457                                     combine_notes_concatenate))
 458                        die("Failed to load %s %s into notes tree "
 459                            "from %s",
 460                            type == PTR_TYPE_NOTE ? "note" : "subtree",
 461                            oid_to_hex(&l->key_oid), t->ref);
 462
 463                continue;
 464
 465handle_non_note:
 466                /*
 467                 * Determine full path for this non-note entry. The
 468                 * filename is already found in entry.path, but the
 469                 * directory part of the path must be deduced from the
 470                 * subtree containing this entry based on our
 471                 * knowledge that the overall notes tree follows a
 472                 * strict byte-based progressive fanout structure
 473                 * (i.e. using 2/38, 2/2/36, etc. fanouts).
 474                 */
 475                {
 476                        struct strbuf non_note_path = STRBUF_INIT;
 477                        const char *q = oid_to_hex(&subtree->key_oid);
 478                        size_t i;
 479                        for (i = 0; i < prefix_len; i++) {
 480                                strbuf_addch(&non_note_path, *q++);
 481                                strbuf_addch(&non_note_path, *q++);
 482                                strbuf_addch(&non_note_path, '/');
 483                        }
 484                        strbuf_addstr(&non_note_path, entry.path);
 485                        add_non_note(t, strbuf_detach(&non_note_path, NULL),
 486                                     entry.mode, entry.oid.hash);
 487                }
 488        }
 489        free(buf);
 490}
 491
 492/*
 493 * Determine optimal on-disk fanout for this part of the notes tree
 494 *
 495 * Given a (sub)tree and the level in the internal tree structure, determine
 496 * whether or not the given existing fanout should be expanded for this
 497 * (sub)tree.
 498 *
 499 * Values of the 'fanout' variable:
 500 * - 0: No fanout (all notes are stored directly in the root notes tree)
 501 * - 1: 2/38 fanout
 502 * - 2: 2/2/36 fanout
 503 * - 3: 2/2/2/34 fanout
 504 * etc.
 505 */
 506static unsigned char determine_fanout(struct int_node *tree, unsigned char n,
 507                unsigned char fanout)
 508{
 509        /*
 510         * The following is a simple heuristic that works well in practice:
 511         * For each even-numbered 16-tree level (remember that each on-disk
 512         * fanout level corresponds to _two_ 16-tree levels), peek at all 16
 513         * entries at that tree level. If all of them are either int_nodes or
 514         * subtree entries, then there are likely plenty of notes below this
 515         * level, so we return an incremented fanout.
 516         */
 517        unsigned int i;
 518        if ((n % 2) || (n > 2 * fanout))
 519                return fanout;
 520        for (i = 0; i < 16; i++) {
 521                switch (GET_PTR_TYPE(tree->a[i])) {
 522                case PTR_TYPE_SUBTREE:
 523                case PTR_TYPE_INTERNAL:
 524                        continue;
 525                default:
 526                        return fanout;
 527                }
 528        }
 529        return fanout + 1;
 530}
 531
 532/* hex oid + '/' between each pair of hex digits + NUL */
 533#define FANOUT_PATH_MAX GIT_MAX_HEXSZ + FANOUT_PATH_SEPARATORS_MAX + 1
 534
 535static void construct_path_with_fanout(const unsigned char *hash,
 536                unsigned char fanout, char *path)
 537{
 538        unsigned int i = 0, j = 0;
 539        const char *hex_hash = hash_to_hex(hash);
 540        assert(fanout < the_hash_algo->rawsz);
 541        while (fanout) {
 542                path[i++] = hex_hash[j++];
 543                path[i++] = hex_hash[j++];
 544                path[i++] = '/';
 545                fanout--;
 546        }
 547        xsnprintf(path + i, FANOUT_PATH_MAX - i, "%s", hex_hash + j);
 548}
 549
 550static int for_each_note_helper(struct notes_tree *t, struct int_node *tree,
 551                unsigned char n, unsigned char fanout, int flags,
 552                each_note_fn fn, void *cb_data)
 553{
 554        unsigned int i;
 555        void *p;
 556        int ret = 0;
 557        struct leaf_node *l;
