notes.con commit git notes merge: Handle real, non-conflicting notes merges (2085b16)
   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;
  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 entry (or a NULL entry if no entries) from the given tree,
 157 * 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        /* replace tree with p in parent[index] */
 177        parent->a[index] = p;
 178        free(tree);
 179        return 0;
 180}
 181
 182/*
 183 * To remove a leaf_node:
 184 * Search to the tree location appropriate for the given leaf_node's key:
 185 * - If location does not hold a matching entry, abort and do nothing.
 186 * - Replace the matching leaf_node with a NULL entry (and free the leaf_node).
 187 * - Consolidate int_nodes repeatedly, while walking up the tree towards root.
 188 */
 189static void note_tree_remove(struct notes_tree *t, struct int_node *tree,
 190                unsigned char n, struct leaf_node *entry)
 191{
 192        struct leaf_node *l;
 193        struct int_node *parent_stack[20];
 194        unsigned char i, j;
 195        void **p = note_tree_search(t, &tree, &n, entry->key_sha1);
 196
 197        assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
 198        if (GET_PTR_TYPE(*p) != PTR_TYPE_NOTE)
 199                return; /* type mismatch, nothing to remove */
 200        l = (struct leaf_node *) CLR_PTR_TYPE(*p);
 201        if (hashcmp(l->key_sha1, entry->key_sha1))
 202                return; /* key mismatch, nothing to remove */
 203
 204        /* we have found a matching entry */
 205        free(l);
 206        *p = SET_PTR_TYPE(NULL, PTR_TYPE_NULL);
 207
 208        /* consolidate this tree level, and parent levels, if possible */
 209        if (!n)
 210                return; /* cannot consolidate top level */
 211        /* first, build stack of ancestors between root and current node */
 212        parent_stack[0] = t->root;
 213        for (i = 0; i < n; i++) {
 214                j = GET_NIBBLE(i, entry->key_sha1);
 215                parent_stack[i + 1] = CLR_PTR_TYPE(parent_stack[i]->a[j]);
 216        }
 217        assert(i == n && parent_stack[i] == tree);
 218        /* next, unwind stack until note_tree_consolidate() is done */
 219        while (i > 0 &&
 220               !note_tree_consolidate(parent_stack[i], parent_stack[i - 1],
 221                                      GET_NIBBLE(i - 1, entry->key_sha1)))
 222                i--;
 223}
 224
 225/*
 226 * To insert a leaf_node:
 227 * Search to the tree location appropriate for the given leaf_node's key:
 228 * - If location is unused (NULL), store the tweaked pointer directly there
 229 * - If location holds a note entry that matches the note-to-be-inserted, then
 230 *   combine the two notes (by calling the given combine_notes function).
 231 * - If location holds a note entry that matches the subtree-to-be-inserted,
 232 *   then unpack the subtree-to-be-inserted into the location.
 233 * - If location holds a matching subtree entry, unpack the subtree at that
 234 *   location, and restart the insert operation from that level.
 235 * - Else, create a new int_node, holding both the node-at-location and the
 236 *   node-to-be-inserted, and store the new int_node into the location.
 237 */
 238static int note_tree_insert(struct notes_tree *t, struct int_node *tree,
 239                unsigned char n, struct leaf_node *entry, unsigned char type,
 240                combine_notes_fn combine_notes)
 241{
 242        struct int_node *new_node;
 243        struct leaf_node *l;
 244        void **p = note_tree_search(t, &tree, &n, entry->key_sha1);
 245        int ret = 0;
 246
 247        assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
 248        l = (struct leaf_node *) CLR_PTR_TYPE(*p);
 249        switch (GET_PTR_TYPE(*p)) {
 250        case PTR_TYPE_NULL:
 251                assert(!*p);
 252                if (is_null_sha1(entry->val_sha1))
 253                        free(entry);
 254                else
 255                        *p = SET_PTR_TYPE(entry, type);
 256                return 0;
 257        case PTR_TYPE_NOTE:
 258                switch (type) {
 259                case PTR_TYPE_NOTE:
 260                        if (!hashcmp(l->key_sha1, entry->key_sha1)) {
 261                                /* skip concatenation if l == entry */
 262                                if (!hashcmp(l->val_sha1, entry->val_sha1))
 263                                        return 0;
 264
 265                                ret = combine_notes(l->val_sha1,
 266                                                    entry->val_sha1);
 267                                if (!ret && is_null_sha1(l->val_sha1))
 268                                        note_tree_remove(t, tree, n, entry);
 269                                free(entry);
 270                                return ret;
 271                        }
 272                        break;
 273                case PTR_TYPE_SUBTREE:
 274                        if (!SUBTREE_SHA1_PREFIXCMP(l->key_sha1,
 275                                                    entry->key_sha1)) {
 276                                /* unpack 'entry' */
 277                                load_subtree(t, entry, tree, n);
 278                                free(entry);
