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![Johan Herland](/assets/img/avatar_default.png)
When loading a notes tree, the code primarily looks for SHA1-like paths whose total length (discounting directory separators) are 40 chars (interpreted as valid note entries) or less (interpreted as subtree entries that may in turn contain note entries when unpacked). However, there is an additional condition that must hold for valid subtree entries: They must be _tree_ objects (duh). This patch adds an appropriate test for this condition, thereby fixing the crash that occured when passing a non-tree object to the tree-walk API. The patch also adds another selftest verifying correct behaviour of non-notes in note trees. Signed-off-by: Johan Herland <johan@herland.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
432 lines
12 KiB
C
432 lines
12 KiB
C
#include "cache.h"
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#include "commit.h"
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#include "notes.h"
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#include "refs.h"
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#include "utf8.h"
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#include "strbuf.h"
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#include "tree-walk.h"
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/*
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* Use a non-balancing simple 16-tree structure with struct int_node as
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* internal nodes, and struct leaf_node as leaf nodes. Each int_node has a
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* 16-array of pointers to its children.
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* The bottom 2 bits of each pointer is used to identify the pointer type
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* - ptr & 3 == 0 - NULL pointer, assert(ptr == NULL)
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* - ptr & 3 == 1 - pointer to next internal node - cast to struct int_node *
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* - ptr & 3 == 2 - pointer to note entry - cast to struct leaf_node *
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* - ptr & 3 == 3 - pointer to subtree entry - cast to struct leaf_node *
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*
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* The root node is a statically allocated struct int_node.
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*/
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struct int_node {
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void *a[16];
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};
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/*
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* Leaf nodes come in two variants, note entries and subtree entries,
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* distinguished by the LSb of the leaf node pointer (see above).
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* As a note entry, the key is the SHA1 of the referenced commit, and the
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* value is the SHA1 of the note object.
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* As a subtree entry, the key is the prefix SHA1 (w/trailing NULs) of the
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* referenced commit, using the last byte of the key to store the length of
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* the prefix. The value is the SHA1 of the tree object containing the notes
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* subtree.
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*/
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struct leaf_node {
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unsigned char key_sha1[20];
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unsigned char val_sha1[20];
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};
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#define PTR_TYPE_NULL 0
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#define PTR_TYPE_INTERNAL 1
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#define PTR_TYPE_NOTE 2
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#define PTR_TYPE_SUBTREE 3
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#define GET_PTR_TYPE(ptr) ((uintptr_t) (ptr) & 3)
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#define CLR_PTR_TYPE(ptr) ((void *) ((uintptr_t) (ptr) & ~3))
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#define SET_PTR_TYPE(ptr, type) ((void *) ((uintptr_t) (ptr) | (type)))
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#define GET_NIBBLE(n, sha1) (((sha1[n >> 1]) >> ((~n & 0x01) << 2)) & 0x0f)
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#define SUBTREE_SHA1_PREFIXCMP(key_sha1, subtree_sha1) \
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(memcmp(key_sha1, subtree_sha1, subtree_sha1[19]))
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static struct int_node root_node;
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static int initialized;
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static void load_subtree(struct leaf_node *subtree, struct int_node *node,
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unsigned int n);
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/*
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* Search the tree until the appropriate location for the given key is found:
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* 1. Start at the root node, with n = 0
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* 2. If a[0] at the current level is a matching subtree entry, unpack that
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* subtree entry and remove it; restart search at the current level.
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* 3. Use the nth nibble of the key as an index into a:
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* - If a[n] is an int_node, recurse from #2 into that node and increment n
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* - If a matching subtree entry, unpack that subtree entry (and remove it);
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* restart search at the current level.
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* - Otherwise, we have found one of the following:
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* - a subtree entry which does not match the key
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* - a note entry which may or may not match the key
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* - an unused leaf node (NULL)
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* In any case, set *tree and *n, and return pointer to the tree location.
