/src/git/notes.c

Source
#define USE_THE_REPOSITORY_VARIABLE
#define DISABLE_SIGN_COMPARE_WARNINGS

#include "git-compat-util.h"
#include "config.h"
#include "environment.h"
#include "hex.h"
#include "notes.h"
#include "object-file.h"
#include "object-name.h"
#include "odb.h"
#include "utf8.h"
#include "strbuf.h"
#include "tree-walk.h"
#include "string-list.h"
#include "refs.h"

/*
 * Use a non-balancing simple 16-tree structure with struct int_node as
 * internal nodes, and struct leaf_node as leaf nodes. Each int_node has a
 * 16-array of pointers to its children.
 * The bottom 2 bits of each pointer is used to identify the pointer type
 * - ptr & 3 == 0 - NULL pointer, assert(ptr == NULL)
 * - ptr & 3 == 1 - pointer to next internal node - cast to struct int_node *
 * - ptr & 3 == 2 - pointer to note entry - cast to struct leaf_node *
 * - ptr & 3 == 3 - pointer to subtree entry - cast to struct leaf_node *
 *
 * The root node is a statically allocated struct int_node.
 */
struct int_node {
  void *a[16];
};

/*
 * Leaf nodes come in two variants, note entries and subtree entries,
 * distinguished by the LSb of the leaf node pointer (see above).
 * As a note entry, the key is the SHA1 of the referenced object, and the
 * value is the SHA1 of the note object.
 * As a subtree entry, the key is the prefix SHA1 (w/trailing NULs) of the
 * referenced object, using the last byte of the key to store the length of
 * the prefix. The value is the SHA1 of the tree object containing the notes
 * subtree.
 */
struct leaf_node {
  struct object_id key_oid;
  struct object_id val_oid;
};

/*
 * A notes tree may contain entries that are not notes, and that do not follow
 * the naming conventions of notes. There are typically none/few of these, but
 * we still need to keep track of them. Keep a simple linked list sorted alpha-
 * betically on the non-note path. The list is populated when parsing tree
 * objects in load_subtree(), and the non-notes are correctly written back into
 * the tree objects produced by write_notes_tree().
 */
struct non_note {
  struct non_note *next; /* grounded (last->next == NULL) */
  char *path;
  unsigned int mode;
  struct object_id oid;
};

#define PTR_TYPE_NULL     0
#define PTR_TYPE_INTERNAL 1
#define PTR_TYPE_NOTE     2
#define PTR_TYPE_SUBTREE  3

#define GET_PTR_TYPE(ptr)       ((uintptr_t) (ptr) & 3)
#define CLR_PTR_TYPE(ptr)       ((void *) ((uintptr_t) (ptr) & ~3))
#define SET_PTR_TYPE(ptr, type) ((void *) ((uintptr_t) (ptr) | (type)))

#define GET_NIBBLE(n, sha1) ((((sha1)[(n) >> 1]) >> ((~(n) & 0x01) << 2)) & 0x0f)

#define KEY_INDEX (the_hash_algo->rawsz - 1)
#define FANOUT_PATH_SEPARATORS (the_hash_algo->rawsz - 1)
#define FANOUT_PATH_SEPARATORS_MAX ((GIT_MAX_HEXSZ / 2) - 1)
#define SUBTREE_SHA1_PREFIXCMP(key_sha1, subtree_sha1) \
  (memcmp(key_sha1, subtree_sha1, subtree_sha1[KEY_INDEX]))

struct notes_tree default_notes_tree;

static struct string_list display_notes_refs = STRING_LIST_INIT_NODUP;
static struct notes_tree **display_notes_trees;

static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,
    struct int_node *node, unsigned int n);

/*
 * Search the tree until the appropriate location for the given key is found:
 * 1. Start at the root node, with n = 0
 * 2. If a[0] at the current level is a matching subtree entry, unpack that
 *    subtree entry and remove it; restart search at the current level.
 * 3. Use the nth nibble of the key as an index into a:
 *    - If a[n] is an int_node, recurse from #2 into that node and increment n
 *    - If a matching subtree entry, unpack that subtree entry (and remove it);
 *      restart search at the current level.
 *    - Otherwise, we have found one of the following:
 *      - a subtree entry which does not match the key
 *      - a note entry which may or may not match the key
 *      - an unused leaf node (NULL)
 *      In any case, set *tree and *n, and return pointer to the tree location.
 */
static void **note_tree_search(struct notes_tree *t, struct int_node **tree,
    unsigned char *n, const unsigned char *key_sha1)
{
  struct leaf_node *l;
  unsigned char i;
  void *p = (*tree)->a[0];

  if (GET_PTR_TYPE(p) == PTR_TYPE_SUBTREE) {
    l = (struct leaf_node *) CLR_PTR_TYPE(p);
    if (!SUBTREE_SHA1_PREFIXCMP(key_sha1, l->key_oid.hash)) {
      /* unpack tree and resume search */
      (*tree)->a[0] = NULL;
      load_subtree(t, l, *tree, *n);
      free(l);
      return note_tree_search(t, tree, n, key_sha1);
    }
  }

  i = GET_NIBBLE(*n, key_sha1);
  p = (*tree)->a[i];
  switch (GET_PTR_TYPE(p)) {
  case PTR_TYPE_INTERNAL:
    *tree = CLR_PTR_TYPE(p);
    (*n)++;
    return note_tree_search(t, tree, n, key_sha1);
  case PTR_TYPE_SUBTREE:
    l = (struct leaf_node *) CLR_PTR_TYPE(p);
    if (!SUBTREE_SHA1_PREFIXCMP(key_sha1, l->key_oid.hash)) {
      /* unpack tree and resume search */
      (*tree)->a[i] = NULL;
      load_subtree(t, l, *tree, *n);
      free(l);
      return note_tree_search(t, tree, n, key_sha1);
    }
    /* fall through */
  default:
    return &((*tree)->a[i]);
  }
}

