notes.con commit Merge branch 'sd/t3200-typofix' (634ccf4)
   1#include "cache.h"
   2#include "notes.h"
   3#include "blob.h"
   4#include "tree.h"
   5#include "utf8.h"
   6#include "strbuf.h"
   7#include "tree-walk.h"
   8#include "string-list.h"
   9#include "refs.h"
  10
  11/*
  12 * Use a non-balancing simple 16-tree structure with struct int_node as
  13 * internal nodes, and struct leaf_node as leaf nodes. Each int_node has a
  14 * 16-array of pointers to its children.
  15 * The bottom 2 bits of each pointer is used to identify the pointer type
  16 * - ptr & 3 == 0 - NULL pointer, assert(ptr == NULL)
  17 * - ptr & 3 == 1 - pointer to next internal node - cast to struct int_node *
  18 * - ptr & 3 == 2 - pointer to note entry - cast to struct leaf_node *
  19 * - ptr & 3 == 3 - pointer to subtree entry - cast to struct leaf_node *
  20 *
  21 * The root node is a statically allocated struct int_node.
  22 */
  23struct int_node {
  24        void *a[16];
  25};
  26
  27/*
  28 * Leaf nodes come in two variants, note entries and subtree entries,
  29 * distinguished by the LSb of the leaf node pointer (see above).
  30 * As a note entry, the key is the SHA1 of the referenced object, and the
  31 * value is the SHA1 of the note object.
  32 * As a subtree entry, the key is the prefix SHA1 (w/trailing NULs) of the
  33 * referenced object, using the last byte of the key to store the length of
  34 * the prefix. The value is the SHA1 of the tree object containing the notes
  35 * subtree.
  36 */
  37struct leaf_node {
  38        unsigned char key_sha1[20];
  39        unsigned char val_sha1[20];
  40};
  41
  42/*
  43 * A notes tree may contain entries that are not notes, and that do not follow
  44 * the naming conventions of notes. There are typically none/few of these, but
  45 * we still need to keep track of them. Keep a simple linked list sorted alpha-
  46 * betically on the non-note path. The list is populated when parsing tree
  47 * objects in load_subtree(), and the non-notes are correctly written back into
  48 * the tree objects produced by write_notes_tree().
  49 */
  50struct non_note {
  51        struct non_note *next; /* grounded (last->next == NULL) */
  52        char *path;
  53        unsigned int mode;
  54        unsigned char sha1[20];
  55};
  56
  57#define PTR_TYPE_NULL     0
  58#define PTR_TYPE_INTERNAL 1
  59#define PTR_TYPE_NOTE     2
  60#define PTR_TYPE_SUBTREE  3
  61
  62#define GET_PTR_TYPE(ptr)       ((uintptr_t) (ptr) & 3)
  63#define CLR_PTR_TYPE(ptr)       ((void *) ((uintptr_t) (ptr) & ~3))
  64#define SET_PTR_TYPE(ptr, type) ((void *) ((uintptr_t) (ptr) | (type)))
  65
  66#define GET_NIBBLE(n, sha1) (((sha1[(n) >> 1]) >> ((~(n) & 0x01) << 2)) & 0x0f)
  67
  68#define SUBTREE_SHA1_PREFIXCMP(key_sha1, subtree_sha1) \
  69        (memcmp(key_sha1, subtree_sha1, subtree_sha1[19]))
  70
  71struct notes_tree default_notes_tree;
  72
  73static struct string_list display_notes_refs = STRING_LIST_INIT_NODUP;
  74static struct notes_tree **display_notes_trees;
  75
  76static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,
  77                struct int_node *node, unsigned int n);
  78
  79/*
  80 * Search the tree until the appropriate location for the given key is found:
  81 * 1. Start at the root node, with n = 0
  82 * 2. If a[0] at the current level is a matching subtree entry, unpack that
  83 *    subtree entry and remove it; restart search at the current level.
  84 * 3. Use the nth nibble of the key as an index into a:
  85 *    - If a[n] is an int_node, recurse from #2 into that node and increment n
  86 *    - If a matching subtree entry, unpack that subtree entry (and remove it);
  87 *      restart search at the current level.
  88 *    - Otherwise, we have found one of the following:
  89 *      - a subtree entry which does not match the key
  90 *      - a note entry which may or may not match the key
  91 *      - an unused leaf node (NULL)
  92 *      In any case, set *tree and *n, and return pointer to the tree location.
  93 */
  94static void **note_tree_search(struct notes_tree *t, struct int_node **tree,
  95                unsigned char *n, const unsigned char *key_sha1)
  96{
  97        struct leaf_node *l;
  98        unsigned char i;
  99        void *p = (*tree)->a[0];
 100
 101        if (GET_PTR_TYPE(p) == PTR_TYPE_SUBTREE) {
 102                l = (struct leaf_node *) CLR_PTR_TYPE(p);
 103                if (!SUBTREE_SHA1_PREFIXCMP(key_sha1, l->key_sha1)) {
 104                        /* unpack tree and resume search */
 105                        (*tree)->a[0] = NULL;
 106                        load_subtree(t, l, *tree, *n);
 107                        free(l);
 108                        return note_tree_search(t, tree, n, key_sha1);
 109                }
 110        }
 111
 112        i = GET_NIBBLE(*n, key_sha1);
 113        p = (*tree)->a[i];
 114        switch (GET_PTR_TYPE(p)) {
 115        case PTR_TYPE_INTERNAL:
 116                *tree = CLR_PTR_TYPE(p);
 117                (*n)++;
 118                return note_tree_search(t, tree, n, key_sha1);
 119        case PTR_TYPE_SUBTREE:
 120                l = (struct leaf_node *) CLR_PTR_TYPE(p);
 121                if (!SUBTREE_SHA1_PREFIXCMP(key_sha1, l->key_sha1)) {
 122                        /* unpack tree and resume search */
 123                        (*tree)->a[i] = NULL;
 124                        load_subtree(t, l, *tree, *n);
 125                        free(l);
 126                        return note_tree_search(t, tree, n, key_sha1);
 127                }
 128                /* fall through */
 129        default:
 130                return &((*tree)->a[i]);
 131        }
 132}
 133
 134/*
 135 * To find a leaf_node:
 136 * Search to the tree location appropriate for the given key:
 137 * If a note entry with matching key, return the note entry, else return NULL.
