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#include "cache.h"
#include "notes.h"
#include "blob.h"
#include "tree.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 {
unsigned char key_sha1[20];
unsigned char val_sha1[20];
};

/*
* 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;
unsigned char sha1[20];
};

#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 SUBTREE_SHA1_PREFIXCMP(key_sha1, subtree_sha1) \
(memcmp(key_sha1, subtree_sha1, subtree_sha1[19]))

struct notes_tree default_notes_tree;

static struct string_list display_notes_refs;
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_sha1)) {
/* 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_sha1)) {
/* 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 (!hashcmp(key_sha1, l->key_sha1))
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 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];
}
}

/* 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[20];
unsigned char i, j;
void **p = note_tree_search(t, &tree, &n, entry->key_sha1);

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 (hashcmp(l->key_sha1, entry->key_sha1))
return; /* key mismatch, nothing to remove */

/* we have found a matching entry */
hashcpy(entry->val_sha1, l->val_sha1);
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_sha1);
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_sha1)))
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_sha1);
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_sha1(entry->val_sha1))
free(entry);
else
*p = SET_PTR_TYPE(entry, type);
return 0;
case PTR_TYPE_NOTE:
switch (type) {
case PTR_TYPE_NOTE:
if (!hashcmp(l->key_sha1, entry->key_sha1)) {
/* skip concatenation if l == entry */
if (!hashcmp(l->val_sha1, entry->val_sha1))
return 0;

ret = combine_notes(l->val_sha1,
entry->val_sha1);
if (!ret && is_null_sha1(l->val_sha1))
note_tree_remove(t, tree, n, entry);
free(entry);
return ret;
}
break;
case PTR_TYPE_SUBTREE:
if (!SUBTREE_SHA1_PREFIXCMP(l->key_sha1,
entry->key_sha1)) {
/* unpack 'entry' */
load_subtree(t, entry, tree, n);
free(entry);
return 0;
}
break;
}
break;
case PTR_TYPE_SUBTREE:
if (!SUBTREE_SHA1_PREFIXCMP(entry->key_sha1, l->key_sha1)) {
/* 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_sha1(entry->val_sha1)) { /* skip insertion of empty note */
free(entry);
return 0;
}
new_node = (struct int_node *) xcalloc(sizeof(struct int_node), 1);
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));
}
}
}

/*
* Convert a partial SHA1 hex string to the corresponding partial SHA1 value.
* - hex - Partial SHA1 segment in ASCII hex format
* - hex_len - Length of above segment. Must be multiple of 2 between 0 and 40
* - sha1 - Partial SHA1 value is written here
* - sha1_len - Max #bytes to store in sha1, Must be >= hex_len / 2, and < 20
* Returns -1 on error (invalid arguments or invalid SHA1 (not in hex format)).
* Otherwise, returns number of bytes written to sha1 (i.e. hex_len / 2).
* Pads sha1 with NULs up to sha1_len (not included in returned length).
*/
static int get_sha1_hex_segment(const char *hex, unsigned int hex_len,
unsigned char *sha1, unsigned int sha1_len)
{
unsigned int i, len = hex_len >> 1;
if (hex_len % 2 != 0 || len > sha1_len)
return -1;
for (i = 0; i < len; i++) {
unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
if (val & ~0xff)
return -1;
*sha1++ = val;
hex += 2;
}
for (; i < sha1_len; i++)
*sha1++ = 0;
return len;
}

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

static void add_non_note(struct notes_tree *t, const 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 = xstrdup(path);
n->mode = mode;
hashcpy(n->sha1, sha1);
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;
hashcpy(p->sha1, n->sha1);
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)
{
unsigned char object_sha1[20];
unsigned int prefix_len;
void *buf;
struct tree_desc desc;
struct name_entry entry;
int len, path_len;
unsigned char type;
struct leaf_node *l;

buf = fill_tree_descriptor(&desc, subtree->val_sha1);
if (!buf)
die("Could not read %s for notes-index",
sha1_to_hex(subtree->val_sha1));

prefix_len = subtree->key_sha1[19];
assert(prefix_len * 2 >= n);
memcpy(object_sha1, subtree->key_sha1, prefix_len);
while (tree_entry(&desc, &entry)) {
path_len = strlen(entry.path);
len = get_sha1_hex_segment(entry.path, path_len,
object_sha1 + prefix_len, 20 - prefix_len);
if (len < 0)
goto handle_non_note; /* entry.path is not a SHA1 */
len += prefix_len;