 279                                return 0;
 280                        }
 281                        break;
 282                }
 283                break;
 284        case PTR_TYPE_SUBTREE:
 285                if (!SUBTREE_SHA1_PREFIXCMP(entry->key_sha1, l->key_sha1)) {
 286                        /* unpack 'l' and restart insert */
 287                        *p = NULL;
 288                        load_subtree(t, l, tree, n);
 289                        free(l);
 290                        return note_tree_insert(t, tree, n, entry, type,
 291                                                combine_notes);
 292                }
 293                break;
 294        }
 295
 296        /* non-matching leaf_node */
 297        assert(GET_PTR_TYPE(*p) == PTR_TYPE_NOTE ||
 298               GET_PTR_TYPE(*p) == PTR_TYPE_SUBTREE);
 299        if (is_null_sha1(entry->val_sha1)) { /* skip insertion of empty note */
 300                free(entry);
 301                return 0;
 302        }
 303        new_node = (struct int_node *) xcalloc(sizeof(struct int_node), 1);
 304        ret = note_tree_insert(t, new_node, n + 1, l, GET_PTR_TYPE(*p),
 305                               combine_notes);
 306        if (ret)
 307                return ret;
 308        *p = SET_PTR_TYPE(new_node, PTR_TYPE_INTERNAL);
 309        return note_tree_insert(t, new_node, n + 1, entry, type, combine_notes);
 310}
 311
 312/* Free the entire notes data contained in the given tree */
 313static void note_tree_free(struct int_node *tree)
 314{
 315        unsigned int i;
 316        for (i = 0; i < 16; i++) {
 317                void *p = tree->a[i];
 318                switch (GET_PTR_TYPE(p)) {
 319                case PTR_TYPE_INTERNAL:
 320                        note_tree_free(CLR_PTR_TYPE(p));
 321                        /* fall through */
 322                case PTR_TYPE_NOTE:
 323                case PTR_TYPE_SUBTREE:
 324                        free(CLR_PTR_TYPE(p));
 325                }
 326        }
 327}
 328
 329/*
 330 * Convert a partial SHA1 hex string to the corresponding partial SHA1 value.
 331 * - hex      - Partial SHA1 segment in ASCII hex format
 332 * - hex_len  - Length of above segment. Must be multiple of 2 between 0 and 40
 333 * - sha1     - Partial SHA1 value is written here
 334 * - sha1_len - Max #bytes to store in sha1, Must be >= hex_len / 2, and < 20
 335 * Returns -1 on error (invalid arguments or invalid SHA1 (not in hex format)).
 336 * Otherwise, returns number of bytes written to sha1 (i.e. hex_len / 2).
 337 * Pads sha1 with NULs up to sha1_len (not included in returned length).
 338 */
 339static int get_sha1_hex_segment(const char *hex, unsigned int hex_len,
 340                unsigned char *sha1, unsigned int sha1_len)
 341{
 342        unsigned int i, len = hex_len >> 1;
 343        if (hex_len % 2 != 0 || len > sha1_len)
 344                return -1;
 345        for (i = 0; i < len; i++) {
 346                unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
 347                if (val & ~0xff)
 348                        return -1;
 349                *sha1++ = val;
 350                hex += 2;
 351        }
 352        for (; i < sha1_len; i++)
 353                *sha1++ = 0;
 354        return len;
 355}
 356
 357static int non_note_cmp(const struct non_note *a, const struct non_note *b)
 358{
 359        return strcmp(a->path, b->path);
 360}
 361
 362static void add_non_note(struct notes_tree *t, const char *path,
 363                unsigned int mode, const unsigned char *sha1)
 364{
 365        struct non_note *p = t->prev_non_note, *n;
 366        n = (struct non_note *) xmalloc(sizeof(struct non_note));
 367        n->next = NULL;
 368        n->path = xstrdup(path);
 369        n->mode = mode;
 370        hashcpy(n->sha1, sha1);
 371        t->prev_non_note = n;
 372
 373        if (!t->first_non_note) {
 374                t->first_non_note = n;
 375                return;
 376        }
 377
 378        if (non_note_cmp(p, n) < 0)
 379                ; /* do nothing  */
 380        else if (non_note_cmp(t->first_non_note, n) <= 0)
 381                p = t->first_non_note;
 382        else {
 383                /* n sorts before t->first_non_note */
 384                n->next = t->first_non_note;
 385                t->first_non_note = n;
 386                return;
 387        }
 388
 389        /* n sorts equal or after p */
 390        while (p->next && non_note_cmp(p->next, n) <= 0)
 391                p = p->next;
 392
 393        if (non_note_cmp(p, n) == 0) { /* n ~= p; overwrite p with n */
 394                assert(strcmp(p->path, n->path) == 0);
 395                p->mode = n->mode;
 396                hashcpy(p->sha1, n->sha1);
 397                free(n);
 398                t->prev_non_note = p;
 399                return;
 400        }
 401
 402        /* n sorts between p and p->next */
 403        n->next = p->next;
 404        p->next = n;
 405}
 406
 407static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,
 408                struct int_node *node, unsigned int n)
 409{
 410        unsigned char object_sha1[20];
 411        unsigned int prefix_len;
 412        void *buf;
 413        struct tree_desc desc;
 414        struct name_entry entry;
 415        int len, path_len;
 416        unsigned char type;