 558        static char path[FANOUT_PATH_MAX];
 559
 560        fanout = determine_fanout(tree, n, fanout);
 561        for (i = 0; i < 16; i++) {
 562redo:
 563                p = tree->a[i];
 564                switch (GET_PTR_TYPE(p)) {
 565                case PTR_TYPE_INTERNAL:
 566                        /* recurse into int_node */
 567                        ret = for_each_note_helper(t, CLR_PTR_TYPE(p), n + 1,
 568                                fanout, flags, fn, cb_data);
 569                        break;
 570                case PTR_TYPE_SUBTREE:
 571                        l = (struct leaf_node *) CLR_PTR_TYPE(p);
 572                        /*
 573                         * Subtree entries in the note tree represent parts of
 574                         * the note tree that have not yet been explored. There
 575                         * is a direct relationship between subtree entries at
 576                         * level 'n' in the tree, and the 'fanout' variable:
 577                         * Subtree entries at level 'n <= 2 * fanout' should be
 578                         * preserved, since they correspond exactly to a fanout
 579                         * directory in the on-disk structure. However, subtree
 580                         * entries at level 'n > 2 * fanout' should NOT be
 581                         * preserved, but rather consolidated into the above
 582                         * notes tree level. We achieve this by unconditionally
 583                         * unpacking subtree entries that exist below the
 584                         * threshold level at 'n = 2 * fanout'.
 585                         */
 586                        if (n <= 2 * fanout &&
 587                            flags & FOR_EACH_NOTE_YIELD_SUBTREES) {
 588                                /* invoke callback with subtree */
 589                                unsigned int path_len =
 590                                        l->key_oid.hash[KEY_INDEX] * 2 + fanout;
 591                                assert(path_len < FANOUT_PATH_MAX - 1);
 592                                construct_path_with_fanout(l->key_oid.hash,
 593                                                           fanout,
 594                                                           path);
 595                                /* Create trailing slash, if needed */
 596                                if (path[path_len - 1] != '/')
 597                                        path[path_len++] = '/';
 598                                path[path_len] = '\0';
 599                                ret = fn(&l->key_oid, &l->val_oid,
 600                                         path,
 601                                         cb_data);
 602                        }
 603                        if (n > fanout * 2 ||
 604                            !(flags & FOR_EACH_NOTE_DONT_UNPACK_SUBTREES)) {
 605                                /* unpack subtree and resume traversal */
 606                                tree->a[i] = NULL;
 607                                load_subtree(t, l, tree, n);
 608                                free(l);
 609                                goto redo;
 610                        }
 611                        break;
 612                case PTR_TYPE_NOTE:
 613                        l = (struct leaf_node *) CLR_PTR_TYPE(p);
 614                        construct_path_with_fanout(l->key_oid.hash, fanout,
 615                                                   path);
 616                        ret = fn(&l->key_oid, &l->val_oid, path,
 617                                 cb_data);
 618                        break;
 619                }
 620                if (ret)
 621                        return ret;
 622        }
 623        return 0;
 624}
 625
 626struct tree_write_stack {
 627        struct tree_write_stack *next;
 628        struct strbuf buf;
 629        char path[2]; /* path to subtree in next, if any */
 630};
 631
 632static inline int matches_tree_write_stack(struct tree_write_stack *tws,
 633                const char *full_path)
 634{
 635        return  full_path[0] == tws->path[0] &&
 636                full_path[1] == tws->path[1] &&
 637                full_path[2] == '/';
 638}
 639
 640static void write_tree_entry(struct strbuf *buf, unsigned int mode,