/*
 * To find a leaf_node:
 * Search to the tree location appropriate for the given key:
 * If a note entry with matching key, return the note entry, else return NULL.
 */
static struct leaf_node *note_tree_find(struct notes_tree *t,
    struct int_node *tree, unsigned char n,
    const unsigned char *key_sha1)
{
  void **p = note_tree_search(t, &tree, &n, key_sha1);
  if (GET_PTR_TYPE(*p) == PTR_TYPE_NOTE) {
    struct leaf_node *l = (struct leaf_node *) CLR_PTR_TYPE(*p);
    if (hasheq(key_sha1, l->key_oid.hash, the_repository->hash_algo))
      return l;
  }
  return NULL;
}

/*
 * How to consolidate an int_node:
 * If there are > 1 non-NULL entries, give up and return non-zero.
 * Otherwise replace the int_node at the given index in the given parent node
 * with the only NOTE entry (or a NULL entry if no entries) from the given
 * tree, and return 0.
 */
static int note_tree_consolidate(struct int_node *tree,
  struct int_node *parent, unsigned char index)
{
  unsigned int i;
  void *p = NULL;

  assert(tree && parent);
  assert(CLR_PTR_TYPE(parent->a[index]) == tree);

  for (i = 0; i < 16; i++) {
    if (GET_PTR_TYPE(tree->a[i]) != PTR_TYPE_NULL) {
      if (p) /* more than one entry */
        return -2;
      p = tree->a[i];
    }
  }

  if (p && (GET_PTR_TYPE(p) != PTR_TYPE_NOTE))
    return -2;
  /* replace tree with p in parent[index] */
  parent->a[index] = p;
  free(tree);
  return 0;
}

/*
 * To remove a leaf_node:
 * Search to the tree location appropriate for the given leaf_node's key:
 * - If location does not hold a matching entry, abort and do nothing.
 * - Copy the matching entry's value into the given entry.
 * - Replace the matching leaf_node with a NULL entry (and free the leaf_node).
 * - Consolidate int_nodes repeatedly, while walking up the tree towards root.
 */
static void note_tree_remove(struct notes_tree *t,
    struct int_node *tree, unsigned char n,
    struct leaf_node *entry)
{
  struct leaf_node *l;
  struct int_node *parent_stack[GIT_MAX_RAWSZ];
  unsigned char i, j;
  void **p = note_tree_search(t, &tree, &n, entry->key_oid.hash);

  assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
  if (GET_PTR_TYPE(*p) != PTR_TYPE_NOTE)
    return; /* type mismatch, nothing to remove */
  l = (struct leaf_node *) CLR_PTR_TYPE(*p);
  if (!oideq(&l->key_oid, &entry->key_oid))
    return; /* key mismatch, nothing to remove */

  /* we have found a matching entry */
  oidcpy(&entry->val_oid, &l->val_oid);
  free(l);
  *p = SET_PTR_TYPE(NULL, PTR_TYPE_NULL);

  /* consolidate this tree level, and parent levels, if possible */
  if (!n)
    return; /* cannot consolidate top level */
  /* first, build stack of ancestors between root and current node */
  parent_stack[0] = t->root;
  for (i = 0; i < n; i++) {
    j = GET_NIBBLE(i, entry->key_oid.hash);
    parent_stack[i + 1] = CLR_PTR_TYPE(parent_stack[i]->a[j]);
  }
  assert(i == n && parent_stack[i] == tree);
  /* next, unwind stack until note_tree_consolidate() is done */
  while (i > 0 &&
         !note_tree_consolidate(parent_stack[i], parent_stack[i - 1],
              GET_NIBBLE(i - 1, entry->key_oid.hash)))
    i--;
}

/*
 * To insert a leaf_node:
 * Search to the tree location appropriate for the given leaf_node's key:
 * - If location is unused (NULL), store the tweaked pointer directly there
 * - If location holds a note entry that matches the note-to-be-inserted, then
 *   combine the two notes (by calling the given combine_notes function).
 * - If location holds a note entry that matches the subtree-to-be-inserted,
 *   then unpack the subtree-to-be-inserted into the location.
 * - If location holds a matching subtree entry, unpack the subtree at that
 *   location, and restart the insert operation from that level.
 * - Else, create a new int_node, holding both the node-at-location and the
 *   node-to-be-inserted, and store the new int_node into the location.
 */
static int note_tree_insert(struct notes_tree *t, struct int_node *tree,
    unsigned char n, struct leaf_node *entry, unsigned char type,
    combine_notes_fn combine_notes)
{
  struct int_node *new_node;
  struct leaf_node *l;
  void **p = note_tree_search(t, &tree, &n, entry->key_oid.hash);
  int ret = 0;

  assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
  l = (struct leaf_node *) CLR_PTR_TYPE(*p);
  switch (GET_PTR_TYPE(*p)) {
  case PTR_TYPE_NULL:
    assert(!*p);
    if (is_null_oid(&entry->val_oid))
      free(entry);
    else
      *p = SET_PTR_TYPE(entry, type);
    return 0;
  case PTR_TYPE_NOTE:
    switch (type) {
    case PTR_TYPE_NOTE:
      if (oideq(&l->key_oid, &entry->key_oid)) {
        /* skip concatenation if l == entry */
        if (oideq(&l->val_oid, &entry->val_oid)) {
          free(entry);
          return 0;
        }

        ret = combine_notes(&l->val_oid,
                &entry->val_oid);
        if (!ret && is_null_oid(&l->val_oid))
          note_tree_remove(t, tree, n, entry);
        free(entry);
        return ret;
      }
      break;
    case PTR_TYPE_SUBTREE:
      if (!SUBTREE_SHA1_PREFIXCMP(l->key_oid.hash,
                entry->key_oid.hash)) {
        /* unpack 'entry' */
        load_subtree(t, entry, tree, n);
        free(entry);
        return 0;
      }
      break;
    }
    break;
  case PTR_TYPE_SUBTREE:
    if (!SUBTREE_SHA1_PREFIXCMP(entry->key_oid.hash, l->key_oid.hash)) {
      /* unpack 'l' and restart insert */
      *p = NULL;
      load_subtree(t, l, tree, n);
      free(l);
      return note_tree_insert(t, tree, n, entry, type,
            combine_notes);
    }
    break;
  }