 138 */
 139static struct leaf_node *note_tree_find(struct notes_tree *t,
 140                struct int_node *tree, unsigned char n,
 141                const unsigned char *key_sha1)
 142{
 143        void **p = note_tree_search(t, &tree, &n, key_sha1);
 144        if (GET_PTR_TYPE(*p) == PTR_TYPE_NOTE) {
 145                struct leaf_node *l = (struct leaf_node *) CLR_PTR_TYPE(*p);
 146                if (!hashcmp(key_sha1, l->key_sha1))
 147                        return l;
 148        }
 149        return NULL;
 150}
 151
 152/*
 153 * How to consolidate an int_node:
 154 * If there are > 1 non-NULL entries, give up and return non-zero.
 155 * Otherwise replace the int_node at the given index in the given parent node
 156 * with the only NOTE entry (or a NULL entry if no entries) from the given
 157 * tree, and return 0.
 158 */
 159static int note_tree_consolidate(struct int_node *tree,
 160        struct int_node *parent, unsigned char index)
 161{
 162        unsigned int i;
 163        void *p = NULL;
 164
 165        assert(tree && parent);
 166        assert(CLR_PTR_TYPE(parent->a[index]) == tree);
 167
 168        for (i = 0; i < 16; i++) {
 169                if (GET_PTR_TYPE(tree->a[i]) != PTR_TYPE_NULL) {
 170                        if (p) /* more than one entry */
 171                                return -2;
 172                        p = tree->a[i];
 173                }
 174        }
 175
 176        if (p && (GET_PTR_TYPE(p) != PTR_TYPE_NOTE))
 177                return -2;
 178        /* replace tree with p in parent[index] */
 179        parent->a[index] = p;
 180        free(tree);
 181        return 0;
 182}
 183
 184/*
 185 * To remove a leaf_node:
 186 * Search to the tree location appropriate for the given leaf_node's key:
 187 * - If location does not hold a matching entry, abort and do nothing.
 188 * - Copy the matching entry's value into the given entry.
 189 * - Replace the matching leaf_node with a NULL entry (and free the leaf_node).
 190 * - Consolidate int_nodes repeatedly, while walking up the tree towards root.
 191 */
 192static void note_tree_remove(struct notes_tree *t,
 193                struct int_node *tree, unsigned char n,
 194                struct leaf_node *entry)
 195{
 196        struct leaf_node *l;
 197        struct int_node *parent_stack[20];
 198        unsigned char i, j;
 199        void **p = note_tree_search(t, &tree, &n, entry->key_sha1);
 200
 201        assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
 202        if (GET_PTR_TYPE(*p) != PTR_TYPE_NOTE)
 203                return; /* type mismatch, nothing to remove */
 204        l = (struct leaf_node *) CLR_PTR_TYPE(*p);
 205        if (hashcmp(l->key_sha1, entry->key_sha1))
 206                return; /* key mismatch, nothing to remove */
 207
 208        /* we have found a matching entry */
 209        hashcpy(entry->val_sha1, l->val_sha1);
 210        free(l);
 211        *p = SET_PTR_TYPE(NULL, PTR_TYPE_NULL);
 212
 213        /* consolidate this tree level, and parent levels, if possible */
 214        if (!n)
 215                return; /* cannot consolidate top level */
 216        /* first, build stack of ancestors between root and current node */
 217        parent_stack[0] = t->root;
 218        for (i = 0; i < n; i++) {
 219                j = GET_NIBBLE(i, entry->key_sha1);
 220                parent_stack[i + 1] = CLR_PTR_TYPE(parent_stack[i]->a[j]);
 221        }
 222        assert(i == n && parent_stack[i] == tree);
 223        /* next, unwind stack until note_tree_consolidate() is done */
 224        while (i > 0 &&
 225               !note_tree_consolidate(parent_stack[i], parent_stack[i - 1],
 226                                      GET_NIBBLE(i - 1, entry->key_sha1)))
 227                i--;
 228}
 229
 230/*
 231 * To insert a leaf_node:
 232 * Search to the tree location appropriate for the given leaf_node's key:
 233 * - If location is unused (NULL), store the tweaked pointer directly there
 234 * - If location holds a note entry that matches the note-to-be-inserted, then
 235 *   combine the two notes (by calling the given combine_notes function).
 236 * - If location holds a note entry that matches the subtree-to-be-inserted,
 237 *   then unpack the subtree-to-be-inserted into the location.
 238 * - If location holds a matching subtree entry, unpack the subtree at that
 239 *   location, and restart the insert operation from that level.
 240 * - Else, create a new int_node, holding both the node-at-location and the
 241 *   node-to-be-inserted, and store the new int_node into the location.
 242 */
 243static int note_tree_insert(struct notes_tree *t, struct int_node *tree,
 244                unsigned char n, struct leaf_node *entry, unsigned char type,
 245                combine_notes_fn combine_notes)
 246{
 247        struct int_node *new_node;
 248        struct leaf_node *l;
 249        void **p = note_tree_search(t, &tree, &n, entry->key_sha1);
 250        int ret = 0;
 251
 252        assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
 253        l = (struct leaf_node *) CLR_PTR_TYPE(*p);
 254        switch (GET_PTR_TYPE(*p)) {
 255        case PTR_TYPE_NULL:
 256                assert(!*p);
 257                if (is_null_sha1(entry->val_sha1))
 258                        free(entry);
 259                else
 260                        *p = SET_PTR_TYPE(entry, type);
 261                return 0;
 262        case PTR_TYPE_NOTE:
 263                switch (type) {
 264                case PTR_TYPE_NOTE:
 265                        if (!hashcmp(l->key_sha1, entry->key_sha1)) {
 266                                /* skip concatenation if l == entry */
 267                                if (!hashcmp(l->val_sha1, entry->val_sha1))
 268                                        return 0;
 269
 270                                ret = combine_notes(l->val_sha1,
 271                                                    entry->val_sha1);
 272                                if (!ret && is_null_sha1(l->val_sha1))
 273                                        note_tree_remove(t, tree, n, entry);
 274                                free(entry);
 275                                return ret;
 276                        }
 277                        break;
 278                case PTR_TYPE_SUBTREE:
 279                        if (!SUBTREE_SHA1_PREFIXCMP(l->key_sha1,
 280                                                    entry->key_sha1)) {
 281                                /* unpack 'entry' */
 282                                load_subtree(t, entry, tree, n);
 283                                free(entry);
 284                                return 0;
 285                        }
 286                        break;
 287                }
 288                break;
 289        case PTR_TYPE_SUBTREE:
 290                if (!SUBTREE_SHA1_PREFIXCMP(entry->key_sha1, l->key_sha1)) {
 291                        /* unpack 'l' and restart insert */
 292                        *p = NULL;
 293                        load_subtree(t, l, tree, n);
 294                        free(l);
 295                        return note_tree_insert(t, tree, n, entry, type,
 296                                                combine_notes);
 297                }
 298                break;
 299        }
 300
 301        /* non-matching leaf_node */
 302        assert(GET_PTR_TYPE(*p) == PTR_TYPE_NOTE ||
 303               GET_PTR_TYPE(*p) == PTR_TYPE_SUBTREE);
 304        if (is_null_sha1(entry->val_sha1)) { /* skip insertion of empty note */
 305                free(entry);
 306                return 0;
 307        }
 308        new_node = (struct int_node *) xcalloc(1, sizeof(struct int_node));
 309        ret = note_tree_insert(t, new_node, n + 1, l, GET_PTR_TYPE(*p),
 310                               combine_notes);
 311        if (ret)
 312                return ret;
 313        *p = SET_PTR_TYPE(new_node, PTR_TYPE_INTERNAL);
 314        return note_tree_insert(t, new_node, n + 1, entry, type, combine_notes);
 315}
 316
 317/* Free the entire notes data contained in the given tree */
 318static void note_tree_free(struct int_node *tree)
 319{
 320        unsigned int i;
 321        for (i = 0; i < 16; i++) {
 322                void *p = tree->a[i];
 323                switch (GET_PTR_TYPE(p)) {
 324                case PTR_TYPE_INTERNAL:
 325                        note_tree_free(CLR_PTR_TYPE(p));
 326                        /* fall through */
 327                case PTR_TYPE_NOTE:
 328                case PTR_TYPE_SUBTREE:
 329                        free(CLR_PTR_TYPE(p));
 330                }
 331        }
 332}
 333
 334/*
 335 * Convert a partial SHA1 hex string to the corresponding partial SHA1 value.