 417        struct leaf_node *l;
 418
 419        buf = fill_tree_descriptor(&desc, subtree->val_sha1);
 420        if (!buf)
 421                die("Could not read %s for notes-index",
 422                     sha1_to_hex(subtree->val_sha1));
 423
 424        prefix_len = subtree->key_sha1[19];
 425        assert(prefix_len * 2 >= n);
 426        memcpy(object_sha1, subtree->key_sha1, prefix_len);
 427        while (tree_entry(&desc, &entry)) {
 428                path_len = strlen(entry.path);
 429                len = get_sha1_hex_segment(entry.path, path_len,
 430                                object_sha1 + prefix_len, 20 - prefix_len);
 431                if (len < 0)
 432                        goto handle_non_note; /* entry.path is not a SHA1 */
 433                len += prefix_len;
 434
 435                /*
 436                 * If object SHA1 is complete (len == 20), assume note object
 437                 * If object SHA1 is incomplete (len < 20), and current
 438                 * component consists of 2 hex chars, assume note subtree
 439                 */
 440                if (len <= 20) {
 441                        type = PTR_TYPE_NOTE;
 442                        l = (struct leaf_node *)
 443                                xcalloc(sizeof(struct leaf_node), 1);
 444                        hashcpy(l->key_sha1, object_sha1);
 445                        hashcpy(l->val_sha1, entry.sha1);
 446                        if (len < 20) {
 447                                if (!S_ISDIR(entry.mode) || path_len != 2)
 448                                        goto handle_non_note; /* not subtree */
 449                                l->key_sha1[19] = (unsigned char) len;
 450                                type = PTR_TYPE_SUBTREE;
 451                        }
 452                        if (note_tree_insert(t, node, n, l, type,
 453                                             combine_notes_concatenate))
 454                                die("Failed to load %s %s into notes tree "
 455                                    "from %s",
 456                                    type == PTR_TYPE_NOTE ? "note" : "subtree",
 457                                    sha1_to_hex(l->key_sha1), t->ref);
 458                }
 459                continue;
 460
 461handle_non_note:
 462                /*
 463                 * Determine full path for this non-note entry:
 464                 * The filename is already found in entry.path, but the
 465                 * directory part of the path must be deduced from the subtree
 466                 * containing this entry. We assume here that the overall notes
 467                 * tree follows a strict byte-based progressive fanout
 468                 * structure (i.e. using 2/38, 2/2/36, etc. fanouts, and not
 469                 * e.g. 4/36 fanout). This means that if a non-note is found at
 470                 * path "dead/beef", the following code will register it as
 471                 * being found on "de/ad/beef".
 472                 * On the other hand, if you use such non-obvious non-note
 473                 * paths in the middle of a notes tree, you deserve what's
 474                 * coming to you ;). Note that for non-notes that are not
 475                 * SHA1-like at the top level, there will be no problems.
 476                 *
 477                 * To conclude, it is strongly advised to make sure non-notes
 478                 * have at least one non-hex character in the top-level path
 479                 * component.
 480                 */
 481                {
 482                        char non_note_path[PATH_MAX];
 483                        char *p = non_note_path;
 484                        const char *q = sha1_to_hex(subtree->key_sha1);
 485                        int i;
 486                        for (i = 0; i < prefix_len; i++) {
 487                                *p++ = *q++;
 488                                *p++ = *q++;
 489                                *p++ = '/';
 490                        }
 491                        strcpy(p, entry.path);
 492                        add_non_note(t, non_note_path, entry.mode, entry.sha1);
 493                }
 494        }
 495        free(buf);
 496}
 497
 498/*
 499 * Determine optimal on-disk fanout for this part of the notes tree
 500 *
 501 * Given a (sub)tree and the level in the internal tree structure, determine
 502 * whether or not the given existing fanout should be expanded for this
 503 * (sub)tree.
 504 *
 505 * Values of the 'fanout' variable:
 506 * - 0: No fanout (all notes are stored directly in the root notes tree)
 507 * - 1: 2/38 fanout
 508 * - 2: 2/2/36 fanout
 509 * - 3: 2/2/2/34 fanout
 510 * etc.
 511 */
 512static unsigned char determine_fanout(struct int_node *tree, unsigned char n,
 513                unsigned char fanout)
 514{
 515        /*
 516         * The following is a simple heuristic that works well in practice:
 517         * For each even-numbered 16-tree level (remember that each on-disk
 518         * fanout level corresponds to _two_ 16-tree levels), peek at all 16
 519         * entries at that tree level. If all of them are either int_nodes or
 520         * subtree entries, then there are likely plenty of notes below this
 521         * level, so we return an incremented fanout.