  /* non-matching leaf_node */
  assert(GET_PTR_TYPE(*p) == PTR_TYPE_NOTE ||
         GET_PTR_TYPE(*p) == PTR_TYPE_SUBTREE);
  if (is_null_oid(&entry->val_oid)) { /* skip insertion of empty note */
    free(entry);
    return 0;
  }
  new_node = (struct int_node *) xcalloc(1, sizeof(struct int_node));
  ret = note_tree_insert(t, new_node, n + 1, l, GET_PTR_TYPE(*p),
             combine_notes);
  if (ret)
    return ret;
  *p = SET_PTR_TYPE(new_node, PTR_TYPE_INTERNAL);
  return note_tree_insert(t, new_node, n + 1, entry, type, combine_notes);
}

/* Free the entire notes data contained in the given tree */
static void note_tree_free(struct int_node *tree)
{
  unsigned int i;
  for (i = 0; i < 16; i++) {
    void *p = tree->a[i];
    switch (GET_PTR_TYPE(p)) {
    case PTR_TYPE_INTERNAL:
      note_tree_free(CLR_PTR_TYPE(p));
      /* fall through */
    case PTR_TYPE_NOTE:
    case PTR_TYPE_SUBTREE:
      free(CLR_PTR_TYPE(p));
    }
  }
}

static int non_note_cmp(const struct non_note *a, const struct non_note *b)
{
  return strcmp(a->path, b->path);
}

/* note: takes ownership of path string */
static void add_non_note(struct notes_tree *t, char *path,
    unsigned int mode, const unsigned char *sha1)
{
  struct non_note *p = t->prev_non_note, *n;
  n = (struct non_note *) xmalloc(sizeof(struct non_note));
  n->next = NULL;
  n->path = path;
  n->mode = mode;
  oidread(&n->oid, sha1, the_repository->hash_algo);
  t->prev_non_note = n;

  if (!t->first_non_note) {
    t->first_non_note = n;
    return;
  }

  if (non_note_cmp(p, n) < 0)
    ; /* do nothing  */
  else if (non_note_cmp(t->first_non_note, n) <= 0)
    p = t->first_non_note;
  else {
    /* n sorts before t->first_non_note */
    n->next = t->first_non_note;
    t->first_non_note = n;
    return;
  }

  /* n sorts equal or after p */
  while (p->next && non_note_cmp(p->next, n) <= 0)
    p = p->next;

  if (non_note_cmp(p, n) == 0) { /* n ~= p; overwrite p with n */
    assert(strcmp(p->path, n->path) == 0);
    p->mode = n->mode;
    oidcpy(&p->oid, &n->oid);
    free(n);
    t->prev_non_note = p;
    return;
  }

  /* n sorts between p and p->next */
  n->next = p->next;
  p->next = n;
}

static void load_subtree(struct notes_tree *t, struct leaf_node *subtree,
    struct int_node *node, unsigned int n)
{
  struct object_id object_oid;
  size_t prefix_len;
  void *buf;
  struct tree_desc desc;
  struct name_entry entry;
  const unsigned hashsz = the_hash_algo->rawsz;

  buf = fill_tree_descriptor(the_repository, &desc, &subtree->val_oid);
  if (!buf)
    die("Could not read %s for notes-index",
         oid_to_hex(&subtree->val_oid));

  prefix_len = subtree->key_oid.hash[KEY_INDEX];
  if (prefix_len >= hashsz)
    BUG("prefix_len (%"PRIuMAX") is out of range", (uintmax_t)prefix_len);
  if (prefix_len * 2 < n)
    BUG("prefix_len (%"PRIuMAX") is too small", (uintmax_t)prefix_len);
  memcpy(object_oid.hash, subtree->key_oid.hash, prefix_len);
  while (tree_entry(&desc, &entry)) {
    unsigned char type;
    struct leaf_node *l;
    size_t path_len = strlen(entry.path);

    if (path_len == 2 * (hashsz - prefix_len)) {
      /* This is potentially the remainder of the SHA-1 */

      if (!S_ISREG(entry.mode))
        /* notes must be blobs */
        goto handle_non_note;

      if (hex_to_bytes(object_oid.hash + prefix_len, entry.path,
           hashsz - prefix_len))
        goto handle_non_note; /* entry.path is not a SHA1 */

      memset(object_oid.hash + hashsz, 0, GIT_MAX_RAWSZ - hashsz);

      type = PTR_TYPE_NOTE;
    } else if (path_len == 2) {
      /* This is potentially an internal node */
      size_t len = prefix_len;

      if (!S_ISDIR(entry.mode))
        /* internal nodes must be trees */
        goto handle_non_note;

      if (hex_to_bytes(object_oid.hash + len++, entry.path, 1))
        goto handle_non_note; /* entry.path is not a SHA1 */

      /*
       * Pad the rest of the SHA-1 with zeros,
       * except for the last byte, where we write
       * the length:
       */
      memset(object_oid.hash + len, 0, hashsz - len - 1);
      object_oid.hash[KEY_INDEX] = (unsigned char)len;

      type = PTR_TYPE_SUBTREE;
    } else {
      /* This can't be part of a note */
      goto handle_non_note;
    }