 336 * - hex      - Partial SHA1 segment in ASCII hex format
 337 * - hex_len  - Length of above segment. Must be multiple of 2 between 0 and 40
 338 * - sha1     - Partial SHA1 value is written here
 339 * - sha1_len - Max #bytes to store in sha1, Must be >= hex_len / 2, and < 20
 340 * Returns -1 on error (invalid arguments or invalid SHA1 (not in hex format)).
 341 * Otherwise, returns number of bytes written to sha1 (i.e. hex_len / 2).
 342 * Pads sha1 with NULs up to sha1_len (not included in returned length).
 343 */
 344static int get_sha1_hex_segment(const char *hex, unsigned int hex_len,
 345                unsigned char *sha1, unsigned int sha1_len)
 346{
 347        unsigned int i, len = hex_len >> 1;
 348        if (hex_len % 2 != 0 || len > sha1_len)
 349                return -1;
 350        for (i = 0; i < len; i++) {
 351                unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
 352                if (val & ~0xff)
 353                        return -1;
 354                *sha1++ = val;
 355                hex += 2;
 356        }
 357        for (; i < sha1_len; i++)
 358                *sha1++ = 0;
 359        return len;
 360}
 361
 362static int non_note_cmp(const struct non_note *a, const struct non_note *b)
 363{
 364        return strcmp(a->path, b->path);
 365}
 366
 367/* note: takes ownership of path string */
 368static void add_non_note(struct notes_tree *t, char *path,
 369                unsigned int mode, const unsigned char *sha1)
 370{
 371        struct non_note *p = t->prev_non_note, *n;
 372        n = (struct non_note *) xmalloc(sizeof(struct non_note));
 373        n->next = NULL;
 374        n->path = path;
 375        n->mode = mode;
 376        hashcpy(n->sha1, sha1);
 377        t->prev_non_note = n;
 378
 379        if (!t->first_non_note) {
 380                t->first_non_note = n;
 381                return;
 382        }
 383
 384        if (non_note_cmp(p, n) < 0)
 385                ; /* do nothing  */
 386        else if (non_note_cmp(t->first_non_note, n) <= 0)
 387                p = t->first_non_note;
 388        else {
 389                /* n sorts before t->first_non_note */
 390                n->next = t->first_non_note;
 391                t->first_non_note = n;
 392                return;
 393        }
 394
 395        /* n sorts equal or after p */
 396        while (p->next && non_note_cmp(p->next, n) <= 0)
 397                p = p->next;
 398
 399        if (non_note_cmp(p, n) == 0) { /* n ~= p; overwrite p with n */
 400                assert(strcmp(p->path, n->path) == 0);
 401                p->mode = n->mode;
 402                hashcpy(p->sha1, n->sha1);
 403                free(n);
 404                t->prev_non_note = p;
 405                return;
 406        }
 407
 408        /* n sorts between p and p->next */
 409        n->next = p->next;
 410        p->next = n;
 411}
 412
 413static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,
 414                struct int_node *node, unsigned int n)
 415{
 416        unsigned char object_sha1[20];
 417        unsigned int prefix_len;
 418        void *buf;
 419        struct tree_desc desc;
 420        struct name_entry entry;
 421        int len, path_len;
 422        unsigned char type;
 423        struct leaf_node *l;
 424
 425        buf = fill_tree_descriptor(&desc, subtree->val_sha1);
 426        if (!buf)
 427                die("Could not read %s for notes-index",
 428                     sha1_to_hex(subtree->val_sha1));
 429
 430        prefix_len = subtree->key_sha1[19];
 431        assert(prefix_len * 2 >= n);
 432        memcpy(object_sha1, subtree->key_sha1, prefix_len);
 433        while (tree_entry(&desc, &entry)) {
 434                path_len = strlen(entry.path);
 435                len = get_sha1_hex_segment(entry.path, path_len,
 436                                object_sha1 + prefix_len, 20 - prefix_len);
 437                if (len < 0)
 438                        goto handle_non_note; /* entry.path is not a SHA1 */
 439                len += prefix_len;
 440
 441                /*
 442                 * If object SHA1 is complete (len == 20), assume note object
 443                 * If object SHA1 is incomplete (len < 20), and current
 444                 * component consists of 2 hex chars, assume note subtree
 445                 */
 446                if (len <= 20) {
 447                        type = PTR_TYPE_NOTE;
 448                        l = (struct leaf_node *)
 449                                xcalloc(1, sizeof(struct leaf_node));
 450                        hashcpy(l->key_sha1, object_sha1);
 451                        hashcpy(l->val_sha1, entry.oid->hash);
 452                        if (len < 20) {
 453                                if (!S_ISDIR(entry.mode) || path_len != 2)
 454                                        goto handle_non_note; /* not subtree */
 455                                l->key_sha1[19] = (unsigned char) len;
 456                                type = PTR_TYPE_SUBTREE;
 457                        }
 458                        if (note_tree_insert(t, node, n, l, type,
 459                                             combine_notes_concatenate))
 460                                die("Failed to load %s %s into notes tree "
 461                                    "from %s",
 462                                    type == PTR_TYPE_NOTE ? "note" : "subtree",
 463                                    sha1_to_hex(l->key_sha1), t->ref);
 464                }
 465                continue;
 466
 467handle_non_note:
 468                /*
 469                 * Determine full path for this non-note entry:
 470                 * The filename is already found in entry.path, but the
 471                 * directory part of the path must be deduced from the subtree
 472                 * containing this entry. We assume here that the overall notes
 473                 * tree follows a strict byte-based progressive fanout
 474                 * structure (i.e. using 2/38, 2/2/36, etc. fanouts, and not
 475                 * e.g. 4/36 fanout). This means that if a non-note is found at
 476                 * path "dead/beef", the following code will register it as
 477                 * being found on "de/ad/beef".