 641                const char *path, unsigned int path_len, const
 642                unsigned char *hash)
 643{
 644        strbuf_addf(buf, "%o %.*s%c", mode, path_len, path, '\0');
 645        strbuf_add(buf, hash, the_hash_algo->rawsz);
 646}
 647
 648static void tree_write_stack_init_subtree(struct tree_write_stack *tws,
 649                const char *path)
 650{
 651        struct tree_write_stack *n;
 652        assert(!tws->next);
 653        assert(tws->path[0] == '\0' && tws->path[1] == '\0');
 654        n = (struct tree_write_stack *)
 655                xmalloc(sizeof(struct tree_write_stack));
 656        n->next = NULL;
 657        strbuf_init(&n->buf, 256 * (32 + the_hash_algo->hexsz)); /* assume 256 entries per tree */
 658        n->path[0] = n->path[1] = '\0';
 659        tws->next = n;
 660        tws->path[0] = path[0];
 661        tws->path[1] = path[1];
 662}
 663
 664static int tree_write_stack_finish_subtree(struct tree_write_stack *tws)
 665{
 666        int ret;
 667        struct tree_write_stack *n = tws->next;
 668        struct object_id s;
 669        if (n) {
 670                ret = tree_write_stack_finish_subtree(n);
 671                if (ret)
 672                        return ret;
 673                ret = write_object_file(n->buf.buf, n->buf.len, tree_type, &s);
 674                if (ret)
 675                        return ret;
 676                strbuf_release(&n->buf);
 677                free(n);
 678                tws->next = NULL;
 679                write_tree_entry(&tws->buf, 040000, tws->path, 2, s.hash);
 680                tws->path[0] = tws->path[1] = '\0';
 681        }
 682        return 0;
 683}
 684
 685static int write_each_note_helper(struct tree_write_stack *tws,
 686                const char *path, unsigned int mode,
 687                const struct object_id *oid)
 688{
 689        size_t path_len = strlen(path);
 690        unsigned int n = 0;
 691        int ret;
 692
 693        /* Determine common part of tree write stack */
 694        while (tws && 3 * n < path_len &&
 695               matches_tree_write_stack(tws, path + 3 * n)) {
 696                n++;
 697                tws = tws->next;
 698        }
 699
 700        /* tws point to last matching tree_write_stack entry */
 701        ret = tree_write_stack_finish_subtree(tws);
 702        if (ret)
 703                return ret;
 704
 705        /* Start subtrees needed to satisfy path */
 706        while (3 * n + 2 < path_len && path[3 * n + 2] == '/') {
 707                tree_write_stack_init_subtree(tws, path + 3 * n);
 708                n++;
 709                tws = tws->next;
 710        }
 711
 712        /* There should be no more directory components in the given path */
 713        assert(memchr(path + 3 * n, '/', path_len - (3 * n)) == NULL);
 714
 715        /* Finally add given entry to the current tree object */
 716        write_tree_entry(&tws->buf, mode, path + 3 * n, path_len - (3 * n),
 717                         oid->hash);
 718
 719        return 0;
 720}
 721
 722struct write_each_note_data {
 723        struct tree_write_stack *root;
 724        struct non_note *next_non_note;
 725};
 726
 727static int write_each_non_note_until(const char *note_path,
 728                struct write_each_note_data *d)
 729{
 730        struct non_note *n = d->next_non_note;
 731        int cmp = 0, ret;
 732        while (n && (!note_path || (cmp = strcmp(n->path, note_path)) <= 0)) {
 733                if (note_path && cmp == 0)
 734                        ; /* do nothing, prefer note to non-note */
 735                else {
 736                        ret = write_each_note_helper(d->root, n->path, n->mode,
 737                                                     &n->oid);
 738                        if (ret)
 739                                return ret;
 740                }
 741                n = n->next;
 742        }
 743        d->next_non_note = n;
 744        return 0;
 745}
 746
 747static int write_each_note(const struct object_id *object_oid,
 748                const struct object_id *note_oid, char *note_path,
 749                void *cb_data)
 750{
 751        struct write_each_note_data *d =
 752                (struct write_each_note_data *) cb_data;
 753        size_t note_path_len = strlen(note_path);