    CALLOC_ARRAY(l, 1);
    oidcpy(&l->key_oid, &object_oid);
    oidcpy(&l->val_oid, &entry.oid);
    oid_set_algo(&l->key_oid, the_hash_algo);
    oid_set_algo(&l->val_oid, the_hash_algo);
    if (note_tree_insert(t, node, n, l, type,
             combine_notes_concatenate))
      die("Failed to load %s %s into notes tree "
          "from %s",
          type == PTR_TYPE_NOTE ? "note" : "subtree",
          oid_to_hex(&object_oid), t->ref);

    continue;

handle_non_note:
    /*
     * Determine full path for this non-note entry. The
     * filename is already found in entry.path, but the
     * directory part of the path must be deduced from the
     * subtree containing this entry based on our
     * knowledge that the overall notes tree follows a
     * strict byte-based progressive fanout structure
     * (i.e. using 2/38, 2/2/36, etc. fanouts).
     */
    {
      struct strbuf non_note_path = STRBUF_INIT;
      const char *q = oid_to_hex(&subtree->key_oid);
      size_t i;
      for (i = 0; i < prefix_len; i++) {
        strbuf_addch(&non_note_path, *q++);
        strbuf_addch(&non_note_path, *q++);
        strbuf_addch(&non_note_path, '/');
      }
      strbuf_addstr(&non_note_path, entry.path);
      oid_set_algo(&entry.oid, the_hash_algo);
      add_non_note(t, strbuf_detach(&non_note_path, NULL),
             entry.mode, entry.oid.hash);
    }
  }
  free(buf);
}

/*
 * Determine optimal on-disk fanout for this part of the notes tree
 *
 * Given a (sub)tree and the level in the internal tree structure, determine
 * whether or not the given existing fanout should be expanded for this
 * (sub)tree.
 *
 * Values of the 'fanout' variable:
 * - 0: No fanout (all notes are stored directly in the root notes tree)
 * - 1: 2/38 fanout
 * - 2: 2/2/36 fanout
 * - 3: 2/2/2/34 fanout
 * etc.
 */
static unsigned char determine_fanout(struct int_node *tree, unsigned char n,
    unsigned char fanout)
{
  /*
   * The following is a simple heuristic that works well in practice:
   * For each even-numbered 16-tree level (remember that each on-disk
   * fanout level corresponds to _two_ 16-tree levels), peek at all 16
   * entries at that tree level. If all of them are either int_nodes or
   * subtree entries, then there are likely plenty of notes below this
   * level, so we return an incremented fanout.
   */
  unsigned int i;
  if ((n % 2) || (n > 2 * fanout))
    return fanout;
  for (i = 0; i < 16; i++) {
    switch (GET_PTR_TYPE(tree->a[i])) {
    case PTR_TYPE_SUBTREE:
    case PTR_TYPE_INTERNAL:
      continue;
    default:
      return fanout;
    }
  }
  return fanout + 1;
}

/* hex oid + '/' between each pair of hex digits + NUL */
#define FANOUT_PATH_MAX GIT_MAX_HEXSZ + FANOUT_PATH_SEPARATORS_MAX + 1

static void construct_path_with_fanout(const unsigned char *hash,
    unsigned char fanout, char *path)
{
  unsigned int i = 0, j = 0;
  const char *hex_hash = hash_to_hex(hash);
  assert(fanout < the_hash_algo->rawsz);
  while (fanout) {
    path[i++] = hex_hash[j++];
    path[i++] = hex_hash[j++];
    path[i++] = '/';
    fanout--;
  }
  xsnprintf(path + i, FANOUT_PATH_MAX - i, "%s", hex_hash + j);
}

static int for_each_note_helper(struct notes_tree *t, struct int_node *tree,
    unsigned char n, unsigned char fanout, int flags,
    each_note_fn fn, void *cb_data)
{
  unsigned int i;
  void *p;
  int ret = 0;
  struct leaf_node *l;
  static char path[FANOUT_PATH_MAX];

  fanout = determine_fanout(tree, n, fanout);
  for (i = 0; i < 16; i++) {
redo:
    p = tree->a[i];
    switch (GET_PTR_TYPE(p)) {
    case PTR_TYPE_INTERNAL:
      /* recurse into int_node */
      ret = for_each_note_helper(t, CLR_PTR_TYPE(p), n + 1,
        fanout, flags, fn, cb_data);
      break;
    case PTR_TYPE_SUBTREE:
      l = (struct leaf_node *) CLR_PTR_TYPE(p);
      /*
       * Subtree entries in the note tree represent parts of
       * the note tree that have not yet been explored. There
       * is a direct relationship between subtree entries at
       * level 'n' in the tree, and the 'fanout' variable:
       * Subtree entries at level 'n < 2 * fanout' should be
       * preserved, since they correspond exactly to a fanout
       * directory in the on-disk structure. However, subtree
       * entries at level 'n >= 2 * fanout' should NOT be
       * preserved, but rather consolidated into the above
       * notes tree level. We achieve this by unconditionally
       * unpacking subtree entries that exist below the
       * threshold level at 'n = 2 * fanout'.
       */
      if (n < 2 * fanout &&
          flags & FOR_EACH_NOTE_YIELD_SUBTREES) {
        /* invoke callback with subtree */
        unsigned int path_len =
          l->key_oid.hash[KEY_INDEX] * 2 + fanout;
        assert(path_len < FANOUT_PATH_MAX - 1);
        construct_path_with_fanout(l->key_oid.hash,
                 fanout,
                 path);
        /* Create trailing slash, if needed */
        if (path[path_len - 1] != '/')
          path[path_len++] = '/';
        path[path_len] = '\0';
        ret = fn(&l->key_oid, &l->val_oid,
           path,
           cb_data);
      }
      if (n >= 2 * fanout ||
          !(flags & FOR_EACH_NOTE_DONT_UNPACK_SUBTREES)) {
        /* unpack subtree and resume traversal */
        tree->a[i] = NULL;
        load_subtree(t, l, tree, n);
        free(l);
        goto redo;
      }
      break;
    case PTR_TYPE_NOTE:
      l = (struct leaf_node *) CLR_PTR_TYPE(p);
      construct_path_with_fanout(l->key_oid.hash, fanout,
               path);
      ret = fn(&l->key_oid, &l->val_oid, path,
         cb_data);
      break;
    }
    if (ret)
      return ret;
  }
  return 0;
}