 478                 * On the other hand, if you use such non-obvious non-note
 479                 * paths in the middle of a notes tree, you deserve what's
 480                 * coming to you ;). Note that for non-notes that are not
 481                 * SHA1-like at the top level, there will be no problems.
 482                 *
 483                 * To conclude, it is strongly advised to make sure non-notes
 484                 * have at least one non-hex character in the top-level path
 485                 * component.
 486                 */
 487                {
 488                        struct strbuf non_note_path = STRBUF_INIT;
 489                        const char *q = sha1_to_hex(subtree->key_sha1);
 490                        int i;
 491                        for (i = 0; i < prefix_len; i++) {
 492                                strbuf_addch(&non_note_path, *q++);
 493                                strbuf_addch(&non_note_path, *q++);
 494                                strbuf_addch(&non_note_path, '/');
 495                        }
 496                        strbuf_addstr(&non_note_path, entry.path);
 497                        add_non_note(t, strbuf_detach(&non_note_path, NULL),
 498                                     entry.mode, entry.oid->hash);
 499                }
 500        }
 501        free(buf);
 502}
 503
 504/*
 505 * Determine optimal on-disk fanout for this part of the notes tree
 506 *
 507 * Given a (sub)tree and the level in the internal tree structure, determine
 508 * whether or not the given existing fanout should be expanded for this
 509 * (sub)tree.
 510 *
 511 * Values of the 'fanout' variable:
 512 * - 0: No fanout (all notes are stored directly in the root notes tree)
 513 * - 1: 2/38 fanout
 514 * - 2: 2/2/36 fanout
 515 * - 3: 2/2/2/34 fanout
 516 * etc.
 517 */
 518static unsigned char determine_fanout(struct int_node *tree, unsigned char n,
 519                unsigned char fanout)
 520{
 521        /*
 522         * The following is a simple heuristic that works well in practice:
 523         * For each even-numbered 16-tree level (remember that each on-disk
 524         * fanout level corresponds to _two_ 16-tree levels), peek at all 16
 525         * entries at that tree level. If all of them are either int_nodes or
 526         * subtree entries, then there are likely plenty of notes below this
 527         * level, so we return an incremented fanout.
 528         */
 529        unsigned int i;
 530        if ((n % 2) || (n > 2 * fanout))
 531                return fanout;
 532        for (i = 0; i < 16; i++) {
 533                switch (GET_PTR_TYPE(tree->a[i])) {
 534                case PTR_TYPE_SUBTREE:
 535                case PTR_TYPE_INTERNAL:
 536                        continue;
 537                default:
 538                        return fanout;
 539                }
 540        }
 541        return fanout + 1;
 542}
 543
 544/* hex SHA1 + 19 * '/' + NUL */
 545#define FANOUT_PATH_MAX 40 + 19 + 1
 546
 547static void construct_path_with_fanout(const unsigned char *sha1,
 548                unsigned char fanout, char *path)
 549{
 550        unsigned int i = 0, j = 0;
 551        const char *hex_sha1 = sha1_to_hex(sha1);
 552        assert(fanout < 20);
 553        while (fanout) {
 554                path[i++] = hex_sha1[j++];
 555                path[i++] = hex_sha1[j++];
 556                path[i++] = '/';
 557                fanout--;
 558        }
 559        xsnprintf(path + i, FANOUT_PATH_MAX - i, "%s", hex_sha1 + j);
 560}
 561
 562static int for_each_note_helper(struct notes_tree *t, struct int_node *tree,
 563                unsigned char n, unsigned char fanout, int flags,
 564                each_note_fn fn, void *cb_data)
 565{
 566        unsigned int i;
 567        void *p;
 568        int ret = 0;
 569        struct leaf_node *l;
 570        static char path[FANOUT_PATH_MAX];
 571
 572        fanout = determine_fanout(tree, n, fanout);
 573        for (i = 0; i < 16; i++) {
 574redo:
 575                p = tree->a[i];
 576                switch (GET_PTR_TYPE(p)) {
 577                case PTR_TYPE_INTERNAL:
 578                        /* recurse into int_node */
 579                        ret = for_each_note_helper(t, CLR_PTR_TYPE(p), n + 1,
 580                                fanout, flags, fn, cb_data);
 581                        break;
 582                case PTR_TYPE_SUBTREE:
 583                        l = (struct leaf_node *) CLR_PTR_TYPE(p);
 584                        /*
 585                         * Subtree entries in the note tree represent parts of
 586                         * the note tree that have not yet been explored. There
 587                         * is a direct relationship between subtree entries at
 588                         * level 'n' in the tree, and the 'fanout' variable:
 589                         * Subtree entries at level 'n <= 2 * fanout' should be
 590                         * preserved, since they correspond exactly to a fanout
 591                         * directory in the on-disk structure. However, subtree
 592                         * entries at level 'n > 2 * fanout' should NOT be
 593                         * preserved, but rather consolidated into the above
 594                         * notes tree level. We achieve this by unconditionally
 595                         * unpacking subtree entries that exist below the
 596                         * threshold level at 'n = 2 * fanout'.