 754        unsigned int mode = 0100644;
 755
 756        if (note_path[note_path_len - 1] == '/') {
 757                /* subtree entry */
 758                note_path_len--;
 759                note_path[note_path_len] = '\0';
 760                mode = 040000;
 761        }
 762        assert(note_path_len <= GIT_MAX_HEXSZ + FANOUT_PATH_SEPARATORS);
 763
 764        /* Weave non-note entries into note entries */
 765        return  write_each_non_note_until(note_path, d) ||
 766                write_each_note_helper(d->root, note_path, mode, note_oid);
 767}
 768
 769struct note_delete_list {
 770        struct note_delete_list *next;
 771        const unsigned char *sha1;
 772};
 773
 774static int prune_notes_helper(const struct object_id *object_oid,
 775                const struct object_id *note_oid, char *note_path,
 776                void *cb_data)
 777{
 778        struct note_delete_list **l = (struct note_delete_list **) cb_data;
 779        struct note_delete_list *n;
 780
 781        if (has_object_file(object_oid))
 782                return 0; /* nothing to do for this note */
 783
 784        /* failed to find object => prune this note */
 785        n = (struct note_delete_list *) xmalloc(sizeof(*n));
 786        n->next = *l;
 787        n->sha1 = object_oid->hash;
 788        *l = n;
 789        return 0;
 790}
 791
 792int combine_notes_concatenate(struct object_id *cur_oid,
 793                              const struct object_id *new_oid)
 794{
 795        char *cur_msg = NULL, *new_msg = NULL, *buf;
 796        unsigned long cur_len, new_len, buf_len;
 797        enum object_type cur_type, new_type;
 798        int ret;
 799
 800        /* read in both note blob objects */
 801        if (!is_null_oid(new_oid))
 802                new_msg = read_object_file(new_oid, &new_type, &new_len);
 803        if (!new_msg || !new_len || new_type != OBJ_BLOB) {
 804                free(new_msg);
 805                return 0;
 806        }
 807        if (!is_null_oid(cur_oid))
 808                cur_msg = read_object_file(cur_oid, &cur_type, &cur_len);
 809        if (!cur_msg || !cur_len || cur_type != OBJ_BLOB) {
 810                free(cur_msg);
 811                free(new_msg);
 812                oidcpy(cur_oid, new_oid);
 813                return 0;
 814        }
 815
 816        /* we will separate the notes by two newlines anyway */
 817        if (cur_msg[cur_len - 1] == '\n')
 818                cur_len--;
 819
 820        /* concatenate cur_msg and new_msg into buf */
 821        buf_len = cur_len + 2 + new_len;
 822        buf = (char *) xmalloc(buf_len);
 823        memcpy(buf, cur_msg, cur_len);
 824        buf[cur_len] = '\n';
 825        buf[cur_len + 1] = '\n';
 826        memcpy(buf + cur_len + 2, new_msg, new_len);
 827        free(cur_msg);
 828        free(new_msg);
 829
 830        /* create a new blob object from buf */
 831        ret = write_object_file(buf, buf_len, blob_type, cur_oid);
 832        free(buf);
 833        return ret;
 834}
 835
 836int combine_notes_overwrite(struct object_id *cur_oid,
 837                            const struct object_id *new_oid)
 838{
 839        oidcpy(cur_oid, new_oid);
 840        return 0;
 841}
 842
 843int combine_notes_ignore(struct object_id *cur_oid,
 844                         const struct object_id *new_oid)
 845{
 846        return 0;
 847}
 848
 849/*
 850 * Add the lines from the named object to list, with trailing
 851 * newlines removed.
 852 */
 853static int string_list_add_note_lines(struct string_list *list,
 854                                      const struct object_id *oid)
 855{
 856        char *data;
 857        unsigned long len;
 858        enum object_type t;
 859
 860        if (is_null_oid(oid))
 861                return 0;
 862
 863        /* read_sha1_file NUL-terminates */
 864        data = read_object_file(oid, &t, &len);
 865        if (t != OBJ_BLOB || !data || !len) {
 866                free(data);
 867                return t != OBJ_BLOB || !data;
 868        }
 869
 870        /*
 871         * If the last line of the file is EOL-terminated, this will
 872         * add an empty string to the list.  But it will be removed
 873         * later, along with any empty strings that came from empty
 874         * lines within the file.