struct tree_write_stack {
  struct tree_write_stack *next;
  struct strbuf buf;
  char path[2]; /* path to subtree in next, if any */
};

static inline int matches_tree_write_stack(struct tree_write_stack *tws,
    const char *full_path)
{
  return  full_path[0] == tws->path[0] &&
    full_path[1] == tws->path[1] &&
    full_path[2] == '/';
}

static void write_tree_entry(struct strbuf *buf, unsigned int mode,
    const char *path, unsigned int path_len, const
    unsigned char *hash)
{
  strbuf_addf(buf, "%o %.*s%c", mode, path_len, path, '\0');
  strbuf_add(buf, hash, the_hash_algo->rawsz);
}

static void tree_write_stack_init_subtree(struct tree_write_stack *tws,
    const char *path)
{
  struct tree_write_stack *n;
  assert(!tws->next);
  assert(tws->path[0] == '\0' && tws->path[1] == '\0');
  n = (struct tree_write_stack *)
    xmalloc(sizeof(struct tree_write_stack));
  n->next = NULL;
  strbuf_init(&n->buf, 256 * (32 + the_hash_algo->hexsz)); /* assume 256 entries per tree */
  n->path[0] = n->path[1] = '\0';
  tws->next = n;
  tws->path[0] = path[0];
  tws->path[1] = path[1];
}

static int tree_write_stack_finish_subtree(struct tree_write_stack *tws)
{
  int ret;
  struct tree_write_stack *n = tws->next;
  struct object_id s;
  if (n) {
    ret = tree_write_stack_finish_subtree(n);
    if (ret)
      return ret;
    ret = odb_write_object(the_repository->objects, n->buf.buf,
               n->buf.len, OBJ_TREE, &s);
    if (ret)
      return ret;
    strbuf_release(&n->buf);
    free(n);
    tws->next = NULL;
    write_tree_entry(&tws->buf, 040000, tws->path, 2, s.hash);
    tws->path[0] = tws->path[1] = '\0';
  }
  return 0;
}

static int write_each_note_helper(struct tree_write_stack *tws,
    const char *path, unsigned int mode,
    const struct object_id *oid)
{
  size_t path_len = strlen(path);
  unsigned int n = 0;
  int ret;

  /* Determine common part of tree write stack */
  while (tws && 3 * n < path_len &&
         matches_tree_write_stack(tws, path + 3 * n)) {
    n++;
    tws = tws->next;
  }

  /* tws point to last matching tree_write_stack entry */
  ret = tree_write_stack_finish_subtree(tws);
  if (ret)
    return ret;

  /* Start subtrees needed to satisfy path */
  while (3 * n + 2 < path_len && path[3 * n + 2] == '/') {
    tree_write_stack_init_subtree(tws, path + 3 * n);
    n++;
    tws = tws->next;
  }

  /* There should be no more directory components in the given path */
  assert(memchr(path + 3 * n, '/', path_len - (3 * n)) == NULL);

  /* Finally add given entry to the current tree object */
  write_tree_entry(&tws->buf, mode, path + 3 * n, path_len - (3 * n),
       oid->hash);

  return 0;
}

struct write_each_note_data {
  struct tree_write_stack *root;
  struct non_note **nn_list;
  struct non_note *nn_prev;
};

static int write_each_non_note_until(const char *note_path,
    struct write_each_note_data *d)
{
  struct non_note *p = d->nn_prev;
  struct non_note *n = p ? p->next : *d->nn_list;
  int cmp = 0, ret;
  while (n && (!note_path || (cmp = strcmp(n->path, note_path)) <= 0)) {
    if (note_path && cmp == 0)
      ; /* do nothing, prefer note to non-note */
    else {
      ret = write_each_note_helper(d->root, n->path, n->mode,
                 &n->oid);
      if (ret)
        return ret;
    }
    p = n;
    n = n->next;
  }
  d->nn_prev = p;
  return 0;
}

static int write_each_note(const struct object_id *object_oid UNUSED,
    const struct object_id *note_oid, char *note_path,
    void *cb_data)
{
  struct write_each_note_data *d =
    (struct write_each_note_data *) cb_data;
  size_t note_path_len = strlen(note_path);
  unsigned int mode = 0100644;

  if (note_path[note_path_len - 1] == '/') {
    /* subtree entry */
    note_path_len--;
    note_path[note_path_len] = '\0';
    mode = 040000;
  }
  assert(note_path_len <= GIT_MAX_HEXSZ + FANOUT_PATH_SEPARATORS);

  /* Weave non-note entries into note entries */
  return  write_each_non_note_until(note_path, d) ||
    write_each_note_helper(d->root, note_path, mode, note_oid);
}

struct note_delete_list {
  struct note_delete_list *next;
  const unsigned char *sha1;
};

static int prune_notes_helper(const struct object_id *object_oid,
            const struct object_id *note_oid UNUSED,
            char *note_path UNUSED,
            void *cb_data)
{
  struct note_delete_list **l = (struct note_delete_list **) cb_data;
  struct note_delete_list *n;

  if (odb_has_object(the_repository->objects, object_oid,
         HAS_OBJECT_RECHECK_PACKED | HAS_OBJECT_FETCH_PROMISOR))
    return 0; /* nothing to do for this note */

  /* failed to find object => prune this note */
  n = (struct note_delete_list *) xmalloc(sizeof(*n));
  n->next = *l;
  n->sha1 = object_oid->hash;
  *l = n;
  return 0;
}

int combine_notes_concatenate(struct object_id *cur_oid,
            const struct object_id *new_oid)
{
  char *cur_msg = NULL, *new_msg = NULL, *buf;
  unsigned long cur_len, new_len, buf_len;
  enum object_type cur_type, new_type;
  int ret;