 597                         */
 598                        if (n <= 2 * fanout &&
 599                            flags & FOR_EACH_NOTE_YIELD_SUBTREES) {
 600                                /* invoke callback with subtree */
 601                                unsigned int path_len =
 602                                        l->key_sha1[19] * 2 + fanout;
 603                                assert(path_len < FANOUT_PATH_MAX - 1);
 604                                construct_path_with_fanout(l->key_sha1, fanout,
 605                                                           path);
 606                                /* Create trailing slash, if needed */
 607                                if (path[path_len - 1] != '/')
 608                                        path[path_len++] = '/';
 609                                path[path_len] = '\0';
 610                                ret = fn(l->key_sha1, l->val_sha1, path,
 611                                         cb_data);
 612                        }
 613                        if (n > fanout * 2 ||
 614                            !(flags & FOR_EACH_NOTE_DONT_UNPACK_SUBTREES)) {
 615                                /* unpack subtree and resume traversal */
 616                                tree->a[i] = NULL;
 617                                load_subtree(t, l, tree, n);
 618                                free(l);
 619                                goto redo;
 620                        }
 621                        break;
 622                case PTR_TYPE_NOTE:
 623                        l = (struct leaf_node *) CLR_PTR_TYPE(p);
 624                        construct_path_with_fanout(l->key_sha1, fanout, path);
 625                        ret = fn(l->key_sha1, l->val_sha1, path, cb_data);
 626                        break;
 627                }
 628                if (ret)
 629                        return ret;
 630        }
 631        return 0;
 632}
 633
 634struct tree_write_stack {
 635        struct tree_write_stack *next;
 636        struct strbuf buf;
 637        char path[2]; /* path to subtree in next, if any */
 638};
 639
 640static inline int matches_tree_write_stack(struct tree_write_stack *tws,
 641                const char *full_path)
 642{
 643        return  full_path[0] == tws->path[0] &&
 644                full_path[1] == tws->path[1] &&
 645                full_path[2] == '/';
 646}
 647
 648static void write_tree_entry(struct strbuf *buf, unsigned int mode,
 649                const char *path, unsigned int path_len, const
 650                unsigned char *sha1)
 651{
 652        strbuf_addf(buf, "%o %.*s%c", mode, path_len, path, '\0');
 653        strbuf_add(buf, sha1, 20);
 654}
 655
 656static void tree_write_stack_init_subtree(struct tree_write_stack *tws,
 657                const char *path)
 658{
 659        struct tree_write_stack *n;
 660        assert(!tws->next);
 661        assert(tws->path[0] == '\0' && tws->path[1] == '\0');
 662        n = (struct tree_write_stack *)
 663                xmalloc(sizeof(struct tree_write_stack));
 664        n->next = NULL;
 665        strbuf_init(&n->buf, 256 * (32 + 40)); /* assume 256 entries per tree */
 666        n->path[0] = n->path[1] = '\0';
 667        tws->next = n;
 668        tws->path[0] = path[0];
 669        tws->path[1] = path[1];
 670}
 671
 672static int tree_write_stack_finish_subtree(struct tree_write_stack *tws)
 673{
 674        int ret;
 675        struct tree_write_stack *n = tws->next;
 676        unsigned char s[20];
 677        if (n) {
 678                ret = tree_write_stack_finish_subtree(n);
 679                if (ret)
 680                        return ret;
 681                ret = write_sha1_file(n->buf.buf, n->buf.len, tree_type, s);
 682                if (ret)
 683                        return ret;
 684                strbuf_release(&n->buf);
 685                free(n);
 686                tws->next = NULL;
 687                write_tree_entry(&tws->buf, 040000, tws->path, 2, s);
 688                tws->path[0] = tws->path[1] = '\0';
 689        }
 690        return 0;
 691}
 692
 693static int write_each_note_helper(struct tree_write_stack *tws,
 694                const char *path, unsigned int mode,
 695                const unsigned char *sha1)
 696{
 697        size_t path_len = strlen(path);
 698        unsigned int n = 0;
 699        int ret;
 700
 701        /* Determine common part of tree write stack */
 702        while (tws && 3 * n < path_len &&
 703               matches_tree_write_stack(tws, path + 3 * n)) {
 704                n++;
 705                tws = tws->next;
 706        }
 707
 708        /* tws point to last matching tree_write_stack entry */
 709        ret = tree_write_stack_finish_subtree(tws);
 710        if (ret)
 711                return ret;
 712
 713        /* Start subtrees needed to satisfy path */
 714        while (3 * n + 2 < path_len && path[3 * n + 2] == '/') {
 715                tree_write_stack_init_subtree(tws, path + 3 * n);
 716                n++;
 717                tws = tws->next;
 718        }
 719
 720        /* There should be no more directory components in the given path */
 721        assert(memchr(path + 3 * n, '/', path_len - (3 * n)) == NULL);
 722
 723        /* Finally add given entry to the current tree object */
 724        write_tree_entry(&tws->buf, mode, path + 3 * n, path_len - (3 * n),
 725                         sha1);
 726
 727        return 0;
 728}
 729
 730struct write_each_note_data {
 731        struct tree_write_stack *root;
 732        struct non_note *next_non_note;
 733};
 734
 735static int write_each_non_note_until(const char *note_path,
 736                struct write_each_note_data *d)
 737{
 738        struct non_note *n = d->next_non_note;
 739        int cmp = 0, ret;
 740        while (n && (!note_path || (cmp = strcmp(n->path, note_path)) <= 0)) {
 741                if (note_path && cmp == 0)
 742                        ; /* do nothing, prefer note to non-note */
 743                else {
 744                        ret = write_each_note_helper(d->root, n->path, n->mode,
 745                                                     n->sha1);
 746                        if (ret)
 747                                return ret;
 748                }
 749                n = n->next;
 750        }
 751        d->next_non_note = n;
 752        return 0;
 753}
 754
 755static int write_each_note(const unsigned char *object_sha1,