 875         */
 876        string_list_split(list, data, '\n', -1);
 877        free(data);
 878        return 0;
 879}
 880
 881static int string_list_join_lines_helper(struct string_list_item *item,
 882                                         void *cb_data)
 883{
 884        struct strbuf *buf = cb_data;
 885        strbuf_addstr(buf, item->string);
 886        strbuf_addch(buf, '\n');
 887        return 0;
 888}
 889
 890int combine_notes_cat_sort_uniq(struct object_id *cur_oid,
 891                                const struct object_id *new_oid)
 892{
 893        struct string_list sort_uniq_list = STRING_LIST_INIT_DUP;
 894        struct strbuf buf = STRBUF_INIT;
 895        int ret = 1;
 896
 897        /* read both note blob objects into unique_lines */
 898        if (string_list_add_note_lines(&sort_uniq_list, cur_oid))
 899                goto out;
 900        if (string_list_add_note_lines(&sort_uniq_list, new_oid))
 901                goto out;
 902        string_list_remove_empty_items(&sort_uniq_list, 0);
 903        string_list_sort(&sort_uniq_list);
 904        string_list_remove_duplicates(&sort_uniq_list, 0);
 905
 906        /* create a new blob object from sort_uniq_list */
 907        if (for_each_string_list(&sort_uniq_list,
 908                                 string_list_join_lines_helper, &buf))
 909                goto out;
 910
 911        ret = write_object_file(buf.buf, buf.len, blob_type, cur_oid);
 912
 913out:
 914        strbuf_release(&buf);
 915        string_list_clear(&sort_uniq_list, 0);
 916        return ret;
 917}
 918
 919static int string_list_add_one_ref(const char *refname, const struct object_id *oid,
 920                                   int flag, void *cb)
 921{
 922        struct string_list *refs = cb;
 923        if (!unsorted_string_list_has_string(refs, refname))
 924                string_list_append(refs, refname);
 925        return 0;
 926}
 927
 928/*
 929 * The list argument must have strdup_strings set on it.
 930 */
 931void string_list_add_refs_by_glob(struct string_list *list, const char *glob)
 932{
 933        assert(list->strdup_strings);
 934        if (has_glob_specials(glob)) {
 935                for_each_glob_ref(string_list_add_one_ref, glob, list);
 936        } else {
 937                struct object_id oid;
 938                if (get_oid(glob, &oid))
 939                        warning("notes ref %s is invalid", glob);
 940                if (!unsorted_string_list_has_string(list, glob))
 941                        string_list_append(list, glob);
 942        }
 943}
 944
 945void string_list_add_refs_from_colon_sep(struct string_list *list,
 946                                         const char *globs)
 947{
 948        struct string_list split = STRING_LIST_INIT_NODUP;
 949        char *globs_copy = xstrdup(globs);
 950        int i;
 951
 952        string_list_split_in_place(&split, globs_copy, ':', -1);
 953        string_list_remove_empty_items(&split, 0);
 954
 955        for (i = 0; i < split.nr; i++)
 956                string_list_add_refs_by_glob(list, split.items[i].string);
 957
 958        string_list_clear(&split, 0);
 959        free(globs_copy);
 960}
 961
 962static int notes_display_config(const char *k, const char *v, void *cb)
 963{
 964        int *load_refs = cb;
 965
 966        if (*load_refs && !strcmp(k, "notes.displayref")) {
 967                if (!v)
 968                        config_error_nonbool(k);
 969                string_list_add_refs_by_glob(&display_notes_refs, v);
 970        }
 971
 972        return 0;
 973}
 974
 975const char *default_notes_ref(void)
 976{
 977        const char *notes_ref = NULL;
 978        if (!notes_ref)
 979                notes_ref = getenv(GIT_NOTES_REF_ENVIRONMENT);
 980        if (!notes_ref)
 981                notes_ref = notes_ref_name; /* value of core.notesRef config */
 982        if (!notes_ref)
 983                notes_ref = GIT_NOTES_DEFAULT_REF;
 984        return notes_ref;
 985}
 986