 522         */
 523        unsigned int i;
 524        if ((n % 2) || (n > 2 * fanout))
 525                return fanout;
 526        for (i = 0; i < 16; i++) {
 527                switch (GET_PTR_TYPE(tree->a[i])) {
 528                case PTR_TYPE_SUBTREE:
 529                case PTR_TYPE_INTERNAL:
 530                        continue;
 531                default:
 532                        return fanout;
 533                }
 534        }
 535        return fanout + 1;
 536}
 537
 538static void construct_path_with_fanout(const unsigned char *sha1,
 539                unsigned char fanout, char *path)
 540{
 541        unsigned int i = 0, j = 0;
 542        const char *hex_sha1 = sha1_to_hex(sha1);
 543        assert(fanout < 20);
 544        while (fanout) {
 545                path[i++] = hex_sha1[j++];
 546                path[i++] = hex_sha1[j++];
 547                path[i++] = '/';
 548                fanout--;
 549        }
 550        strcpy(path + i, hex_sha1 + j);
 551}
 552
 553static int for_each_note_helper(struct notes_tree *t, struct int_node *tree,
 554                unsigned char n, unsigned char fanout, int flags,
 555                each_note_fn fn, void *cb_data)
 556{
 557        unsigned int i;
 558        void *p;
 559        int ret = 0;
 560        struct leaf_node *l;
 561        static char path[40 + 19 + 1];  /* hex SHA1 + 19 * '/' + NUL */
 562
 563        fanout = determine_fanout(tree, n, fanout);
 564        for (i = 0; i < 16; i++) {
 565redo:
 566                p = tree->a[i];
 567                switch (GET_PTR_TYPE(p)) {
 568                case PTR_TYPE_INTERNAL:
 569                        /* recurse into int_node */
 570                        ret = for_each_note_helper(t, CLR_PTR_TYPE(p), n + 1,
 571                                fanout, flags, fn, cb_data);
 572                        break;
 573                case PTR_TYPE_SUBTREE:
 574                        l = (struct leaf_node *) CLR_PTR_TYPE(p);
 575                        /*
 576                         * Subtree entries in the note tree represent parts of
 577                         * the note tree that have not yet been explored. There
 578                         * is a direct relationship between subtree entries at
 579                         * level 'n' in the tree, and the 'fanout' variable:
 580                         * Subtree entries at level 'n <= 2 * fanout' should be
 581                         * preserved, since they correspond exactly to a fanout
 582                         * directory in the on-disk structure. However, subtree
 583                         * entries at level 'n > 2 * fanout' should NOT be
 584                         * preserved, but rather consolidated into the above
 585                         * notes tree level. We achieve this by unconditionally
 586                         * unpacking subtree entries that exist below the
 587                         * threshold level at 'n = 2 * fanout'.
 588                         */
 589                        if (n <= 2 * fanout &&
 590                            flags & FOR_EACH_NOTE_YIELD_SUBTREES) {
 591                                /* invoke callback with subtree */
 592                                unsigned int path_len =
 593                                        l->key_sha1[19] * 2 + fanout;
 594                                assert(path_len < 40 + 19);
 595                                construct_path_with_fanout(l->key_sha1, fanout,
 596                                                           path);
 597                                /* Create trailing slash, if needed */
 598                                if (path[path_len - 1] != '/')
 599                                        path[path_len++] = '/';
 600                                path[path_len] = '\0';
 601                                ret = fn(l->key_sha1, l->val_sha1, path,
 602                                         cb_data);
 603                        }
 604                        if (n > fanout * 2 ||
 605                            !(flags & FOR_EACH_NOTE_DONT_UNPACK_SUBTREES)) {
 606                                /* unpack subtree and resume traversal */
 607                                tree->a[i] = NULL;
 608                                load_subtree(t, l, tree, n);
 609                                free(l);
 610                                goto redo;
 611                        }
 612                        break;
 613                case PTR_TYPE_NOTE:
 614                        l = (struct leaf_node *) CLR_PTR_TYPE(p);
 615                        construct_path_with_fanout(l->key_sha1, fanout, path);
 616                        ret = fn(l->key_sha1, l->val_sha1, path, cb_data);
 617                        break;
 618                }
 619                if (ret)
 620                        return ret;
 621        }
 622        return 0;
 623}
 624
 625struct tree_write_stack {
 626        struct tree_write_stack *next;
 627        struct strbuf buf;
 628        char path[2]; /* path to subtree in next, if any */
 629};
 630
 631static inline int matches_tree_write_stack(struct tree_write_stack *tws,
 632                const char *full_path)
 633{
 634        return  full_path[0] == tws->path[0] &&
 635                full_path[1] == tws->path[1] &&
 636                full_path[2] == '/';
 637}