 756                const unsigned char *note_sha1, char *note_path,
 757                void *cb_data)
 758{
 759        struct write_each_note_data *d =
 760                (struct write_each_note_data *) cb_data;
 761        size_t note_path_len = strlen(note_path);
 762        unsigned int mode = 0100644;
 763
 764        if (note_path[note_path_len - 1] == '/') {
 765                /* subtree entry */
 766                note_path_len--;
 767                note_path[note_path_len] = '\0';
 768                mode = 040000;
 769        }
 770        assert(note_path_len <= 40 + 19);
 771
 772        /* Weave non-note entries into note entries */
 773        return  write_each_non_note_until(note_path, d) ||
 774                write_each_note_helper(d->root, note_path, mode, note_sha1);
 775}
 776
 777struct note_delete_list {
 778        struct note_delete_list *next;
 779        const unsigned char *sha1;
 780};
 781
 782static int prune_notes_helper(const unsigned char *object_sha1,
 783                const unsigned char *note_sha1, char *note_path,
 784                void *cb_data)
 785{
 786        struct note_delete_list **l = (struct note_delete_list **) cb_data;
 787        struct note_delete_list *n;
 788
 789        if (has_sha1_file(object_sha1))
 790                return 0; /* nothing to do for this note */
 791
 792        /* failed to find object => prune this note */
 793        n = (struct note_delete_list *) xmalloc(sizeof(*n));
 794        n->next = *l;
 795        n->sha1 = object_sha1;
 796        *l = n;
 797        return 0;
 798}
 799
 800int combine_notes_concatenate(unsigned char *cur_sha1,
 801                const unsigned char *new_sha1)
 802{
 803        char *cur_msg = NULL, *new_msg = NULL, *buf;
 804        unsigned long cur_len, new_len, buf_len;
 805        enum object_type cur_type, new_type;
 806        int ret;
 807
 808        /* read in both note blob objects */
 809        if (!is_null_sha1(new_sha1))
 810                new_msg = read_sha1_file(new_sha1, &new_type, &new_len);
 811        if (!new_msg || !new_len || new_type != OBJ_BLOB) {
 812                free(new_msg);
 813                return 0;
 814        }
 815        if (!is_null_sha1(cur_sha1))
 816                cur_msg = read_sha1_file(cur_sha1, &cur_type, &cur_len);
 817        if (!cur_msg || !cur_len || cur_type != OBJ_BLOB) {
 818                free(cur_msg);
 819                free(new_msg);
 820                hashcpy(cur_sha1, new_sha1);
 821                return 0;
 822        }
 823
 824        /* we will separate the notes by two newlines anyway */
 825        if (cur_msg[cur_len - 1] == '\n')
 826                cur_len--;
 827
 828        /* concatenate cur_msg and new_msg into buf */
 829        buf_len = cur_len + 2 + new_len;
 830        buf = (char *) xmalloc(buf_len);
 831        memcpy(buf, cur_msg, cur_len);
 832        buf[cur_len] = '\n';
 833        buf[cur_len + 1] = '\n';
 834        memcpy(buf + cur_len + 2, new_msg, new_len);
 835        free(cur_msg);
 836        free(new_msg);
 837
 838        /* create a new blob object from buf */
 839        ret = write_sha1_file(buf, buf_len, blob_type, cur_sha1);
 840        free(buf);
 841        return ret;
 842}
 843
 844int combine_notes_overwrite(unsigned char *cur_sha1,
 845                const unsigned char *new_sha1)
 846{
 847        hashcpy(cur_sha1, new_sha1);
 848        return 0;
 849}
 850
 851int combine_notes_ignore(unsigned char *cur_sha1,
 852                const unsigned char *new_sha1)
 853{
 854        return 0;
 855}
 856
 857/*
 858 * Add the lines from the named object to list, with trailing
 859 * newlines removed.
 860 */
 861static int string_list_add_note_lines(struct string_list *list,
 862                                      const unsigned char *sha1)
 863{
 864        char *data;
 865        unsigned long len;
 866        enum object_type t;
 867
 868        if (is_null_sha1(sha1))
 869                return 0;
 870
 871        /* read_sha1_file NUL-terminates */
 872        data = read_sha1_file(sha1, &t, &len);
 873        if (t != OBJ_BLOB || !data || !len) {
 874                free(data);
 875                return t != OBJ_BLOB || !data;
 876        }
 877
 878        /*
 879         * If the last line of the file is EOL-terminated, this will
 880         * add an empty string to the list.  But it will be removed
 881         * later, along with any empty strings that came from empty
 882         * lines within the file.
 883         */
 884        string_list_split(list, data, '\n', -1);
 885        free(data);
 886        return 0;
 887}
 888
 889static int string_list_join_lines_helper(struct string_list_item *item,
 890                                         void *cb_data)
 891{
 892        struct strbuf *buf = cb_data;
 893        strbuf_addstr(buf, item->string);
 894        strbuf_addch(buf, '\n');
 895        return 0;
 896}
 897
 898int combine_notes_cat_sort_uniq(unsigned char *cur_sha1,
 899                const unsigned char *new_sha1)
 900{
 901        struct string_list sort_uniq_list = STRING_LIST_INIT_DUP;
 902        struct strbuf buf = STRBUF_INIT;
 903        int ret = 1;
 904
 905        /* read both note blob objects into unique_lines */
 906        if (string_list_add_note_lines(&sort_uniq_list, cur_sha1))
 907                goto out;
 908        if (string_list_add_note_lines(&sort_uniq_list, new_sha1))
 909                goto out;
 910        string_list_remove_empty_items(&sort_uniq_list, 0);
 911        string_list_sort(&sort_uniq_list);
 912        string_list_remove_duplicates(&sort_uniq_list, 0);
 913
 914        /* create a new blob object from sort_uniq_list */
 915        if (for_each_string_list(&sort_uniq_list,
 916                                 string_list_join_lines_helper, &buf))
 917                goto out;
 918
 919        ret = write_sha1_file(buf.buf, buf.len, blob_type, cur_sha1);
 920
 921out:
 922        strbuf_release(&buf);
 923        string_list_clear(&sort_uniq_list, 0);
 924        return ret;
 925}
 926
 927static int string_list_add_one_ref(const char *refname, const struct object_id *oid,
 928                                   int flag, void *cb)
 929{
 930        struct string_list *refs = cb;
 931        if (!unsorted_string_list_has_string(refs, refname))
 932                string_list_append(refs, refname);
 933        return 0;
 934}
 935
 936/*
 937 * The list argument must have strdup_strings set on it.
