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![Johan Herland](/assets/img/avatar_default.png)
Created by a simple cleanup and rename of lookup_notes(). Signed-off-by: Johan Herland <johan@herland.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
531 lines
15 KiB
C
531 lines
15 KiB
C
#include "cache.h"
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#include "notes.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 object, 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 object, 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 object %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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/*
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* How to consolidate an int_node:
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* If there are > 1 non-NULL entries, give up and return non-zero.
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* Otherwise replace the int_node at the given index in the given parent node
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* with the only entry (or a NULL entry if no entries) from the given tree,
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* and return 0.
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*/
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static int note_tree_consolidate(struct int_node *tree,
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struct int_node *parent, unsigned char index)
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{
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unsigned int i;
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void *p = NULL;
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assert(tree && parent);
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assert(CLR_PTR_TYPE(parent->a[index]) == tree);
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for (i = 0; i < 16; i++) {
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if (GET_PTR_TYPE(tree->a[i]) != PTR_TYPE_NULL) {
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if (p) /* more than one entry */
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return -2;
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p = tree->a[i];
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}
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}
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/* replace tree with p in parent[index] */
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parent->a[index] = p;
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free(tree);
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return 0;
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}
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/*
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* To remove 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 does not hold a matching entry, abort and do nothing.
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* - Replace the matching leaf_node with a NULL entry (and free the leaf_node).
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* - Consolidate int_nodes repeatedly, while walking up the tree towards root.
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*/
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static void note_tree_remove(struct int_node *tree, unsigned char n,
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struct leaf_node *entry)
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{
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struct leaf_node *l;
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struct int_node *parent_stack[20];
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unsigned char i, j;
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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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if (GET_PTR_TYPE(*p) != PTR_TYPE_NOTE)
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return; /* type mismatch, nothing to remove */
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l = (struct leaf_node *) CLR_PTR_TYPE(*p);
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if (hashcmp(l->key_sha1, entry->key_sha1))
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return; /* key mismatch, nothing to remove */
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/* we have found a matching entry */
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free(l);
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*p = SET_PTR_TYPE(NULL, PTR_TYPE_NULL);
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/* consolidate this tree level, and parent levels, if possible */
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if (!n)
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return; /* cannot consolidate top level */
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/* first, build stack of ancestors between root and current node */
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parent_stack[0] = &root_node;
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for (i = 0; i < n; i++) {
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j = GET_NIBBLE(i, entry->key_sha1);
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parent_stack[i + 1] = CLR_PTR_TYPE(parent_stack[i]->a[j]);
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}
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assert(i == n && parent_stack[i] == tree);
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/* next, unwind stack until note_tree_consolidate() is done */
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while (i > 0 &&
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!note_tree_consolidate(parent_stack[i], parent_stack[i - 1],
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GET_NIBBLE(i - 1, entry->key_sha1)))
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i--;
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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 object_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(object_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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object_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 object SHA1 is complete (len == 20), assume note object
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* If object 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, object_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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void init_notes(const char *notes_ref, int flags)
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{
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unsigned char sha1[20], object_sha1[20];
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unsigned mode;
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struct leaf_node root_tree;
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assert(!initialized);
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initialized = 1;
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if (!notes_ref)
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notes_ref = getenv(GIT_NOTES_REF_ENVIRONMENT);
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if (!notes_ref)
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notes_ref = notes_ref_name; /* value of core.notesRef config */
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if (!notes_ref)
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notes_ref = GIT_NOTES_DEFAULT_REF;
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if (flags & NOTES_INIT_EMPTY || !notes_ref ||
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read_ref(notes_ref, object_sha1))
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return;
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if (get_tree_entry(object_sha1, "", sha1, &mode))
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die("Failed to read notes tree referenced by %s (%s)",
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notes_ref, object_sha1);
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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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void add_note(const unsigned char *object_sha1, const unsigned char *note_sha1)
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{
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struct leaf_node *l;
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assert(initialized);
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l = (struct leaf_node *) xmalloc(sizeof(struct leaf_node));
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hashcpy(l->key_sha1, object_sha1);
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hashcpy(l->val_sha1, note_sha1);
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note_tree_insert(&root_node, 0, l, PTR_TYPE_NOTE);
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}
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void remove_note(const unsigned char *object_sha1)
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{
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struct leaf_node l;
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assert(initialized);
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hashcpy(l.key_sha1, object_sha1);
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hashclr(l.val_sha1);
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return note_tree_remove(&root_node, 0, &l);
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}
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const unsigned char *get_note(const unsigned char *object_sha1)
|
|
{
|
|
struct leaf_node *found;
|
|
|
|
assert(initialized);
|
|
found = note_tree_find(&root_node, 0, object_sha1);
|
|
return found ? found->val_sha1 : NULL;
|
|
}
|
|
|
|
void free_notes(void)
|
|
{
|
|
note_tree_free(&root_node);
|
|
memset(&root_node, 0, sizeof(struct int_node));
|
|
initialized = 0;
|
|
}
|
|
|
|
void format_note(const unsigned char *object_sha1, struct strbuf *sb,
|
|
const char *output_encoding, int flags)
|
|
{
|
|
static const char utf8[] = "utf-8";
|
|
const unsigned char *sha1;
|
|
char *msg, *msg_p;
|
|
unsigned long linelen, msglen;
|
|
enum object_type type;
|
|
|
|
if (!initialized)
|
|
init_notes(NULL, 0);
|
|
|
|
sha1 = get_note(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 &&
|
|
strcmp(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 (flags & NOTES_SHOW_HEADER)
|
|
strbuf_addstr(sb, "\nNotes:\n");
|
|
|
|
for (msg_p = msg; msg_p < msg + msglen; msg_p += linelen + 1) {
|
|
linelen = strchrnul(msg_p, '\n') - msg_p;
|
|
|
|
if (flags & NOTES_INDENT)
|
|
strbuf_addstr(sb, " ");
|
|
strbuf_add(sb, msg_p, linelen);
|
|
strbuf_addch(sb, '\n');
|
|
}
|
|
|
|
free(msg);
|
|
}
|