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*/
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static void **note_tree_search(struct int_node **tree,
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unsigned char *n, const unsigned char *key_sha1)
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{
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struct leaf_node *l;
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unsigned char i;
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void *p = (*tree)->a[0];
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if (GET_PTR_TYPE(p) == PTR_TYPE_SUBTREE) {
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l = (struct leaf_node *) CLR_PTR_TYPE(p);
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if (!SUBTREE_SHA1_PREFIXCMP(key_sha1, l->key_sha1)) {
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/* unpack tree and resume search */
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(*tree)->a[0] = NULL;
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load_subtree(l, *tree, *n);
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free(l);
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return note_tree_search(tree, n, key_sha1);
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}
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}
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i = GET_NIBBLE(*n, key_sha1);
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p = (*tree)->a[i];
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switch(GET_PTR_TYPE(p)) {
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case PTR_TYPE_INTERNAL:
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*tree = CLR_PTR_TYPE(p);
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(*n)++;
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return note_tree_search(tree, n, key_sha1);
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case PTR_TYPE_SUBTREE:
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l = (struct leaf_node *) CLR_PTR_TYPE(p);
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if (!SUBTREE_SHA1_PREFIXCMP(key_sha1, l->key_sha1)) {
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/* unpack tree and resume search */
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(*tree)->a[i] = NULL;
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load_subtree(l, *tree, *n);
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free(l);
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return note_tree_search(tree, n, key_sha1);
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}
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/* fall through */
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default:
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return &((*tree)->a[i]);
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}
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}
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/*
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* To find a leaf_node:
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* Search to the tree location appropriate for the given key:
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* If a note entry with matching key, return the note entry, else return NULL.
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*/
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static struct leaf_node *note_tree_find(struct int_node *tree, unsigned char n,
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const unsigned char *key_sha1)
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{
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void **p = note_tree_search(&tree, &n, key_sha1);
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if (GET_PTR_TYPE(*p) == PTR_TYPE_NOTE) {
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struct leaf_node *l = (struct leaf_node *) CLR_PTR_TYPE(*p);
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if (!hashcmp(key_sha1, l->key_sha1))
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return l;
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}
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return NULL;
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}
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/* Create a new blob object by concatenating the two given blob objects */
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static int concatenate_notes(unsigned char *cur_sha1,
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const unsigned char *new_sha1)
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{
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char *cur_msg, *new_msg, *buf;
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unsigned long cur_len, new_len, buf_len;
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enum object_type cur_type, new_type;
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int ret;
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/* read in both note blob objects */
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new_msg = read_sha1_file(new_sha1, &new_type, &new_len);
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if (!new_msg || !new_len || new_type != OBJ_BLOB) {
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free(new_msg);
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return 0;
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}
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cur_msg = read_sha1_file(cur_sha1, &cur_type, &cur_len);
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if (!cur_msg || !cur_len || cur_type != OBJ_BLOB) {
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free(cur_msg);
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free(new_msg);
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hashcpy(cur_sha1, new_sha1);
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return 0;
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}
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/* we will separate the notes by a newline anyway */
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if (cur_msg[cur_len - 1] == '\n')
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cur_len--;
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/* concatenate cur_msg and new_msg into buf */
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buf_len = cur_len + 1 + new_len;
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buf = (char *) xmalloc(buf_len);
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memcpy(buf, cur_msg, cur_len);
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buf[cur_len] = '\n';
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memcpy(buf + cur_len + 1, new_msg, new_len);
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free(cur_msg);
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free(new_msg);
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/* create a new blob object from buf */
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ret = write_sha1_file(buf, buf_len, "blob", cur_sha1);
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free(buf);
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return ret;
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}
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/*
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* To insert a leaf_node:
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* Search to the tree location appropriate for the given leaf_node's key:
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* - If location is unused (NULL), store the tweaked pointer directly there
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* - If location holds a note entry that matches the note-to-be-inserted, then
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* concatenate the two notes.
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* - If location holds a note entry that matches the subtree-to-be-inserted,
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* then unpack the subtree-to-be-inserted into the location.
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* - If location holds a matching subtree entry, unpack the subtree at that
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* location, and restart the insert operation from that level.
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* - Else, create a new int_node, holding both the node-at-location and the
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* node-to-be-inserted, and store the new int_node into the location.