/*
* If object SHA1 is complete (len == 20), assume note object
* If object SHA1 is incomplete (len < 20), and current
* component consists of 2 hex chars, assume note subtree
*/
if (len <= 20) {
type = PTR_TYPE_NOTE;
l = (struct leaf_node *)
xcalloc(sizeof(struct leaf_node), 1);
hashcpy(l->key_sha1, object_sha1);
hashcpy(l->val_sha1, entry.sha1);
if (len < 20) {
if (!S_ISDIR(entry.mode) || path_len != 2)
goto handle_non_note; /* not subtree */
l->key_sha1[19] = (unsigned char) len;
type = PTR_TYPE_SUBTREE;
}
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",
sha1_to_hex(l->key_sha1), 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. We assume here that the overall notes
* tree follows a strict byte-based progressive fanout
* structure (i.e. using 2/38, 2/2/36, etc. fanouts, and not
* e.g. 4/36 fanout). This means that if a non-note is found at
* path "dead/beef", the following code will register it as
* being found on "de/ad/beef".
* On the other hand, if you use such non-obvious non-note
* paths in the middle of a notes tree, you deserve what's
* coming to you ;). Note that for non-notes that are not
* SHA1-like at the top level, there will be no problems.
*
* To conclude, it is strongly advised to make sure non-notes
* have at least one non-hex character in the top-level path
* component.
*/
{
char non_note_path[PATH_MAX];
char *p = non_note_path;
const char *q = sha1_to_hex(subtree->key_sha1);
int i;
for (i = 0; i < prefix_len; i++) {
*p++ = *q++;
*p++ = *q++;
*p++ = '/';
}
strcpy(p, entry.path);
add_non_note(t, non_note_path, entry.mode, entry.sha1);
}
}
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;
}

static void construct_path_with_fanout(const unsigned char *sha1,
unsigned char fanout, char *path)
{
unsigned int i = 0, j = 0;
const char *hex_sha1 = sha1_to_hex(sha1);
assert(fanout < 20);
while (fanout) {
path[i++] = hex_sha1[j++];
path[i++] = hex_sha1[j++];
path[i++] = '/';
fanout--;
}
strcpy(path + i, hex_sha1 + 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[40 + 19 + 1]; /* hex SHA1 + 19 * '/' + NUL */

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_sha1[19] * 2 + fanout;
assert(path_len < 40 + 19);
construct_path_with_fanout(l->key_sha1, fanout,
path);
/* Create trailing slash, if needed */
if (path[path_len - 1] != '/')
path[path_len++] = '/';
path[path_len] = '\0';
ret = fn(l->key_sha1, l->val_sha1, path,
cb_data);
}
if (n > fanout * 2 ||
!(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_sha1, fanout, path);
ret = fn(l->key_sha1, l->val_sha1, 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 *sha1)
{
strbuf_addf(buf, "%o %.*s%c", mode, path_len, path, '\0');
strbuf_add(buf, sha1, 20);
}

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 + 40)); /* 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;
unsigned char s[20];
if (n) {
ret = tree_write_stack_finish_subtree(n);
if (ret)
return ret;
ret = write_sha1_file(n->buf.buf, n->buf.len, tree_type, s);
if (ret)
return ret;
strbuf_release(&n->buf);
free(n);
tws->next = NULL;
write_tree_entry(&tws->buf, 040000, tws->path, 2, s);
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 unsigned char *sha1)
{
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),
sha1);

return 0;
}

struct write_each_note_data {
struct tree_write_stack *root;
struct non_note *next_non_note;
};

static int write_each_non_note_until(const char *note_path,
struct write_each_note_data *d)
{
struct non_note *n = d->next_non_note;
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->sha1);
if (ret)
return ret;
}
n = n->next;
}
d->next_non_note = n;
return 0;
}

static int write_each_note(const unsigned char *object_sha1,
const unsigned char *note_sha1, 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 <= 40 + 19);

/* 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_sha1);
}

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

static int prune_notes_helper(const unsigned char *object_sha1,
const unsigned char *note_sha1, char *note_path,
void *cb_data)
{
struct note_delete_list **l = (struct note_delete_list **) cb_data;
struct note_delete_list *n;

if (has_sha1_file(object_sha1))
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_sha1;
*l = n;
return 0;
}

int combine_notes_concatenate(unsigned char *cur_sha1,
const unsigned char *new_sha1)
{
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_sha1(new_sha1))
new_msg = read_sha1_file(new_sha1, &new_type, &new_len);
if (!new_msg || !new_len || new_type != OBJ_BLOB) {
free(new_msg);
return 0;
}
if (!is_null_sha1(cur_sha1))
cur_msg = read_sha1_file(cur_sha1, &cur_type, &cur_len);
if (!cur_msg || !cur_len || cur_type != OBJ_BLOB) {
free(cur_msg);
free(new_msg);
hashcpy(cur_sha1, new_sha1);
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 = write_sha1_file(buf, buf_len, blob_type, cur_sha1);
free(buf);
return ret;
}

int combine_notes_overwrite(unsigned char *cur_sha1,
const unsigned char *new_sha1)
{
hashcpy(cur_sha1, new_sha1);
return 0;
}

int combine_notes_ignore(unsigned char *cur_sha1,
const unsigned char *new_sha1)
{
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 unsigned char *sha1)
{
char *data;
unsigned long len;
enum object_type t;

if (is_null_sha1(sha1))
return 0;