  /* read in both note blob objects */
  if (!is_null_oid(new_oid))
    new_msg = odb_read_object(the_repository->objects, new_oid,
            &new_type, &new_len);
  if (!new_msg || !new_len || new_type != OBJ_BLOB) {
    free(new_msg);
    return 0;
  }
  if (!is_null_oid(cur_oid))
    cur_msg = odb_read_object(the_repository->objects, cur_oid,
            &cur_type, &cur_len);
  if (!cur_msg || !cur_len || cur_type != OBJ_BLOB) {
    free(cur_msg);
    free(new_msg);
    oidcpy(cur_oid, new_oid);
    return 0;
  }

  /* we will separate the notes by two newlines anyway */
  if (cur_msg[cur_len - 1] == '\n')
    cur_len--;

  /* concatenate cur_msg and new_msg into buf */
  buf_len = cur_len + 2 + new_len;
  buf = (char *) xmalloc(buf_len);
  memcpy(buf, cur_msg, cur_len);
  buf[cur_len] = '\n';
  buf[cur_len + 1] = '\n';
  memcpy(buf + cur_len + 2, new_msg, new_len);
  free(cur_msg);
  free(new_msg);

  /* create a new blob object from buf */
  ret = odb_write_object(the_repository->objects, buf,
             buf_len, OBJ_BLOB, cur_oid);
  free(buf);
  return ret;
}

int combine_notes_overwrite(struct object_id *cur_oid,
          const struct object_id *new_oid)
{
  oidcpy(cur_oid, new_oid);
  return 0;
}

int combine_notes_ignore(struct object_id *cur_oid UNUSED,
       const struct object_id *new_oid UNUSED)
{
  return 0;
}

/*
 * Add the lines from the named object to list, with trailing
 * newlines removed.
 */
static int string_list_add_note_lines(struct string_list *list,
              const struct object_id *oid)
{
  char *data;
  unsigned long len;
  enum object_type t;

  if (is_null_oid(oid))
    return 0;

  /* read_sha1_file NUL-terminates */
  data = odb_read_object(the_repository->objects, oid, &t, &len);
  if (t != OBJ_BLOB || !data || !len) {
    free(data);
    return t != OBJ_BLOB || !data;
  }

  /*
   * If the last line of the file is EOL-terminated, this will
   * add an empty string to the list.  But it will be removed
   * later, along with any empty strings that came from empty
   * lines within the file.
   */
  string_list_split(list, data, "\n", -1);
  free(data);
  return 0;
}

static int string_list_join_lines_helper(struct string_list_item *item,
           void *cb_data)
{
  struct strbuf *buf = cb_data;
  strbuf_addstr(buf, item->string);
  strbuf_addch(buf, '\n');
  return 0;
}

int combine_notes_cat_sort_uniq(struct object_id *cur_oid,
        const struct object_id *new_oid)
{
  struct string_list sort_uniq_list = STRING_LIST_INIT_DUP;
  struct strbuf buf = STRBUF_INIT;
  int ret = 1;

  /* read both note blob objects into unique_lines */
  if (string_list_add_note_lines(&sort_uniq_list, cur_oid))
    goto out;
  if (string_list_add_note_lines(&sort_uniq_list, new_oid))
    goto out;
  string_list_remove_empty_items(&sort_uniq_list, 0);
  string_list_sort(&sort_uniq_list);
  string_list_remove_duplicates(&sort_uniq_list, 0);

  /* create a new blob object from sort_uniq_list */
  if (for_each_string_list(&sort_uniq_list,
         string_list_join_lines_helper, &buf))
    goto out;

  ret = odb_write_object(the_repository->objects, buf.buf,
             buf.len, OBJ_BLOB, cur_oid);

out:
  strbuf_release(&buf);
  string_list_clear(&sort_uniq_list, 0);
  return ret;
}

static int string_list_add_one_ref(const struct reference *ref, void *cb)
{
  struct string_list *refs = cb;
  if (!unsorted_string_list_has_string(refs, ref->name))
    string_list_append(refs, ref->name);
  return 0;
}

/*
 * The list argument must have strdup_strings set on it.
 */
void string_list_add_refs_by_glob(struct string_list *list, const char *glob)
{
  assert(list->strdup_strings);
  if (has_glob_specials(glob)) {
    refs_for_each_glob_ref(get_main_ref_store(the_repository),
               string_list_add_one_ref, glob, list);
  } else {
    struct object_id oid;
    if (repo_get_oid(the_repository, glob, &oid))
      warning("notes ref %s is invalid", glob);
    if (!unsorted_string_list_has_string(list, glob))
      string_list_append(list, glob);
  }
}

void string_list_add_refs_from_colon_sep(struct string_list *list,
           const char *globs)
{
  struct string_list split = STRING_LIST_INIT_NODUP;
  char *globs_copy = xstrdup(globs);
  int i;

  string_list_split_in_place_f(&split, globs_copy, ":", -1,
             STRING_LIST_SPLIT_NONEMPTY);

  for (i = 0; i < split.nr; i++)
    string_list_add_refs_by_glob(list, split.items[i].string);

  string_list_clear(&split, 0);
  free(globs_copy);
}

static int notes_display_config(const char *k, const char *v,
        const struct config_context *ctx UNUSED,
        void *cb)
{
  int *load_refs = cb;

  if (*load_refs && !strcmp(k, "notes.displayref")) {
    if (!v)
      return config_error_nonbool(k);
    string_list_add_refs_by_glob(&display_notes_refs, v);
  }

  return 0;
}

char *default_notes_ref(struct repository *repo)
{
  char *notes_ref = NULL;

  if (!notes_ref)
    notes_ref = xstrdup_or_null(getenv(GIT_NOTES_REF_ENVIRONMENT));
  if (!notes_ref)
    repo_config_get_string(repo, "core.notesref", &notes_ref);
  if (!notes_ref)
    notes_ref = xstrdup(GIT_NOTES_DEFAULT_REF);
  return notes_ref;
}

void init_notes(struct notes_tree *t, const char *notes_ref,
    combine_notes_fn combine_notes, int flags)
{
  struct object_id oid, object_oid;
  unsigned short mode;
  struct leaf_node root_tree;
  char *to_free = NULL;