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*/
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static void note_tree_insert(struct int_node *tree, unsigned char n,
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struct leaf_node *entry, unsigned char type)
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{
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struct int_node *new_node;
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struct leaf_node *l;
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void **p = note_tree_search(&tree, &n, entry->key_sha1);
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assert(GET_PTR_TYPE(entry) == 0); /* no type bits set */
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l = (struct leaf_node *) CLR_PTR_TYPE(*p);
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switch(GET_PTR_TYPE(*p)) {
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case PTR_TYPE_NULL:
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assert(!*p);
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*p = SET_PTR_TYPE(entry, type);
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return;
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case PTR_TYPE_NOTE:
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switch (type) {
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case PTR_TYPE_NOTE:
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if (!hashcmp(l->key_sha1, entry->key_sha1)) {
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/* skip concatenation if l == entry */
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if (!hashcmp(l->val_sha1, entry->val_sha1))
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return;
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if (concatenate_notes(l->val_sha1,
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entry->val_sha1))
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die("failed to concatenate note %s "
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"into note %s for commit %s",
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sha1_to_hex(entry->val_sha1),
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sha1_to_hex(l->val_sha1),
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sha1_to_hex(l->key_sha1));
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free(entry);
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return;
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}
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break;
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case PTR_TYPE_SUBTREE:
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if (!SUBTREE_SHA1_PREFIXCMP(l->key_sha1,
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entry->key_sha1)) {
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/* unpack 'entry' */
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load_subtree(entry, tree, n);
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free(entry);
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return;
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}
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break;
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}
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break;
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case PTR_TYPE_SUBTREE:
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if (!SUBTREE_SHA1_PREFIXCMP(entry->key_sha1, l->key_sha1)) {
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/* unpack 'l' and restart insert */
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*p = NULL;
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load_subtree(l, tree, n);
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free(l);
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note_tree_insert(tree, n, entry, type);
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return;
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}
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break;
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}
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/* non-matching leaf_node */
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assert(GET_PTR_TYPE(*p) == PTR_TYPE_NOTE ||
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GET_PTR_TYPE(*p) == PTR_TYPE_SUBTREE);
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new_node = (struct int_node *) xcalloc(sizeof(struct int_node), 1);
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note_tree_insert(new_node, n + 1, l, GET_PTR_TYPE(*p));
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*p = SET_PTR_TYPE(new_node, PTR_TYPE_INTERNAL);
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note_tree_insert(new_node, n + 1, entry, type);
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}
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/* Free the entire notes data contained in the given tree */
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static void note_tree_free(struct int_node *tree)
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{
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unsigned int i;
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for (i = 0; i < 16; i++) {
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void *p = tree->a[i];
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switch(GET_PTR_TYPE(p)) {
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case PTR_TYPE_INTERNAL:
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note_tree_free(CLR_PTR_TYPE(p));
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/* fall through */
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case PTR_TYPE_NOTE:
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case PTR_TYPE_SUBTREE:
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free(CLR_PTR_TYPE(p));
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}
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}
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}
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/*
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* Convert a partial SHA1 hex string to the corresponding partial SHA1 value.
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* - hex - Partial SHA1 segment in ASCII hex format
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* - hex_len - Length of above segment. Must be multiple of 2 between 0 and 40
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* - sha1 - Partial SHA1 value is written here
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* - sha1_len - Max #bytes to store in sha1, Must be >= hex_len / 2, and < 20
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* Returns -1 on error (invalid arguments or invalid SHA1 (not in hex format).
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* Otherwise, returns number of bytes written to sha1 (i.e. hex_len / 2).
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* Pads sha1 with NULs up to sha1_len (not included in returned length).