 638
 639static void write_tree_entry(struct strbuf *buf, unsigned int mode,
 640                const char *path, unsigned int path_len, const
 641                unsigned char *sha1)
 642{
 643        strbuf_addf(buf, "%o %.*s%c", mode, path_len, path, '\0');
 644        strbuf_add(buf, sha1, 20);
 645}
 646
 647static void tree_write_stack_init_subtree(struct tree_write_stack *tws,
 648                const char *path)
 649{
 650        struct tree_write_stack *n;
 651        assert(!tws->next);
 652        assert(tws->path[0] == '\0' && tws->path[1] == '\0');
 653        n = (struct tree_write_stack *)
 654                xmalloc(sizeof(struct tree_write_stack));
 655        n->next = NULL;
 656        strbuf_init(&n->buf, 256 * (32 + 40)); /* assume 256 entries per tree */
 657        n->path[0] = n->path[1] = '\0';
 658        tws->next = n;
 659        tws->path[0] = path[0];
 660        tws->path[1] = path[1];
 661}
 662
 663static int tree_write_stack_finish_subtree(struct tree_write_stack *tws)
 664{
 665        int ret;
 666        struct tree_write_stack *n = tws->next;
 667        unsigned char s[20];
 668        if (n) {
 669                ret = tree_write_stack_finish_subtree(n);
 670                if (ret)
 671                        return ret;
 672                ret = write_sha1_file(n->buf.buf, n->buf.len, tree_type, s);
 673                if (ret)
 674                        return ret;
 675                strbuf_release(&n->buf);
 676                free(n);
 677                tws->next = NULL;
 678                write_tree_entry(&tws->buf, 040000, tws->path, 2, s);
 679                tws->path[0] = tws->path[1] = '\0';
 680        }
 681        return 0;
 682}
 683
 684static int write_each_note_helper(struct tree_write_stack *tws,
 685                const char *path, unsigned int mode,
 686                const unsigned char *sha1)
 687{
 688        size_t path_len = strlen(path);
 689        unsigned int n = 0;
 690        int ret;
 691
 692        /* Determine common part of tree write stack */
 693        while (tws && 3 * n < path_len &&
 694               matches_tree_write_stack(tws, path + 3 * n)) {
 695                n++;
 696                tws = tws->next;
 697        }
 698
 699        /* tws point to last matching tree_write_stack entry */
 700        ret = tree_write_stack_finish_subtree(tws);
 701        if (ret)
 702                return ret;
 703
 704        /* Start subtrees needed to satisfy path */
 705        while (3 * n + 2 < path_len && path[3 * n + 2] == '/') {
 706                tree_write_stack_init_subtree(tws, path + 3 * n);
 707                n++;
 708                tws = tws->next;
 709        }
 710
 711        /* There should be no more directory components in the given path */
 712        assert(memchr(path + 3 * n, '/', path_len - (3 * n)) == NULL);
 713
 714        /* Finally add given entry to the current tree object */
 715        write_tree_entry(&tws->buf, mode, path + 3 * n, path_len - (3 * n),
 716                         sha1);
 717
 718        return 0;
 719}
 720
 721struct write_each_note_data {
 722        struct tree_write_stack *root;
 723        struct non_note *next_non_note;
 724};
 725
 726static int write_each_non_note_until(const char *note_path,
 727                struct write_each_note_data *d)
 728{
 729        struct non_note *n = d->next_non_note;
 730        int cmp = 0, ret;
 731        while (n && (!note_path || (cmp = strcmp(n->path, note_path)) <= 0)) {
 732                if (note_path && cmp == 0)
 733                        ; /* do nothing, prefer note to non-note */
 734                else {
 735                        ret = write_each_note_helper(d->root, n->path, n->mode,
 736                                                     n->sha1);
 737                        if (ret)
 738                                return ret;
 739                }
 740                n = n->next;
 741        }
 742        d->next_non_note = n;
 743        return 0;
 744}
 745
 746static int write_each_note(const unsigned char *object_sha1,
 747                const unsigned char *note_sha1, char *note_path,
 748                void *cb_data)
 749{
 750        struct write_each_note_data *d =
 751                (struct write_each_note_data *) cb_data;
 752        size_t note_path_len = strlen(note_path);
 753        unsigned int mode = 0100644;
 754
 755        if (note_path[note_path_len - 1] == '/') {
 756                /* subtree entry */
 757                note_path_len--;
 758                note_path[note_path_len] = '\0';
 759                mode = 040000;
 760        }
 761        assert(note_path_len <= 40 + 19);
 762
 763        /* Weave non-note entries into note entries */
 764        return  write_each_non_note_until(note_path, d) ||
 765                write_each_note_helper(d->root, note_path, mode, note_sha1);
 766}
 767
 768struct note_delete_list {
 769        struct note_delete_list *next;
 770        const unsigned char *sha1;
 771};
 772
 773static int prune_notes_helper(const unsigned char *object_sha1,
 774                const unsigned char *note_sha1, char *note_path,
 775                void *cb_data)
 776{
 777        struct note_delete_list **l = (struct note_delete_list **) cb_data;
 778        struct note_delete_list *n;
 779
 780        if (has_sha1_file(object_sha1))