/* read_sha1_file NUL-terminates */
data = read_sha1_file(sha1, &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(unsigned char *cur_sha1,
const unsigned char *new_sha1)
{
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_sha1))
goto out;
if (string_list_add_note_lines(&sort_uniq_list, new_sha1))
goto out;
string_list_remove_empty_items(&sort_uniq_list, 0);
sort_string_list(&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 = write_sha1_file(buf.buf, buf.len, blob_type, cur_sha1);

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

static int string_list_add_one_ref(const char *refname, const unsigned char *sha1,
int flag, void *cb)
{
struct string_list *refs = cb;
if (!unsorted_string_list_has_string(refs, refname))
string_list_append(refs, refname);
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)) {
for_each_glob_ref(string_list_add_one_ref, glob, list);
} else {
unsigned char sha1[20];
if (get_sha1(glob, sha1))
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(&split, globs_copy, ':', -1);
string_list_remove_empty_items(&split, 0);

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, void *cb)
{
int *load_refs = cb;

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

return 0;
}

const char *default_notes_ref(void)
{
const char *notes_ref = NULL;
if (!notes_ref)
notes_ref = getenv(GIT_NOTES_REF_ENVIRONMENT);
if (!notes_ref)
notes_ref = notes_ref_name; /* value of core.notesRef config */
if (!notes_ref)
notes_ref = 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)
{
unsigned char sha1[20], object_sha1[20];
unsigned mode;
struct leaf_node root_tree;

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

if (!notes_ref)
notes_ref = default_notes_ref();

if (!combine_notes)
combine_notes = combine_notes_concatenate;

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

if (flags & NOTES_INIT_EMPTY || !notes_ref ||
read_ref(notes_ref, object_sha1))
return;
if (get_tree_entry(object_sha1, "", sha1, &mode))
die("Failed to read notes tree referenced by %s (%s)",
notes_ref, sha1_to_hex(object_sha1));

hashclr(root_tree.key_sha1);
hashcpy(root_tree.val_sha1, sha1);
load_subtree(t, &root_tree, t->root, 0);
}

struct notes_tree **load_notes_trees(struct string_list *refs)
{
struct string_list_item *item;
int counter = 0;
struct notes_tree **trees;
trees = xmalloc((refs->nr+1) * sizeof(struct notes_tree *));
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, 0);
trees[counter++] = t;
}
trees[counter] = NULL;
return trees;
}

void init_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(&display_notes_refs, default_notes_ref());
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;
}

git_config(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);
string_list_clear(&display_notes_refs, 0);
}

int add_note(struct notes_tree *t, const unsigned char *object_sha1,
const unsigned char *note_sha1, 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));
hashcpy(l->key_sha1, object_sha1);
hashcpy(l->val_sha1, note_sha1);
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);
hashcpy(l.key_sha1, object_sha1);
hashclr(l.val_sha1);
note_tree_remove(t, t->root, 0, &l);
if (is_null_sha1(l.val_sha1)) /* no note was removed */
return 1;
t->dirty = 1;
return 0;
}

const unsigned char *get_note(struct notes_tree *t,
const unsigned char *object_sha1)
{
struct leaf_node *found;

if (!t)
t = &default_notes_tree;
assert(t->initialized);
found = note_tree_find(t, t->root, 0, object_sha1);
return found ? found->val_sha1 : 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, unsigned char *result)
{
struct tree_write_stack root;
struct write_each_note_data cb_data;
int ret;

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 + 40)); /* assume 256 entries */
root.path[0] = root.path[1] = '\0';
cb_data.root = &root;
cb_data.next_non_note = t->first_non_note;

/* Write tree objects representing current notes tree */
ret = for_each_note(t, FOR_EACH_NOTE_DONT_UNPACK_SUBTREES |
FOR_EACH_NOTE_YIELD_SUBTREES,
write_each_note, &cb_data) ||
write_each_non_note_until(NULL, &cb_data) ||
tree_write_stack_finish_subtree(&root) ||
write_sha1_file(root.buf.buf, root.buf.len, tree_type, 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) {
if (flags & NOTES_PRUNE_VERBOSE)
printf("%s\n", sha1_to_hex(l->sha1));
if (!(flags & NOTES_PRUNE_DRYRUN))
remove_note(t, l->sha1);
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 unsigned char *object_sha1,
struct strbuf *sb, const char *output_encoding, int raw)
{
static const char utf8[] = "utf-8";
const unsigned char *sha1;
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);

sha1 = get_note(t, object_sha1);
if (!sha1)
return;

if (!(msg = read_sha1_file(sha1, &type, &msglen)) || !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 {
if (starts_with(ref, "refs/"))
ref += 5;
if (starts_with(ref, "notes/"))
ref += 6;
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 unsigned char *object_sha1,
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_sha1, sb,
output_encoding, raw);
}

int copy_note(struct notes_tree *t,
const unsigned char *from_obj, const unsigned char *to_obj,
int force, combine_notes_fn combine_notes)
{
const unsigned char *note = get_note(t, from_obj);
const unsigned char *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_sha1, 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_insert(sb, 0, "refs/", 5);
else
strbuf_insert(sb, 0, "refs/notes/", 11);
}
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