 987void init_notes(struct notes_tree *t, const char *notes_ref,
 988                combine_notes_fn combine_notes, int flags)
 989{
 990        struct object_id oid, object_oid;
 991        unsigned short mode;
 992        struct leaf_node root_tree;
 993
 994        if (!t)
 995                t = &default_notes_tree;
 996        assert(!t->initialized);
 997
 998        if (!notes_ref)
 999                notes_ref = default_notes_ref();
1000
1001        if (!combine_notes)
1002                combine_notes = combine_notes_concatenate;
1003
1004        t->root = (struct int_node *) xcalloc(1, sizeof(struct int_node));
1005        t->first_non_note = NULL;
1006        t->prev_non_note = NULL;
1007        t->ref = xstrdup_or_null(notes_ref);
1008        t->update_ref = (flags & NOTES_INIT_WRITABLE) ? t->ref : NULL;
1009        t->combine_notes = combine_notes;
1010        t->initialized = 1;
1011        t->dirty = 0;
1012
1013        if (flags & NOTES_INIT_EMPTY || !notes_ref ||
1014            get_oid_treeish(notes_ref, &object_oid))
1015                return;
1016        if (flags & NOTES_INIT_WRITABLE && read_ref(notes_ref, &object_oid))
1017                die("Cannot use notes ref %s", notes_ref);
1018        if (get_tree_entry(the_repository, &object_oid, "", &oid, &mode))
1019                die("Failed to read notes tree referenced by %s (%s)",
1020                    notes_ref, oid_to_hex(&object_oid));
1021
1022        oidclr(&root_tree.key_oid);
1023        oidcpy(&root_tree.val_oid, &oid);
1024        load_subtree(t, &root_tree, t->root, 0);
1025}
1026
1027struct notes_tree **load_notes_trees(struct string_list *refs, int flags)
1028{
1029        struct string_list_item *item;
1030        int counter = 0;
1031        struct notes_tree **trees;
1032        ALLOC_ARRAY(trees, refs->nr + 1);
1033        for_each_string_list_item(item, refs) {
1034                struct notes_tree *t = xcalloc(1, sizeof(struct notes_tree));
1035                init_notes(t, item->string, combine_notes_ignore, flags);
1036                trees[counter++] = t;
1037        }
1038        trees[counter] = NULL;
1039        return trees;
1040}
1041
1042void init_display_notes(struct display_notes_opt *opt)
1043{
1044        char *display_ref_env;
1045        int load_config_refs = 0;
1046        display_notes_refs.strdup_strings = 1;
1047
1048        assert(!display_notes_trees);
1049
1050        if (!opt || opt->use_default_notes > 0 ||
1051            (opt->use_default_notes == -1 && !opt->extra_notes_refs.nr)) {
1052                string_list_append(&display_notes_refs, default_notes_ref());
1053                display_ref_env = getenv(GIT_NOTES_DISPLAY_REF_ENVIRONMENT);
1054                if (display_ref_env) {
1055                        string_list_add_refs_from_colon_sep(&display_notes_refs,
1056                                                            display_ref_env);
1057                        load_config_refs = 0;
1058                } else
1059                        load_config_refs = 1;
1060        }
1061
1062        git_config(notes_display_config, &load_config_refs);
1063
1064        if (opt) {
1065                struct string_list_item *item;
1066                for_each_string_list_item(item, &opt->extra_notes_refs)
1067                        string_list_add_refs_by_glob(&display_notes_refs,
1068                                                     item->string);
1069        }
1070
1071        display_notes_trees = load_notes_trees(&display_notes_refs, 0);
1072        string_list_clear(&display_notes_refs, 0);
1073}
1074
1075int add_note(struct notes_tree *t, const struct object_id *object_oid,
1076                const struct object_id *note_oid, combine_notes_fn combine_notes)
1077{
1078        struct leaf_node *l;
1079
1080        if (!t)
1081                t = &default_notes_tree;
1082        assert(t->initialized);
1083        t->dirty = 1;
1084        if (!combine_notes)
1085                combine_notes = t->combine_notes;
1086        l = (struct leaf_node *) xmalloc(sizeof(struct leaf_node));
