diff options
Diffstat (limited to 'notes.c')
| -rw-r--r-- | notes.c | 431 |
1 files changed, 431 insertions, 0 deletions
@@ -0,0 +1,431 @@ +#include "cache.h" +#include "commit.h" +#include "notes.h" +#include "refs.h" +#include "utf8.h" +#include "strbuf.h" +#include "tree-walk.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 commit, 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 commit, 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]; +}; + +#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])) + +static struct int_node root_node; + +static int initialized; + +static void load_subtree(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 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(l, *tree, *n); + free(l); + return note_tree_search(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(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(l, *tree, *n); + free(l); + return note_tree_search(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 int_node *tree, unsigned char n, + const unsigned char *key_sha1) +{ + void **p = note_tree_search(&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; +} + +/* Create a new blob object by concatenating the two given blob objects */ +static int concatenate_notes(unsigned char *cur_sha1, + const unsigned char *new_sha1) +{ + char *cur_msg, *new_msg, *buf; + unsigned long cur_len, new_len, buf_len; + enum object_type cur_type, new_type; + int ret; + + /* read in both note blob objects */ + 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; + } + 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 a newline anyway */ + if (cur_msg[cur_len - 1] == '\n') + cur_len--; + + /* concatenate cur_msg and new_msg into buf */ + buf_len = cur_len + 1 + new_len; + buf = (char *) xmalloc(buf_len); + memcpy(buf, cur_msg, cur_len); + buf[cur_len] = '\n'; + memcpy(buf + cur_len + 1, 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", cur_sha1); + free(buf); + return ret; +} + +/* + * 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 + * concatenate the two notes. + * - 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 void note_tree_insert(struct int_node *tree, unsigned char n, + struct leaf_node *entry, unsigned char type) +{ + struct int_node *new_node; + struct leaf_node *l; + void **p = note_tree_search(&tree, &n, entry->key_sha1); + + 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); + *p = SET_PTR_TYPE(entry, type); + return; + 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; + + if (concatenate_notes(l->val_sha1, + entry->val_sha1)) + die("failed to concatenate note %s " + "into note %s for commit %s", + sha1_to_hex(entry->val_sha1), + sha1_to_hex(l->val_sha1), + sha1_to_hex(l->key_sha1)); + free(entry); + return; + } + break; + case PTR_TYPE_SUBTREE: + if (!SUBTREE_SHA1_PREFIXCMP(l->key_sha1, + entry->key_sha1)) { + /* unpack 'entry' */ + load_subtree(entry, tree, n); + free(entry); + return; + } + 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(l, tree, n); + free(l); + note_tree_insert(tree, n, entry, type); + return; + } + break; + } + + /* non-matching leaf_node */ + assert(GET_PTR_TYPE(*p) == PTR_TYPE_NOTE || + GET_PTR_TYPE(*p) == PTR_TYPE_SUBTREE); + new_node = (struct int_node *) xcalloc(sizeof(struct int_node), 1); + note_tree_insert(new_node, n + 1, l, GET_PTR_TYPE(*p)); + *p = SET_PTR_TYPE(new_node, PTR_TYPE_INTERNAL); + note_tree_insert(new_node, n + 1, entry, type); +} + +/* 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 void load_subtree(struct leaf_node *subtree, struct int_node *node, + unsigned int n) +{ + unsigned char commit_sha1[20]; + unsigned int prefix_len; + void *buf; + struct tree_desc desc; + struct name_entry entry; + + 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(commit_sha1, subtree->key_sha1, prefix_len); + while (tree_entry(&desc, &entry)) { + int len = get_sha1_hex_segment(entry.path, strlen(entry.path), + commit_sha1 + prefix_len, 20 - prefix_len); + if (len < 0) + continue; /* entry.path is not a SHA1 sum. Skip */ + len += prefix_len; + + /* + * If commit SHA1 is complete (len == 20), assume note object + * If commit SHA1 is incomplete (len < 20), assume note subtree + */ + if (len <= 20) { + unsigned char type = PTR_TYPE_NOTE; + struct leaf_node *l = (struct leaf_node *) + xcalloc(sizeof(struct leaf_node), 1); + hashcpy(l->key_sha1, commit_sha1); + hashcpy(l->val_sha1, entry.sha1); + if (len < 20) { + if (!S_ISDIR(entry.mode)) + continue; /* entry cannot be subtree */ + l->key_sha1[19] = (unsigned char) len; + type = PTR_TYPE_SUBTREE; + } + note_tree_insert(node, n, l, type); + } + } + free(buf); +} + +static void initialize_notes(const char *notes_ref_name) +{ + unsigned char sha1[20], commit_sha1[20]; + unsigned mode; + struct leaf_node root_tree; + + if (!notes_ref_name || read_ref(notes_ref_name, commit_sha1) || + get_tree_entry(commit_sha1, "", sha1, &mode)) + return; + + hashclr(root_tree.key_sha1); + hashcpy(root_tree.val_sha1, sha1); + load_subtree(&root_tree, &root_node, 0); +} + +static unsigned char *lookup_notes(const unsigned char *commit_sha1) +{ + struct leaf_node *found = note_tree_find(&root_node, 0, commit_sha1); + if (found) + return found->val_sha1; + return NULL; +} + +void free_notes(void) +{ + note_tree_free(&root_node); + memset(&root_node, 0, sizeof(struct int_node)); + initialized = 0; +} + +void get_commit_notes(const struct commit *commit, struct strbuf *sb, + const char *output_encoding, int flags) +{ + static const char utf8[] = "utf-8"; + unsigned char *sha1; + char *msg, *msg_p; + unsigned long linelen, msglen; + enum object_type type; + + if (!initialized) { + const char *env = getenv(GIT_NOTES_REF_ENVIRONMENT); + if (env) + notes_ref_name = getenv(GIT_NOTES_REF_ENVIRONMENT); + else if (!notes_ref_name) + notes_ref_name = GIT_NOTES_DEFAULT_REF; + initialize_notes(notes_ref_name); + initialized = 1; + } + + sha1 = lookup_notes(commit->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); +} |