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*/
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static int get_sha1_hex_segment(const char *hex, unsigned int hex_len,
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unsigned char *sha1, unsigned int sha1_len)
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{
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unsigned int i, len = hex_len >> 1;
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if (hex_len % 2 != 0 || len > sha1_len)
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return -1;
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for (i = 0; i < len; i++) {
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unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
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if (val & ~0xff)
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return -1;
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*sha1++ = val;
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hex += 2;
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}
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for (; i < sha1_len; i++)
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*sha1++ = 0;
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return len;
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}
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static void load_subtree(struct leaf_node *subtree, struct int_node *node,
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unsigned int n)
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{
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unsigned char commit_sha1[20];
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unsigned int prefix_len;
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void *buf;
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struct tree_desc desc;
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struct name_entry entry;
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buf = fill_tree_descriptor(&desc, subtree->val_sha1);
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if (!buf)
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die("Could not read %s for notes-index",
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sha1_to_hex(subtree->val_sha1));
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prefix_len = subtree->key_sha1[19];
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assert(prefix_len * 2 >= n);
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memcpy(commit_sha1, subtree->key_sha1, prefix_len);
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while (tree_entry(&desc, &entry)) {
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int len = get_sha1_hex_segment(entry.path, strlen(entry.path),
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commit_sha1 + prefix_len, 20 - prefix_len);
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if (len < 0)
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continue; /* entry.path is not a SHA1 sum. Skip */
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len += prefix_len;
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/*
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* If commit SHA1 is complete (len == 20), assume note object
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* If commit SHA1 is incomplete (len < 20), assume note subtree
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*/
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if (len <= 20) {
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unsigned char type = PTR_TYPE_NOTE;
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struct leaf_node *l = (struct leaf_node *)
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xcalloc(sizeof(struct leaf_node), 1);
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hashcpy(l->key_sha1, commit_sha1);
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hashcpy(l->val_sha1, entry.sha1);
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if (len < 20) {
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if (!S_ISDIR(entry.mode))
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continue; /* entry cannot be subtree */
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l->key_sha1[19] = (unsigned char) len;
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type = PTR_TYPE_SUBTREE;
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}
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note_tree_insert(node, n, l, type);
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}
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}
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free(buf);
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}
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static void initialize_notes(const char *notes_ref_name)
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{
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unsigned char sha1[20], commit_sha1[20];
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unsigned mode;
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struct leaf_node root_tree;
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if (!notes_ref_name || read_ref(notes_ref_name, commit_sha1) ||
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get_tree_entry(commit_sha1, "", sha1, &mode))
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return;
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hashclr(root_tree.key_sha1);
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hashcpy(root_tree.val_sha1, sha1);
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load_subtree(&root_tree, &root_node, 0);
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}
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static unsigned char *lookup_notes(const unsigned char *commit_sha1)
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{
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struct leaf_node *found = note_tree_find(&root_node, 0, commit_sha1);
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if (found)
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return found->val_sha1;
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return NULL;
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}
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void free_notes(void)
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{
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note_tree_free(&root_node);
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memset(&root_node, 0, sizeof(struct int_node));
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initialized = 0;
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}
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void get_commit_notes(const struct commit *commit, struct strbuf *sb,
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const char *output_encoding, int flags)
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{
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static const char utf8[] = "utf-8";
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unsigned char *sha1;
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char *msg, *msg_p;
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unsigned long linelen, msglen;
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enum object_type type;
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if (!initialized) {
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const char *env = getenv(GIT_NOTES_REF_ENVIRONMENT);
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if (env)
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notes_ref_name = getenv(GIT_NOTES_REF_ENVIRONMENT);
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else if (!notes_ref_name)
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notes_ref_name = GIT_NOTES_DEFAULT_REF;
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initialize_notes(notes_ref_name);
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initialized = 1;
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}
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sha1 = lookup_notes(commit->object.sha1);
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if (!sha1)
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return;
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if (!(msg = read_sha1_file(sha1, &type, &msglen)) || !msglen ||
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type != OBJ_BLOB) {
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free(msg);
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return;
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}
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if (output_encoding && *output_encoding &&
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strcmp(utf8, output_encoding)) {
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char *reencoded = reencode_string(msg, output_encoding, utf8);
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if (reencoded) {
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free(msg);
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msg = reencoded;
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msglen = strlen(msg);
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}
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}
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/* we will end the annotation by a newline anyway */
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if (msglen && msg[msglen - 1] == '\n')
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msglen--;
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if (flags & NOTES_SHOW_HEADER)
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strbuf_addstr(sb, "\nNotes:\n");
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for (msg_p = msg; msg_p < msg + msglen; msg_p += linelen + 1) {
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linelen = strchrnul(msg_p, '\n') - msg_p;
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if (flags & NOTES_INDENT)
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strbuf_addstr(sb, " ");
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strbuf_add(sb, msg_p, linelen);
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strbuf_addch(sb, '\n');
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}
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free(msg);
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}
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