 781                return 0; /* nothing to do for this note */
 782
 783        /* failed to find object => prune this note */
 784        n = (struct note_delete_list *) xmalloc(sizeof(*n));
 785        n->next = *l;
 786        n->sha1 = object_sha1;
 787        *l = n;
 788        return 0;
 789}
 790
 791int combine_notes_concatenate(unsigned char *cur_sha1,
 792                const unsigned char *new_sha1)
 793{
 794        char *cur_msg = NULL, *new_msg = NULL, *buf;
 795        unsigned long cur_len, new_len, buf_len;
 796        enum object_type cur_type, new_type;
 797        int ret;
 798
 799        /* read in both note blob objects */
 800        if (!is_null_sha1(new_sha1))
 801                new_msg = read_sha1_file(new_sha1, &new_type, &new_len);
 802        if (!new_msg || !new_len || new_type != OBJ_BLOB) {
 803                free(new_msg);
 804                return 0;
 805        }
 806        if (!is_null_sha1(cur_sha1))
 807                cur_msg = read_sha1_file(cur_sha1, &cur_type, &cur_len);
 808        if (!cur_msg || !cur_len || cur_type != OBJ_BLOB) {
 809                free(cur_msg);
 810                free(new_msg);
 811                hashcpy(cur_sha1, new_sha1);
 812                return 0;
 813        }
 814
 815        /* we will separate the notes by two newlines anyway */
 816        if (cur_msg[cur_len - 1] == '\n')
 817                cur_len--;
 818
 819        /* concatenate cur_msg and new_msg into buf */
 820        buf_len = cur_len + 2 + new_len;
 821        buf = (char *) xmalloc(buf_len);
 822        memcpy(buf, cur_msg, cur_len);
 823        buf[cur_len] = '\n';
 824        buf[cur_len + 1] = '\n';
 825        memcpy(buf + cur_len + 2, new_msg, new_len);
 826        free(cur_msg);
 827        free(new_msg);
 828
 829        /* create a new blob object from buf */
 830        ret = write_sha1_file(buf, buf_len, blob_type, cur_sha1);
 831        free(buf);
 832        return ret;
 833}
 834
 835int combine_notes_overwrite(unsigned char *cur_sha1,
 836                const unsigned char *new_sha1)
 837{
 838        hashcpy(cur_sha1, new_sha1);
 839        return 0;
 840}
 841
 842int combine_notes_ignore(unsigned char *cur_sha1,
 843                const unsigned char *new_sha1)
 844{
 845        return 0;
 846}
 847
 848static int string_list_add_one_ref(const char *path, const unsigned char *sha1,
 849                                   int flag, void *cb)
 850{
 851        struct string_list *refs = cb;
 852        if (!unsorted_string_list_has_string(refs, path))
 853                string_list_append(refs, path);
 854        return 0;
 855}
 856
 857void string_list_add_refs_by_glob(struct string_list *list, const char *glob)
 858{
 859        if (has_glob_specials(glob)) {
 860                for_each_glob_ref(string_list_add_one_ref, glob, list);
 861        } else {
 862                unsigned char sha1[20];
 863                if (get_sha1(glob, sha1))
 864                        warning("notes ref %s is invalid", glob);
 865                if (!unsorted_string_list_has_string(list, glob))
 866                        string_list_append(list, glob);
 867        }
 868}
 869
 870void string_list_add_refs_from_colon_sep(struct string_list *list,
 871                                         const char *globs)
 872{
 873        struct strbuf globbuf = STRBUF_INIT;
 874        struct strbuf **split;
 875        int i;
 876
 877        strbuf_addstr(&globbuf, globs);
 878        split = strbuf_split(&globbuf, ':');
 879
 880        for (i = 0; split[i]; i++) {
 881                if (!split[i]->len)
 882                        continue;
 883                if (split[i]->buf[split[i]->len-1] == ':')
 884                        strbuf_setlen(split[i], split[i]->len-1);
 885                string_list_add_refs_by_glob(list, split[i]->buf);
 886        }
 887
 888        strbuf_list_free(split);
 889        strbuf_release(&globbuf);
 890}
 891
 892static int string_list_add_refs_from_list(struct string_list_item *item,
 893                                          void *cb)
 894{
 895        struct string_list *list = cb;
 896        string_list_add_refs_by_glob(list, item->string);
 897        return 0;
 898}
 899
 900static int notes_display_config(const char *k, const char *v, void *cb)
 901{
 902        int *load_refs = cb;
 903
 904        if (*load_refs && !strcmp(k, "notes.displayref")) {
 905                if (!v)
 906                        config_error_nonbool(k);
 907                string_list_add_refs_by_glob(&display_notes_refs, v);
 908        }
 909
 910        return 0;
 911}
 912
 913const char *default_notes_ref(void)
 914{
 915        const char *notes_ref = NULL;
 916        if (!notes_ref)
 917                notes_ref = getenv(GIT_NOTES_REF_ENVIRONMENT);
 918        if (!notes_ref)
 919                notes_ref = notes_ref_name; /* value of core.notesRef config */
 920        if (!notes_ref)
 921                notes_ref = GIT_NOTES_DEFAULT_REF;
 922        return notes_ref;
 923}
 924
 925void init_notes(struct notes_tree *t, const char *notes_ref,
 926                combine_notes_fn combine_notes, int flags)
 927{
 928        unsigned char sha1[20], object_sha1[20];
 929        unsigned mode;
 930        struct leaf_node root_tree;
 931
 932        if (!t)
 933                t = &default_notes_tree;