  if (!t)
    t = &default_notes_tree;
  assert(!t->initialized);

  if (!notes_ref)
    notes_ref = to_free = default_notes_ref(the_repository);
  update_ref_namespace(NAMESPACE_NOTES, xstrdup(notes_ref));

  if (!combine_notes)
    combine_notes = combine_notes_concatenate;

  t->root = (struct int_node *) xcalloc(1, sizeof(struct int_node));
  t->first_non_note = NULL;
  t->prev_non_note = NULL;
  t->ref = xstrdup(notes_ref);
  t->update_ref = (flags & NOTES_INIT_WRITABLE) ? t->ref : NULL;
  t->combine_notes = combine_notes;
  t->initialized = 1;
  t->dirty = 0;

  if (flags & NOTES_INIT_EMPTY ||
      repo_get_oid_treeish(the_repository, notes_ref, &object_oid))
    goto out;
  if (flags & NOTES_INIT_WRITABLE && refs_read_ref(get_main_ref_store(the_repository), notes_ref, &object_oid))
    die("Cannot use notes ref %s", notes_ref);
  if (get_tree_entry(the_repository, &object_oid, "", &oid, &mode))
    die("Failed to read notes tree referenced by %s (%s)",
        notes_ref, oid_to_hex(&object_oid));

  oidclr(&root_tree.key_oid, the_repository->hash_algo);
  oidcpy(&root_tree.val_oid, &oid);
  load_subtree(t, &root_tree, t->root, 0);

out:
  free(to_free);
}

struct notes_tree **load_notes_trees(struct string_list *refs, int flags)
{
  struct string_list_item *item;
  int counter = 0;
  struct notes_tree **trees;
  ALLOC_ARRAY(trees, refs->nr + 1);
  for_each_string_list_item(item, refs) {
    struct notes_tree *t = xcalloc(1, sizeof(struct notes_tree));
    init_notes(t, item->string, combine_notes_ignore, flags);
    trees[counter++] = t;
  }
  trees[counter] = NULL;
  return trees;
}

void init_display_notes(struct display_notes_opt *opt)
{
  memset(opt, 0, sizeof(*opt));
  opt->use_default_notes = -1;
  string_list_init_dup(&opt->extra_notes_refs);
}

void release_display_notes(struct display_notes_opt *opt)
{
  string_list_clear(&opt->extra_notes_refs, 0);
}

void enable_default_display_notes(struct display_notes_opt *opt, int *show_notes)
{
  opt->use_default_notes = 1;
  *show_notes = 1;
}

void enable_ref_display_notes(struct display_notes_opt *opt, int *show_notes,
    const char *ref) {
  struct strbuf buf = STRBUF_INIT;
  strbuf_addstr(&buf, ref);
  expand_notes_ref(&buf);
  string_list_append_nodup(&opt->extra_notes_refs,
         strbuf_detach(&buf, NULL));
  *show_notes = 1;
}

void disable_display_notes(struct display_notes_opt *opt, int *show_notes)
{
  opt->use_default_notes = -1;
  string_list_clear(&opt->extra_notes_refs, 0);
  *show_notes = 0;
}

void load_display_notes(struct display_notes_opt *opt)
{
  char *display_ref_env;
  int load_config_refs = 0;
  display_notes_refs.strdup_strings = 1;

  assert(!display_notes_trees);

  if (!opt || opt->use_default_notes > 0 ||
      (opt->use_default_notes == -1 && !opt->extra_notes_refs.nr)) {
    string_list_append_nodup(&display_notes_refs, default_notes_ref(the_repository));
    display_ref_env = getenv(GIT_NOTES_DISPLAY_REF_ENVIRONMENT);
    if (display_ref_env) {
      string_list_add_refs_from_colon_sep(&display_notes_refs,
                  display_ref_env);
      load_config_refs = 0;
    } else
      load_config_refs = 1;
  }

  repo_config(the_repository, notes_display_config, &load_config_refs);

  if (opt) {
    struct string_list_item *item;
    for_each_string_list_item(item, &opt->extra_notes_refs)
      string_list_add_refs_by_glob(&display_notes_refs,
                 item->string);
  }

  display_notes_trees = load_notes_trees(&display_notes_refs, 0);
  string_list_clear(&display_notes_refs, 0);
}

int add_note(struct notes_tree *t, const struct object_id *object_oid,
    const struct object_id *note_oid, combine_notes_fn combine_notes)
{
  struct leaf_node *l;

  if (!t)
    t = &default_notes_tree;
  assert(t->initialized);
  t->dirty = 1;
  if (!combine_notes)
    combine_notes = t->combine_notes;
  l = (struct leaf_node *) xmalloc(sizeof(struct leaf_node));
  oidcpy(&l->key_oid, object_oid);
  oidcpy(&l->val_oid, note_oid);
  return note_tree_insert(t, t->root, 0, l, PTR_TYPE_NOTE, combine_notes);
}

int remove_note(struct notes_tree *t, const unsigned char *object_sha1)
{
  struct leaf_node l;

  if (!t)
    t = &default_notes_tree;
  assert(t->initialized);
  oidread(&l.key_oid, object_sha1, the_repository->hash_algo);
  oidclr(&l.val_oid, the_repository->hash_algo);
  note_tree_remove(t, t->root, 0, &l);
  if (is_null_oid(&l.val_oid)) /* no note was removed */
    return 1;
  t->dirty = 1;
  return 0;
}

const struct object_id *get_note(struct notes_tree *t,
    const struct object_id *oid)
{
  struct leaf_node *found;

  if (!t)
    t = &default_notes_tree;
  assert(t->initialized);
  found = note_tree_find(t, t->root, 0, oid->hash);
  return found ? &found->val_oid : NULL;
}

int for_each_note(struct notes_tree *t, int flags, each_note_fn fn,
    void *cb_data)
{
  if (!t)
    t = &default_notes_tree;
  assert(t->initialized);
  return for_each_note_helper(t, t->root, 0, 0, flags, fn, cb_data);
}

int write_notes_tree(struct notes_tree *t, struct object_id *result)
{
  struct tree_write_stack root;
  struct write_each_note_data cb_data;
  int ret;
  int flags;

  if (!t)
    t = &default_notes_tree;
  assert(t->initialized);