 938 */
 939void string_list_add_refs_by_glob(struct string_list *list, const char *glob)
 940{
 941        assert(list->strdup_strings);
 942        if (has_glob_specials(glob)) {
 943                for_each_glob_ref(string_list_add_one_ref, glob, list);
 944        } else {
 945                unsigned char sha1[20];
 946                if (get_sha1(glob, sha1))
 947                        warning("notes ref %s is invalid", glob);
 948                if (!unsorted_string_list_has_string(list, glob))
 949                        string_list_append(list, glob);
 950        }
 951}
 952
 953void string_list_add_refs_from_colon_sep(struct string_list *list,
 954                                         const char *globs)
 955{
 956        struct string_list split = STRING_LIST_INIT_NODUP;
 957        char *globs_copy = xstrdup(globs);
 958        int i;
 959
 960        string_list_split_in_place(&split, globs_copy, ':', -1);
 961        string_list_remove_empty_items(&split, 0);
 962
 963        for (i = 0; i < split.nr; i++)
 964                string_list_add_refs_by_glob(list, split.items[i].string);
 965
 966        string_list_clear(&split, 0);
 967        free(globs_copy);
 968}
 969
 970static int notes_display_config(const char *k, const char *v, void *cb)
 971{
 972        int *load_refs = cb;
 973
 974        if (*load_refs && !strcmp(k, "notes.displayref")) {
 975                if (!v)
 976                        config_error_nonbool(k);
 977                string_list_add_refs_by_glob(&display_notes_refs, v);
 978        }
 979
 980        return 0;
 981}
 982
 983const char *default_notes_ref(void)
 984{
 985        const char *notes_ref = NULL;
 986        if (!notes_ref)
 987                notes_ref = getenv(GIT_NOTES_REF_ENVIRONMENT);
 988        if (!notes_ref)
 989                notes_ref = notes_ref_name; /* value of core.notesRef config */
 990        if (!notes_ref)
 991                notes_ref = GIT_NOTES_DEFAULT_REF;
 992        return notes_ref;
 993}
 994
 995void init_notes(struct notes_tree *t, const char *notes_ref,
 996                combine_notes_fn combine_notes, int flags)
 997{
 998        struct object_id oid, object_oid;
 999        unsigned mode;
1000        struct leaf_node root_tree;
1001
1002        if (!t)
1003                t = &default_notes_tree;
1004        assert(!t->initialized);
1005
1006        if (!notes_ref)
1007                notes_ref = default_notes_ref();
1008
1009        if (!combine_notes)
1010                combine_notes = combine_notes_concatenate;
1011
1012        t->root = (struct int_node *) xcalloc(1, sizeof(struct int_node));
1013        t->first_non_note = NULL;
1014        t->prev_non_note = NULL;
1015        t->ref = xstrdup_or_null(notes_ref);
1016        t->update_ref = (flags & NOTES_INIT_WRITABLE) ? t->ref : NULL;
1017        t->combine_notes = combine_notes;
1018        t->initialized = 1;
1019        t->dirty = 0;
1020
1021        if (flags & NOTES_INIT_EMPTY || !notes_ref ||
1022            get_sha1_treeish(notes_ref, object_oid.hash))
1023                return;
1024        if (flags & NOTES_INIT_WRITABLE && read_ref(notes_ref, object_oid.hash))
1025                die("Cannot use notes ref %s", notes_ref);
1026        if (get_tree_entry(object_oid.hash, "", oid.hash, &mode))
1027                die("Failed to read notes tree referenced by %s (%s)",
1028                    notes_ref, oid_to_hex(&object_oid));
1029
1030        hashclr(root_tree.key_sha1);
1031        hashcpy(root_tree.val_sha1, oid.hash);
1032        load_subtree(t, &root_tree, t->root, 0);
1033}
1034
1035struct notes_tree **load_notes_trees(struct string_list *refs, int flags)
1036{
1037        struct string_list_item *item;
1038        int counter = 0;
1039        struct notes_tree **trees;
1040        ALLOC_ARRAY(trees, refs->nr + 1);
1041        for_each_string_list_item(item, refs) {
1042                struct notes_tree *t = xcalloc(1, sizeof(struct notes_tree));
1043                init_notes(t, item->string, combine_notes_ignore, flags);
1044                trees[counter++] = t;
1045        }
1046        trees[counter] = NULL;
1047        return trees;
1048}
1049
1050void init_display_notes(struct display_notes_opt *opt)
1051{
1052        char *display_ref_env;
1053        int load_config_refs = 0;
1054        display_notes_refs.strdup_strings = 1;
1055
1056        assert(!display_notes_trees);
1057
1058        if (!opt || opt->use_default_notes > 0 ||
1059            (opt->use_default_notes == -1 && !opt->extra_notes_refs.nr)) {
1060                string_list_append(&display_notes_refs, default_notes_ref());
1061                display_ref_env = getenv(GIT_NOTES_DISPLAY_REF_ENVIRONMENT);
1062                if (display_ref_env) {
1063                        string_list_add_refs_from_colon_sep(&display_notes_refs,
1064                                                            display_ref_env);
1065                        load_config_refs = 0;
1066                } else
1067                        load_config_refs = 1;
1068        }
1069
1070        git_config(notes_display_config, &load_config_refs);
1071
1072        if (opt) {
1073                struct string_list_item *item;
1074                for_each_string_list_item(item, &opt->extra_notes_refs)
1075                        string_list_add_refs_by_glob(&display_notes_refs,
1076                                                     item->string);
1077        }
1078
1079        display_notes_trees = load_notes_trees(&display_notes_refs, 0);
1080        string_list_clear(&display_notes_refs, 0);
1081}
1082
1083int add_note(struct notes_tree *t, const unsigned char *object_sha1,
1084                const unsigned char *note_sha1, combine_notes_fn combine_notes)
1085{
1086        struct leaf_node *l;
1087
1088        if (!t)
1089                t = &default_notes_tree;
1090        assert(t->initialized);
1091        t->dirty = 1;
1092        if (!combine_notes)
1093                combine_notes = t->combine_notes;
1094        l = (struct leaf_node *) xmalloc(sizeof(struct leaf_node));
1095        hashcpy(l->key_sha1, object_sha1);
1096        hashcpy(l->val_sha1, note_sha1);
1097        return note_tree_insert(t, t->root, 0, l, PTR_TYPE_NOTE, combine_notes);
1098}
1099
1100int remove_note(struct notes_tree *t, const unsigned char *object_sha1)
1101{
1102        struct leaf_node l;
1103
1104        if (!t)
1105                t = &default_notes_tree;
1106        assert(t->initialized);
1107        hashcpy(l.key_sha1, object_sha1);
1108        hashclr(l.val_sha1);
1109        note_tree_remove(t, t->root, 0, &l);
1110        if (is_null_sha1(l.val_sha1)) /* no note was removed */
1111                return 1;
1112        t->dirty = 1;
1113        return 0;
1114}
1115
1116const unsigned char *get_note(struct notes_tree *t,
1117                const unsigned char *object_sha1)
1118{
1119        struct leaf_node *found;
1120
1121        if (!t)
1122                t = &default_notes_tree;
1123        assert(t->initialized);
1124        found = note_tree_find(t, t->root, 0, object_sha1);