 934        assert(!t->initialized);
 935
 936        if (!notes_ref)
 937                notes_ref = default_notes_ref();
 938
 939        if (!combine_notes)
 940                combine_notes = combine_notes_concatenate;
 941
 942        t->root = (struct int_node *) xcalloc(sizeof(struct int_node), 1);
 943        t->first_non_note = NULL;
 944        t->prev_non_note = NULL;
 945        t->ref = notes_ref ? xstrdup(notes_ref) : NULL;
 946        t->combine_notes = combine_notes;
 947        t->initialized = 1;
 948        t->dirty = 0;
 949
 950        if (flags & NOTES_INIT_EMPTY || !notes_ref ||
 951            read_ref(notes_ref, object_sha1))
 952                return;
 953        if (get_tree_entry(object_sha1, "", sha1, &mode))
 954                die("Failed to read notes tree referenced by %s (%s)",
 955                    notes_ref, sha1_to_hex(object_sha1));
 956
 957        hashclr(root_tree.key_sha1);
 958        hashcpy(root_tree.val_sha1, sha1);
 959        load_subtree(t, &root_tree, t->root, 0);
 960}
 961
 962struct load_notes_cb_data {
 963        int counter;
 964        struct notes_tree **trees;
 965};
 966
 967static int load_one_display_note_ref(struct string_list_item *item,
 968                                     void *cb_data)
 969{
 970        struct load_notes_cb_data *c = cb_data;
 971        struct notes_tree *t = xcalloc(1, sizeof(struct notes_tree));
 972        init_notes(t, item->string, combine_notes_ignore, 0);
 973        c->trees[c->counter++] = t;
 974        return 0;
 975}
 976
 977struct notes_tree **load_notes_trees(struct string_list *refs)
 978{
 979        struct notes_tree **trees;
 980        struct load_notes_cb_data cb_data;
 981        trees = xmalloc((refs->nr+1) * sizeof(struct notes_tree *));
 982        cb_data.counter = 0;
 983        cb_data.trees = trees;
 984        for_each_string_list(refs, load_one_display_note_ref, &cb_data);
 985        trees[cb_data.counter] = NULL;
 986        return trees;
 987}
 988
 989void init_display_notes(struct display_notes_opt *opt)
 990{
 991        char *display_ref_env;
 992        int load_config_refs = 0;
 993        display_notes_refs.strdup_strings = 1;
 994
 995        assert(!display_notes_trees);
 996
 997        if (!opt || !opt->suppress_default_notes) {
 998                string_list_append(&display_notes_refs, default_notes_ref());
 999                display_ref_env = getenv(GIT_NOTES_DISPLAY_REF_ENVIRONMENT);
1000                if (display_ref_env) {
1001                        string_list_add_refs_from_colon_sep(&display_notes_refs,
1002                                                            display_ref_env);
1003                        load_config_refs = 0;
1004                } else
1005                        load_config_refs = 1;
1006        }
1007
1008        git_config(notes_display_config, &load_config_refs);
1009
1010        if (opt && opt->extra_notes_refs)
1011                for_each_string_list(opt->extra_notes_refs,
1012                                     string_list_add_refs_from_list,
1013                                     &display_notes_refs);
1014
1015        display_notes_trees = load_notes_trees(&display_notes_refs);
1016        string_list_clear(&display_notes_refs, 0);
1017}
1018
1019int add_note(struct notes_tree *t, const unsigned char *object_sha1,
1020                const unsigned char *note_sha1, combine_notes_fn combine_notes)
1021{
1022        struct leaf_node *l;
1023
1024        if (!t)
1025                t = &default_notes_tree;
1026        assert(t->initialized);
1027        t->dirty = 1;
1028        if (!combine_notes)
1029                combine_notes = t->combine_notes;
1030        l = (struct leaf_node *) xmalloc(sizeof(struct leaf_node));
1031        hashcpy(l->key_sha1, object_sha1);
1032        hashcpy(l->val_sha1, note_sha1);
1033        return note_tree_insert(t, t->root, 0, l, PTR_TYPE_NOTE, combine_notes);
1034}
1035
1036void remove_note(struct notes_tree *t, const unsigned char *object_sha1)
1037{
1038        struct leaf_node l;
1039
1040        if (!t)
1041                t = &default_notes_tree;
1042        assert(t->initialized);
1043        t->dirty = 1;
1044        hashcpy(l.key_sha1, object_sha1);
1045        hashclr(l.val_sha1);
1046        note_tree_remove(t, t->root, 0, &l);
1047}
1048
1049const unsigned char *get_note(struct notes_tree *t,
1050                const unsigned char *object_sha1)
1051{
1052        struct leaf_node *found;
1053
1054        if (!t)
1055                t = &default_notes_tree;
1056        assert(t->initialized);
1057        found = note_tree_find(t, t->root, 0, object_sha1);
1058        return found ? found->val_sha1 : NULL;
1059}
1060
1061int for_each_note(struct notes_tree *t, int flags, each_note_fn fn,
1062                void *cb_data)
1063{
1064        if (!t)
1065                t = &default_notes_tree;
1066        assert(t->initialized);
1067        return for_each_note_helper(t, t->root, 0, 0, flags, fn, cb_data);
1068}
1069
1070int write_notes_tree(struct notes_tree *t, unsigned char *result)
1071{
1072        struct tree_write_stack root;
1073        struct write_each_note_data cb_data;
1074        int ret;
1075
1076        if (!t)
1077                t = &default_notes_tree;
1078        assert(t->initialized);
1079
1080        /* Prepare for traversal of current notes tree */