1087        oidcpy(&l->key_oid, object_oid);
1088        oidcpy(&l->val_oid, note_oid);
1089        return note_tree_insert(t, t->root, 0, l, PTR_TYPE_NOTE, combine_notes);
1090}
1091
1092int remove_note(struct notes_tree *t, const unsigned char *object_sha1)
1093{
1094        struct leaf_node l;
1095
1096        if (!t)
1097                t = &default_notes_tree;
1098        assert(t->initialized);
1099        hashcpy(l.key_oid.hash, object_sha1);
1100        oidclr(&l.val_oid);
1101        note_tree_remove(t, t->root, 0, &l);
1102        if (is_null_oid(&l.val_oid)) /* no note was removed */
1103                return 1;
1104        t->dirty = 1;
1105        return 0;
1106}
1107
1108const struct object_id *get_note(struct notes_tree *t,
1109                const struct object_id *oid)
1110{
1111        struct leaf_node *found;
1112
1113        if (!t)
1114                t = &default_notes_tree;
1115        assert(t->initialized);
1116        found = note_tree_find(t, t->root, 0, oid->hash);
1117        return found ? &found->val_oid : NULL;
1118}
1119
1120int for_each_note(struct notes_tree *t, int flags, each_note_fn fn,
1121                void *cb_data)
1122{
1123        if (!t)
1124                t = &default_notes_tree;
1125        assert(t->initialized);
1126        return for_each_note_helper(t, t->root, 0, 0, flags, fn, cb_data);
1127}
1128
1129int write_notes_tree(struct notes_tree *t, struct object_id *result)
1130{
1131        struct tree_write_stack root;
1132        struct write_each_note_data cb_data;
1133        int ret;
1134        int flags;
1135
1136        if (!t)
1137                t = &default_notes_tree;
1138        assert(t->initialized);
1139
1140        /* Prepare for traversal of current notes tree */
1141        root.next = NULL; /* last forward entry in list is grounded */
1142        strbuf_init(&root.buf, 256 * (32 + the_hash_algo->hexsz)); /* assume 256 entries */
1143        root.path[0] = root.path[1] = '\0';
1144        cb_data.root = &root;
1145        cb_data.next_non_note = t->first_non_note;
1146
1147        /* Write tree objects representing current notes tree */
1148        flags = FOR_EACH_NOTE_DONT_UNPACK_SUBTREES |
1149                FOR_EACH_NOTE_YIELD_SUBTREES;
1150        ret = for_each_note(t, flags, write_each_note, &cb_data) ||
1151              write_each_non_note_until(NULL, &cb_data) ||
1152              tree_write_stack_finish_subtree(&root) ||
1153              write_object_file(root.buf.buf, root.buf.len, tree_type, result);
1154        strbuf_release(&root.buf);
1155        return ret;
1156}
1157
1158void prune_notes(struct notes_tree *t, int flags)
1159{
1160        struct note_delete_list *l = NULL;
1161
1162        if (!t)
1163                t = &default_notes_tree;
1164        assert(t->initialized);
1165
1166        for_each_note(t, 0, prune_notes_helper, &l);
1167
1168        while (l) {
1169                if (flags & NOTES_PRUNE_VERBOSE)
1170                        printf("%s\n", hash_to_hex(l->sha1));
1171                if (!(flags & NOTES_PRUNE_DRYRUN))
1172                        remove_note(t, l->sha1);
1173                l = l->next;
1174        }
1175}
1176
1177void free_notes(struct notes_tree *t)
1178{
1179        if (!t)
1180                t = &default_notes_tree;
1181        if (t->root)
1182                note_tree_free(t->root);
1183        free(t->root);
1184        while (t->first_non_note) {
1185                t->prev_non_note = t->first_non_note->next;
1186                free(t->first_non_note->path);
1187                free(t->first_non_note);
1188                t->first_non_note = t->prev_non_note;
1189        }
1190        free(t->ref);
1191        memset(t, 0, sizeof(struct notes_tree));
1192}
1193
1194/*
1195 * Fill the given strbuf with the notes associated with the given object.
1196 *
1197 * If the given notes_tree structure is not initialized, it will be auto-
1198 * initialized to the default value (see documentation for init_notes() above).