1125        return found ? found->val_sha1 : NULL;
1126}
1127
1128int for_each_note(struct notes_tree *t, int flags, each_note_fn fn,
1129                void *cb_data)
1130{
1131        if (!t)
1132                t = &default_notes_tree;
1133        assert(t->initialized);
1134        return for_each_note_helper(t, t->root, 0, 0, flags, fn, cb_data);
1135}
1136
1137int write_notes_tree(struct notes_tree *t, unsigned char *result)
1138{
1139        struct tree_write_stack root;
1140        struct write_each_note_data cb_data;
1141        int ret;
1142
1143        if (!t)
1144                t = &default_notes_tree;
1145        assert(t->initialized);
1146
1147        /* Prepare for traversal of current notes tree */
1148        root.next = NULL; /* last forward entry in list is grounded */
1149        strbuf_init(&root.buf, 256 * (32 + 40)); /* assume 256 entries */
1150        root.path[0] = root.path[1] = '\0';
1151        cb_data.root = &root;
1152        cb_data.next_non_note = t->first_non_note;
1153
1154        /* Write tree objects representing current notes tree */
1155        ret = for_each_note(t, FOR_EACH_NOTE_DONT_UNPACK_SUBTREES |
1156                                FOR_EACH_NOTE_YIELD_SUBTREES,
1157                        write_each_note, &cb_data) ||
1158                write_each_non_note_until(NULL, &cb_data) ||
1159                tree_write_stack_finish_subtree(&root) ||
1160                write_sha1_file(root.buf.buf, root.buf.len, tree_type, result);
1161        strbuf_release(&root.buf);
1162        return ret;
1163}
1164
1165void prune_notes(struct notes_tree *t, int flags)
1166{
1167        struct note_delete_list *l = NULL;
1168
1169        if (!t)
1170                t = &default_notes_tree;
1171        assert(t->initialized);
1172
1173        for_each_note(t, 0, prune_notes_helper, &l);
1174
1175        while (l) {
1176                if (flags & NOTES_PRUNE_VERBOSE)
1177                        printf("%s\n", sha1_to_hex(l->sha1));
1178                if (!(flags & NOTES_PRUNE_DRYRUN))
1179                        remove_note(t, l->sha1);
1180                l = l->next;
1181        }
1182}
1183
1184void free_notes(struct notes_tree *t)
1185{
1186        if (!t)
1187                t = &default_notes_tree;
1188        if (t->root)
1189                note_tree_free(t->root);
1190        free(t->root);
1191        while (t->first_non_note) {
1192                t->prev_non_note = t->first_non_note->next;
1193                free(t->first_non_note->path);
1194                free(t->first_non_note);
1195                t->first_non_note = t->prev_non_note;
1196        }
1197        free(t->ref);
1198        memset(t, 0, sizeof(struct notes_tree));
1199}
1200
1201/*
1202 * Fill the given strbuf with the notes associated with the given object.
1203 *
1204 * If the given notes_tree structure is not initialized, it will be auto-
1205 * initialized to the default value (see documentation for init_notes() above).
1206 * If the given notes_tree is NULL, the internal/default notes_tree will be
1207 * used instead.
1208 *
1209 * (raw != 0) gives the %N userformat; otherwise, the note message is given
1210 * for human consumption.
1211 */
1212static void format_note(struct notes_tree *t, const unsigned char *object_sha1,
1213                        struct strbuf *sb, const char *output_encoding, int raw)
1214{
1215        static const char utf8[] = "utf-8";
1216        const unsigned char *sha1;
1217        char *msg, *msg_p;
1218        unsigned long linelen, msglen;
1219        enum object_type type;
1220
1221        if (!t)
1222                t = &default_notes_tree;
1223        if (!t->initialized)
1224                init_notes(t, NULL, NULL, 0);
1225
1226        sha1 = get_note(t, object_sha1);
1227        if (!sha1)
1228                return;
1229
1230        if (!(msg = read_sha1_file(sha1, &type, &msglen)) || type != OBJ_BLOB) {
1231                free(msg);
1232                return;
1233        }
1234
1235        if (output_encoding && *output_encoding &&
1236            !is_encoding_utf8(output_encoding)) {
1237                char *reencoded = reencode_string(msg, output_encoding, utf8);
1238                if (reencoded) {
1239                        free(msg);
1240                        msg = reencoded;
1241                        msglen = strlen(msg);
1242                }
1243        }
1244
1245        /* we will end the annotation by a newline anyway */
1246        if (msglen && msg[msglen - 1] == '\n')
1247                msglen--;
1248
1249        if (!raw) {
1250                const char *ref = t->ref;
1251                if (!ref || !strcmp(ref, GIT_NOTES_DEFAULT_REF)) {
1252                        strbuf_addstr(sb, "\nNotes:\n");
1253                } else {
1254                        if (starts_with(ref, "refs/"))
1255                                ref += 5;
1256                        if (starts_with(ref, "notes/"))
1257                                ref += 6;
1258                        strbuf_addf(sb, "\nNotes (%s):\n", ref);
1259                }
1260        }
1261
1262        for (msg_p = msg; msg_p < msg + msglen; msg_p += linelen + 1) {
1263                linelen = strchrnul(msg_p, '\n') - msg_p;
1264
1265                if (!raw)
1266                        strbuf_addstr(sb, "    ");
1267                strbuf_add(sb, msg_p, linelen);
1268                strbuf_addch(sb, '\n');
1269        }
1270
1271        free(msg);
1272}
1273
1274void format_display_notes(const unsigned char *object_sha1,
1275                          struct strbuf *sb, const char *output_encoding, int raw)
1276{
1277        int i;
1278        assert(display_notes_trees);
1279        for (i = 0; display_notes_trees[i]; i++)
1280                format_note(display_notes_trees[i], object_sha1, sb,
1281                            output_encoding, raw);
1282}
1283
1284int copy_note(struct notes_tree *t,
1285              const unsigned char *from_obj, const unsigned char *to_obj,
1286              int force, combine_notes_fn combine_notes)
1287{
1288        const unsigned char *note = get_note(t, from_obj);
1289        const unsigned char *existing_note = get_note(t, to_obj);
1290
1291        if (!force && existing_note)
1292                return 1;
1293
1294        if (note)
1295                return add_note(t, to_obj, note, combine_notes);
1296        else if (existing_note)
1297                return add_note(t, to_obj, null_sha1, combine_notes);
1298
1299        return 0;
1300}
1301
1302void expand_notes_ref(struct strbuf *sb)
1303{
1304        if (starts_with(sb->buf, "refs/notes/"))
1305                return; /* we're happy */
1306        else if (starts_with(sb->buf, "notes/"))
1307                strbuf_insert(sb, 0, "refs/", 5);
1308        else
1309                strbuf_insert(sb, 0, "refs/notes/", 11);
1310}
1311
1312void expand_loose_notes_ref(struct strbuf *sb)
1313{
1314        unsigned char object[20];
1315
1316        if (get_sha1(sb->buf, object)) {
1317                /* fallback to expand_notes_ref */
1318                expand_notes_ref(sb);
1319        }
1320}