1081        root.next = NULL; /* last forward entry in list is grounded */
1082        strbuf_init(&root.buf, 256 * (32 + 40)); /* assume 256 entries */
1083        root.path[0] = root.path[1] = '\0';
1084        cb_data.root = &root;
1085        cb_data.next_non_note = t->first_non_note;
1086
1087        /* Write tree objects representing current notes tree */
1088        ret = for_each_note(t, FOR_EACH_NOTE_DONT_UNPACK_SUBTREES |
1089                                FOR_EACH_NOTE_YIELD_SUBTREES,
1090                        write_each_note, &cb_data) ||
1091                write_each_non_note_until(NULL, &cb_data) ||
1092                tree_write_stack_finish_subtree(&root) ||
1093                write_sha1_file(root.buf.buf, root.buf.len, tree_type, result);
1094        strbuf_release(&root.buf);
1095        return ret;
1096}
1097
1098void prune_notes(struct notes_tree *t, int flags)
1099{
1100        struct note_delete_list *l = NULL;
1101
1102        if (!t)
1103                t = &default_notes_tree;
1104        assert(t->initialized);
1105
1106        for_each_note(t, 0, prune_notes_helper, &l);
1107
1108        while (l) {
1109                if (flags & NOTES_PRUNE_VERBOSE)
1110                        printf("%s\n", sha1_to_hex(l->sha1));
1111                if (!(flags & NOTES_PRUNE_DRYRUN))
1112                        remove_note(t, l->sha1);
1113                l = l->next;
1114        }
1115}
1116
1117void free_notes(struct notes_tree *t)
1118{
1119        if (!t)
1120                t = &default_notes_tree;
1121        if (t->root)
1122                note_tree_free(t->root);
1123        free(t->root);
1124        while (t->first_non_note) {
1125                t->prev_non_note = t->first_non_note->next;
1126                free(t->first_non_note->path);
1127                free(t->first_non_note);
1128                t->first_non_note = t->prev_non_note;
1129        }
1130        free(t->ref);
1131        memset(t, 0, sizeof(struct notes_tree));
1132}
1133
1134void format_note(struct notes_tree *t, const unsigned char *object_sha1,
1135                struct strbuf *sb, const char *output_encoding, int flags)
1136{
1137        static const char utf8[] = "utf-8";
1138        const unsigned char *sha1;
1139        char *msg, *msg_p;
1140        unsigned long linelen, msglen;
1141        enum object_type type;
1142
1143        if (!t)
1144                t = &default_notes_tree;
1145        if (!t->initialized)
1146                init_notes(t, NULL, NULL, 0);
1147
1148        sha1 = get_note(t, object_sha1);
1149        if (!sha1)
1150                return;
1151
1152        if (!(msg = read_sha1_file(sha1, &type, &msglen)) || !msglen ||
1153                        type != OBJ_BLOB) {
1154                free(msg);
1155                return;
1156        }
1157
1158        if (output_encoding && *output_encoding &&
1159                        strcmp(utf8, output_encoding)) {
1160                char *reencoded = reencode_string(msg, output_encoding, utf8);
1161                if (reencoded) {
1162                        free(msg);
1163                        msg = reencoded;
1164                        msglen = strlen(msg);
1165                }
1166        }
1167
1168        /* we will end the annotation by a newline anyway */
1169        if (msglen && msg[msglen - 1] == '\n')
1170                msglen--;
1171
1172        if (flags & NOTES_SHOW_HEADER) {
1173                const char *ref = t->ref;
1174                if (!ref || !strcmp(ref, GIT_NOTES_DEFAULT_REF)) {
1175                        strbuf_addstr(sb, "\nNotes:\n");
1176                } else {
1177                        if (!prefixcmp(ref, "refs/"))
1178                                ref += 5;
1179                        if (!prefixcmp(ref, "notes/"))
1180                                ref += 6;
1181                        strbuf_addf(sb, "\nNotes (%s):\n", ref);
1182                }
1183        }
1184
1185        for (msg_p = msg; msg_p < msg + msglen; msg_p += linelen + 1) {
1186                linelen = strchrnul(msg_p, '\n') - msg_p;
1187
1188                if (flags & NOTES_INDENT)
1189                        strbuf_addstr(sb, "    ");
1190                strbuf_add(sb, msg_p, linelen);
1191                strbuf_addch(sb, '\n');
1192        }
1193
1194        free(msg);
1195}
1196
1197void format_display_notes(const unsigned char *object_sha1,
1198                          struct strbuf *sb, const char *output_encoding, int flags)
1199{
1200        int i;
1201        assert(display_notes_trees);
1202        for (i = 0; display_notes_trees[i]; i++)
1203                format_note(display_notes_trees[i], object_sha1, sb,
1204                            output_encoding, flags);
1205}
1206
1207int copy_note(struct notes_tree *t,
1208              const unsigned char *from_obj, const unsigned char *to_obj,
1209              int force, combine_notes_fn combine_notes)
1210{
1211        const unsigned char *note = get_note(t, from_obj);
1212        const unsigned char *existing_note = get_note(t, to_obj);
1213
1214        if (!force && existing_note)
1215                return 1;
1216
1217        if (note)
1218                return add_note(t, to_obj, note, combine_notes);
1219        else if (existing_note)
1220                return add_note(t, to_obj, null_sha1, combine_notes);
1221
1222        return 0;
1223}