1199 * If the given notes_tree is NULL, the internal/default notes_tree will be
1200 * used instead.
1201 *
1202 * (raw != 0) gives the %N userformat; otherwise, the note message is given
1203 * for human consumption.
1204 */
1205static void format_note(struct notes_tree *t, const struct object_id *object_oid,
1206                        struct strbuf *sb, const char *output_encoding, int raw)
1207{
1208        static const char utf8[] = "utf-8";
1209        const struct object_id *oid;
1210        char *msg, *msg_p;
1211        unsigned long linelen, msglen;
1212        enum object_type type;
1213
1214        if (!t)
1215                t = &default_notes_tree;
1216        if (!t->initialized)
1217                init_notes(t, NULL, NULL, 0);
1218
1219        oid = get_note(t, object_oid);
1220        if (!oid)
1221                return;
1222
1223        if (!(msg = read_object_file(oid, &type, &msglen)) || type != OBJ_BLOB) {
1224                free(msg);
1225                return;
1226        }
1227
1228        if (output_encoding && *output_encoding &&
1229            !is_encoding_utf8(output_encoding)) {
1230                char *reencoded = reencode_string(msg, output_encoding, utf8);
1231                if (reencoded) {
1232                        free(msg);
1233                        msg = reencoded;
1234                        msglen = strlen(msg);
1235                }
1236        }
1237
1238        /* we will end the annotation by a newline anyway */
1239        if (msglen && msg[msglen - 1] == '\n')
1240                msglen--;
1241
1242        if (!raw) {
1243                const char *ref = t->ref;
1244                if (!ref || !strcmp(ref, GIT_NOTES_DEFAULT_REF)) {
1245                        strbuf_addstr(sb, "\nNotes:\n");
1246                } else {
1247                        if (starts_with(ref, "refs/"))
1248                                ref += 5;
1249                        if (starts_with(ref, "notes/"))
1250                                ref += 6;
1251                        strbuf_addf(sb, "\nNotes (%s):\n", ref);
1252                }
1253        }
1254
1255        for (msg_p = msg; msg_p < msg + msglen; msg_p += linelen + 1) {
1256                linelen = strchrnul(msg_p, '\n') - msg_p;
1257
1258                if (!raw)
1259                        strbuf_addstr(sb, "    ");
1260                strbuf_add(sb, msg_p, linelen);
1261                strbuf_addch(sb, '\n');
1262        }
1263
1264        free(msg);
1265}
1266
1267void format_display_notes(const struct object_id *object_oid,
1268                          struct strbuf *sb, const char *output_encoding, int raw)
1269{
1270        int i;
1271        assert(display_notes_trees);
1272        for (i = 0; display_notes_trees[i]; i++)
1273                format_note(display_notes_trees[i], object_oid, sb,
1274                            output_encoding, raw);
1275}
1276
1277int copy_note(struct notes_tree *t,
1278              const struct object_id *from_obj, const struct object_id *to_obj,
1279              int force, combine_notes_fn combine_notes)
1280{
1281        const struct object_id *note = get_note(t, from_obj);
1282        const struct object_id *existing_note = get_note(t, to_obj);
1283
1284        if (!force && existing_note)
1285                return 1;
1286
1287        if (note)
1288                return add_note(t, to_obj, note, combine_notes);
1289        else if (existing_note)
1290                return add_note(t, to_obj, &null_oid, combine_notes);
1291
1292        return 0;
1293}
1294
1295void expand_notes_ref(struct strbuf *sb)
1296{
1297        if (starts_with(sb->buf, "refs/notes/"))
1298                return; /* we're happy */
1299        else if (starts_with(sb->buf, "notes/"))
1300                strbuf_insert(sb, 0, "refs/", 5);
1301        else
1302                strbuf_insert(sb, 0, "refs/notes/", 11);
1303}
1304
1305void expand_loose_notes_ref(struct strbuf *sb)
1306{
1307        struct object_id object;
1308
1309        if (get_oid(sb->buf, &object)) {
1310                /* fallback to expand_notes_ref */
1311                expand_notes_ref(sb);
1312        }
1313}