  /* Prepare for traversal of current notes tree */
  root.next = NULL; /* last forward entry in list is grounded */
  strbuf_init(&root.buf, 256 * (32 + the_hash_algo->hexsz)); /* assume 256 entries */
  root.path[0] = root.path[1] = '\0';
  cb_data.root = &root;
  cb_data.nn_list = &(t->first_non_note);
  cb_data.nn_prev = NULL;

  /* Write tree objects representing current notes tree */
  flags = FOR_EACH_NOTE_DONT_UNPACK_SUBTREES |
    FOR_EACH_NOTE_YIELD_SUBTREES;
  ret = for_each_note(t, flags, write_each_note, &cb_data) ||
        write_each_non_note_until(NULL, &cb_data) ||
        tree_write_stack_finish_subtree(&root) ||
        odb_write_object(the_repository->objects, root.buf.buf,
             root.buf.len, OBJ_TREE, result);
  strbuf_release(&root.buf);
  return ret;
}

void prune_notes(struct notes_tree *t, int flags)
{
  struct note_delete_list *l = NULL;

  if (!t)
    t = &default_notes_tree;
  assert(t->initialized);

  for_each_note(t, 0, prune_notes_helper, &l);

  while (l) {
    struct note_delete_list *next;

    if (flags & NOTES_PRUNE_VERBOSE)
      printf("%s\n", hash_to_hex(l->sha1));
    if (!(flags & NOTES_PRUNE_DRYRUN))
      remove_note(t, l->sha1);

    next = l->next;
    free(l);
    l = next;
  }
}

void free_notes(struct notes_tree *t)
{
  if (!t)
    t = &default_notes_tree;
  if (t->root)
    note_tree_free(t->root);
  free(t->root);
  while (t->first_non_note) {
    t->prev_non_note = t->first_non_note->next;
    free(t->first_non_note->path);
    free(t->first_non_note);
    t->first_non_note = t->prev_non_note;
  }
  free(t->ref);
  memset(t, 0, sizeof(struct notes_tree));
}

/*
 * Fill the given strbuf with the notes associated with the given object.
 *
 * If the given notes_tree structure is not initialized, it will be auto-
 * initialized to the default value (see documentation for init_notes() above).
 * If the given notes_tree is NULL, the internal/default notes_tree will be
 * used instead.
 *
 * (raw != 0) gives the %N userformat; otherwise, the note message is given
 * for human consumption.
 */
static void format_note(struct notes_tree *t, const struct object_id *object_oid,
      struct strbuf *sb, const char *output_encoding, int raw)
{
  static const char utf8[] = "utf-8";
  const struct object_id *oid;
  char *msg, *msg_p;
  unsigned long linelen, msglen;
  enum object_type type;

  if (!t)
    t = &default_notes_tree;
  if (!t->initialized)
    init_notes(t, NULL, NULL, 0);

  oid = get_note(t, object_oid);
  if (!oid)
    return;

  if (!(msg = odb_read_object(the_repository->objects, oid, &type, &msglen)) ||
      type != OBJ_BLOB) {
    free(msg);
    return;
  }

  if (output_encoding && *output_encoding &&
      !is_encoding_utf8(output_encoding)) {
    char *reencoded = reencode_string(msg, output_encoding, utf8);
    if (reencoded) {
      free(msg);
      msg = reencoded;
      msglen = strlen(msg);
    }
  }

  /* we will end the annotation by a newline anyway */
  if (msglen && msg[msglen - 1] == '\n')
    msglen--;

  if (!raw) {
    const char *ref = t->ref;
    if (!ref || !strcmp(ref, GIT_NOTES_DEFAULT_REF)) {
      strbuf_addstr(sb, "\nNotes:\n");
    } else {
      skip_prefix(ref, "refs/", &ref);
      skip_prefix(ref, "notes/", &ref);
      strbuf_addf(sb, "\nNotes (%s):\n", ref);
    }
  }

  for (msg_p = msg; msg_p < msg + msglen; msg_p += linelen + 1) {
    linelen = strchrnul(msg_p, '\n') - msg_p;

    if (!raw)
      strbuf_addstr(sb, "    ");
    strbuf_add(sb, msg_p, linelen);
    strbuf_addch(sb, '\n');
  }

  free(msg);
}

void format_display_notes(const struct object_id *object_oid,
        struct strbuf *sb, const char *output_encoding, int raw)
{
  int i;
  assert(display_notes_trees);
  for (i = 0; display_notes_trees[i]; i++)
    format_note(display_notes_trees[i], object_oid, sb,
          output_encoding, raw);
}

int copy_note(struct notes_tree *t,
        const struct object_id *from_obj, const struct object_id *to_obj,
        int force, combine_notes_fn combine_notes)
{
  const struct object_id *note = get_note(t, from_obj);
  const struct object_id *existing_note = get_note(t, to_obj);

  if (!force && existing_note)
    return 1;

  if (note)
    return add_note(t, to_obj, note, combine_notes);
  else if (existing_note)
    return add_note(t, to_obj, null_oid(the_hash_algo), combine_notes);

  return 0;
}

void expand_notes_ref(struct strbuf *sb)
{
  if (starts_with(sb->buf, "refs/notes/"))
    return; /* we're happy */
  else if (starts_with(sb->buf, "notes/"))
    strbuf_insertstr(sb, 0, "refs/");
  else
    strbuf_insertstr(sb, 0, "refs/notes/");
}

void expand_loose_notes_ref(struct strbuf *sb)
{
  struct object_id object;

  if (repo_get_oid(the_repository, sb->buf, &object)) {
    /* fallback to expand_notes_ref */
    expand_notes_ref(sb);
  }
}

Coverage Report

Created: 2026-01-09 07:10